Cu–Ni alloys are thermally and chemically operationally stable alloys. Even though its wear resistance is superior to that of its pure metal components, the addition of reinforcing phases can further ...improve the wear behaviour of the alloys in an attempt to develop lighter materials resistant to degradation by corrosion and wear. The dry sliding wear behaviour of Cu10Ni matrix composites reinforced with 55 vol% TiC particles was investigated in an experimental pin-on-ring arrangement with a AISI M2 hardened steel ring as a counterpart at normal loads of 25 N, 52 N and 103 N, and sliding velocities of 0.3 m/s, 0.6 m/s and 0.8 m/s. The worn surfaces and wear debris were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (SEM-EDS) and x-ray diffraction (XRD) techniques. The infiltrated composites had less than 1.8% porosity. The Cu10Ni alloy exhibited significant material displacement towards the wear track margin and a highly deformed subsurface up to more than 200 μm deep. Despite the higher wear rate of the unreinforced alloy, the coefficient of friction (COF) of Cu10Ni was lower because of the hard-particles exposed in the surface of the composites. The dominant wear mechanism of the alloy was adhesive and oxidative wear. In the least case, the TiC/Cu10Ni composite has three times more wear resistance than the pure Cu10Ni matrix. The wear behaviour of the composite is characterized by a tribochemical reaction that involves oxidation of the matrix and transferred material forming protective tribolayers through an additional sliding process. The surface consists of numerous simple and mixed oxides of Fe, Cu and Ni. The highest rate of composite wear was achieved in the combination of maximum sliding velocity and higher applied load. The mechanism that governs the wear process in composites combines abrasive, adhesive and oxidative wear.
•TiC/Cu–10Ni composites are successfully prepared by capillary infiltration.•TiC/Cu–10Ni has three times better wear resistance than the pure Cu–10Ni matrix.•The lower rate of wear of TiC/Cu–10Ni is related to the formation of a tribolayer.•The dominant wear mechanism of Cu–10Ni alloy against M2 steel ring is adhesive.•The wear mechanism of TiC/Cu–10Ni combines abrasive, adhesive and oxidative wear.
Joint replacement is a very successful medical treatment. However, the survivorship of the implants could be adversely affected due to the loss of materials in the form of particles or ions as the ...bearing surfaces articulate against earch other. The consequent tissue and immune response to the wear products, remain one of the key factors of their failure.
Tribology has been defined as the science and technology of interacting surfaces in relative motion and all related wear products (e.g., particles, ions, etc.).
Over the last few decades, in an attempt to understand and improve joint replacement technology, the tribological performance of several material combinations have been studied experimentally and assessed clinically. In addition, research has focused on the biological effects and long term consequences of wear products.
Improvements have been made in manufacturing processes, precision engineering capabilities, device designs and materials properties in order to minimize wear and friction and maximize component longevity in vivo.
This book investigates the in vivo and in vitro performance of the orthopaedic implants and their advanced bearings. Contributions are solicited from the researchers working in the field of biotribology and bioengineering
The present work aims to fabricate CrMnFeCoNi high-entropy alloy (HEA) possessing outstanding wear and corrosion properties via laser additive manufacturing (LAM) and subsequent laser shock peening ...(LSP). The surface morphology, microstructure, microhardness and residual stress of LAM-fabricated specimen were characterized before and after LSP. Additionally, sliding wear and electrochemical corrosion experiments were conducted to evaluate the suitability of LSP for improving wear and corrosion resistance. Results indicated that friction coefficients and wear rates of LAM-fabricated specimens obviously decreased after LSP. Both untreated and LSP-treated specimens displayed uniform wear mechanisms, including abrasive and adhesive wear, while the wear damage level of the high-energy LSP-treated specimen was the mildest. Moreover, LSP-treated specimens exhibited lower corrosion current density and higher corrosion potential as compared with the untreated specimen, suggesting an enhancement in corrosion resistance. The hardened surface layer had positive effects on inhibiting furrow and spalling to resist material removal, and the compressive residual stress enhanced the adhesion of tribo-layers on the worn surface to protect the underlying layer from further damage. The grain refinement and compressive residual stress synergistically contributed to form compact passive films, thereby restraining the aggression of corrosive ions to enhance the corrosion resistance.
•LAM-fabricated CrMnFeCoNi HEA is treated by LSP.•LSP improves the wear and corrosion resistance of LAM-fabricated CrMnFeCoNi HEA.•The wear and corrosion mechanisms of CrMnFeCoNi HEA treated by LSP are discussed.
