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Nanoadditives SiO2 and TiO2 in Process Fluids
Abstract
Productivity growth in the machining industry is associated with a reduction in the cost of cleaning and recycling contaminated process fluids. The proper use of process fluids or lubricants can bring a significant reduction in friction and the amount of wear, thereby leading to a reduction in power consumption. The use of nanolubricants in modern technologies is a major advancement. Nanolubricant is a new system composed of nanometer-sized particles dispersed in a base lubricant. The use of nanoadditives in the form of nanoparticles is highly efficient due to their high chemical and biological activity. The doping of lubricants with nanoparticles is one of the ways to solve problems with the removal of bacteria, whereby improving the biological, chemical and technological stability of process fluids. In the article, we monitor the effects of doping process fluids with nanoparticles of silica (SiO2) and titanium dioxide (TiO2) on the friction coefficient of friction pairs of Si3N4 balls against steel 16MnCr5, EN 10084-94 and Si3N4 balls against aluminium AlCu4BiPb balls.
... An explanation of the various scientific disciplines is often essential for an understanding of tribological problems. [7][8][9] During relative movement between solid bodies, friction and wear are an inevitable occurrence. Both a low friction coefficient and low wear are desirable for most systems; this is associated with ensuring the reliable working of the system and less energy consumption, which leads to an extension of lifespan. ...
... pencils), but most effort is focused on developing application systems with a low a friction coefficient and minimal wear. [7][8][9] Wear is usually defined as "damage to the hard surface comprising a progressive loss of material due to relative movement between the surface and the surface of another material or substance" [10]. ...
... The development of structures of various mechanical systems is associated with the selection of suitable materials with specific properties. Friction and wear depend on many parameters and conditions, including: material pairing, contact geometry, applied normal load, contact pressures, relative sliding speed, material surface topography and roughness, environment, temperature, chemical interactions, sliding direction (unidirectional, reciprocating, random, etc.) [7][8][9] Many mechanical systems need to work in various different environments. Some components must provide reliable wear and friction against several different types of materials. ...
The process of friction between two solid surfaces is inevitably accompanied by the occurrence and energy losses. If the surfaces are separated by a layer of dissimilar material, the friction process also takes place within the layer, and the wear of the surface and possibly the energy losses due to friction are reduced considerably. AlCN films with differing composition are deposited on the samples from high-speed steel by reactive DC magnetron sputtering of pure Al (99.99%) with various different gas ratios of N 2 and CH 4. The deposition chamber, before films growth processes, is evacuated up to approximately 5.2 ×10-3 Pa by a turbomolecular pump. During the deposition process and Ar plasma cleaning process the bias voltage is applied with r.f. source (13.56 MHz).Tribological testing (EN1071-13:2010) is conducted with a constant load of 5 N at room temperature and humidity of 40 ± 2 %, by using a ball made from steel ISO 683/13 (X105CrMo17) with a diameter of 6.350 mm.
... Several attempts to improve the tribological characteristics of the machining processes have been made for machining operations under lubricated conditions [14], dry conditions [3], determination of minimum quantity lubrication [19], and optimization of surface roughness [16], like optimization of parameters, improvements in the materials of the cutting tools, redesign of the cutting tools, development of new lubricants and recently the addition of additives such as nano particles to the cutting fluids. The incorporation of additives as an improvement of coefficient of friction for extreme pressure (EP) applications on for cutting fluids [4], anti-wear (AW) applications [13], and process energy reduction [22] is not new. However, the application of nano particles has been developed in the last 10 years for lubricant oils [1] metalworking fluids [20] and engine oils [24]. ...
