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Structural state and tribological properties of Co-P coatings
Abstract
The structural state and the tribological properties of electrochemical Co-P coatings with a concentration of phosphorus of 1.5–20 at % have been studied. It has been found that, in the Co-P coatings with phosphorus concentrations of less than 8 at %, a solid solution is formed of phosphorus in the matrix α-Co phase. The Co92P8 coating has an amorphous-crystalline structure. At phosphorus concentrations of ≥10 at %, coatings with an amorphous structure are formed. The mechanism of the formation of the structure during the deposition of coatings with various concentrations of phosphorus has been discussed. It has been shown that the best tribological properties are characteristic of the crystalline Co-P coatings with a phosphorus concentration of 3 at % and of the amorphous coatings with a phosphorus concentration of 20 at %. The conclusion has been drawn that the wear resistance of the amorphous Co-P coatings is determined by the deformation-thermal stability of their amorphous structure.
... In Table 2, the wear rate was 4 × 10 −6 -5 × 10 −6 mm 3 /N m and changed little no matter how the samples were deposited or treated, and the value was within the measurement error range. The wear rate of coatings was controlled not only by hardness, but also other factors such as microstructure (grain size, crystalline, P concentration [22]). Co-P coatings transformed from amorphous to a nanocrystalline state after heat treatment. ...
... Co-P coatings transformed from amorphous to a nanocrystalline state after heat treatment. The crystallized zones of coatings, having a substantially smaller specific atomic volume than the amorphous matrix, underwent higher tensile stresses, leading to the accelerated nucleation and propagation of microcracks in the crystalline layer, eventually increasing the wear rate of coatings during friction [22]. The second possible reason is that the nanocrystalline structure and Co-P compounds made it easier for the coatings to form hard particles during the wear, rather than only plastic deformation. ...
Cobalt-phosphorus (Co-P) alloy is a promising material for the replacement of traditional hard chromium alloy of high hardness. In this paper, the cobalt-phosphorus alloy layer with high phosphorus content was formed by electrodeposition in a cobalt sulfate solution system under direct current (DC), single pulse (SP) current and double pulse (DP) current, separately. Surface morphology, structure and properties of the deposited layer were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Vickers microhardness and a neutral salt spray test, respectively. The results showed that the dense Co-P coatings could be obtained by DC, SP and DP with P content of 9.6, 8.9 and 9.1 wt %, respectively. After 30 min heat treatment at 400 °C, coatings deposited under DC, SP and DP currents transformed from an amorphous to a nanocrystalline state, while the grain size was 12-13 nm, 10-12 nm and 8-10 nm, respectively. Among all these conditions, the microhardness of coatings deposited under DP current was the highest, which was 1211 HV, while the microhardness of coatings deposited under DC current was the lowest but higher than that of hard chromium. The wear rate of Co-P coatings was 4 × 10 ⁻⁶ -5 × 10 ⁻⁶ mm ³ /N m with Si 3 N 4 ball as bearing material, which was lower than that of hard chromium. In coatings deposited under different currents with a thickness of ca. 40 μm, no visible corrosion area appeared after 1000 h of a neutral salt spray test. Coatings heated at 300 and 400 °C reached the corrosion grade 7 and grade 4-5, respectively after 1000 h of a neutral salt spray test, so the wear resistance of Co-P coatings was better than that of hard chromium.
... Molecules can be separated by the effects of shape and size on their possible orientation in the pores, or by differences in adsorption power. Zeolites have a porous structure that can replace a wide range of cations such as Na+, K+, Ca2+, Mg2+ and others [16][17][18][19]. ...
Marijuana use has increased in Chile in recent years, especially among young people and adolescents, and there seems to be a general perception that its use does not entail greater risks. The current discussion on the legalization of marijuana must make the necessary distinction between medicinal use and recreational use of it. There are few indications approved by international health organizations for its medicinal use, all of them with synthetic derivatives for oral administration, and countless other indications based mostly on studies that suffer from serious methodological deficiencies. The recreational use of marijuana, in addition to the widely known deleterious psychosocial effects, induces the appearance of chronic airway symptoms, local inflammation and immunomodulatory effects on the respiratory system and, depending on the time and amount of exposure, has been associated with adverse effects. negative on lung function, development of COPD and lung cancer. Therefore, the unrestricted recreational use of this drug could have a great unfavorable impact on personal and public health in the future, so the free consumption of marijuana should not be recommended.
