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Wear mapping of CoCrMo alloy in simulated bio-tribocorrosion conditions of a hip prosthesis bearing in calf serum solution
Abstract
Wear maps were developed following a series of micro-abrasion-corrosion testing during idealised hip contact conditions for a CoCrMo alloy in a foetal calf serum solution. The main aim of the study was to characterise wear-corrosion or bio-tribocorrosion regimes of the alloy over a range of applied loads and applied potentials. The transitioning micro-abrasion-corrosion mechanisms, synergisms and wastage behaviours in the presence of additional abrasive particles were identified and mapped. Wear maps in earlier work show the wear-corrosion transitions of CoCrMo alloy in the absence of abrasive particles for similar conditions; the wear maps developed in this work were compared. Mapping the micro-abrasion-corrosion regimes indicated that proteins present in foetal calf serum solution, resulting in development of a graphitic tribo-layer, may play a critical role in enhancing or protecting against tribo-corrosive degradation.
Copyright © 2015. Published by Elsevier B.V.
... Such a tool in engineering can provide a powerful means to describe wear mechanisms, interactions and transitions during the wear process [31,32] serving as a quick, albeit approximate, guide of suitable operating conditions for components intended for tribological interactions in a larger system. Lim and Ashby demonstrated mapping of wear mechanisms as early as 1987 [33], and in more recent times, wear behaviours for biomedical implant materials [34,35], and biological materials [36] have been demonstrated. Wear mapping for biomedical implants is a developing and essential area of research. ...
... The data presented in Figure 4 suggest that wear volume, for the test conditions in this study, do not necessarily exhibit a linear trend in all cases. This has also been found to be the case in other studies investigating micro-scale abrasion [35,45,48]. Trezona et al. [44] have previously shown that for twobody grooving wear with slurries of very low abrasive volume fractions, below 0.003, the wear volume is almost independent of the normal load. ...
... The data presented in Figure 4 suggest that wear volume, for the test conditions in this study, do not necessarily exhibit a linear trend in all cases. This has also been found to be the case in other studies investigating micro-scale abrasion [35,45,48]. Trezona et al. [44] have previously shown that for two-body grooving wear with slurries of very low abrasive volume fractions, below 0.003, the wear volume is almost independent of the normal load. ...
The micro-abrasion wear mechanisms for CoCrMo against variable size alumina balls, representing typical artificial femoral head sizes, were investigated over a range of applied loads in foetal calf serum solution. SEM analysis of resulting wear scars displayed two-body and mixed-mode abrasion modes of wear. The wear factor, κ, was found to range between 0.86 and 22.87 (10−6 mm3/Nm). Micro-abrasion mechanism and wastage maps were constructed for the parameter range tested. A dominant two- to three-body abrasion regime was observed with an increasing load and ball diameter. The 28-mm ball diameter displayed the lowest wastage, with an increasing load. Proteins may act to reduce the severity of contact between abrasive particles and bearing surfaces. Wear volumes did not necessarily increase linearly with applied load and ball diameter; therefore, there is a need to develop more accurate models for wear prediction during micro-abrasion conditions. Wear mapping for hip replacements could provide a useful aid for pre-clinical hip wear evaluations and long-term performance.
... Continuous development in improving joint implants and a deeper understanding of the wear-and-tear processes may contribute to future patients being given a much more positive outlook. In the UK, concerns around factors such as an ageing population and an increase in chronic diseases requiring health interventions such as hip replacements mean that there is an increasing demand and cost related to the health care service [9][10][11][12][13][14]. ...
... It can be seen clearly that the electrochemical mass loss (Kc) remains a consistent fraction of the total mass loss contribution (Kac). This is consistent with previous papers [12,20,24] and should be expected, since Ti-6Al-4V is a highly corrosion resistant material. The majority of Kc/Ka values are less than 0.1, which indicates that micro- Tables 5 and 6 show that, for every test condition, the total and micro-abrasion mass loss values are very higher in magnitude for tests without solid particles, whilst the corrosion mass loss is significantly lower for both, without and with solid particles. ...
... It can be seen clearly that the electrochemical mass loss (K c ) remains a consistent fraction of the total mass loss contribution (K ac ). This is consistent with previous papers [12,20,24] and should be expected, since Ti-6Al-4V is a highly corrosion resistant material. The majority of K c /K a values are less than 0.1, which indicates that micro-abrasion is the dominant wear regime in both conditions. ...
Wear and corrosion in artificial hip replacements are known to result in metal ion release and wear debris induced osteolysis. This may lead to pain and sensitivity for patients. This infers that pre-clinical testing is critical in determining the long-term performance, safety, and reliability of the implant materials. For this purpose, micro-abrasion-corrosion tests were carried out on a biocompatible material, Ti-6Al-4V ELI, using a T-66, Plint micro-abrasion test rig in conjunction with Gill Ac corrosion testing apparatus for the range of applied loads and electrical potentials in the hip joint simulated environment. A Ringer’s solution, with and without an abrasive particle (silicon carbide), was used to enable the interactions between abrasion and corrosion. In this paper, the effects of applied load and electrochemical potential on the tribo-corrosion behaviour of Ti-6Al-4V in a bio-simulated environment are presented. The wastage, micro-abrasion-corrosion mechanisms, and synergy behaviour were identified and mapped. A significant difference in corrosion current densities was observed in the presence of abrasive particles, suggesting the removal of the protective oxide layer. The results also indicate that Ti-6Al-4V had significant abrasive wear loss when coupled with a ceramic counterpart. According to the mechanism, micro-abrasion plays a predominant role in the abrasion-corrosion behaviour of this material and the material losses by mechanical processes are substantially larger than losses, due to electrochemical processes.
... To date, numerous studies about micro-abrasion-corrosion have focused on the construction of wear maps, such as wastage map, wear regime map, micro-abrasion-corrosion synergism map, etc. [17,24,29,30,[35][36][37][38][39]. The micro-abrasion-corrosion maps could present the effects of particle concentration and applied load on the tribocorrosion behaviours of implant materials in a simulated body fluid; e.g., the micro-abrasion-corrosion maps of the Ti-25Nb-3Mo-3Zr-2Sn alloy in Hank's solution [24] and Hank's with protein [17] showed the transitions and interactions between the wear and corrosion regimes with various particle concentrations and applied loads [37]. ...
... According to material loss and the analysis of the synergy between corrosion and abrasion, a series of wear maps can be plotted for a given material describing the wear behaviour in a corrosive environment [17,39]. These wear maps could offer an effective method to settle abrasion-corrosion-related problems for implant materials operating in a wide range of conditions [37,39]. ...
... According to material loss and the analysis of the synergy between corrosion and abrasion, a series of wear maps can be plotted for a given material describing the wear behaviour in a corrosive environment [17,39]. These wear maps could offer an effective method to settle abrasion-corrosion-related problems for implant materials operating in a wide range of conditions [37,39]. ...
The tribocorrosion behaviour of biomaterial Ti-25Nb-3Mo-3Zr-2Sn alloy in Ringer's solution was evaluated by micro-abrasion experiments, electrochemical tests and scanning electron microscope (SEM) observations. Potentiodynamic polarization results suggested that the effect of particle concentration on the electrochemistry characteristic is greater than the applied load. When the particle concentration and applied load were 0.05 g·cm− 3 and 0.25 N, respectively, the Ecorr reached the maximum as − 0.381 V. The micro-abrasion-corrosion results showed that the wear rates of the Ti-25Nb-3Mo-3Zr-2Sn alloy increased with increasing particle concentration and decreased as applied load increased. The wear rates acquired under various conditions regarding to the main wear mechanism of two-body grooving wear with less three-body rolling wear; three-body abrasive wear modes are more efficient at material loss than two-body wear. The variation in material loss indicated that the contribution of corrosion is lower than the contribution of micro-abrasion. The wear regime, wastage and micro-abrasion-corrosion synergy maps associated with the particle concentration and applied load were established to evaluate the tribocorrosion behaviour of the Ti-25Nb-3Mo-3Zr-2Sn alloy as a potential surgical implant material.
... After degreasing with acetone, rinsing with deionized (DI) water, and drying with compressed air, the CoCrMo samples were used directly for tribocorrosion testing. This preparation method aligns with practices within the field [52][53][54][55] and complies with ASTM G5 [56] and G59 [57] guidance. ...
... It has been noted in studies [79,83] that the resulting products of metal debris-electrolyte interaction, including oxides or complex compounds, tended to accumulate and function as third bodies, escalating abrasive wear within the tribological interface, consequently increasing ΔW C . This observation aligned with the studies conducted by Sadiq et al. [55,84], who explored the tribocorrosion synergistic approach using CoCrMo coupled with UHMWPE in calf serum electrolyte. Their synergy mapping demonstrated that shifts between wear regimes are influenced by the interaction of proteins with the metal surface or the formation of a tribofilm. ...
Previous investigation has established the formation of tribofilm is influenced by tribochemical reactions between the electrolyte and the articulating surface of cobalt alloy through sliding tests in various simulated fluids. Although it has successfully characterized the film composition via spectroscopy analysis and indicated to have impact on material loss, a comprehensive understanding of the material degradation mechanism in tribocorrosion condition was still lacking. Therefore, this study aims to investigate the role of protein in the tribocorrosive degradation of cobalt-chromium-molybdenum (CoCrMo) alloy in different simulated physiological electrolytes. Using a similar testing protocol, tribocorrosion tests were conducted with reciprocating ceramic ball against CoCrMo samples immersed in saline and culture medium, compared to both electrolytes diluted with 25% fetal bovine serum (FBS). Synergistic and mechanistic approaches were employed to model the tribocorrosive degradation. Results reveal that protein plays a beneficial role in reducing corrosive (electrochemical) surface degradation under tribocorrosion condition, whilst increasing mechanical wear degradation in the process. Despite studies have shown that tribocorrosion behavior in metal alloys is highly influenced by the presence of organic matter, this study provides a more clarity of the roles played by protein in tribocorrosive degradation on CoCrMo surface as its novel finding.
... Tribocorrosion is a synergetic process, where these processes that occur simultaneously require the knowledge of the material's behavior under these situations as it is a reliable technique to develop safe, and long-lived biomaterials [4,5]. Several works in literature are predominantly concerned with conventional biomaterials (stainless steel, Co-Cr-Mo, Ti, Ti-6Al-4V, and more recently with Mg) [6,7], and although the new beta Ti alloys are reported to be suitable for load-bearing implants, their tribocorrosion behavior is not yet thoroughly understood [8][9][10][11][12]. ...
... Ti-35Nb alloy's surface revealed a square shape for the indentation impression caused by a spherical indenter. This result can be related to the microstructure of the material [5], which is coarse and composed of large grains [25]. The nanotubes (Figs. ...
