Change In Wear Mechanism Research Articles

Effect of applied load on transition behavior of wear mechanism in Cu−15Ni−8Sn alloy under oil lubrication

Tribological behavior of Cu−15Ni−8Sn (mass fraction, %) alloy against GCr15 ring under various loads was investigated on a ring-on-block tester in oil lubrication. The results showed that the wear rate increased slowly from 1.7×10−7 to 9.8× 10−7 mm3/mm under the load lower than 300 N, and then increased dramatically to the climax of 216×10−7 mm3/mm under the load over 300 N, which indicated the transition of wear mechanism with the increase of applied load. The wear mechanism mainly was plastic deformation and abrasive wear under the load less than 300 N. As the applied load was more than 300 N, the wear mechanism of Cu−15Ni−8Sn alloy primarily was delamination wear. Besides, the transition can also be confirmed from the different morphologies of worn surface, subsurface and wear debris. It is distinctly indicated that the appearance of flaky debris at the applied load over 300 N may be a critical point for the change of wear mechanism.

Time-frequency analysis of the tribological behaviors of Ti6Al4V alloy under a dry sliding condition

Application of titanium and its alloys in the aerospace, biomedical and chemical industry has renewed researchers' interests in their tribological properties. This paper presents a new method for evaluating the kinetic friction and wear performances of Ti6Al4V alloy using a time-frequency approach. The short-time Fourier transform (STFT) was selected to analyze the time-frequency properties of the friction force signals collected in the tribological tests of Ti6Al4V alloy sliding against three different materials. The obtained results showed that the amplitudes of friction force signals were closely related to the differences in wear rates of the tribo-pairs. Furthermore, the frequency amplitudes of the friction force where high energy appeared increased with the sliding time during adhesive wear process and fluctuated significantly during abrasive wear. Meanwhile, the high amplitude at the fundamental frequency of the friction force in STFT indicate the formation of transfer films. To confirm the STFT-based tribological behaviors of Ti6Al4V against different counterbodies in a dry sliding condition, the wear rates and worn surfaces were examined using conventional methods. This study demonstrates that the wear rates and wear mechanisms of the tested samples as well as their changes with time can be identified from the amplitude, distribution and fluctuation of the frequency peaks of the friction force signals. Furthermore, the time-frequency analysis of the friction force is an effective way to study the time-dependent wear process of materials, in particular, changes in the dominant wear mechanism and wear rate.

Possibilities of increasing wear resistance of steel surface by plasma electrolytic treatment

The paper considers the effect of the anode plasma electrolytic treatment (PET) on tribological properties of steels after their boriding (PEB), nitriding (PEN), and nitrocarburising (PEN/C). Electrolyte compositions and processing temperatures improved wear resistance of samples under dry friction condition using a ball-on-disk test with an Al2O3 ball as counter-body are determined. The anode PEB of medium carbon steel in solution of boric acid and ammonium chloride (850°C, 5min) followed by quenching in electrolyte enables to decrease friction coefficient, surface roughness 3 by times, and volume loss by 3.7 times. This treatment results in the change of wear mechanism from abrasive-adhesive wear to polishing mode. The PEN of medium carbon steel in a solution containing ammonia and ammonium chloride (650°C, 5min) followed by quenching in electrolyte leads to decrease in friction coefficient from 0.65 to 0.45, surface roughness by a factor of 1.74, and volume loss by 4.6 times. PEN/C of low-carbon steel in electrolyte containing glycerol, ammonium chloride and ammonium nitride at 950°C also promotes surface roughness and wear rate reduction of by 9.5 times.