An experimental design to optimize machining surface roughness measured by Ra is developed in this paper. The objective is to develop a grinding lubricant containing nano particles as the main additive. A study of the influence of titanium dioxide (TiO2) nano particles in surface roughness measured on cutting tool applications for the metal-mechanic industry (with illustration on slitting knives) is performed. Literature shows that a concentration of nano particles less or equal than 0.1% in weight has a significant influence. A response surface statistical analysis with control variables: concentration of nano particle, and manufacturing variables as: spindle speed and feed rate on grinding machines were included. The analysis on slitting knives determines that spindle speed and feed rate have not significant influence on the surface quality, meanwhile the nano particles weight percentage in the oil based lubricant was the only significant influence in the study. Response surface methodology leads to the best nano particle proportion making a significant improvement on the value of Ra, from 0.9449 (for lubricant with no nano particles) to Ra of 0.2805 with the best nano particle weight proportion of 0.055%, an almost 69% improvement on the response. Since the metal-mechanic industry is intensive in cutting processes, which is fundamental for industrial steel product transformation, this study opens the way to analyze another cutting tools that can be benefited from other nano particle types and concentrations.
Not only engineering production at present is characterized by increasing an international competition. It is achieved higher productivity with simultaneous improvement of quality parameters of machined parts by using of process fluids. In other words, the use of process fluids positively improves and increases the both the qualitative as well as quantitative parameters of the technological processes. Process liquids in machining occupy an important place and influence the outcome of the all processes. Choosing a suitable process fluid should be carefully considered. It is well known that, different machining technologies have different cutting conditions and thus completely different requirements on process fluids. Selection of a suitable process fluid is more important that the management of manufacturing companies admits. Unfortunately, the selection of suitable process fluids is very often underestimated.
Nanoparticles (NPs) of TiO2 or SiO2 (size of 10–25 nm) added to a cooling lubricant emulsion (CLE) have a positive effect on the machining process due to a reduction in the average friction coefficient, a reduction in the variance of the measured values and a reduction in the wear of the cutting tool resulting in increased durability. The functional properties of NPs were evaluated using two different CLEs – CLE1 with the majority content oxygen molecule and various amines; and CLE2 composed of oxygenated organic compounds comprising glycols and higher alcohols. Conventional face milling was selected as the machining process type with the cutting speed 119 m min⁻¹; rotor speed 600 rpm; feed per tooth 0.1 mm; feed rate per minute 60 mm; depth of cut 1 mm and width of cut 40 mm. The addition of spherical SiO2 NPs and TiO2 NPs with a flat surface texture with smooth edges led to a reduction in wear, in the sticking region there was no evidence chipping, cracking or peeling of the coating. The different compositions of CLE1 and CLE2 influence the biocidal effects of the NPs on bacteria cells; CLE1 with SiO2 of 56.6%, and with TiO2 of 18.4%; CLE2 with SiO2 of 26.5%, and with TiO2 of 55.3%. The presence of NPs in the CLEs does not increase the cytotoxic effect on mouse fibroblast cells; however, the composition of CLE1 and CLE2 affects the cytotoxicity for mouse fibroblast cells; CLE1 has an up to 59.6% higher cytotoxic effect than CLE2.
This research is engaged in monitoring changes in the tribological behaviour of CrCN thin films at room and elevated (300°C) temperatures. The monitored thin films are deposited by cathodic arc deposition of a pure Cr (99.99 %) cathode under an atmosphere of a mixture of CH4 and N2 gasses. Tribological measurements were performed at a load of 10N, a rotational speed of 60 rpm, and a counterpart of ceramic material (Al2O3). The article also describes the evaluation of wear on the studied thin films due to tribological measurement and temperature.
AlSiN coatings were prepared by the cathodic arc deposition method at a temperature of 400°C and pressure of 2.6 Pa. The chemical composition, determined by SEM/EDS analysis, shows that the AlSiN coating presented here has a stoichiometry structure (Al40Si9N51). XPS and XRD analyses indicated AlN in both cubic and hexagonal modifications in the coating, and that the coating has a not fully completed nanocomposite structure. Nanoindentation measurements indicate nanohardness and elastic modulus of 39 GPa and 389 GPa, respectively. The coating has a very good adhesion strength with an average critical load of 28.3N (first cohesive failure) and 62.3N (first adhesion failure). The estimated wear rate and coefficient of friction of the coating are 27.2×10⁻⁶ mm³N⁻¹m⁻¹ and 0.7, respectively (using the friction pair AlSiN/Al2O3).