In this study, we evaluated the tribocorrosion and mechanical properties of nanotubes grown on a Ti-35Nb alloy. The nanotube arrays, approximately 2.0 µm thick, were formed through controlled anodization and annealing, composed of Ti and Nb oxides. The compact oxide film at the nanotube/substrate interface provided corrosion resistance, lubricating properties in worn tracks, and improved wear resistance. The nanotubes exhibited lower coefficient of friction, hardness, and elastic modulus compared to untreated Ti-35Nb. The crystalline structure of the nanotubes and the oxide interface layer enhanced adhesion, preventing plastic deformation and improving tribocorrosion resistance.
... In another experiment by Milosev et al. [11], HA + NaCl and Hanks solution were used and they found that the passive current density remains constant in NaCl up to 0.6V vs SCE, whereas, on an addition of HA passive current density remains constant only up to 0.2V vs SCE. In the past five years, various authors have worked on Co-Cr-Mo alloys as regards to wear [12][13] [14][15] [16], surface modification and coatings [17] [18], bio-functionalization and bio-tribocorrosion [19] [20][21] [22] [23], micro structural transformation and metallic dissolution, adsorption and electrochemical behavior [24][25] [26]. ...
... Figure 15 (d) shows the EDS of after potentiodynamic polarization test. It can be observed that there is decrease in Cr and Co A c c e p t e d M a n u s c r i p t 14 content in the pit as compared to base metal which could be the preferable site for pit initiation in the sample [48]. Figure 16 shows SEM images before and after polarization of Co-Cr-Mo samples in 321mg/100mL HA solution with variation in Ra (0.03 µm, 0.450 µm, and 1.056 µm). ...
The work presented in this paper is based on the study of electrochemical corrosion behavior of Co-Cr-Mo alloy as a function of the concentration of simulated biological fluid (hyaluronic acid), the influence of Cl- on hyaluronic acid (HA) and machining configurations. For the electrochemical tests, electrochemical impedance spectroscopy and potentiodynamic polarization test were undertaken. With the increase in HA concentration, high metal dissolution was observed. Whereas with the addition of NaCl in the solution, the corrosion resistance of the sample was enhanced. Also, an increase in surface roughness of sample surface HA caused a decrease in i corr. This is due to the adhesion property of the HA on the sample surface. X-ray photoelectron spectroscopy was executed to analyze the passive film formed due to HA and NaCl on Co-Cr-Mo. Scanning electron microscope were carried out to analyze the surface morphology. Energy dispersive spectroscopy shows lower Cr at the pit. The study reveals the adsorption of HA on the surface. This adsorbed HA on the surface caused the metal dissolution and hence initiation sites for pitting. When compared with the sample in HA +NaCl solution, better passive film property was observed to cause better corrosion resistance.
... For younger patients, ceramicon-ceramic (CoC) and metal-on-metal (MoM) surfaces are still considered because they can withstand the increased loads on the implant [4][5][6]. MoM THRs, made of CoCrMo alloys, demonstrate biocompatibility, high corrosion resistance, and wear properties [7][8][9][10]. Although MoM THR implants do provide a solution to hip arthritis, concerns about the devices have grown and since 2009, these implants have been excluded from the US implant market. ...
... The films also formed on pure molybdenum thin films during potentiodynamic tests at potentials near ?0.06 V versus SCE, but not on the pure Co and Cr surfaces, suggesting that molybdenum is necessary to initiate the film formation [20]. X-ray photoelectron spectroscopy (XPS) analysis confirmed that the films are derived from the serum proteins because the nitrogen was found in the amide or amine states and the nitrogen-carbon ratio was the same as that of serum proteins, including albumin [9,15]. ...
Metal-on-metal (MoM) hip retrievals exhibited the presence of carbonaceous tribofilms, derived from synovial proteins, particularly on the articulating surfaces. Studies suggest that the films decrease corrosion and wear. To extend implant longevity and minimize the side effects due to released metal ions/debris, it is important to investigate the possibility of generating such films artificially on the implant surfaces (before implantation) and evaluate its corrosion resistance in a simulated hip environment. Hence, in this study, a film that mimics tribolayer is generated on CoCrMo alloy surface through electrochemical treatment. The mechanism of formation and corrosion resistance is evaluated by electrochemical impedance spectroscopy (EIS) technique. A standard three-electrode corrosion cell was used to conduct the experiments on polished (Ra < 10.0 nm) CoCrMo alloy disks in bovine calf serum with three different protein concentrations (0, 15, and 30 g/L) and at four different treatment potentials (−0.4, +0.6, +0.7, and +0.8 V). EIS testing (at Eoc, potential amplitude: ±10 mV, frequency range 100 kHz to 0.005 Hz) was conducted pre- and post-potentiostatic treatment. Tribofilm was evaluated by scanning electron microscopy, white light interferometry, and Raman spectroscopy. Results suggest evidence of electrochemically induced film formation and their potential ability to increase the corrosion resistance of biomedical implants.
Graphical Abstract
... In this study, a G10 epoxy glass laminate composite has been tested for its erosion resistance during sub-sea conditions. The synergistic effects and erosive wear mechanisms have been studied on the basis of mass loss, SEM micrographs of the surfaces, EDX analysis and related research work found in the literature using wear mechanisms map techniques [27][28][29][30]. Further work will be to compare with tribological performance of different types of composite materials and coatings to evaluate the optimum material for the range of environmental conditions encountered in service. ...
... In view of the tests results, a slurry erosion wear mechanistic map has been developed. Wear mechanistic maps [27][28][29][30] can be useful tools to identify various wear mechanisms encountered over the range of tests parameters. This may be helpful in the selection of materials, designing of tidal turbine blades, and defining operational limits. ...
Tidal energy, of all marine renewables energy, possesses higher persistency and predictability over long-time scales. Moreover, the higher density of water than air also results in greater power output from a tidal turbine than a wind turbine with similar dimensions. Due to the aggressive marine environment, there are barriers in the development of tidal power generation technology. In particular, with regard to increased rotor diameter, the selection of material presents significant challenges to be addressed including the tribological environment, such as solid particle erosion, cavitation erosion, the effect of high thrust loading on the turbine blade tips and the synergy between sea water conditions and such tribological phenomena. This research focuses on producing and testing a variety of composite materials with different fibres and reinforcement layouts to evaluate two main tribological issues in tidal environments: matrix cutting and reinforcement fracture. A slurry pot test rig was used to measure the effects of different impact angles and particles sizes at constant tip speeds.
... The tribocorrosion, or the (bio)tribocorrosion if referred to biological area [1], can be defined as the simultaneous action of mechanical such as fretting, abrasive, adhesive, fatigue and chemical wear like pitting, crevice, galvanic, uniform corrosion, in an extent that the total volume is not the simple sum of the single elements. Unfortunately it is likely to occur in dental prosthesis especially in the contacting zone between abutment and implant [2] or in hip prosthesis between cup and femoral head [3]. Indeed, both are continuously subjected to mechanical efforts arisen from everyday actions like walking [4] or eating [5,6], aggravated by the aggressivity of biological fluids as saliva and synovial ones. ...
... In this context, several authors [8,[34][35][36][37][38] have used saline solution, bovine serum, bovine calf serum (BCS), bovine serum albumin (BSA), distilled water, Hanks solution, and Phosphatase bovine serum (PBS)-like lubricating liquids in the simulation of corporate liquids. In the review paper, Shahini et al. [39] noted disagreements after using the electrolytes used in the experiments. ...
This study investigates the tribocorrosion performance of a cast Co-Cr-Mo alloy prepared using casting and electromagnetic stirring (EMS) at specific frequencies. The tribocorrosion behaviour of the alloy was evaluated when exposed to Ringer’s lactate solution to optimize the EMS parameters and improve its properties. The research focuses on biomedical implant applications and explores how EMS affects alloy wear and corrosion resistance. As did the friction coefficient and wear volume, the wear rate of samples produced with EMS frequencies of 75 Hz and 150 Hz decreased. These improvements are attributed to the ability of EMS to refine grain size and homogenize the microstructure, thereby increasing the resistance to tribocorrosion. Techniques such as scanning electron microscopy (SEM) and profilometry were used for surface and wear analysis, while mechanical properties were evaluated through instrumented indentation tests. The findings confirm that EMS improves the alloy’s durability and tribocorrosion resistance, making it highly suitable for demanding biomedical applications such as joint replacements. This highlights the importance of advanced manufacturing techniques in optimizing biomedical alloys for simulated body conditions.
... These parameters have been directly related to the wear maps in order to predict, evaluate, analyze, and optimize the wear behavior of the materials under the influence of the experimental conditions. Sadiq et al. [27] establish that the most important variables to carry out tribocorrosion tests can be divided as continuous and discrete, which can be related to the concept of wear maps. These variables can be used to optimize, evaluate, and predict the wear behavior for different tribopairs. ...
Tribocorrosion is denominated as the interaction between wear and corrosion during sliding where different parameters such as speed, applied load, total wear distance, stroke length, type of material, type of lubricant, wear technique, among others, which affect the wear behavior of the materials used for different industrial applications and a large place the lifespan of the mechanical components. In this work, an exhaustive review of the conditions applied (test parameters) during tribocorrosion in the hard coating is developed using a bibliometric analysis to identify a general overview and trends in this important topic for devices exposed to mechanical contact in industrial applications. The results revealed that tribocorrosion in hard coatings associated with scientific production represents around 418 documents with an annual growth rate of 13.83% published by 1242 authors, mainly from China and the United States of America, with an international collaboration index of 3.14 related to two topics (corrosion and wear behavior) considering that are the main concepts to evaluated the tribocorrosion phenomena (synergistic effect), and how the keywords are associated to medical and industrial areas in mechanical and biological elements. Finally, the most relevant journals are wear, surface, and coatings technology, followed by tribology international, which are very important journals in tribology and materials science (Quartile-Q1).
... Under a tribological contact, proteins were reported to form a biofilm on the articulating surface, which deposited a complex structure of inorganic and organic compounds and enhanced the lubricity [13]. The surface potential, along with the contact pressure and normal load in the articulating surfaces, can affect the lubricating ability of the protein films [13,22,27]. Hence, it is useful to discuss the chemical reactions between biological species and the metallic surface under tribo-corrosion condition; termed as tribo-chemistry. ...
Cobalt-chromium-molybdenum (CoCrMo) alloys are commonly employed for load-bearing implants, such as hip and knee prostheses, owing to their mechanical properties and excellent passivity characteristics to reduce corrosion. The interaction between biological environment and the metallic surface under an articulating condition is extremely complex. The metal is exposed not only to the harsh biological environment as well as mechanical loading, leading to the conjoined action of mechanical (wear) and electrochemical (corrosion) degradations of the material; termed as tribo-corrosion. Tribo-chemical film formation can affect the surface response towards tribo-corrosive processes. The fundamental mechanisms of the tribo-corrosive degradation and surface chemistry are recognized to contribute to the orthopaedic implants’ longevity problem; an understanding of those mechanisms is therefore essential. This manuscript aimed to briefly review the current knowledge of the tribo-corrosion and tribo-chemistry phenomena from the pre-clinical studies’ point of view on the CoCrMo alloys used for hip bearing implants. This overview highlighted that the tribo- corrosion and tribo-chemical reactions during sliding are sensitive to the biological species interaction, as well as several unexplored factors in the environment. These findings contribute to the further knowledge and pre-clinical understanding of protein-metal interactions occurring in films formation and the system variables effect on the metallic load-bearing surfaces.