... Molecules can be separated by the effects of shape and size on their possible orientation in the pores, or by differences in adsorption power. Zeolites have a porous structure that can replace a wide range of cations such as Na+, K+, Ca2+, Mg2+ and others [16][17][18][19]. ...
Zeolites are a group of hydrated aluminosilicates crystallized with fine pores that contain equilibrium cations of alkaline and alkaline earth metals (Na+, K+, Mg2+ and Ca2+) and reversibly absorb and release water. One of their characteristics is that they are able to reabsorb and re-release water and exchange some of their own building cations without major changes in their building. The presence of metals in the water of rivers and seawater poses a serious threat to the health of the aquatic community, the most common of which is damage to the gills of fish. Metals such as lead, cadmium, copper, arsenic, nickel, chromium, zinc, mercury, iron are known as heavy metals. These metals tend to accumulate in environmental systems and seriously contaminate soil and water, which can be harmful to humans, animals and plants even in low concentrations. Unlike biodegradable organic matter, metal ions are not removed from aquatic ecosystems by natural processes, which encourages scientists to develop new methods for removing heavy metal ions from water. As a result, in many countries, laws have been introduced to control water pollution. Various regulatory bodies have set maximum limits for the discharge of toxic heavy metals into aquatic systems. However, metal ions with a much higher concentration than usual are discharged into the water by industrial activities, leading to health hazards and environmental degradation.
... This powder also used increasingly in ceramic industry especially in pipe industry and valve and also is used very pervasive in pipes which coated with alumina to prevent heat exchange and heat-resistant high [9][10][11][12]. Present alumina are used widely in industries like paints, inks, coatings of various Posts glue rubber, pharmaceutical industry, tiles, refractory bricks, kitchen, electronics, accessories, accessories, and dental plastics [13][14][15][16][17]. Material drying with spraying feed into the tower, which called spray dryer briefly, has definition as the following: Transformation of feed flow from fluidity to the solid state and dry using hot air spraying into the food inside a tower [18][19][20][21][22]. Spraying operation occurs with spray (Atomizer) which liquid feed broken to a large number of small droplets and as a result of this action large level of Corresponding author. ...
Spray dryers are one of the most important dryers and have many applications in the food, drug and chemical industries. In this investigation, a model is suggested to predict the product temperature, drying time and the dryer height In order to evaluate the dryer performance in different operational conditions. To achieve this, knowledge of the drying kinetics and the transfer phenomenon are necessary. The main aim in this project is, modeling of the spray drying of Alumina Slurry in a co current dryer.In this modeling Mass, heat and momentum transfer equations on droplets and hot air have been written. By writing a computer program for the simultaneous solution of mass, energy and momentum balances, a mathematical model is introduced. In order to evaluate the accuracy of the model, the experimental data were used and results showed good agreement between the theory and the experiments. By using the results of the model, the change in the dryer input parameters and their effect on final product characterizations have been studied.
... For this, the importance of using other adsorbents that have a higher adsorption capacity and are also inexpensive, to remove heavy metals from the effluent can be justified. Beta zeolite nanocrystals have certain abilities to absorb elements such as lead, cadmium, zinc, arsenic, vanadium and uranium due to the presence of various reactive surface areas on beta zeolite nanocrystals [5][6][7][8][9]. The efficiency of copper removal from water using nanocrystals is beta zeolite, which is made and released in laboratory conditions [10]. ...
Heavy metals, including copper, are one of the most toxic pollutants in the world today due to the consumption prevalence in industry. There are several ways to remove copper from wastewater, each of which has advantages and limitations. Adsorption is one of the easiest and most commonly used methods to remove heavy metals from aqueous environments. On the other hand, the production of cheap adsorbents using waste from different factories can play an important role in reducing environmental pollution. For this, using copper ion (II) adsorption was investigated using a nanoscale zeolite beta adsorbent through batch adsorption experiments. In the following, various parameters affecting the adsorption process such as pH, initial concentration, temperature, adsorbent amount and contact time were investigated. The highest removal efficiency was observed at pH = 5 at 25 °C for 25 minutes, with a 0.25 g of nanocrystalline zeolite beta in 20 ml of copper solution. The traditional study of copper adsorption by nanocrystalline zeolite beta results in a well-respected second-order pseudo-model. Also, the adsorption thermodynamic studies indicate that the adsorption data is followed by the Doubinin-Raduskovich equivalence model with a correlation coefficient (R2 = 0.9963) at a temperature of C50.