Manufacture of new parts of machineries, devices, etc., especially in engineering and metallurgy requires machining of the feedstock in a mechanical way. During machining occurs immediate contact between the tested specimen and the tool and in their mutual relative movement of friction and wear. One of the possible variants how to eliminate this fact is the application of process fluids during machining. Currently, we are trying to simulate long-term testing by laboratory testing called tribology. The experiment presents friction between two materials that are under real sliding contact. This article examines the tribological characteristics between two materials (tool - ball and workpiece material - disc). The paper contains findings when examining process fluids by tribological test Ball - on - disc, this test is currently used in practice, very widespread, this test can imitate various operations of cutting machining. This paper deals with the evaluation of tribological properties (the coefficient of friction, wear of disc and wear of ball) between the ball from ceramic material Si3N4 and the test material (stainless steel X5CrNi18-10, EN 10088-3 and steel commonly used in engineering 16MnCr5, EN 10084-94) by using two kinds of process fluids. © 2017. Published by Manufacturing Technology. All rights reserved.
The paper presents the research results of the various coatings deposited using the cathodic arc evaporation Physical Vapour Deposition (PVD) method at 300°C, suitable for application on temperature-sensitive steels and alloys. Three main groups of coatings are deposited, denoted as E1, E2 and E3. The deposited bi-layer numbers for E2, E3 and E4 are 103, 207 and 107, respectively. Each group consists of two subgroups, S1 and S2, TiN/AlTiN and AlTiN/TiN nanomultilayer (NML) coatings, respectively. The coating deposition time for E1 and E2 is 60 min, and the carousel rotation speed is 35s and 17.5s, respectively. The coating thicknesses for these two coatings groups are 2.4 µm and 2.3 µm, and the calculated bi-layers thicknesses are 23.3 nm and 11.6 nm, respectively. TiN/AlTiN and AlTiN/TiN as NML or superlattice coatings are deposited onto high-speed steel substrates using pure titanium and aluminium-titanium (70/30 at. %) cathodes. Tribological testing is conducted using an Al2O3 ball and a ball made from steel ISO 683/13, and the applied load and path length at the used speed of 60 RPM are 10N and 25m, respectively. Measurements are performed at room temperature and a humidity of 44 ± 2%.
The aim of this paper is to compare the mechanical and tribological properties of TiCN and CrCN coatings. These coatings are widely used in industrial applications to improve both friction and wear. They are deposited at the same deposition parameters using anindustrial Physical Vapour Deposition (PVD) system. Estimation of the tribology properties is made in a “ball-on-disc” mode, and the wear and wear rates of the coatings and counter-bodies are compared. The test study is conducted using a ball made from Al2O3 with a diameter of 6.350 mm and a load of 10 N, at room temperature and a humidity of 44 ± 2 %. The mechanical properties are estimated by nanoindentation, a scanning electron microscope and a mechanical profilometer, and the hardness, elastic module, chemical composition, and surface coating morphology are estimated. The scratch test is performed on the coatings using a CETR UMI Multi-Specimen Test System scratch tester device with a progressive load from 2 to 100 N and speed of 10 mm/min, according to the ISO EN 1071-3:2005 standard.
Thanks to their chemical and mechanical properties, the process fluids (PFs) can significantly affect the process of machining [2], [15], [16], [18]. It is particularly important that PFs should positively influence the quality of the machined surfaces of machine parts and durability of cutting tools [4], [5], [6], [7], [10], [11], [12], [14]. Other significant factors in PFs are economic and environmental [17]. The costs of the acquisition, use and disposal of PFs must not be too high. As part of the research project in collaboration with the company Paramo, a.s. and the Technical University of Liberec, completely new environment-friendly PFs (labeled as PF01, PF02, PF03, PF04, and PF05) have been developed and evaluated. In the Laboratory of Machining at the Technical University of Liberec, the effects of these new PFs were examined from a viewpoint of a number of technological aspects. This article presents the results of experiments conducted on structural steel 16MnCr5 and stainless steel X2CrNiMo18-14-3 face milling using these newly developed eco-PFs.