... This increment can be linked to the complexation of metal with the protein [109]. However, it was demonstrated that the protein that exists in the fetal calf serum could help the generation of a graphitic layer on the CoCrMo alloy which was followed by an improvement in the tribocorrosion resistance [110]. Moreover, the comparison of the NaCl and BCS uncovered the fact that the latter could diminish ion release via protein film adsorption on the surface [44]. ...
As a destructive phenomenon with possible detrimental impact especially when it comes to human life, tribocorrosion has always been imperative to be researched. Hence, various investigations have outlined its influential role in the biomaterial apparatuses. Also, disparate routes have been introduced to address this problem. The use of several types of alloys, the application of various types of coatings, and the production of porous layers are some of these efforts made till now. Because of this issue’s importance, and lack of a comprehensive review paper in this area of research, this paper shows an overview of existing publications in this area of research. This study presents the important ideas behind studies and provides a perspective of the research trend. In this exploration, the critical elements of the tribocorrosion-related studies were discussed thoroughly. The origin of the problem and the influential parameters in the process like loading, manufacturing, environment, and surface innate oxide film were scrutinized. Also, the efficacy of the use of different alloys, coatings, and the recommended modifications with respect to the tribocorrosion was discovered. We hope that this survey helps promote the emergence of new ideas for future research.
... Although the tribological behavior of borided biomedical materials using SBF solutions has been studied under different wear test configurations as mentioned above, tribological maps for borided AISI 316L steel under SBF Hank's solution have not been reported. Because there are several wear mechanisms which change in relative importance as the operating conditions are changed [16], and no single wear mechanism operates over a wide range of conditions, tribological maps are a useful tool for elucidating the role of the operating environment on wear mechanisms [9,17]. Several regimes of wear for a particular test configuration can be observed on a wear regime map plotted on axes of sliding speed, pressure, load, among others [18,19]. ...
Tribological maps on powder-pack borided and non-borided AISI 316 L steel under a Hank’s solution medium, during linear reciprocating sliding wear tests with a ball-on-flat configuration, are presented with the aim of elucidating the role of the operating environment on wear mechanisms and tribological performance. 2D maps obtained by Response Surface Methodology showed the coefficient of friction, wear volume and specific wear rate as a function of load and sliding speed. Findings showed k for the non-borided AISI 316 L steel was between 5.40-34.90 ×10⁻⁶ mm³/Nm, while it was between 2.37-4.91×10⁻⁶ mm³/Nm for the borided AISI 316 L steel. Grooving, smearing, plastic deformation and the formation of a passive film were the identified wear mechanisms on the wear tracks using Scanning Electron Microscopy.
... In recent years, a comprehensive approach to construct microabrasion-corrosion maps was introduced by Stack and co-workers for characterizing tribo-corrosion behaviors as a function of various test parameters in a corrosive medium [43,[45][46][47][48][49][50][51]. The maps consist of the following three parts: (i) a mechanism map for identifying the leading mechanism of material degradation. ...
The fretting-corrosion performance of 6082 aluminum alloy in 3.5% NaCl solution was investigated in this work. The effects of displacements (5–50 μm) and loads (10–80 N) were considered. A running condition fretting map (RCFM) was established, which was composed of partial slip regime (PSR), mixed fretting regime (MFR), and slip regime (SR). In PSR and MFR, the worn surface could be divided into the outer micro-slip zone and the central sticking zone and the wear mechanism was mainly adhesive wear with slight corrosion. In SR, the whole contact surface was in slip, and the wear mechanism was mainly severe abrasive and corrosive wear. Compared to the static corrosion, the corrosion of 6082 alloys in MFR and SR was accelerated. However, the corrosion in PSR was weakened, which may result from the lackage of oxygen in the contact zone. The wastage level, the dominant mechanism of fretting corrosion, and synergy between corrosion and wear under different loads and displacements were quantitatively analyzed, and micro-abrasion-corrosion maps were constructed.
... This phenomenon could be improved by applied thermal or thermochemical treatments that reducing the damage generated on the surface of the material. Because there are several wear mechanisms that change in relative importance as the operating conditions are changed, and no single wear mechanism operates over a wide range of conditions, wear maps are a useful tool for explaining the role of the operating environment on wear mechanisms ( Ref 5,6,7). Several regimes of wear for a particular test configuration can appear on a single wear regime map plotted on axes of sliding speed, pressure, load, among others ( Ref 8,9). ...
In the present work, 2D wear maps and statistical approaches on commercial samples of AISI 316L stainless steel were obtained to provide a general visualization of response variables and wear regimes under different dry sliding conditions. Dry sliding wear tests on the AISI 316L steel were performed according to the ASTM G133-05 standard procedure guidelines. A linear reciprocating sliding tribometer with a ball-on-flat configuration and a counterpart of Al 2 O 3 was used. Wear tests were performed at room temperature with the following conditions: sliding distance of 100 m, a constant applied load of 5, 10, and 20 N, and sliding speeds of 5, 10, 20, and 30 mm/s. The analysis of variance showed that the load influences the depth, volume, and CoF response variables in a positive way with more than 97% of confidence; while the specific wear rate response variable is mainly affected by the sliding speed with more than 42% of confidence. 2D maps of the response variables were obtained using response surface methodology as a function of the load and sliding speed. The maximum specific wear rate was $450310-6 mm 3 /Nm for the condition of 5 N and 5 mm/s, influenced by the test conditions. From SEM analysis, wear regimes were classified as mild and severe and thus plowing, and material agglomeration predominate as failure mechanisms during mild wear. For severe wear, differences are more evident, with smearing being predominant on the worn tracks.
... However, coupling three-electrode electrochemical systems in contacts with multiple abrasives is very challenging so that techniques for abrasion-corrosion tests are still under development [15]. In that direction, the development of microabrasion-corrosion tests, pioneered by Prof. Stack's group [16,17] and Prof. Wood's group [18,19], combined microabrasion tests with a potentiostat. In our group, we recently developed a microabrasion-corrosion test rig that presents the further advantage of controlling and measuring the forces acting in the contact during the tests. ...
Microabrasion-corrosion tests were carried out to investigate how small changes in dilution affect abrasion-corrosion resistance of Ni–Cr PTA welded deposits onto carbon steel. For each specimen, corrosion tests, microabrasion tests and combined microabrasion-corrosion tests were conducted. Potentiodynamic corrosion tests under aerated conditions used three different electrolytes. Abrasion resistance was evaluated using a fixed-ball microabrasion test rig, for slurries of SiO2 in distilled water (20 wt%). Microabrasion-corrosion tests used SiO2 slurries for the same electrolytes used in the corrosion tests under potentiodynamic conditions. For the most aggressive electrolyte (NaCl + H2SO4 solution) it was possible to identify small variations in current density with dilution in the microabrasion-corrosion tests, whereas no significant differences were identified for the other electrochemical variables. However, as a general trend, all deposits presented high abrasion-corrosion resistance, evidencing that small variations in dilution do not compromise their performance for the conditions tested. As expected, the wear coefficients measured under microabrasion-corrosion conditions were higher than under pure microabrasion conditions. On the other hand, friction coefficients for microabrasion-corrosion were lower when compared with conventional microabrasion tests for all the slurries tested. This was apparently due to how the passive film affects particle entrainment during the tests.
... Firstly, because of the cup dimensions, the specimen could not be positioned into the microscope and thus any direct measurements could not be performed on the worn surface. In order to overcome this issue, the replica method was adopted ( Fig. 4): basically, wear assessment was performed on a negative replica of the cup specimen made of silicone [24]. The silicone by Loci Forensics was used: originally in putty status, it was positioned into the cup using a syringe, so to fill the cup and cover it and its edge, and then was left dried for 30 min (Fig. 4(a and b)). ...
In the literature, wear damage of hip prostheses is typically expressed as volumetric wear. Details on wear distribution are rarely provided despite being fundamental to better understand the damaging process and improve implant design.
This study presents a preliminary experimental investigation on the evolution of the wear map of hip replacements during wear testing. A ceramic-on-UHMWPE hip prosthesis was tested in-vitro and wear maps of the cup surface were measured throughout the test in a novel way, combining focus variation microscope inspections to the replica method. Wear maps revealed important characteristics of the damaging process not highlighted by the standard gravimetric procedure such as worn area location and shape as well as the progress of local damages.
... The lowest specific wear rate of 9.47×10 −5 mm 3 /Nm corresponded to the applied load of 1.5 N and the abrasive particle concentration of 0.03 g cm −3 . The results were not only related to the material parameter, but also to the corrosion products and wear mechanism during corrosion-wear [26,27]. Studies demonstrated that the wear rate of the metal alloy, induced under the corrosion-wear conditions, is higher than the wear rate induced during wear, due to the fact that the corrosion can accelerate wear, whereas the wear can deteriorate the corrosion during wear and corrosion [11,12,19]. ...
The tribocorrosion behavior of a biomedical NiTi alloy in Ringer’s simulated body fluid was investigated through friction experimentation, electrochemical testing and abrasion mapping. The effects of applied load and particle concentration were considered. Due to the wear accelerated corrosion, the corrosion potential of the NiTi alloy shifted negatively and the corrosion current density increased by an order of magnitude, compared to the static electrochemical corrosion. The applied load effect on the wear rates of the NiTi alloy was higher than that of the particle concentration. The wear rates were decreased with the applied load increased, whereas the wear rates were decreased with the increase of abrasive particle concentrations. When the applied load was 1.5 N, the particle concentration was 0.03 g cm⁻³, while the lowest wear rate of 9.47 × 10⁻⁵ mm³/Nm was acquired under the corrosion-wear conditions. The SEM wear morphology showed that the two-body abrasive wear is the main wear mechanism. The waste map of the NiTi alloy was constructed, demonstrating that the applied load highly affected the material loss. And the material loss of the NiTi alloy belonged to the medium loss under most service situations in this paper. The low material loss region was located within the map at both low applied load and high particle concentration. The wear contribution on the material loss exceeded the corrosion contribution, signifying the wear responsibility for the material loss. Consequently, the corrosion-wear regime was mechanical abrasion dominant with corrosion in the paper.
... Surface roughness properties play an important role in the fabrication of prosthesis as the materials need excellent tolerate contact with the bones and tissues in the body [2]. The improper surface roughness of the prosthesis may find difficulties in joint with adjacent bones and other tissues, which will cause the loosening of the implant [3]. On the other hand, the rough surface also will contribute to high wear rate and corrosion, where the ion release from these processes may go to the surrounding tissue and cause allergic and problematic symptoms [4]. ...