We investigated the wear formation during a single-asperity sliding against a rigid substrate using molecular dynamics simulations. Two distinct wear mechanisms were observed: low-load atomic wear ...(isolated debris atoms or clusters) and high-load plastic wear (collective debris formation from plastic flow). The atomic wear rate depends on the normal stress exponentially, in agreement with the mechanically assisted bond-rupture theory. However, the plastic wear rate exhibits linear dependency on the normal stress. It was found that the asperity-substrate adhesion reduces the critical normal stress for the atomic-to-plastic wear transition, suppressing the atomic wear mode. Finally, a wear mechanism map of atomic/plastic wear was constructed in the domain of normal stress and adhesion, which is consistent with existing simulation and experimental results. This wear map could resolve the recent controversy on whether Archard׳s linear law is applicable for low-load tip wear.
•Both atomic and plastic wear were observed in tip wear MD simulations.•Tip wear formula was obtained for atomic wear and plastic wear.•High adhesion suppresses atomic wear in single-asperity sliding.•A new stress-adhesion wear mechanism map is proposed.
The objective of this study is to evaluate the effect of slip ratio on the wear and rolling contact fatigue (RCF) of wheel/rail materials using a rolling–sliding wear testing apparatus. The results ...indicate that two wear types are presented in terms of wear rate: type I (mild wear) and type II (severe wear). In type I wear, cracks propagate parallel to the surface. While in type II, the peeling is aggravated and spalling can be observed. With the slip ratio increasing, the wear mechanism of rollers transforms from slight oxidation wear and peeling to severe fatigue wear and spalling. Due to the mild wear and light plastic deformation in type I, the angle and depth of cracks show no obvious differences between the wheel and rail rollers. The crack depth and angle increase in type II wear owing to severe plastic deformation, while the depth is smaller on the wheel rollers. The size of flake wear debris presents an increasing trend and the main composition is Fe2O3 and metallic iron, and the content of iron diminishes with increasing oxidation.
•Two wear types are defined in terms of wear rate of wheel/rail rollers.•The slip ratio has a significant effect on the hardness and friction coefficient.•Two wear types present different subsurface damages.•The size of debris with flake structure has a downtrend with slip ratio increasing.
Dry sliding wear behavior of rheocast AZ91 magnesium alloy and AZ91/SiCp composites reinforced with 5 and 10vol% SiC particles were investigated under normal loads of 10–250N and sliding speeds of ...0.1, 0.3, 0.5 and 1m/s using pin-on-disc configuration against a 1045 steel disc counterbody. In this work, rheocast alloys and composites have been tested to determine the role played by the globular microstructure, and to evaluate if the increase observed in other mechanical properties is also translated to wear behavior. Wear rates and friction coefficients were registered during wear tests. Worn tracks and wear debris were studied by Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectrometry (EDS) in order to obtain the predominant wear mechanisms maps of the studied materials. The following wear mechanisms were found in the worn surface of the three materials: abrasion, oxidation delamination and melt wear. The composites with globular microstructure exhibit slightly superior wear resistance at low testing sliding speeds (0.1 and 0.3m/s) and medium loads (40–80N) than the AZ91 Mg alloy. But, for other conditions, the presence of SiC particles seems to be detrimental to the wear behavior of AZ91 magnesium alloy. A wear mechanisms map that allows identifying the main wear mechanisms for each wear condition and material composition has been developed. Rheocast microstructure improves the wear resistance of alloys in most conditions but the addition of SiCp reinforcement is only favorable in few of them.
•Wear behavior of rheocast AZ91, AZ91/5%SiCp and AZ91/5%SiCp was studied.•Abrasion, oxidation, delamination and melt wear mechanisms were found.•Al low testing sliding speeds and medium loads, composites have better wear behavior than the alloy.•At the most severe condition, the SiC particles seem to be detrimental to the wear behavior.•A mechanism wear map was developed.
The influence of laser shock peening (LSP) on tribological properties of magnesium alloy ZK60 was investigated adopting different laser power density. Surface wear morphology, elemental composition ...and content in wear debris were observed and analyzed using SEM and EDS. Meanwhile, surface roughness, profiles, microhardness, and microstructure were also characterized. It was proven that the roughness increased from 0.32 μm to 9.3 μm, microhardness improved by 39%, the number of grains augmented from 1045 to 1461, and wear rate decreased by 17.6% in maximum. Adhesive wear and oxidation wear were the main mechanisms of the original sample, and the wear mechanism of modified specimens was dominated by abrasive wear. In conclusion, LSP can improve wear resistance under the higher normal force.
•The anti-oxidation wear ability of magnesium alloys ZK60 was improved by LSP process.•Wear mechanism were changed from adhesive wear to abrasive wear after LSP.•Adhesive wear resistance under higher normal force was improved by LSP process.