Hardened steel AISI 4140 material is commonly used to produce automotive parts such as shafts, gears and bearings. Machining this material significantly increases the temperature in the cutting zone and is critical in deciding workpiece quality. Though cutting fluids are widely employed to dissipate the heat in machining, they threaten the ecology and health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of a nano-lubrication system. For this purpose, a novel uses of nano-lubricants in minimum quantity lubrication (MQL) system were studied. In the present work, a mist of SiO2 nano-lubrication was used and applied by air pressure in turning of hardened steel AISI4140. In this research work, the optimum SiO2 nano-lubrication parameters to achieve correct lubrication conditions for the lowest tool wear and best surface quality were investigated. These parameters include nano-lubricant concentration, nozzle angle and air carrier pressure. The Taguchi optimization method is used with standard orthogonal array L16(4)3. This research is investigating on the new and novel uses of SiO2 nano-lubricant by conducting analysis on tool wear and surface roughness using fuzzy logic and response analysis to determine which process parameters are statistically significant. Besides, these analyses were conducted in order to prove the effectiveness of nano-lubricant. Finally, confirmation tests were carried out to investigate optimization improvements.
New technology using nanoparticles as an additive in lubricants is recently becoming an attractive topic of study. The performance of SiO2 nanoparticles in the lubrication system is investigated. Tests were conducted for nanolubrication mixing ratios of 0.0, 0.1, 0.2, 0.5, 0.55, 0.6, and 0.8 wt% with plain bearings rotated by a 2,750-rpm high-speed motor. For each mixing ratio, the frictional temperature and wear rate of the rotating sliding bearings were recorded and compared. During surface testing, the surface roughness values of the sliding bearings were compared and the results showed an improvement in surface roughness after the tests. According to the outcome, the optimum tribological performance of nanolubricant was obtained at 0.5 wt% mixing ratio.
Manufacturing industries have been pressured to use less power and reduce pollution by the development of power-efficient and pollution-preventing policies from the government. However, quality and cost are of main concern in this agenda. In machining, the key solution for this issue is by increasing the effectiveness of existing lubrication systems as this reduces the power required to overcome the friction component in machining processes for less fuel consumption and pollution. In machining processes, in particular, improved lubrication systems will increase batch production rates with better product quality. Introducing nanolubrication reduces power consumption as the rolling action of a billion units of nanoparticles in the tool chip interface decreases the cutting forces significantly. Additionally, using nanolubrication in machining minimizes the consumption of the lubrication oil, which decreases pollution. Detailed analysis and implementation of nanolubrication in machining process with the proper parameter setup are mandatory to ensure the efficiency of implementing nanolubrication. In this research, SiO2 nanoparticles are mixed with ordinary mineral oil having 0.2% weight concentration. A proper sonification method is used to mix and suspend the particles thoroughly and efficiently. The results show a reduction in the coefficient of friction in the tool/chip interface. Hence, the cutting force and working power are reduced considerably compared with conventional lubrication systems. Consequently, considerable power savings, less oil consumption, and less pollution are achieved.
Aluminium AL6061-T6 is a common alloy which is used for many purposes since it has the superior mechanical properties such as hardness and weldability. It is commonly used in aircraft, automotive and packaging food industries. Milling of Al6061-T6 would be a good process especially in producing varieties shape of products to adapt with different applications. The capability of the CNC milling machine to make batch production would be a noteworthy advantage. However, the demand for high quality focuses attention on product quality, especially the roughness of the machined surface, because of its effect on product appearance, function and reliability. Introducing correct lubrication in the machining zone could improve the tribological characteristic of Al6061-T6 leading to higher product quality. In this research work, the optimum SiO 2 nanolubrication parameters in milling of Al6061-T6 are investigated to achieve correct lubrication conditions for the lowest cutting force, cutting temperature and surface roughness. These parameters include nanolubricant concentration, nozzle angle and air carrier pressure. Taguchi optimization method is used with standard orthogonal array L 16(4) 3. Furthermore, analyses on surface roughness and cutting force are conducted using signal-to-noise (S/N) response analysis and the analysis of variance (Pareto ANOVA) to determine which process parameters are statistically significant. Finally, confirmation tests were carried out to investigate the optimization improvements.