Smoothly polished prosthesis surface is a crucial requirement in medical application and important feature that determine the proper response to corrosion and biocompatibility in the human body. Tumbling is one of the pre-polishing processes that can be conducted in order to improve the surface roughness of the machined prosthesis. However, the using of ceramic media for the tumbling process in medical application is not widely reported. This study was conducted to investigate the effect of mechanical tumbling parameters on the surface roughness of medical grade CoCr alloy by using alumina (Al2O3) based ceramic media. The experiment was performed with a different level of rotational speed (35, 55, and 75 rpm) and soaking time (4, 6 and 8 hours) of the tumbling process. The surface roughness of specimens before and after the process was measured using Mitutoyo Formtracer CS- 5000 and the edge radius was measured using Olympus SZX9 microscope integrated with I-solution Lite software. It was figured that 6 hours tumbling time at 55 rpm showed the most significant reduction (32 %) in surface roughness (Ra) of the CoCr alloy specimen, while 8 hours tumbling time at 75 rpm showed the highest effect on the edge radius of the specimen at 63 % increment.
... albumin) and/or tribological stress (tribocorrosion), the alloys release significantly higher amounts of cobalt ions and metal particles (Gil and Munoz 2011;Mathew et al. 2012). The local release of wear debris particles further contributes to degrading the prosthesis surface(micro-abrasion) (Sadiq et al. 2015). 3.3.2. ...
This article summarizes recent experimental and epidemiological data on the genotoxic and carcinogenic activities of cobalt compounds. Emphasis is on the respiratory system, but endogenous exposure from Co-containing alloys used in endoprostheses, and limited data on nanomaterials and oral exposures are also considered. Two groups of cobalt compounds are differentiated on the basis of their mechanisms of toxicity: (1) those essentially involving the solubilization of Co(II) ions, and (2) metallic materials for which both surface corrosion and release of Co(II) ions act in concert. For both groups, identified genotoxic and carcinogenic mechanisms are non-stochastic and thus expected to exhibit a threshold. Cobalt compounds should, therefore, be considered as genotoxic carcinogens with a practical threshold. Accumulating evidence indicates that chronic inhalation of cobalt compounds can induce respiratory tumors locally. No evidence of systemic carcinogenicity upon inhalation, oral or endogenous exposure is available. The scarce data available for Co-based nanosized materials does not allow deriving a specific mode of action or assessment for these species.
... These changes are associated with the corrosion and wear phenomena. The observed phenomenon (low friction coefficient) after first region (zone 1) can be attributed to reduction of surface degradation generated by the materials' interactions; however both mechanisms such as wear and corrosion can produce more asperities, increasing the surface roughness and friction coefficient [22]. For DLC coating the friction coefficient is reduced in relation to the Ti-Substrate due to the high hardness and elastic modulus; Moreover, the covalent bound present in the C-Si system offers high corrosion resistance [23]. ...
Studies of materials in biomedical applications have focused on the generation of new biomaterials and the development of surface modifications, mainly of metals. Amorphous silicon containing diamond like carbon DLC-Si coating deposited on titanium substrate with the purpose of studying its biofunctionality. The behavior against the phenomenon of tribocorrosion of coatings DLC-Si deposited on titanium was evaluated, through the plasma-assisted chemical vapor deposition technique. The nanoindentation technique was used to determine the coating mechanical properties. The DLC-Si coatings were structurally analyzed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, the characteristic binding energy for the signal C1s was obtained from XPS. Via XRD results the amorphous structure of DLC-Si coating was determined. The triboelectrochemical results indicate that the coating shows an adequate wear and to corrosion protection when exposed to the synergic mechanism, thus demonstrating the protective coating effect.
... These proteins have been found to form a biofilm on the alloy surface, composed of inorganic graphitic carbon, which acts as a boundary lubricant [64]. However, high applied potentials and normal loads can inhibit the lubricating ability of the proteins, as observed in several studies such as Liau et al. [64], Hiromoto and Mischler (2006) [67]. As reported by Runa et al. (2013) [68], the effect of proteins can be either favourable or undesired, depending on the characteristics of the passive film formed at different applied potentials under mechanical exposure. ...
This paper reviews the most recent available literature relating to the electrochemical techniques and test procedures employed to assess tribocorrosion behaviour of passive materials. Over the last few decades, interest in tribocorrosion studies has notably increased, and several electrochemical techniques have been adapted to be applied on tribocorrosion research. Until 2016, the only existing standard to study tribocorrosion and to determine the synergism between wear and corrosion was the ASTM G119. In 2016, the UNE 112086 standard was developed, based on a test protocol suggested by several authors to address the drawbacks of the ASTM G119 standard. Current knowledge on tribocorrosion has been acquired by combining different electrochemical techniques. This work compiles different test procedures and a combination of electrochemical techniques used by noteworthy researchers to assess tribocorrosion behaviour of passive materials. A brief insight is also provided into the electrochemical techniques and studies made by tribocorrosion researchers.
... In order to identify the distinction between the different corrosion mechanisms affecting the erosion, an erosion-corrosion mechanism map was constructed, which could indicate the dominant erosion mechanism of a given material [34,35]. The criteria utilized for an erosion mechanism map were consistent with the results of Stack [13] as well as the ratio of micro-abrasion to the corrosion contribution defining the dominant erosion mechanism, as presented in equations (8)- (11). ...
The erosion-corrosion behaviour of QSn6 alloy used as propellers in marine environment was evaluated by erosion-corrosion experiments with/without cathodic protection, electrochemical tests and scanning electron microscope (SEM) observations. The analysis was focused on the effect of flow velocity. The dynamic polarization curves showed that the corrosion rate of the QSn6 alloy increased as the flow velocity increased, due to the protective surface film removal at higher velocities. The lowest corrosion current densities of 1.26 ×10⁻⁴ A cm⁻² was obtained at the flow velocity of 7 m s⁻¹. Because of the higher particle kinetic energies at higher flow velocity, the mass loss rate of the QSn6 alloy increased as the flow velocity increased. The mass loss rate with cathodic protection was lower than that without cathodic protection under the same conditions. Also, the lowest mass loss rate of 0.7 g m⁻² •h⁻¹ was acquired at the flow velocity of 7 m s⁻¹ with cathodic protection. However, the increase rate of corrosion rate and mass loss were decreased with increasing the flow velocity. Through observation the SEM morphologies of the worn surfaces, the main wear mechanism was ploughing with/without cathodic protection. The removal rates of the QSn6 alloy increased as the flow velocity increased in both pure erosion and erosion-corrosion, whereas the erosion and corrosion intensified each other. At the flow velocity of 7 m s⁻¹, the synergy rate (ΔW) exceeded by 5 times the erosion rate (Wwear). Through establishment and observation the erosion-corrosion mechanism map, the erosion-corrosion was the dominant regime in the study due to the contribution of erosion on the mass loss rate exceeded the corrosion contribution. The QSn6 alloy with cathodic protection is feasible as propellers, there are higher security at lower flow velocity, such as the flow velocity of 7 m s⁻¹ in the paper.
... The concerns arise about the long-term stability of MoM implants due to the release of metallic nano-particles and ions having a carcinogenic potential, as well as associated hypersensitivity reactions, muscle and bone destruction, and prosthetic loosening, leaving some patients with long-term disabilities [13,25,26]. There are reports showing the wear map of CoCrMo hip prosthesis during tribocorrosion [27]. ...
There has been significant progress in implant research during last the 10 years (2005–2015). The increase in the elderly population coupled with a lack of proper physical activity is a potential cause for the sudden increment in implant usage. Implant life and performance are influenced by several parameters; however, literature showed that corrosion, tribology, and tribocorrosion processes of implant materials are main concern and driving mechanisms in the degradation processes. There is currently a large need for research in this area. Furthermore, there has been no recent systematic literature review to analyze the progress of research and published work in this area. The objective of this work is to provide a trend in the published articles in the area of corrosion, tribology, and tribocorrosion during last century, with emphasis on the progress over the last 10 years. The paper also tries to report the current state-of-the-art research in the area of corrosion, tribology, and tribocorrosion research in bio-implants based on number of published articles. The reviews demonstrate that during the last 10 years, there has been significant progress in implant research, particularly in the tribocorrosion area, however, significantly lower than tribology and corrosion research.
... The concerns arise about the long-term stability of MoM implants due to the release of metallic nano-particles and ions having a carcinogenic potential, as well as associated hypersensitivity reactions, muscle and bone destruction, and prosthetic loosening, leaving some patients with long-term disabilities [13,25,26]. There are reports showing the wear map of CoCrMo hip prosthesis during tribocorrosion [27]. ...
There has been significant progress in implant
research during last the 10 years (2005–2015). The
increase in the elderly population coupled with a lack of
proper physical activity is a potential cause for the sudden
increment in implant usage. Implant life and performance
are influenced by several parameters; however, literature
showed that corrosion, tribology, and tribocorrosion processes
of implant materials are main concern and driving
mechanisms in the degradation processes. There is currently
a large need for research in this area. Furthermore,
there has been no recent systematic literature review to
analyze the progress of research and published work in this
area. The objective of this work is to provide a trend in the
published articles in the area of corrosion, tribology, and
tribocorrosion during last century, with emphasis on the
progress over the last 10 years. The paper also tries to
report the current state-of-the-art research in the area of
corrosion, tribology, and tribocorrosion research in bioimplants
based on number of published articles. The
reviews demonstrate that during the last 10 years, there has
been significant progress in implant research, particularly
in the tribocorrosion area, however, significantly lower
than tribology and corrosion research.
... The analogy with a topographic map is that the contour lines of the terrain (constant elevation over the sea level) are the analogy of constant rate of waste, whereas the spatial coordinates correspond with variables modifying the waste mechanism. The variables that are relevant to consider for biotribocorrosion Fig. 19.6 Schematic representation of the relationship between corrosion, surface roughness and the coefficient of friction are velocity of sliding, applied load as well as composition of the lubricating film [54]. ...
... To better examine the MAC behaviour of biomedical implants, MAC maps were constructed to assess the performance of implants, indicating the changes in material loss with regard to wastage, mechanisms of abrasion and synergy between micro-abrasion and corrosion in simulated implants conditions (Adachi and Hutchings, 2003;Stack et al., 2005;Sadiq et al., 2014;Hayes et al., 2015;Antonov et al., 2015;Sadiq et al., 2015). MAC maps could help to select the appropriate implants for different disease or patients. ...
... The analogy with a topographic map is that the contour lines of the terrain (constant elevation over the sea level) are the analogy of constant rate of waste, whereas the spatial coordinates correspond with variables modifying the waste mechanism. The variables that are relevant to consider for biotribocorrosion Fig. 19.6 Schematic representation of the relationship between corrosion, surface roughness and the coefficient of friction are velocity of sliding, applied load as well as composition of the lubricating film [54]. ...