To gain a comprehensive understanding of the wear mechanism and the combined effect of low stacking fault energy (SFE) and external elevated temperature on sliding-induced plastic deformation of ...CoCrNi medium-entropy alloy (MEA), herein, we report on the wear response of fine-grained CoCrNi MEA against Inconel alloy 718 counterparts between room temperature (RT) and 300 °C, with particular focus on the wear mechanism transition and sliding-induced subsurface microstructure evolution. The results show that the hardness of the MEA and coefficients of friction (CoFs) start to decrease at 200 °C, but wear rates monotonously decrease with rising temperatures. The wear mode changes from abrasive wear at RT to oxidative and adhesive wear at 200 °C. Between RT and 150 °C, stacking faults and deformation twins play a significant role in the formation of gradient subsurface microstructure. The improved wear resistance is mainly attributed to the thermal softening of the mating material and the increased contribution of adhesive wear. However, at 200 °C and above, the reduced wear rates and CoFs are associated with the formation of glaze layer. The present findings provide insights into understanding the wear mechanism and sliding-induced deformation of metallic alloys with low SFE at elevated temperatures.
Display omitted
•Wear mechanism and sliding-induced plastic deformation of CoCrNi alloy was investigated.•Sliding wear tests were performed between 25 °C and 300 °C.•The hardness and CoFs start to decrease at 200 °C but wear rates keep decreasing.•The wear mode changes from abrasive wear to oxidative and adhesive wear at 200 °C.•The sliding-induced gradient microstructure and the glaze layer were characterized.
The wear behavior of a powder metallurgical γ-TiAl alloy, Ti-45Al-5Nb-0.4W + 2Nb (in at. %), containing Nb particles was investigated using pin-on-disk wear tests at room temperature. The dry sliding ...wear tests were performed against a zirconia disk in different environments: argon, a hydrogen in nitrogen mixture, air and oxygen. The wear rates of the TiAl pins were significantly greater in the presence of oxygen but little affected by water vapor or molecular hydrogen. The worn surface of the TiAl pins and the wear debris were examined using both a scanning electron microscope and an X-ray diffractometer. The tribolayer in the Nb rich area near the worn tip of the pin was investigated using transmission electron microscopy on specimens prepared by focused ion beam milling. It was found that both pure Nb particle residues present in the β phase of the alloy and new compounds precipitated in the Nb-rich area around the Nb particles substantially enhanced the wear-resistance. The zirconia disk underwent a phase transformation induced by the high stresses and temperature during the wear tests. The abrasive particles produced during the wear testing, which largely consisted of the zirconia particles, were found to be embedded into a tribolayer on the worn tips of the TiAl pins. The results indicate that the main wear mechanisms of the (Ti-45Al-5Nb-0.4W) + 2Nb alloy were two-body and three-body abrasive wear, some delamination, and plastic deformation.
•Ti-45Al-5Nb-0.4W (at. %) pre-alloyed powder was mixed with 2 at. % of Nb elemental powder to produced (Ti-45Al-5Nb-0.4W) +2Nb alloy using the hot isostatic pressing (HIP) method.•The tribological properties were sensitive to the environmental effect.•The hard compounds precipitated in the Nb-rich areas in (Ti-45Al-5Nb-0.4W) +2Nb alloy enhanced the wear-resistance greatly in oxygen-containing environments.•The dominant wear mechanism was two-body and three-body abrasive wear, plastic deformation and delamination.
The nitrided layer was prepared on the AlCoCrFeNi high-entropy alloy by plasma nitriding. The microstructure and tribological property of the nitrided layer and as-cast high-entropy alloy were ...studied at dry sliding condition, deionized water and the acid rain, respectively. The results showed that the hardness of the nitrided high-entropy alloy was increased from HV 522 of as-cast high-entropy alloy to HV 720 of nitrided high-entropy alloy due to the presence of hard phases and solid-solution strengthening. In addition, the wear resistance of the nitride layer was superior to that of the as-cast alloy in the same condition. Moreover, the wear rate of nitride layer obtained a minimum of 2.8 × 10−5mm3/(Nm)in the acid rain due to the oxidation film, nitrided layer and the lubrication action in solution. The dominant wear mechanism of the as-cast alloys and the nitrided HEAs in the acid rain was abrasive wear, oxidative wear and corrosive wear. However, the main wear mechanism of the as-cast alloys and the nitrided HEAs in air and deionized water was abrasive wear, adhesive wear and oxidative wear.
•Wear rate of nitrided HEAs was lower than that of as-cast HEAs in the same condition.•The wear mechanism of as-cast alloys in air was abrasive wear of oxide particles.•The wear mechanism of the nitrided HEAs in air was adhesive wear and abrasive wear.•The wear mechanism of HEAs in acid rain was abrasive, oxidative and corrosive wear.•The lubrication action of deionized water and acid rain led to the lower wear rate.
PDF