In machining of very high precision Duralumin AL-2017-T4 for aerospace applications, the shape varieties of the product lead to many different complicated shapes to be developed. The computer numerical control (CNC) milling machine facilities provides a wide variety of parameter set-up, making the machining process on the Duralumin AL-2017-T4 excellent in manufacturing complicated special products compared with other machining processes. However, the demand for high quality and fully automated production focuses attention on the cutting process, which are partial determinant of the quality of surface and affects the appearance, function, and reliability of the products. The key solution is to increase the effectiveness of existing lubrication systems in the machining process in order to improve product quality as it could reduce the friction component at the tool-chip interface. For further improvement, introducing the nanolubrication system could reduce the cutting force and produce much better surface quality as the rolling action of billions units of nanoparticles at the tool-chip interface could reduce the coefficient of friction significantly. In this study, carbon onion has been used as nanoparticle mixed with ordinary mineral oil at different concentrations to investigate the cutting force reduction and the surface quality improvement of CNC end-milling machined Duralumin AL-2017-T4. From the results, with using of carbon onion nanolubricant, the cutting force and surface roughness values are reduced by 21.99 and 46.32 %, respectively, compared with the case of using ordinary lubrication systems. This can be attributed to the tribological properties of carbon onion, which reduces the coefficient of friction at the tool-chip interface during the machining process.
Aluminium AL6061-T6 is a common alloy which is used for many purposes since it has the superior mechanical properties such as hardness and weldability. It is commonly used in aircraft, automotive and packaging food industries. Milling of Al6061-T6 would be a good process especially in producing varieties shape of products to adapt with different applications. The capability of the CNC milling machine to make batch production would be a noteworthy advantage. However, the demand for high quality focuses attention on product quality, especially the roughness of the machined surface, because of its effect on product appearance, function and reliability. Introducing correct lubrication in the machining zone could improve the tribological characteristic of Al6061-T6 leading to higher product quality. In this research work, the optimum SiO2 nanolubrication parameters in milling of Al6061-T6 are investigated to achieve correct lubrication conditions for the lowest cutting force, cutting temperature and surface roughness. These parameters include nanolubricant concentration, nozzle angle and air carrier pressure. Taguchi optimization method is used with standard orthogonal array L16(4)3. Furthermore, analyses on surface roughness and cutting force are conducted using signal-to-noise (S/N) response analysis and the analysis of variance (Pareto ANOVA) to determine which process parameters are statistically significant. Finally, confirmation tests were carried out to investigate the optimization improvements.
Metal cutting is accompanied by extensive plastic deformation and fracture. Quick stop sectional specimens of the chip formation of medium carbon and resulphurised free cutting steel have been studied in order to determine the nucleation and growth mechanism of cracks during machining and their relation to the fracture process. During machining two main types of cracks were observed: internal crack formation in the primary shear zone and cracks associated with the formation of the built up edge (BUE). Internal crack formation is due to void formation either at MnS inclusions or on the ferrite/pearlite interface, while cracks associated with the BUE were formed below the flank face and ahead of the rake face of the tool. The type of chip formation was classified according to the mechanism of crack formation. In both of the steels used, quasicontinuous chips and chips with BUEs were obtained. Although, the quasicontinuous chips contained cracks and voids, they did not propagate right through the shear band, so that the chip remained continuous. Discontinuous chip formation occurred only in resulphurised free cutting steel as crack propagation and void coalescence progressed right through the shear band.
Friction between the rake face of a cutting tool and the freshly formed chip surface plays a vital role in influencing both the ease of cutting and the quality of the resultant machined surface. The existence of clean surfaces together with the high local hydrostatic stresses favour the formation of strong adhesion between the cutting tool or insert and the machined component. These adhesive bonds can lead to poor surface integrity although their extent can be limited by the provision of a suitable machining lubricant.In an effort to identify the essential lubricating aspects of fluid activity, as opposed to any role as a coolant, experiments involving the orthogonal machining of precipitation hardened aluminium alloys, principally 2014, have been carried out in controlled low pressure environments in which, for a given feed (that is the depth of cut), speed and temperature have been varied while using a variety of lubricating species in vapour form in combination with high speed steel cutting inserts. The results indicate that there can be unexpectedly subtle, but significant, interactions between the metallurgy of the workpiece, the surface of the tool and the surrounding environment. These are not wholly consistent with conventional theories of vapour phase lubrication in which transport of the lubricant has been assumed to control the effectiveness of the lubricating agent. The implications of these observations for the complex tribological system constituted by the combination of workpiece, tool surface and local environment are discussed.