Biotribocorrosion can be broadly defined as all the aspects of tribocorrosion, i.e. the degradation of surfaces by the combined effect of corrosion and wear, related to biological systems. Whereas tribology alone, also extended to friction-corrosion, corrosion-wear, wear-corrosion or (micro) abrasion-corrosion, is concerned with the phenomena occurring at the interface of surfaces in mutual motion (friction, lubrication and wear), corrosion is the science and engineering of chemical and electrochemical reactions at the interface between a material and the environment it is exposed to. In the case of biotribocorrosion, the environment is necessarily that of a living organism or a combination of living organisms (biofilm). Although all materials may suffer biotribocorrosion it is especially pronounced in case of metallic alloys due to the electrochemical nature of their interaction with aqueous environments such as the interior of a human body. Both corrosion and wear result in the weight loss over the exposed surface; however, the total weight loss of a tribosystem immersed in a corrosive environment is larger than a simple sum of the losses cause by corrosion and wear alone.
... 7,8 Thus, many efforts have been made in the past decade to investigate the tribocorrosion behavior of biomedical alloys in laboratory and simulator tests. [9][10][11][12] One of the ways to improve the tribocorrosion properties of metallic alloys is by forming a barrier layer at the surface through surface engineering, in particular by applying hard and corrosion resistant coatings. 13,14 Indeed, many efforts have been made to improve the tribocorrosion performance of biodemical alloys by surface coatings, including diamond-like carbon coatings, 15 ion implantation, 16 TiN and TiC based coatings, 17 CrN based coatings 18 and surface alloying. ...
Two duplex coatings, Cr(N)/S and Cr(C)/S, were deposited on 316 L stainless steel by magnetron sputtering. The effectiveness of these duplex coatings in improving the tribocorrosion behavior of medical alloys under elastic contact conditions has been demonstrated in a recent publication. The present work focused on the response of these duplex coatings to tribocorrosion under plastic contact conditions. Tribocorrosion tests were conducted in 0.89% NaCl solution at 37°C at an initial contact pressure of 740 MPa and under unidirectional sliding conditions for sliding duration up to 24 h. The results showed that during sliding in the corrosive solution, the duplex coatings were plastically deformed into the substrate to a depth about 1 μm. The Cr(C)/S duplex coating had sufficient ductility to accommodate the deformation without cracking, such that it was worn through gradually, leading to the gradual increase in open circuit potential (OCP) and coefficient of friction (COF). On the other hand, the Cr(N)/S duplex coating suffered from cracking at all tested potentials, leading to coating blistering after prolonged sliding at OCP and stable pit formation in the substrate beneath the coating at applied anodic potentials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.
... Particularly, the CoCrMo alloy used for joint replacements is exposed to tribological contacts and loads so their performance relies on both their corrosion and wear resistance. 1 Surface treatments are widely used to enhance the mechanical properties and corrosion resistance of CoCrMo alloy, and to reduce the potential for implant failure. 2 Boriding is a thermochemical treatment that increases the wear and corrosion resistance of ferrous and non-ferrous alloys by forming hard boride coatings at the surface of the material. 3 In recent years, research on the boriding of cobalt alloys has advanced, specifically regarding the wear and oxidation properties of the cobalt boride coatings. ...
New results about the scratch practical adhesion-resistance of the CoB–Co2B/substrate system developed at the surface of CoCrMo (ASTM-F75) alloy were estimated. The boron diffusion on the surface of the cobalt alloy was conducted using the powder-pack boriding process at temperatures of 1223 and 1273 K with different exposure times for each temperature. The scratch tests over the surface of cobalt borided alloy were performed with a 200 micrometres Rockwell C diamond indenter considering a continuously increasing normal force for the entire set of experimental conditions of the boriding process. The worn tracks produced on the coating/substrate system were analysed by optical and scanning electron microscopy to estimate and identify the critical loads and failure mechanisms, respectively. The results indicated that the critical loads varied between 95 and 142 N as a function of the boride coating thicknesses with a development of various types of failure mechanisms over the surface of the coating/substrate system.
A dual layer PVD coating consisting of a CrN layer on top of a CoCrMo(C) S-phase underlayer (CrN/S) was deposited on a low-carbon wrought CoCrMo alloy discs and CoCrMo Stellite® 21 spheres. The tribocorrosion response of the uncoated CoCrMo tribopairs and coated CrN/S tribopairs was studied under reciprocating sliding conditions in Ringer's and diluted foetal bovine serum (FBS) solutions under anodic potential and elastic contact for a sliding time of 2 h. Compared to the uncoated tribopair, CrN/S successfully mitigated both oxidation and mechanical material losses and resulted in a low dynamic coefficient of friction and smoother scar morphologies in both test solutions. For the uncoated tribopair, the presence of proteins acted as a barrier to charge transfer and lowered the friction during tribocorrosion testing contributing to a marked reduction in material loss, primarily by a reduction in oxidative losses, but resulted in a rougher scar morphology. Tribocorrosion tests of the coated tribopair were also carried out for a duration of 24 h and revealed minimal material losses in diluted FBS and no evidence of other damage. It, however, resulted in substantial thinning of the outer CrN layer, transverse microcracking and delamination when testing in Ringer's solution. This coating loss produced a source for coating debris which led to three-body micro-abrasion damage. FIB investigation revealed that the observed transverse microcracks were limited to the outer layer and hence have not provided electrolytic pathways to the substrate interface. The excellent tribocorrosion response of dual layer CrN/S on CoCrMo metal tribopairs in diluted FBS renders them good candidates for further investigation to mitigate tribocorrosion damage of biomedical CoCrMo alloys.
The formation of tribochemical reaction layers, better known as tribofilms, on cobalt-chromium-molybdenum (CoCrMo) alloys commonly used in orthopaedic applications has been hypothesized to reduce degradation owing to wear and corrosion. However, the mechanisms and pathways influencing tribofilm formation remain largely unknown. This study aims to develop a clearer understanding of the role of protein structures and its concentration on tribocorrosion and surface tribofilms formed on CoCrMo alloys during boundary regime sliding. A reciprocating tribometer with a three-electrode electrochemical cell was employed to simulate and monitor the tribocorrosion of CoCrMo in situ. As-received Foetal Bovine Serum (as-FBS) and pre-heated FBS at 70 °C for 1 h (de-FBS) were diluted with saline (0.9% NaCl) at different concentrations (25% and 75% v/v) and utilized as electrolytes during the tribocorrosion tests. The result shows that the denatured protein structure in electrolyte tends to reduce the volume losses due to wear and corrosion on the CoCrMo samples with an appreciation of the protein tribofilms. On the other hand, an increased protein concentration increased the total volume loss due to corrosive processes. A novel finding revealed in this study is that the tribocorrosion mechanism of the CoCrMo surface is dependent on the protein structure, concentration and sliding duration due to the change in surface condition.
Co-Cr-Mo alloy is an excellent wear-resistant material which is widely used in many industrial fields. Due to external vibrations, fretting wear often occurs at the interfaces of well-matched connectors and induces surface wear, resulting in an accumulation of wear debris on the contact surfaces. This leads to a damage at the interface and the deterioration of matching contact pairs. Excellent wear and corrosion resistance are essential requirements for ideal industrial materials to resist the increasingly harsh working conditions of Co-Cr-Mo alloy, such as elevated temperatures. In this study, the fretting wear resistance of a Co-Cr-Mo alloy was investigated for different test parameters (temperatures, normal loads and displacements) with friction equipment. The fretting wear degree of the alloy was slight at 25 °C, and the wear mechanism at 25 °C was mainly abrasive wear. The analyses showed that elevated temperatures accelerated oxidative adhesion wear due to the formation of an oxide layer inside the interfaces and led to severe adhesive wear.
Current hip prostheses make extensive use of Ti-6Al-4 V alloy. This material was originally designed for aerospace applications. Moreover, its poor tribological properties are well known. However, beta, or near beta Ti alloys are known to have superior properties in that its elastic modulus is closer to that of bone coupled with a good fatigue resistance. Therefore, this work aims to analyse the tribocorrosion behaviour of 4 different titanium alloys (Ti-13Nb-13Zr, Ti-12Mo-6Zr-2Fe and Ti–29Nb–13Ta–4.6Zr aged at 300 °C and at 400 °C) at anodic potential, OCP and cathodic potential at 0.5 N, 1 N and 2 N in bovine serum to identify the main cause of material degradation, effect of microstructure and the synergism between corrosion and wear. The results show the alloys become more active when subjected to sliding in all conditions, but the material loss is lower at anodic potential. Finally, at anodic potential wear is lower than at cathodic potential which is explained by increase in the mechanical wear at cathodic potential.
Fretting crevice corrosion in modular tapers of total hip replacements has become a major concern in orthopedic medical devices. Solid and ionic debris arising from fretting crevice corrosion have been implicated in device failure and revision surgery. This study aims to use a 2D pin-on-disk fretting corrosion test system to visualize damage progression and debris generation during fretting corrosion of CoCrMo alloys in phosphate buffered saline (PBS). The results provide direct evidence of rapid debris generation during fretting corrosion (after only 12 min of testing). Debris was generated and either extruded from the contact region or impacted into adjacent crevice sites as long as fretting continued. After testing, the fretting region consisted of a damaged and plastically deformed contact region surrounded by a halo of fretting debris consisting entirely of oxides and phosphates within the crevice region. Evidence of pitting corrosion and grain boundary corrosion was observed. Solid debris consisted of chromium (Cr), phosphate (P) and oxygen (O). X-ray photoelectron spectroscopy analysis of the near-fretted metal surface area showed a thicker oxygen (O1s) containing film with the depth profile of O1s above 10% penetrating up to 5.75 nm while the O1s concentration on the unfretted area fell to below 10% after 1 nm depth. Ion concentration in the PBS, measured using inductively coupled mass spectrometry, showed cobalt (Co) ions were most prevalent (1.46 ppm) compare to chromium (Cr) (0.07 ppm) and molybdenum (Mo) (0.05 ppm) (p <0.05). All of these results are consistent with the analysis of in vivo modular taper corrosion processes.
Wear behaviors of the FeCoCrMoCBY bulk metallic glass (BMG), 316 L stainless steel (SS), and CoCrMo alloy under wet sliding in the phosphate buffered saline (PBS) solution were studied and compared with those under dry sliding. The Fe-based BMG exhibited an excellent corrosive wear resistance with a low wear rate of 1.84 × 10⁻⁸ mm³ mm⁻¹•N ⁻ ¹. On the contrary, the CoCrMo alloy and 316 L SS suffered from the synergistic effect of corrosion and wear in the PBS solution. The electrochemical results revealed that the Fe-based BMG possessed the greatest corrosion performance in the PBS solution among three alloys. The excellent corrosion behavior of the Fe-based BMG was attributed to the highly-protective surface passivation film enriched in Cr and Mo elements. The triobocorrosion results manifested that the great anti-corrosive-wear capacity of the Fe-based BMG can be ascribed to the high stable passivation process during wet sliding.