... According to shape and size, particles of active carbon are divided into powder, grain and pellets [55]. If between 65 to 90 percent of the particles pass through sieve mesh 325, it called powder and if the average particle diameter be 200 microns, the carbon calls grain [56][57][58]. ...
Use of activated carbon in waste water treatment is not a new idea, therefore since 1935 experience has been gained in its use to increases the coagulation and flocculation of solids, anaerobic digestion of sludge and for removal of water from it. Experience has shown that activated carbon powder as an additive at the time of addition of hydraulic load of waste water, results in the compression of sludge and facilitates the removal of water from it. In these experiments the usefulness of Powered Activated Carbon (PAC) is determined, but due to economical and the fact that high degree of treatment was not required, this was not fully accepted. In the past use of Granular Activated Carbon (GAC) was more popular compared to its powered type, and it also had higher efficiency. In this article, initially a literature review of work done on the use of Activated Carbon Powder and the trend of growth in its use and the modifications made during last few years in the world and Iran and finally various experiments performed on activated carbon pilot unit at one of the petro-chemical units in Iran, in order to analyze the usefulness of this material in waste water treatment. In addition, two type of commercial activated carbon powder were used from two different suppliers giving different results, the reason for these different results was also analyzed and this difference in result was attributed to different constituents. For every experiment 4kg of activated carbon was used in the pilot plant column. The samples for experiment were taken from the exit stream from the clarifier. Results were obtained for effect of parameters such as inlet volumetric flow rate of waste water and activated carbon structure on its performance.
... solution. Amine tetra-acetic acid ethylene (EDTA) is an amino acid is insoluble in water so used sodium salt solution which is soluble in water [15][16][17][18][19]. Zinc produced in variety business forms, including ingot, lump, sheet, wire bulleted lists, bar, Cornish and Polk. ...
Zinc is white, bluish or silver metal, very soft which is brittle in normal temperatures, easily breaks with hammer blows and could not be roll in ambient temperatures and could easily roll into sheets at 100- 150 degrees centigrade. Considering the importance of electrical energy consumption in electrical refining processes, electrowining, its great effect on production cost and other products parameters, including zinc and modeling process with SPSS software that have high credit grade model result, respectively. In this study, by using test equipment indicated that rising temperature causes reduce efficiency and increase consumed energy, and the most optimal flow density value for this process is 2400-300 A/m and electrolyte solution optimum concentration as: 60-50 zinc 140-120 Sulfuric acid, 200ppm manganese sulfate, 500ppm permanganate and gum are 500ppm. Also, energy consumption in Iran’s zinc production industry is 4.5 and in developed countries industry is 3.3 . In this study, consumption energy reduced to 2.75 , which, reduction in energy consumption is about 17 percent of advanced industrial countries and about 40 percent of Iran’s industry.
... There are two factors involved in wear resistance decrement in amorphous deposits after heat treatment, (i) the higher atomic volume fraction in crystalline films than amorphous ones, experienced more severe tensile stress, resulting in faster nucleation and propagation of the microcracks. This can markedly enhance the wear rate during the wear test [150] and (ii) the crystalline structure favours the formation of hard Co-P compounds during the post-annealing, rather than plastic deformation. These compounds give rise to abrasive wear, degrading the wear resistance [95]. ...
Hard chromium coatings have attracted much attention due to their strong tribological and corrosion performance. There is a global need to replace such coatings in industrial applications owing to technical problems, environmental concerns and legislation. Co-P electrodeposits are a promising alternative to hard chromium in a variety of engineering applications due to their appreciable microhardness and high corrosion resistance. Attractive magnetic, tribomechanical and electrical properties are evident together with excellent thermal stability. Environmentally acceptable process conditions may be used which allow controlled deposition on diverse workpieces across a wide scale. This review provides an overview of the influence of operational parameters, including type of current control, electrolyte composition, pH, current density and electrolyte agitation on the physicochemical and mechanical characteristics of the deposits. The incorporation of ceramic particles into Co-P electrodeposits to produce tailored composite coatings is also considered. An insight is given into the development of next generation alloy and composite deposits to replace hard chromium deposits from acidic Cr(VI) baths. Diverse applications for Co-P electrodeposits are considered and topics deserving further R & D are highlighted.