In machining of very high precision Duralumin AL-2017-T4 for aerospace applications, the shape varieties of the product lead to many different complicated shapes to be developed. The computer numerical control (CNC) mill-ing machine facilities provides a wide variety of parameter set-up, making the machining process on the Duralumin AL-2017-T4 excellent in manufacturing complicated special products compared with other machining processes. How-ever, the demand for high quality and fully automated production focuses attention on the cutting process, which are partial determinant of the quality of surface and affects the appearance, function, and reliability of the products. The key solution is to increase the effectiveness of existing lubrication systems in the machining process in order to improve product quality as it could reduce the friction component at the tool–chip interface. For further improve-ment, introducing the nanolubrication system could reduce the cutting force and produce much better surface quality as the rolling action of billions units of nanoparticles at the tool–chip interface could reduce the coefficient of friction significantly. In this study, carbon onion has been used as nanoparticle mixed with ordinary mineral oil at different concentrations to investigate the cutting force reduction and the surface quality improvement of CNC end-milling ma-chined Duralumin AL-2017-T4. From the results, with using of carbon onion nanolubricant, the cutting force and surface roughness values are reduced by 21.99 and 46.32 %, respec-tively, compared with the case of using ordinary lubrication systems. This can be attributed to the tribological properties of carbon onion, which reduces the coefficient of friction at the tool–chip interface during the machining process.
Cost, the effect on the environment, and health issues are all relevant when considering the choice of a lubricant and application system in a modern metal cutting process. The need to use less, limit the disposal and operator contact are all now very important. This paper shows the results of preliminary tests using very low quantities (200–300 ml h−1) of lubricant when machining steel. The low quantities were applied in a fast flowing air stream. The results are compared to traditional flood cooling as a benchmark with 5.2I min−1. The results show that surface finish, chip thickness and force variation are all affected beneficially with the low coolant volume compared to flood cooling.
When using cooling and lubricating process fluids (PF), a contamination occurs, due to the technological process. These contaminations have a negative effect on decreasing the fluids lifespan and changes in their functional attributes. That can be strongly expressed not only by inappropriate actions of the fluid during the technological process, but also increased economic costs. Using natural fillers in a form of nanoparticles has a high efficiency due to their high chemical and biological activity. Using nanoparticles is one of the ways to inhibit bacteria and improve biological, chemical and technological stability of the process fluids. Not less important are technological attributes of the process fluids, especially their tribological and anti-adhesion behaviour. Main goal of the tribology is to ensure that the relative motion of two surfaces is happening with the least energy and material loss. Lifespan of the water miscible fluids is one of the main factors defining the fluid quality.
The marketplace is continually demanding better functionality in the surface and near-surface properties of metal components and tools. In the last 20 years, plasma and ion-assisted techniques have enabled new methods to substantially improve wear, corrosion, and fatigue resistance. In most cases, plasmas are used to enhance well-established processes such as thermochemical diffusion treatment and physical and chemical vapor deposition (PVD and CVD), but their operation in a plasma atmosphere has led to major improvements in their reliability and efficacy, as well as extending the range of materials and components that can be treated.