To evaluate the wear performance of a Cr3C2-25(80Ni20Cr) in several corrosive media, coatings were deposited by High Velocity Oxy-Fuel (HVOF) thermal spraying on 316L stainless steel (SS) substrates. Ball-on-plate reciprocating wear tests were performed on both coating and substrate in air, double-distilled de-aerated water, 3.5 wt% NaCl, 0.2 M NaOH and 0.2 M H2SO4 solutions. Tribocorrosion tests were performed under open circuit potential, potentiodynamic and cathodic protection conditions. The results showed that the coating has a wear resistance comparable to 316L in distilled water, NaOH and NaCl solutions. For H2SO4, the coating showed significantly improved wear resistance relatively to SS.
A nanocrystalline TiZrN graded coating was deposited on biomedical titanium alloy by DC reactive magnetron sputtering process. The microstructure and compositions of the coating were characterized by XRD, TEM and EPMA. The electrochemical corrosion and bio-tribocorrosion behavior of the coated titanium alloy under open circuit potential (OCP) and applied potentials (−0.15 V ~ +0.25 V) were investigated in Hank's solution with and without 25% calf serum. Compared with TiN coating, the hardness of TiZrN coating is greatly increased due to the Zr solid solution strengthening and nanocrystalline strengthening. Under the conditions of OCP and applied anodic potentials, the TiZrN coated Ti alloy exhibits significantly improved anti-tribocorrosion and anti-friction performances, which are attributed to that the stable Ti and Zr oxide or oxynitride passive film on coating near surface and the increased mechanical properties of the coating decrease the synergistic effect of corrosion and wear. 25% calf serum in Hank's solution enhances the chemical stability of the TiZrN coating through adsorption and bio-lubrication mechanism, and therefore further improves the tribocorrosion performance of the coated Ti alloy.
The corrosion and tribology are all closely related to the interface/surface of materials, which are extremely important for the mechanical components used in harsh marine environment. In this work, we fabricated Cr/GLC multilayered films with different modulation period on the 316L stainless steel by direct current magnetron sputtering. Tribocorrosion tests in artificial seawater show that the tribocorrosion resistance of the Cr/GLC films is improved as the modulation period decreases from 1000 to 333 nm, and then drastically drops with further decreasing to 250 nm. By taking top-layer thickening strategy for the Cr/GLC film with 250 nm modulation period, the tribocorrosion performance was significantly enhanced. The corresponded mechanisms were discussed in terms of the film structure and electrochemical corrosion behavior.
The Co-Cr-Mo alloys are widely used as structural materials for biomedical applications, such as coronary stent, arthroplasty (artificial joint replacement) and dental implants, due to their good biocompatibility, wear resistance, corrosion resistance and favorable mechanical properties. Tremendous amount of work is performed on nearly the single composition Co28Cr8Mo. This alloy is denoted as F75 in ASTM Standard 1998.
Cited references - 325, figures - 8, tables - 4, chapters - 9
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In studies of the interactions of erosion and corrosion, there are many variables which may affect the wastage rate, i.e. relating to properties of the impacting particles, the target and the environment. In this chapter, an overview is presented of models of solid particle erosion for metallic materials, metals and composites. Combining erosion models with those for corrosion may provide tools for prediction of lifetimes and for describing the regime of erosion-corrosion, depending on the ratios of the mechanical to chemical degradation, in active and passive corrosion environments. Mapping approaches for erosion-corrosion are presented in both two and three dimensions, indicating how such interactions can be presented in a multi-dimensional space.
In studies of tribo-corrosion, the degradation of bio-materials has become of increasing research interest in recent years. This is because, in many cases, the interactions of the tribological and corrosion component in biological environments are not well understood. Moreover, the wide range of variables involved in the tribo-corrosion process, and the variety of materials used in such conditions, mean that there are few systematic studies where materials and operating conditions are optimized.In the total replacement of hip joints, the Co–Cr/UHMWPE couple has been used widely. However, the application of any replacement joint for biological conditions will depend on many factors including the activity of the patient and the overall load imposed on the artificial joint. This means evaluation of the tribo-corrosion behaviour over a multi parameter space is important in order to assess the degradation possible for many patient/activity and body mass categories.In this work, the performance of a Co–Cr/UHMWPE couple was evaluated in Ringer's solution in a tribological situation where micron size particles were entrained in the contact – micro-abrasion–corrosion. The effects of applied load and potential were investigated in the study. Micro-abrasion–corrosion maps were constructed for the material indicating the mechanism of degradation, the extent of wastage and of synergy/antagonism involved in the tribo-corrosion interaction.
In studies of sliding wear in dry environments, there have been many attempts at mapping the processes. For steels, the classical “wear map” has been developed and various other studies have extended the approach to composites, ceramics and coated materials. Despite this work, there have been few attempts to extend the methodology to wet conditions, where the wear process interacts with solutions that are defined by pH and electrochemical potential.The object of this work was to study the sliding wear–corrosion behaviour of steels in a pin-on-disc apparatus in aqueous conditions. The effects of applied load and velocity were evaluated at various electrochemical potentials in carbonate/bicarbonate solution pH 9.8). The results were analysed using weight loss and scanning electron microscopy techniques.Wear mechanisms were identified in the various environments and a method of identifying the wear–corrosion transitions, in aqueous conditions, was proposed in the work. These regimes were superimposed on wear–corrosion maps, where the change in wear–corrosion regime was identified as a function of velocity and electrochemical potential. Possible reasons for the differences in the boundaries of the map at various applied loads are discussed in this paper.
Significant progress has been made in the understanding of micro-abrasion transitions of various materials in recent years, where abrasion is caused by particle sizes which are typically less than 10 μm. Research has shown reasonable consistency on effects of applied load and sliding distance, for studies carried out in various laboratories. In addition, attempts have been made to construct abrasion “diagrams” showing the transitions between the various regimes as a function of the above parameters.A puzzling aspect of the results to date, however, is the effect of “ridge” development on the micro-abrasion wear pattern. This ridge formation leads to a reduction in wear rate because the size of abrading particles, which account for the three-body effect, is less than the size of the ridge developed as a result of the wear process. The particles thus become lost in the ridge and cause no further abrasion.In this paper, the transition to ridge formation, as a function of sliding distance and load, is described for a range of pure metals of different hardness, using a TE-66, Plint micro-abrasion test rig. Tally-surf and optical microscopy techniques were used to measure the wear rate. Micro-abrasion maps were constructed showing differences in the transition boundaries between the wear regimes, and the implications of such results, for predictive modelling of micro-abrasion, are addressed in this paper.
Although numerous in vitro studies report on the tribological performance of and, separately, on the corrosion properties of cobalt-based alloys in metal-on-metal (MoM) bearings, the few studies that take into account the synergistic interaction of wear and corrosion (tribocorrosion) have used canonical tribo-test methods. We therefore developed synergistic study using a test method that more closely simulates hip bearing conditions.
(1) Is the total material loss during tribocorrosion larger than the sum of its components generated during isolated mechanical wear and isolated corrosion? (2) How is the tribocorrosive process affected by the presence of protein?
High carbon CoCrMo alloy discs (18) were subjected to corrosion and tribocorrosion tests under potentiostatic conditions in an apparatus simulating hip contact conditions. The input variables were the applied potential and the protein content of the electrolyte (NaCl solution versus bovine serum, 30 g/L protein). The output variables were mass loss resulting from wear in the absence of corrosion, mass loss resulting from corrosion in the absence of wear, and the total mass loss under tribocorrosion, from which the additional mass loss resulting from the combined action of wear and corrosion, or synergism, was determined in the presence and absence of protein.
The degradation mechanisms were sensitive to the interaction of wear and corrosion. The synergistic component (64 μg) in the presence of protein amounted to 34% of total material loss (187 μg). The presence of protein led to a 23% decrease in the total mass loss and to a considerable reduction in the mean current (4 μA to 0.05 μA) under tribocorrosion.
Synergistic effects during tribocorrosion may account for a considerable portion of MoM degradation and are affected by proteins.
The in vivo performance of some large-diameter MoM joints is unsatisfactory. The synergistic component resulting from tribocorrosion may have been missed in conventional preclinical wear tests.
In this study, the wear-corrosion of cast CoCrMo, more specifically, sliding wear-corrosion and abrasive wearcorrosion (using
∼ 4 μm SiC abrasive particles) have been investigated using a modified ball-cratering rig with a threeelectrode electrochemical
cell. The concentration effects of proteinaceous material (25% and 50% bovine serum) and pH levels, i.e., pH 4.0 (the possible pH for an infected joint area) and pH 7.4 (the normal pH for a healthy joint) on the tribocorrosion
performance of the alloy are explored. Results show that protein adsorption was dependent on pH and protein concentration.
The protein adsorption in turn influenced the overall tribo-corrosion performance of the CoCrMo alloy, including the in situ electrochemical noise, the specific wear rates, as well as the wear scar morphologies. The proteins and the pH level of hip
joint environments play a significant role in the tribo-corrosion performance of the cast CoCrMo and a discussion of the combined
wear and corrosion mechanisms will be presented.
KeywordsCoCrMo-Tribo-corrosion-Protein adsorption
Arthritis is a leading cause of disability, and when nonoperative methods have failed, a prosthetic implant is a cost-effective
and clinically successful treatment. Metal-on-metal replacements are an attractive implant technology, a lower-wear alternative
to metal-on-polyethylene devices. Relatively little is known about how sliding occurs in these implants, except that proteins
play a critical role and that there is a tribological layer on the metal surface. We report evidence for graphitic material
in the tribological layer in metal-on-metal hip replacements retrieved from patients. As graphite is a solid lubricant, its
presence helps to explain why these components exhibit low wear and suggests methods of improving their performance; simultaneously,
this raises the issue of the physiological effects of graphitic wear debris.
Recently, “tribocorrosion,” a research area combining the science of tribology and corrosion, has drawn attention from scientists and engineers belonging to a wide spectrum of research domains. This is due to its practical impact on daily life and also the accompanying economical burdens. It encompasses numerous applications including the offshore, space, and biomedical industry, for instance, in the case of artificial joints (Total Hip Replacement, THR) in orthopedic surgery, where implant metals are constantly exposed to tribological events (joint articulations) in the presence of corrosive solutions, that is, body fluids. Keeping the importance of this upcoming area of research in biomedical applications in mind, it was thought to consolidate the work in this area with some fundamental aspects so that a comprehensive picture of the current state of knowledge can be depicted. Complexity of tribocorrosion processes has been highlighted, as it is influenced by several parameters (mechanical and corrosion) and also due to the lack of an integrated/efficient test system. Finally a review of the recent work in the area of biotribocorrosion is provided, by focusing on orthopedic surgery and dentistry.