On the microstructure, hardness and wear behavior of Al-Fe-Cr quasicrystal reinforced Al matrix composite prepared by selective laser melting

Al91Fe4Cr5 quasicrystal (QC) reinforced α-Al matrix composite materials from the mixture of pure aluminum and Al65Cu20Fe10Cr5 QC powders were prepared by Selective Laser Melting (SLM) which can produce parts with sophisticated form and fine microstructure with near-zero material waste. The effects of process parameters (such as laser power and scanning speed) on the microstructure, hardness and wear behavior of SLMed composites were investigated with a special focus on the size and morphology of Al91Fe4Cr5 QC reinforcement. After laser melting process, an Al-rich QC phase (Al91Fe4Cr5) is formed. The grain size increases and its morphology changes from spherical to irregular with increment of laser power. Additionally, the sample obtained at relatively low laser power presents a mixed microstructure (partially melted QC, micro-QC and nano-QC) and high wear resistance. The instrumented indentation tests indicate that the partially melted QC particle present higher hardness than that of the other structure in the composite. Moreover, the wear mechanism changes from oxidation to delamination as the laser power increases.

Lubricated Wear of Machinable Lithium Disilicate Glass Ceramic

An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of Sa = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D /I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

Wear Characterization of High Temperature Oxidized Ni Based Superalloys

Objectives: Present manuscript deals with the study of wear performance of nickel superalloys namely Superni-76 and Superni750-X, by means of two bodies dry sliding wear method. Methods/Statistical Analysis: The wear performance of the superalloys was noted in as received conditions and after oxidizing the sample at 900°C for 50 hours. Hardened steel balls were used as abrasive body to evaluate the wear volume in each as received and oxidized samples. Findings: The wear volume was calculated with respect to time and sliding distance and graphs were plotted for both the superalloys. The weight change and types of oxides formed after oxidation were identified by XRD and EDX/EDS analysis. The wear surface was also characterised by using FE-SEM/EDS analysis to ascertain the mechanism of wear in the samples. From various characterisation results and observations of volume loss, the effect of oxidation was analysed for these superalloys. Oxidation affects the wear behaviour of nickel based superalloys. The wear mechanism changes due to increase in hardness and brittleness after high temperature exposure. Application/Improvements: It has been found that the oxidation phenomenon leads to the formation of very fine oxide scale on the superalloys. This oxide layer especially in case of Hastelloy-X (Superni-76) was responsible for the improvement in the wear resistance despite of some initial fast volume loss.

Effects of impact energy on the wear resistance and work hardening mechanism of medium manganese austenitic steel

Medium manganese austenitic steel (MMAS) fabricated through the hot rolling process has been used in the mining, military, and mechanical industries. In this paper, the abrasion performance and hardening mechanism were measured under a series of impact energies. The impact wear was tested at different impact energies from 0.5 J to 6 J using a dynamic load abrasive wear tester (MLD-10). Microstructure and surface morphologies were analyzed using scanning electron microscopy, X-Ray diffraction, and transmission electron microscopy. The results suggest that MMSA has the best wear resistance at 3.5 J and the worst wear resistance at 1.5 J. Furthermore, the wear mechanism and worn surface microstructure change with different impact energies. There are small differences between a large amount of martensite on the worn surfaces under different impact energies and the shapes of dislocation and twins change with different impact energies.

Effect of abrasive particle size on friction and wear behaviour of various microstructures of 25CD4 steel

Many parameters, such as normal load and material bulk hardness, control the wear and friction behaviours of materials. Nonetheless, the investigation of the coupled contributions of microstructure and abrasive particle size are still lacking. A contribution is proposed by using steel pins with various microstructures with a similar macro-hardness (around 410HV) and chemical composition. A quenched martensitic microstructure, a tempered martensitic microstructure and three ferrite-martensite dual-phase microstructures, with a similar martensite volume fraction (around 67%) and different martensite colony morphologies, are established. Friction tests are performed between these pins and abrasive papers with different sizes ranging from 15μm to 200μm. Compared to single-phase microstructures (quenched and tempered martensitic microstructures) and whatever the abrasive particle size, ferrite-martensite dual-phase microstructures reduce the friction coefficient and provide better wear resistance. For the ferrite-martensite dual-phase microstructures and unlike fine and fibrous martensite colonies, coarse and granular martensite colonies minimize the friction coefficient. In addition, characterized by a change of wear mechanisms between abrasion and adhesion, an intermediate abrasive particle around 35 μm minimizes the friction coefficient. This study also reveals that the wear rate increases with the abrasive particle size which is associated to an increase of the attack angle of abrasive grains.