Owing to environmental concerns and growing regulations over contamination and pollution, the demand for renewable and biodegradable cutting fluids is rising. In this review paper, an attempt is made regarding of green machining including the cutting fluid type as well as the methods to apply the cutting fluids in machining process. Knowledge of the cutting fluid types and its machining conditions are critically important in order to maximize the efficiency of cutting fluids in any machining process. Generally, heat generation at the cutting zone due to the friction at tool-chip interface, and friction between the clearance face of the tool and work-piece is always the decisive factor on the surface quality of the work-piece. A good understanding of the methods to apply cutting fluid at the cutting zone may significantly reduce the heat generation in machining and thus improve the surface roughness. Surface roughness and tool wear are always used as a quality indicator of a finished or semi-finished product. This paper reviews the developments in bio-based cutting fluids by using various vegetable oils and their performances in machining. Undoubtedly, these bio-based cutting fluids have significantly reduced the ecological problems caused by mineral-based cutting fluids. An overview of the cleaner application techniques of dry cutting, minimum quantity lubrication (MQL), and cryogenic cooling is also well presented. These techniques largely minimized the amount of cutting fluids used in machining while providing similar or even better cutting performances compared to wet cooling methods.
This detailed the tribological and tribochemical properties of magnetite (Fe3O4) nanoflakes used as additives in #40 base oil in a four-ball tribo-tester. The average friction coefficient of the friction pair for lubricant containing the Fe3O4 nanoflakes of 1.5 wt% as a lubricant additive in the base oil is decreased by 18.06% compared to that of solely base oil. The chemical composition of base oil with the Fe3O4 nanoflake additives did not change during the 48-h friction assessment. The decreased saturation magnetization and increased coercivity of magnetite nanoflakes occurred due to the distortion of the basal planes and the presence of hematite (α-Fe2O3) generated by the tribochemical reactions during the friction process. The multi-layer low-shear-stress tribochemical lubrication films on the surface of the friction pair could form because the nanoflake particles arrange and adhere onto the surface of the friction pair in an orderly manner, and the tribochemical reactions of the friction pair in the presence of the nanoflakes occur as Fe → FeO → Fe3O4 → γ-FeOOH → γ-Fe2O3 → α-Fe2O3. The formation of the films can improve the tribological properties.
This paper presents an experimental study on the enhancement effect of the low viscosity cutting fluid enriched with nano-droplets (NDCF) in ultra-precision turning. Unlike the conventional method in which the enhancement is done by adding nano-metric particles, no suspension particles are mixed to produce the NDCF in this paper. Instead, the NDCFs are produced by atomisation of the cutting fluid that circulates in a closed-loop treatment device. The atomisation process is found to reduce the viscosity of the NDCF significantly by the formation of nano-droplets (NDs). The reduced viscosity of the NDCFs could be increased by diluting them with water. The bench tests on wetting properties reveal that the NDCF demonstrates two distinct properties: a very linear spreading rate and a relatively low contact angle. These two properties assist the NDCF in penetrating deeper into the tool–chip and tool–work interfaces and hence provides a better lubrication effect at these interfaces. In this paper, the ultra-precision cylindrical turning experiments reveal that the droplet size of the NDCF is a more important factor than viscosity on affecting the surface finish in ultra-precision machining.
This work studies the tribological properties of liquid paraffin to which diamond and SiO2 nanoparticles, which were prepared by the surface modification method using oleic acid, had been added and observed by scanning electron microscopy (SEM) and infrared (IR) spectroscopy. Also, the dispersion capability and stability dispersivity of both modified nanoparticles in liquid paraffin were measured using a spectrophotometer. The measurements show the dispersion capacity and the dispersing stability of oleic acid-modified diamond and SiO2 nanoparticles in liquid paraffin.The tribological properties are evaluated using a ball-on-ring wear tester. The results show that both nanoparticles as additives in liquid paraffin at a tiny concentration have better antiwear and antifriction properties than the pure paraffin oil. Also, SEM was used to observe the plowing of nanoscale grooves of worn surfaces by diamond and SiO2 nanoparticles.
Four kinds of solid lubricants were tested in order to examine the frictional characteristics and the yield shear str ess by the friction resting apparatus developed by the authors. The frictional shea stresses tau (f) increased approximate linearly with the punch pressure p in every solid lubricant, and the friction coefficients mu were approximately constant The yield shear stress k was also increased with the punch pressure p. In order to investigate lubrication behaviors of solid lubricants in upsetting processes, FEM simulations Sor upsetting of circular plates have been carried out. Some experimental upsetting tests of circular plate were tried using some kinds of solid lubricants. It has been confirmed that the solid lubricants can lubricate successfully without metal-to-metal contact when mu (D) at the interface between tool and solid lubricant is relatively low and mu (M) at the interface between work piece and solid lubricant is relatively high. On the other hand, metal-to-metal contact occurs easily at the peripheral regions of the work piece, when mu (D) is relatively high and mu (M) is relatively low. [S0742-4787(00)00804-3].