Load bearing implant prostheses such as orthopaedic hip and knee implants may be considered as tribocorrosion systems since the wear processes are a result of combined mechanical and chemical mechanisms. The long-term success of implant prostheses depends on a number of factors, including age, body weight and activity levels. Pre-clinical testing is therefore crucial in determining the long-term performance, safety and reliability of the implant in-vivo. In this study a CoCrMo alloy - UHMWPE couple were tested in a physiological solution of foetal calf serum (FCS) in 0.9 wt% NaCl to assess the underlying wear mechanisms as a result of applied load (0–5 N) and applied potential (−600, −400, −200, 0 and +200 mV). The transitioning behaviours due to micro-abrasion and corrosion were studied; corresponding micro-abrasion–corrosion wear maps were constructed to indicate the mass loss transitions in scope of wastage, mechanisms of wear and synergies between abrasion–corrosion for simulated hip contact conditions.
A good biocompatibility, excellent mechanical properties and high corrosion resistance characterize CoCrMo alloys. Therefore they are widely used for artificial joints in biomedical implants. However, the degradation of the implants during service life leads to the release into the body of toxic ions and wear particles. This continuous degradation is of concern for long-term stability of the implants. Published literature has highlighted the relevance of lubrication as well as metallurgical and contact mechanical factors on the degradation of CoCrMo implant alloys. Recent experimental investigations have proposed tribocorrosion, i.e., the interplay of mechanical wear and corrosion by the body fluids, as one of the crucial degradation mechanism of implants. Tribocorrosion is sub-discipline of tribology and corrosion that recently made significant progresses in mechanistic understanding and modelling. The present work aims at evaluating published results on the degradation of CoCrMo alloys using existing tribocorrosion concepts. Results show that wear accelerated corrosion due to mechanical removal of the passive film during sliding is a major contribution to the overall degradation. Further, a transition from low (10−6 N/mm3 m) to high (10−4 N/mm3 m) wear coefficients was found at a threshold electrode potential close to 0.2 VSHE These findings clearly show that electrochemical phenomena play a key role on the tribological behaviour of biomedical CoCrMo alloy implants.
The potential of Wear-Mechanism Diagrams is explored. Diagrams which show the rate and the regime of dominance of each of a number of mechanisms of dry wear (delamination, mild and severe oxidation, melting, seizure, etc.)are constructed empirically ( that is, from experimental data alone) and by modelling ( by theoretical analysis calibrated to experiment). The method is applied to steels, and has wider application as a way of classifying and ordering wear data, and of showing the relationships between competing wear mechanisms.
Tribo-corrosion is the term which describes the interaction between a tribological process with corrosion. This process may include sliding or abrasive wear, erosion by solid particles or liquid impact, or cavitation, fretting or fatigue. Corrosion environments may be complex; they can be alternately dry (i.e. at elevated temperatures) or wet aqueous conditions at room temperatures. Significant progress has been made in the study of tribo-corrosion in the past 20 years. Erosion–corrosion in particular has received much attention, because of the increasing prevalence in minerals processing and in the oil and gas industries. Mechanistic maps for such processes have been generated, showing the transitions between the tribo-corrosion regimes as a function of tribological and corrosive variables. This paper reviews the recent research in the area, from the inception of the initial wear map, to current work in the area. The significance of the various maps will be discussed, and their potential application to “real” environments will be described. New directions for the work will be highlighted with emphasis on extension to advanced materials and a wider range of variables.
The passive oxide films formed by electrochemical oxidation on CoCrMo alloy (ASTM F75) in simulated physiological solution were studied using X-ray photoelectron spectroscopy (XPS). The oxidation was performed in a closed system without exposure to laboratory air. The fitting procedure used allowed the separation of the measured spectra, Co 2p, Cr 2p, Mo 3d and O 1s, into contributions of various species. Quantitative evaluation included the determination of the composition, cationic fraction and thickness of the oxide layer formed. An insight into the structure of the layer was offered by angle-resolved XPS measurements. The addition of complexing agent, in the form of Na–citrate, to the physiological solution affects the passivation of CoCrMo alloy.
The corrosion behavior of CoCrMo alloy in simulated body fluids has been analyzed by electrochemical techniques and surface analysis. Interaction of albumin and phosphates present in the body fluids on the passive film of the alloy was also investigated. Electrochemical techniques such as potentiodynamic and potentiostatic polarization and electrochemical impedance spectroscopy were employed. Further, ex situ X-ray photoelectron spectroscopy and Auger electron spectroscopy analysis of the passive films were carried out. The study reveals that phosphates and proteins present in simulated body fluid play a significant role in the electrochemical properties of the metal/oxide/electrolyte interface. Surface analysis showed that both species competitively adsorb on the alloy surface. For a given passive potential, the impedance behavior of passive CoCrMo was found to depend on the way passive conditions were established. A simple model has been developed assuming a multilayer structure of the surface including an outer layer where albumin and phosphate ions adsorb, the passive film (inner layer), and the metal. This model is consistent with the obtained electrochemical and surface analysis results. (c) 2007 The Electrochemical Society.
The metallic materials used for implantable medical devices are predominantly stainless steels, Ti and its alloys, and Co-Cr alloys. The corrosion resistance of each of these materials is associated with a passive oxide film on its surface. Since corrosion resistance is crucial to implant performance, considerable effort has been focused on understanding the nature of the passive film present under physiological conditions. Surface analytical techniques and electrochemical impedance spectroscopy (EIS) have been used in a number of studies to investigate the passive film formed on metallic biomaterials in simulated physiological solutions. This review focuses on the surface characteristics of these materials with regard to composition, thickness, and impedance of the passive films. Of particular interest are changes in the films with surface treatment and the nature of the films developed over time in the simulated solutions.
The mechanical design of biological materials has generated widespread interest in recent years, providing many insights into their intriguing structure-property relationships. A critical characteristic of load-bearing materials, which is central to the survival of many species, is their wear and abrasion tolerance. In order to be fully functional, protective armours, dentitious structures, as well as dynamic appendages must be able to tolerate repetitive contact loads without significant loss of materials or internal damage. However, very little is known about this tribological performance. Using a contact mechanics framework, we have constructed materials selection charts that provide general predictions about the wear performance of biological materials as a function of their fundamental mechanical properties. One key assumption in constructing these selection charts is that abrasion tolerance is governed by the first irreversible damage at the contact point. The maps were generated using comprehensive data from the literature and encompass a wide range of materials from heavily-mineralized to fully-organic materials. Our analysis shows that the tolerance of biological materials against abrasion depends on contact geometry, which is ultimately correlated to environmental and selective pressures. Comparisons with experimental data from nanoindentation experiments are also drawn in order to verify our predictions. With the increasing amount of data available for biological materials also comes the challenge of selecting relevant model systems for bioinspired materials engineering. We suggest that these maps will guide this selection, by providing an overview of biological materials that are predicted to exhibit the best abrasion tolerance, which is of fundamental interest for a wide range of applications, for instance in restorative implants and protective devices.
After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in vivo and in vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair.
There has been significant recent interest in the interactions of micro-abrasion in aqueous conditions, particularly when the environment is corrosive. This is due to the fact that there are many micro-scale-abrasion processes where the presence of the corrosive media may modify the wear on the surface. Furthermore, if the surface dissolves, the mechanical properties of the surface may be modified as a result of the effects of corrosion.In this work, the micro-abrasion of a steel/polymer couple was studied in carbonate/bicarbonate solution. The effects of two variables, applied load and potential, were investigated on the wear rate enabling quantification of the corrosion and wear contributions. Scanning Electron and Atomic Force Microscopy were used to characterize the surfaces following micro-abrasion-corrosion.The results indicated possible micro-abrasion-corrosion mechanisms on the surface. These regimes were suggested on the basis of the ratio of the micro-abrasion to the corrosion rate. In addition, micro-abrasion-corrosion maps were constructed showing the transitions between the micro-abrasion-corrosion regimes as a function of load and applied potential.
Micro-scale abrasion (commonly referred to as 'ball cratering') is a small-scale tribological test method which can be operated on a desktop. It offers the possibility of providing a quick, cheap, localized abrasion test that can be used with small samples. In principle its operation is simple, but in practice there are issues with wear scar measurement, wear mode and its applicability to a wide variety of monolithic materials and coatings.
The potential of Wear-Mechanism Diagrams is explored. Diagrams which show the rate and the regime of dominance of each of a number of mechanisms of dry wear (delamination, mild and severe oxidation, melting, seizure, etc.) are constructed empirically (that is, from experimental data alone) and by modelling (by theoretical analysis calibrated to experiment). The method is applied to steels, and has wider application as a way of classifying and ordering wear data, and of showing the relationships between competing wear mechanisms.RésuméNous explorons les possibilités des diagrammes de mécanismes d'usure. Nous construisons empiriquement (c'est à dire, à partir des seules données expérimentales) et à l'aide de modèles (grâce à des analyses théoriques étalonnées sur l'expérience) des diagrammes qui fournissent la vitesse et le régime de prédominance de chacun des mécanismes d'usure sèche (délamination, oxydation légère et prononcée, fusion etc). Nous appliquons cette méthode aux aciers, mais elle a des applications plus larges en tant que moyen de classification et de tri des données d'usure, ou pour montrer les relations entre les mécanismes d'usure en compétition.ZusammenfassungDie Anwendungsmöglichkeiten von Diagrammen der Abriebmechanismen werden untersucht. Diagramme, die Geschwindigkeit und Bereich des Auftretens einer Reihe von Mechanismen des trockenen Abriebes (Delamiantion, schwache und starke Oxidation, Schmelzen usw) aufzeigen, werden empirisch (d.h. aus experimentellen Werten) und im Modell (d.h. durch theoretische, an das Experiment angeglichene Analyse) konstruiert. Diese Methode wird auf Stähle angewendet. Sie hat einen weiteren Anwendungsbereich, indem sie Abriebdaten klassifizieren und ordnen und die Zusammenhänge zwischen konkurrierenden Abriebmechanism en aufzeigen kann.
In corrosion wear, one of the most commonly observed phenomena is the synergism where both corrosion and wear are significantly increased by the tribo-corrosion interactions, leading to much greater material losses than produced by the sum of losses by either process alone. However, mechanisms for the synergistic effect are generally not well understood and there has been little effort in modelling synergistic processes. In this paper, mechanisms for the interactions between corrosion and sliding wear of metals are proposed and a mathematical model is developed which incorporates the various factors affecting corrosion wear, including experimental and environmental conditions and material properties. Many of the observed phenomena in corrosion wear can be explained. It also provides a good basis for wear map construction and would be especially useful in carrying out dimensional analyses for constructing such maps.