Tribological behaviour of Cu based materials produced by mechanical milling/alloying and spark plasma sintering

Aim of the work is to investigate the tribological behaviour of Cu based materials produced by mechanical milling (MM), mechanical alloying (MA) and finally sintered by Spark Plasma Sintering (SPS). MM causes a significant strain hardening of Cu, while MA by 0.5wt%TiB2 adds a further dispersion hardening contribution. During dry sliding contact against high speed steel a close relation has been found between friction coefficient and contact temperature highlighting two regimes. The first one, occurring at an early stage of the process, is characterized by a high friction coefficient (~1), typical of the strong adhesion of Cu–Cu contact. The second one is characterized by a lower steady-state friction (~0.7) related to the change of wear mechanism from adhesive metallic into triboxidative. By increasing the load the friction coefficient decreases, the transition time from the adhesive to triboxidative friction regime decreases and the contact temperature increases. Under abrasive wear conditions the penetration depth of the indenter is progressively reduced by increasing hardness, highlighting the benefits of MM and, even more, of MA. The Cu+0.5wt.%TiB2 composite alloyed for 240min shows the best wear resistance under both wear conditions. The good wear resistance combined to high thermal conductivity represent very attractive properties for many applications.

High-stress abrasive wear behavior of Al–Mg–Si hybrid composites using regression analysis

PurposeThe purpose of the present study is to analyze the wear behavior of developed aluminum hybrid composites under high-stress conditions through developed power law and quadratic equations.Design/methodology/approachThe abrasive wear behavior of Al–Mg–Si (Al 6082) alloy reinforced with hard silicon carbide (SiC) and soft graphite (Gr) particulates fabricated by stir casting route was studied at loads of 5-15 N, sliding distance of 75 m and abrasive grit size of 100-200 μm. The power law and quadratic equations were developed to understand the wear behavior with respect to the load applied and the abrasive grit size. The worn surfaces of the test specimens and grit papers were examined under scanning electron microscope.FindingsThe density and hardness of the hybrid composites decreased when compared to Al–SiC composites, whereas the wear properties improved because of the presence of Gr. There was further improvement in the wear properties of the materials because of T6 heat treatment. The change in abrasive wear mechanism was observed at a grit size of 125 μm when traversed from alloy to hybrid composite as indicated in terms of exponents in the power law equation. The worn surfaces of hybrid composite pins were comparable with those of alloy pins.Practical implicationsIn the automobile sector, components like cylinder liner, piston, crankshafts, brake drums, etc. also undergo abrasive wear along with sliding against the counter surface in working conditions.Originality/valueThe results prove that better wear resistance was obtained under the abrasion condition.

Effect of Operating Temperature on Tribological Behavior of As-Plated Ni-B Coating Deposited by Electroless Method

ABSTRACTThe present work investigates the tribological behavior of electroless Ni-B coating in its as-plated condition at elevated operating temperatures. Ni-B coating is deposited using an electroless method on AISI 1040 steel specimens. Coating characterization is done using scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction techniques. Vicker's microhardness and surface roughness are measured. Friction and wear tests are carried out on a pin-on-disc tribological test setup at room and elevated temperatures of 100, 300, and 500°C. The tribological behavior deteriorates at 100°C compared to room temperature. Electroless Ni-B coating shows excellent wear resistance at 300°C, which again degrades at 500°C due to severe oxidation and softening of the deposits. The worn surface of the coatings is analyzed using optical microscopy and scanning electron microscopy. Within the temperature range considered, the wear mechanism changes from adhesion to a combination of adhesion and abrasion as the temperature rises from ambient condition to 100°C, following which the wear mechanism is predominantly abrasive. The formation of a tribochemical oxide film also affects the tribological behavior of the coatings at high temperature.