The hard chromium coatings have drawn vast attention due to their fascinating tribological behavior, however, there is a serious determination to alleviate their industrial applications. In this assay, an attempt is made to evaluate whether the electrodeposited Co-P-MoS2 films with various loadings of MoS2 nanoparticles, 0-20 g/L, fabricated under different current densities from 20 to 35 A dm⁻² are suitable alternative tribological coatings to hard chromium. The tribomechanical behavior of layers was assessed using Vickers microhardness and pin-on-disc surveys. Co-P-10 g/L MoS2 film obtained at 25 A dm⁻² offers the highest wear resistance. An increase of 18% in microhardness, a decrease of 50% in the coefficient of friction, and a decrease of 95% in wear volume loss are obtained.
The effects of heat treatment on the properties of electrodeposited Co–P–TiO2 nanocomposite coatings were systematically investigated. The TiO2 nanoparticles-reinforced Co–P–TiO2 nanocomposites were heat-treated at different temperatures. Thermal analysis was conducted to characterize the structural transitions. The phase constituents and surface morphology of nanocomposites were identified. The mechanical properties including microhardness and wear tests were examined, and the electrochemical behaviour of Co–P–TiO2 was determined. At the increasing heating temperature, the structure of Co–P–TiO2 was gradually changed from amorphous into crystalline, with its surface morphology being smoother. Proper heat treatment can significantly improve the mechanical properties and corrosion resistance of coatings. When Co–P–TiO2 coating was heat-treated at 350°C, a smooth and flat surface morphology was obtained and optimal physicochemical performance among the examined coatings was achieved.
The structural state and durometric properties of electrodeposited Ni–P and Co–P coatings subjected to low-temperature annealing at 520–540 K have been investigated. It has been shown that the low-temperature annealing of crystalline Ni–P and Co–P coatings is accompanied by a substantial increase in the parameters of crystal lattices of the solid solutions of phosphorus in nickel and cobalt, and also by an increase in the hardness of coatings. The conclusion has been drawn that an increase in the hardness and in the lattice parameters of Ni–P and Co–P solid solutions upon annealing is connected with the passage of phosphorus atoms from the substitutional into interstitial positions by the Frank–Turnbull dissociative mechanism.
The structure and tribological properties of Ni-B and Co-B galvanic coatings with boron concentration from 4 to 20 at % are
investigated. The coatings containing over 8 at % B are shown to have amorphous structures. Ni-B and Co-B coatings with boron
concentrations preceding the onset of amorphization (6–7.5 at %) possess optimal tribological properties under dry sliding.
Coatings with metastable amorphous structure demonstrate the worst tribological behavior. An increase in boron concentration
up to 20 at % stabilizes the amorphous structure and improves the wear resistance, microhardness, and thermal stability of
the galvanic coatings in question.
Co-B alloys containing 3–22 at % boron were produced by electroplating from a cobalting bath containing sodium decahydro-closo-decaborate as a source of boron. Alloys containing 3–8 at % boron are found to be mixed substitutional-interstitial solid solutions with an α-Co crystal lattice. At a boron content of 15 at % or higher, amorphous coatings are formed. The microstructure of amorphous alloys is characterized by the existence of regions with different substance density. With an increase in the boron content from 16 to 20 at %, the regions of the increased and decreased substance density become larger and more pronounced. The existence of chemical bonds between cobalt and boron atoms was discovered with the use of X-ray photoelectron spectroscopy.
The influence of electroless plating conditions on the magnetic properties and structure of Co-P films was studied. The coercivity and the morphology of the coatings were found to be dependent on the ratio of glycine to Co(II), the concentration of hypophosphite, the pH and the temperature of the solution. No direct correlation between the coercivity and the prevailing orientation of crystallites in the Co-P films was found. The inclusion of glycine and Co(OH)(2) in the coatings was found to occur under certain conditions as a result of the adsorption on crystallites modifying their growth.
The structural condition and wear resistance of electrochemical Co-B and Ni-B coatings with different amounts of boron, as well as Ni-Co-Fe-Cr-Mo-Si-B and Ni-Fe-Si-B amorphous alloys obtained by rapid solidification from the melt have been studied. It has been found that in Co-B and Ni-B coatings with a boron concentration less than 8 at %, there is formed a solid solution of boron in the matrix phase, and the coatings are characterized by a high fracture strength upon friction. At a boron concentration from 8 to 15 at %, there is formed in the coatings a metastable amorphous structure with a decreased wear resistance. An increase in the B concentration to 20 at % stabilizes the amorphous structure of coatings, which leads to an increase in their fracture strength. A conclusion is made that during friction interaction at the surface of amorphous layers there are formed crystalline layers, which are subject to tensile stresses and are characterized by a decreased fracture strength. The difference in the wear resistance of the alloys studied is explained by a different deformation and thermal stability of the amorphous structure of the material.