The interpretation of certain phenomena occuring at nominally flat surfaces in stationary or sliding contact is dependent on the assumed distribution of the real area of contact between the surfaces. Since there is little direct evidence on which to base an estimate of this distribution, the approach used is to set up a simple model and compare the deduced theory (e.g., the deduced dependence of the experimental observables on the load) with the experimental evidence. The main conclusions are as follows. (a) The electrical contact resistance depends on the model used to represent the surfaces; the most realistic model is one in which increasing the load increases both the number and size of the contact areas. (b) In general, mechanical wear should also depend on the model. However, in wear experiments showing the simplest behavior, the wear rate is proportional to the load, and these results can be explained by assuming removal of lumps at contact areas formed by plastic deformation; moreover, this particular deduction is independent of the assumed model. This suggests that a basic assumption of previous theories, that increasing the load increases the number of contacts without affecting their average size, is redundant.
Metal-on-metal (MOM) hip joint bearings are currently under discussion as alternatives to metal-on-polymer (MOP) bearings. Some criteria under scrutiny are the wear resistance, the influence of wear particles on the surrounding tissue, as well as the frictional torque. In order to understand and control the wear behavior of such a bearing a close correlation between the microstructures of the alloys used and the acting wear mechanisms has to be found. Thus, commercially available CoCrMo-balls were tested against self mating concave pins in a physiological fluid at 37°C under reciprocating sliding wear (1 Hz). The compressive load was 750 N (body weight). For 2×106 cycles tests were carried out continuously and with periodically occurring resting periods. On the basis of the observed wear appearances the acting wear mechanisms are defined and evaluated as to their contribution to the wear behavior. Due to the high local contact stresses surface fatigue prevails initially. Cr– and Mo–carbides are fractured and torn off the surfaces bringing about additional surface fatigue by indentations and initiating abrasion. The weight loss can be predominately attributed to these mechanically dominated wear mechanisms. In a parallel occurring tribochemical reaction layers are generated from denatured proteins. These adhere rigidly to the surfaces and cover parts of the contacting surfaces avoiding adhesion. Thus, the wear behavior is mainly influenced by the alternating balance between surface fatigue and abrasion on the one side and by tribochemical reactions on the other side.
The objective of this study was to develop a theoretical model and associated wear-mode map to identify the regimes in which two-body abrasion (grooving abrasion) and three-body abrasion (rolling abrasion) dominate in the micro-scale abrasive wear test (also known as the ball-cratering abrasion test).The critical condition for the transition between two-body and three-body abrasion was determined from a continuum mechanics model for the penetration of the abrasive particles into the surfaces of the ball and the specimen, coupled with considerations of equilibrium.Micro-scale abrasion tests were performed with different combinations of ball and specimen materials, under different test conditions such as abrasive concentration and load, and a wear-mode map has been produced which defines the regimes of abrasive particle motion. The map is plotted between two dimensionless groups as vertical and horizontal axes: the hardness ratio between the ball and the specimen, and a newly introduced parameter which represents the severity of contact. Experimental data generated in this work and also taken from previous studies show that the map represents behaviour in the micro-scale abrasion test well, for a wide range of ball and specimen counterface materials.
In this work, the behaviour of a CoCrMo alloy under simulated body conditions was investigated. More specifically, the electrochemical properties of the alloy and the relevant mechanisms in the passive and transpassive states were studied in detail. Electrochemical techniques such as potentiodynamic and potentiostatic polarisation, cyclic voltammetry, rotating disc electrode and electrochemical impedance spectroscopy were employed. Further, ex situ X-ray photoelectron spectroscopy analysis of the passive films was carried out. A good correlation between the results obtained from all the experimental techniques was achieved. Overall, it was found that the passive film on CoCrMo changed in composition and thickness with both potential and time. The passive behaviour of the CrCrMo alloy is due to a formation an oxide film highly enriched with Cr (≈90% Cr oxides) on the alloy surface. The passive and transpassive behaviour of the alloy is hence dominated by the alloying element Cr. In the transpassive region, strong thickening of the oxide film takes place, combined with a change in the composition of the film, and strongly increased dissolution rate. In the transpassive region, all alloying elements dissolve according to the composition of the alloy. The metal ion release is also very strongly enhanced by cyclic variation of the potential between reducing and oxidizing conditions. In this case, during activation/repassivation cycles, cobalt dissolution is greater than expected from the composition of the alloy. Therefore, active dissolution behaviour is mainly dominated by the alloying element Co.
This study aims to investigate the synergistic effects of corrosion and wear of artificial human joints made from a surgical grade cast F-75 cobalt–chromium–molybdenum (CoCrMo) alloy. Both electrochemical and gravimetric measurements have been used to determine the performance of CoCrMo samples in static environments and under predominantly three-body abrasive wear conditions using the micro-abrasion test method. Electrochemical measurements are presented from embedded corrosion cells within a micro-abrasion rig. Micro-abrasion–corrosion has been studied using an aggressive abrasive slurry (SiC/Ringer's) to identify depassivation and repassivation processes. These initial conditions are an attempt to simulate worst-case scenarios where wear, cement or bone debris are entrained into the contact. The in situ wear-corrosion measurements have been used to identify the implications of wear and corrosion on both the implant and tentative implications for the patient over the long term. Results show strong synergistic effects occur ranging from negative to positive (i.e. beneficial to accelerated surface removal rates). The synergistic levels appear to be dependent on the integrity of the passive films and the repassivation kinetics. Corrosion potentials are presented which corroborate depassivation within the scar.
Tribocorrosion is an irreversible transformation of a material resulting from simultaneous physico-chemical and mechanical surface interactions in a tribological contact. Electrochemical methods are well suited for the study of tribocorrosion phenomena because they allow one to simulate the corrosive effect of the environment by imposing a fixed potential. Furthermore, the measurement of the anodic current permits one to determine the amount of material removed by oxidation as opposed to mechanical wear. In the present paper, experimental and theoretical aspects of applying electrochemical methods in tribology are discussed and recent results obtained with passivating metals in the authors' laboratory are presented. The importance of controlling the mechanical parameters and the contact geometry is stressed, and it is shown that these parameters can significantly affect the electrochemical response of a tribocorrosion system.
A review of wear mechanisms has been carried out in this paper for the hip prostheses. The primary causes of premature failure in hip prostheses are due to wearing of the implants. Multiple variables interact and increase the resultant wear rates. A summary of clinical in vivo and bulk material wear rate data from published literature has been presented for polyethylene-on-metal, metal-on-metal, and ceramic implants. This article addresses the engineering aspects concerning the advantages and disadvantages of each type of articulation. Wear mechanisms are discussed as a function of contact stresses, lubricants and clearance, surface hardness and roughness, type of articulation due to motion, number of cycles, solution particle count and distribution, oxidation of materials, and surface abrasions of both metal and polyethylene particulates. These issues are reviewed in this review.
Due to the renewed interest in hard-on-hard hip replacement, especially metal-on-metal (MoM) or metal-on-ceramic (MoC) joints, issues relating to their long-term durability need to be addressed. Their effects on the operating environment (human body) and how the body fluid affects the implant materials are the primary concern. For widely used metallic implant materials, such as cobalt–chromium–molybdenum (CoCrMo) alloys, released ions due to electrochemical (corrosion) processes and mechanical-enhanced electrochemical (corrosion-wear/tribocorrosion) processes may cause biological reactions in the human hosts. Proteins are a primary constituent of the synovial fluid in human joints with other organic components such as hyaluronic acid and lubricin, and, although numerous tribological studies in protein-containing fluids have been conducted, there is still a need to fully understand the role of proteins and adsorbed-protein layers in wear, corrosion and tribocorrosion processes in artificial joints.
Metal-on-metal (MoM) bearings are at the forefront in hip resurfacing arthroplasty. Because of their good wear characteristics and design flexibility, MoM bearings are gaining wider acceptance with market share reaching nearly 10% worldwide. However, concerns remain regarding potential detrimental effects of metal particulates and ion release. Growing evidence is emerging that the local cell response is related to the amount of debris generated by these bearing couples. Thus, an urgent clinical need exists to delineate the mechanisms of debris generation to further reduce wear and its adverse effects. In this study, we investigated the microstructural and chemical composition of the tribochemical reaction layers forming at the contacting surfaces of metallic bearings during sliding motion. Using X-ray photoelectron spectroscopy and transmission electron microscopy with coupled energy dispersive X-ray and electron energy loss spectroscopy, we found that the tribolayers are nanocrystalline in structure, and that they incorporate organic material stemming from the synovial fluid. This process, which has been termed "mechanical mixing," changes the bearing surface of the uppermost 50 to 200 nm from pure metallic to an organic composite material. It hinders direct metal contact (thus preventing adhesion) and limits wear. This novel finding of a mechanically mixed zone of nanocrystalline metal and organic constituents provides the basis for understanding particle release and may help in identifying new strategies to reduce MoM wear.
Numerous parameters control the long-term performance of a total hip joint arthroplasty. The articulating motions between the femoral and the acetabular components produce wear debris in a hip implant. Surface roughness, clearance, coefficient of friction and sliding distance are found to be contributing parameters that affect wear rates. Wear produced in a hip implant leads to the loosening of a hip prosthesis and thus failure of the hip implant. Ultra-high-molecular-weight polyethylene (UHMWPE) has been successfully used as an acetabular weight bearing component in the THR applications. Cross-linked UHMWPE was found to improve the lifespan of an artificial hip. A gradient cross-linking of UHMWPE has been observed to be a recent development in implant bearing materials. During in vitro studies, gradient cross-linked UHMWPE showed nearly undetectable wear rates.
Interest in the rheology and effects of interacting surfaces is as ancient as man. This subject can be represented by a recently coined word: tribology. This term is derived from the Greek word "tribos" and means the "science of rubbing". Friction, lubrication, and wear mechanism in the common English language means the precise field of interest of tribology. Wear of total hip prosthesis is a significant clinical problem that involves, nowadays, a too high a number of patients. In order to acquire further knowledge on the tribological phenomena that involve hip prosthesis wear tests are conducted on employed materials to extend lifetime of orthopaedic implants. The most basic type of test device is the material wear machine, however, a more advanced one may more accurately reproduce some of the in vivo conditions. Typically, these apparatus are called simulators, and, while there is no absolute definition of a joint simulator, its description as a mechanical rig used to test a joint replacement, under conditions approximating those occurring in the human body, is acceptable. Simulator tests, moreover, can be used to conduct accelerated protocols that replicate/simulate particularly extreme conditions, thus establishing the limits of performance for the material. Simulators vary in their level of sophistication and the international literature reveals many interpretations of the design of machines used for joint replacement testing. This paper aims to review the current state of the art of the hip joint simulators worldwide. This is specified through a schematic overview by describing, in particular, constructive solutions adopted to reproduce in vivo conditions. An exhaustive commentary on the evolution and actually existing simulation standards is proposed by the authors. The need of a shared protocol among research laboratories all over the world could lead to a consensus conference.
Wear Maps. Modern Tribology Handbook, Two Volume Set
- Stephen
- Mh
- Ming
- Cs
Stephen MH, Ming CS. Wear Maps. Modern Tribology Handbook, Two Volume Set. Mechanics & Materials Science: CRC Press; 2000.