Improvement the wear behavior of low carbon steels by friction stir processing

A low carbon structural steel was surface-hardened by friction stir processing (FSP) through 4 mm thickness from the surface. The hardness of the alloy increased from 140 Hv0.1 to about 240 Hv0.1 after single-pass FSP. This improvement came from the substantial microstructural refinement due to both severe plastic deformation and dynamic recrystallization. Both yield and tensile strength of the alloy increased without a considerable decrease in ductility after FSP. Friction and wear behavior of the alloy before and after FSP was investigated by a pin-on-disk type tribometer according to ASTM-G133. The substantial increase in both hardness and yield strength resulted in a considerable improvement in wear resistance of the alloy depending on applied pressure. In this study, metallurgical and mechanical reasons for such improvement in wear behavior and any change in wear mechanisms after FSP were investigated.

Friction and wear behavior of annealed Ti-20Zr-6.5Al-4V alloy sliding against 440C steel in vacuum

Tribological behavior of a recently-developed Ti-20Zr-6.5Al-4V alloy was tested in vacuum at different annealing temperatures (800°C, 900°C and 1000°C). Coefficient of friction and wear volume of the Ti-20Zr-6.5Al-4V alloy in vacuum were obtained. Scanning electron microscopy analysis was employed to determine the wear mechanism. Results show that the main wear mechanism changes from mild adhesive and severe abrasive wear at 10N loading to severe plastic deformation and delamination wear at 30N loading. A transfer layer was found on the stainless steel ball surface and the EDS results reveal that the layer originates from the Ti-20Zr-6.5Al-4V alloy. The three dimensional topography of the Ti-20Zr-6.5Al-4V worn surface was also explored.

Study on the High Temperature Friction and Wear Behaviors of Cu-Based Friction Pairs in Wet Clutches by Pin-on-Disc Tests

This work is devoted to the study of the high temperature friction and wear behaviors of Cu-based friction pairs in wet clutches under different temperatures, rotation speeds, and loads. Pin-on-disc tests are carried out on the UMT-3. The friction coefficient, wear factor, and high temperature wear mechanism are primarily analyzed. The results show that as the temperature rises from 120°C to 420°C, the friction coefficient increases from 0.28 to 0.35 at first and then decreases to 0.30, when the vibration of friction coefficient is significantly identified. Meanwhile, the wear factor grows gradually from K=7.9×10-8 g/Nm to K=41.8×10-8 g/Nm at first and then grows sharply to K=112.2×10-8 g/Nm. The main wear mechanisms are abrasive wear and ploughing wear when the temperature is below 345°C, and the wear seriously deteriorates when the temperature exceeds 345°C, when the wear mechanism changes to adhesive wear and delamination wear.

THE IMPORTANCE OF PRIMARY CARBIDES FOR THE TRIBOLOGICAL PROPERTIES OF FERROUS ALLOYS

Among the materials used for the mill rolls, one of the main groups are materials with eutectoid primary carbides in their microstructure. The volume fraction and morphology of these carbides influent in a significant way on the tribological properties of tool materials. In the paper, the role of the primary carbides morphology on the fatigue wear of mill rolls after exploitation was presented. The role of the primary carbides morphology in the sliding wear of tool materials was also investigated. The evaluation of the sliding wear mechanism and its degree was performed by the investigation of the mill rolls surface roughness after exploitation. Whereas, the role of ledeburite cementite morphology in wear mechanism changes ware investigated by the laboratory tests. Tests were performed with the use of different loads, time, and temperature during the trials. The microcutting of counter sample material by the primary carbides from the tested samples was observed.