This paper surveys some ideas on the glass forming tendency of monatomic systems. According to the free volume model, glass formation in such systems would result primarily from “jamming” due to the action of repulsive forces. From this viewpoint the metals most prone to glass formation should be those in which the repulsive part of the pair potential is, relatively, the largest; these are the noble, transition and polyvalent metals. Actually the most stable metal glasses formed so far are alloys of noble or transition metals (A) with compositions predominantly in the range A3B to A5B where B is a metalloid. The A elements may form a skeleton having a Bernal dense random packed structure which may be somewhat stabilized by filling its holes with metalloid atoms in the manner suggested by Polk. Some additional ideas on the effect of alloying on metal glass forming tendency are discussed.
Polycrystalline and amorphous cobalt-boron coatings were electrochemically deposited. The effect of the boron content and
heating temperature on the physicomechanical properties of the coatings was studied. A relationship between the composition,
structure, and properties of the coatings was established.
Structural evolution of the amorphous alloy Ni70Mo10P20 has been studied by x-ray diffraction, and by following transmission and high-resolution electron microscopy annealing both
above and below the glass-transition temperature. When annealed above this temperature, the amorphous phase undergoes segregation
into regions about 100 nm in size having different chemical composition. Diffraction from such samples produces diffuse rings,
and the scattering vector corresponding to the maximum intensity varies from point to point within the interval of 4.88 to
4.78 nm−1. When occurring between the glass-transition and crystallization temperatures, crystallization produces groups of nanocrystals,
20–30 nm in size, which are in direct contact with one another and form a polymorphic mechanism. The crystallization mechanism
changes when the annealing temperature is brought below the glass-transition point. At these temperatures the amorphous matrix
crystallizes entectically with formation of eutectic colonies.
A phenomenological theory of the martensitic fcc-hcp transformation is proposed and applied to the illustrative example of cobalt. The fcc and hcp structures are shown to result from different ordering mechanisms from a disordered polytypic structure and to be intrinsically faulted. The three, fcc, hcp, and disordered polytype, structures are inserted in the framework of the segregation process which leads to the formation of close-packed structures from the melt. The essential features reported for the fcc-hcp transformation in cobalt are explained within the preceding model, namely, the asymmetry of the interphase region, the phonon spectrum, the δ-shape of its specific heat anomaly, and the existence of an intermediate modulated structure. The property of the transformation enthalpy to be different on heating and cooling is related to the different degree of order of the hcp and fcc structures. The partial dislocation mechanism currently assumed for the transformation is deduced from the secondary shear strains involved at the transformation.
X-ray diffraction and differential thermal analysis are used to study the effect of pulse-current regimes on the structure
and thermal stability of electrodeposited Co-P alloys. The temperature of the onset of crystallization of these alloys upon
heating is found to increase as the phosphorus content increases. Phases, such as β-Co and Co2P, are determined to be the end products of crystallization of the Co-P amorphous (in terms of X-ray diffraction) and microcrystalline
alloys. Relaxation processes in these amorphous and microcrystalline structures are shown to be mainly affected by nonequilibrium
crystallization conditions upon pulsecurrent electrolysis that are caused by high-rate changes in the cathode overvoltage.
Titanium and zirconium alloys are considered to be promising materials for orthopaedics because of their biocompatibility with tissues. Their main drawbacks for application as implants have generally been considered to be insufficient levels of mechanical and tribological properties. In this research the influence of equal channel angular pressing and nitrogen ion implantation on the structure and properties of Ti and Zr alloys has been investigated to ensure the optimum combination of the bulk material and surface layer properties. The data obtained showed that equal channel angular pressing and nitrogen ion implantation can be efficiently used to improve bulk and surface properties of Ti and Zr based implants.
Après une revue détaillée des différents modèles d'assemblage compact désordonné qui ont été construits, soit à la main, soit par ordinateur, on effectue une comparaison entre ceux-ci en utilisant une description en polyèdres de Voronoï. On pose ensuite le problème de la reconnaissance parmi ces modèles, de celui qui serait susceptible de représenter le mieux la structure des alliages métalliques amorphes et des agrégats isolés. A critical review of laboratory and computer built random packings is given. The structural differences between these models are analysed using the Voronoï polyhedron description. Special attention is paid to the problem of identifying the best variant of random packings for modeling amorphous alloys and isolated aggregates.