Nanofluids, which are liquids with engineered nanometer-sized particles suspensions, have drawn remarkable attraction from
the researchers because of their enormous potential to enhance the efficiency in heat-transfer fluids. In the present study,
water-based calcined mesoporous silica nanofluids were prepared and characterized. The commercial mesoporous silica (MPSiO2) nanoparticles were dispersed in deionized water by means of pH adjustment and ultrasonic agitation. MPSiO2 nanoparticles were observed to have an average particle size of 350 ± 100 nm by SEM analysis. The concentration of MPSiO2 was varied between 1 and 6 wt%. The physicochemical properties of nanofluids were characterized using various techniques,
such as particle size analyzer, zeta-potential meter, TEM, and FT-IR. The thermal conductivity was measured by Transient Plane
Source (TPS) method, and nanofluids showed a higher thermal conductivity than the base liquid for all the tested concentrations.
The intense heat generated in grinding process, if not controlled, will lead to major quality defects. Conventional liquid coolants, employed in flood form, have many limitations from technical, environmental and economic angles. Minimization or possible elimination of cutting fluids by substituting their functions by some other means is emerging as a thrust area of research in grinding. The authors have reported the feasibility of application of solid lubricants in grinding. This paper deals with the detailed investigations on solid lubricant integrated grinding wheels, by providing peripheral graphite sandwiching. Improvement in process results has been observed with this concept.
The vast majority of machining operations exploit the good cooling and lubricating characteristics of cooling lubricants (CL). But, as costs for waste disposal increase, companies are now being forced to implement strategies in order to reduce the amount of CL used in their production lines. The most logical measure which can be taken to eliminate all of the problems associated with the use of CL is dry machining. In most cases, however, a machining operation without lubricant finds acceptance only when it is possible to guarantee that the part quality and machining times achieved in wet machining are equalled or surpassed. The introduction of dry machining techniques may also include the use of minimal quantities of lubricant (MQL). The following paper deals with the most recent developments in dry cutting.
Eight titanium complex greases (i.e., benzoic acid/stearic acid and sebacic acid/stearic acid titanium complex greases, and
greases containing PTFE, or nano-titanium dioxide, or nano-silicon dioxide) were synthesized using 3-L reaction vessel. Their
physical characteristics were characterized and their tribological properties were evaluated by using a four-ball tester.
Chemical compositions of the boundary films generated on worn surfaces were analyzed with the use of scanning electron microscope
and X-ray photoelectron spectrometer. Results show titanium complex greases containing PTFE, or nano-titanium dioxide, or
nano-silicon dioxide exhibited excellent tribological performance. The mechanism for the friction-reduction and antiwear effect
of all titanium complex greases was also proposed and discussed from a tribochemistry point of view.
KeywordsNanoparticle-Polytetrafluoroethylene-Titanium complex grease-Antiwear ability-Load-carrying capacity-Friction-reduction property
This paper presents a combined static and dynamic mechanisms-based model for predicting the effective thermal conductivity of nanofluids. The model includes the effects of particle size, nanolayer, Brownian motion, and particle surface chemistry and interaction potential which are the static and dynamic mechanisms responsible for the enhanced effective thermal conductivity of nanofluids. Present model shows reasonably good agreement with the experimental results of several types of nanofluids and gives better predictions compared to the existing models.
Environmental friendly cutting fluids and cooling techniques in machining
- S Debnath
- M Reddy M
- Q S Yi
DEBNATH, S., REDDY M. M., YI, Q. S. (2014). Environmental friendly cutting fluids and cooling techniques
in machining, Journal of Cleaner Production 83, p. 33-47, ISSN: 0959-6526.
The impact of natural nanoadditive on the tribological and chemical properties of process fluids
- T Bakalova
- P Louda
- L Voleský
- L Iklavová
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