Influences of extrusion temperatures on the wear behavior of magnesium alloy AZ31 fabricated by the extrusion shear process

Abstract The wear resistance of as-cast AZ31 magnesium alloy samples fabricated by extrusion shear (ES) with various preheating temperatures (420, 400, 370 °C) of billets was tested by using pin-on-disc experiments under dry sliding wear conditions. Wear rates and friction coefficient were measured at various sliding frequencies and normal forces. To define the wear mechanism for each tested condition, the worn surfaces were analyzed using scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS). Based on the test results, the wear resistance of the ES-processed samples decreases with drop of the billet temperatures. The friction coefficients and wear rates of the samples with a preheating temperature of 370 °C are lower than those with deformation temperatures of 400 °C and 420 °C. With the increase of normal loads and reciprocating frequencies, the wear mechanism changes from mild wear (adhesion, abrasion and oxidation) to severe wear (delamination, plastic deformation and melting). Therefore, the extrusion methods have significant influences on the wear behaviors of the samples, and the wear resistance of AZ31 magnesium alloy can be improved by ES process.

Design of friction and wear resistant titanium- and cobalt-modified nickel-base repair alloys by spray forming

Powder injection molding (PIM) is a newly developed method for repairing gas turbine components in recent years. However, the PIM method needs a sacrificial binder, which increases working procedure and cost. To overcome this disadvantage, a new method of maintenance, i.e. spray forming (SF) technique, is put forward in this study. Three kinds of Ni-base repair alloys have been designed and prepared by the SF process. And these alloys were subjected to friction, wear and material analysis tests. Results reveal that the alloy with high titanium and cobalt content has the best friction and wear resistance. The increase in titanium and cobalt content will result in the increase of γ/γ′ misfit, grain size, and coherent γ′ size, and enhance the formation of good oxides lubricants, which leads to a decrease of the coefficient of friction. Moreover, with increasing titanium and cobalt content, the predominant wear mechanism changes from delamination wear to abrasive wear and adhesive wear. The high titanium and cobalt content give a large improvement in wear resistance by strongly hindering dislocations motion and reducing crack growth rate, which resists delamination wear.

Wear behaviors and wear mechanisms of wrought magnesium alloy AZ31 fabricated by extrusion-shear

Abstract Extrusion-Shear (ES) process for magnesium alloy is a newly developed plastic deformation technique which combines direct extrusion (DE) with ECAP (equal-channel angular pressing). Grains of ES-processed magnesium alloys can be refined effectively and mechanical properties can be improved, but the tribological properties have not been studied. In this study, the wear behaviors and wear mechanisms of AZ31 magnesium alloy samples produced by direct extrusion (DE) and extrusion-shear (ES) technologies, respectively, have been evaluated by fiction coefficient and wear frequencies obtained from the dry sliding tests conducted at different loads and frequencies by using a high speed dry sliding test machine. SEM and EDS analyses technologies also have been used to analyze the wear surfaces and wear debris in different fiction conditions. Based on the results, the ES-processed samples show a better wear resistance than those prepared by DE process as the ES-process samples show a lower friction coefficient comparing to those fabricated by DE process at the same conditions of loads and wear frequencies. With the increase of normal loads and reciprocating frequencies, the wear mechanism change from mild wear (adhesion, abrasion and oxidation) to severe wear (delamination, plastic deformation and melting). Therefore, the extrusion ways have significant influences on the wear behaviors of the samples and that the wear resistance of AZ31 magnesium alloy can be improved by extrusion-shear.

Effect of Boron on the Microstructure, Phase Assemblage and Wear Properties of Al0.5CoCrCuFeNi High-Entropy Alloy

Abstract The microstructure, phase assemblages, hardness and wear properties of Al0.5CoCrCuFeNiBx (x = 0∼1) high-entropy alloys were investigated. The results show that without boron addition, the alloy is composed of simple fcc solid solution structure. In the alloys with boron additions, boron precipitates as borides instead of entering the crystal structure and thus there is no change in the lattice constant of the matrix fcc phase. Borides precipitation significantly hardens the alloys and the hardness shows strong correlation with the boron content. There is no distinct difference in the wear resistance of the alloys with x ≤ 0.4, but the wear resistance increases linearly with the boron content increasing in the alloys with x ≥ 0.6. With the boron content increasing, the wear mechanism changes from delamination wear to oxidative wear. The great enhancement in the hardness and wear resistance is attributed to the combination of the large hard borides and ductile and tough fcc matrix.