Wear Mechanisms Research Articles

Tribological Behavior and In‐Vitro Biocompatibility of a Newly Designed TiZrNbMoTa High‐Entropy Alloy

A novel Ti35Zr15Nb25Mo15Ta10 high‐entropy alloy has been designed, fabricated, and characterized as a viable substitute for the conventional Ti‐6Al‐4V alloy in biomaterial applications. Alloy design is conducted based on various parameters including mixing enthalpy (ΔHmix), omega parameter (Ω), delta parameter (δ), valence electron concentration (VEC), and biocompatibility aspects of its constituent elements with CALPHAD approach. The fabricated Ti35Zr15Nb25Mo15Ta10 alloy demonstrated a body‐centered‐cubic (BCC) solid solution phase with no evidence of intermetallics. Nanoindentation investigations exhibited high hardness of ≈5.1 GPa and a young modulus of ≈140 GPa. The alloy proposed better surface properties and tribological behaviour in comparison with the Ti‐6Al‐4V alloy in dry and wet (under PBS solution) conditions. Furthermore, the newly designed alloy revealed promising behaviour after investigation of in‐vitro biocompatibility compared to the Ti‐6Al‐4V alloy. These initial benefits of the Ti35Zr15Nb25Mo15Ta10 alloy concerning mechanical properties and wear resistance over the conventional Ti‐6Al‐4V alloy present an avenue for exploring novel orthopedic implant alloys.

Utilization of graphene nanoplatelets for friction coefficient reduction in NiCu/WC-12Ni composite materials

Graphene Nanoplates (GNPs), known for their outstanding performance, have found extensive applications in the preparation of metal composite carbon materials. In this investigation, a Directed Energy Deposition system was employed to effectively produce deposition specimens of NiCu/WC-12Ni + x wt% GNPs (x = 0, 0.5, 1.0, 1.5) composite material. The findings suggest that incorporating GNPs improved the microstructure of the NiCu/WC-12Ni deposited specimens, leading to a reduction in grain size with predominantly equiaxed and cellular grains. GNPs transformed into amorphous graphene spheres, uniformly distributed within the deposited structure. When 1 wt% GNPs were added, the average microhardness of the deposited specimens increased by approximately 15 %, the friction coefficient decreased from the original 0.318 to 0.257, and the wear rate decreased by 23.2 %. The primary wear mechanism observed was abrasive wear, demonstrating excellent wear resistance. Moreover, introducing a suitable quantity of graphene improved the electrochemical corrosion resistance of the deposited specimen.

Effect of pv factor on carbo-graphite and copper impregnated carbo-graphite material under dry conditions

This study investigates the tribological behaviour of copper-impregnated carbo-graphite (ICG) compared to plain carbo-graphite (CG) under various parameter-product (PV) values and temperatures. Impregnation significantly enhanced ICG's hardness (70%) and reduced porosity (98.6%) compared to CG. The CoF for CG was lower than that for ICG attributed to the formation of a lubricating graphite-rich tribo-film that facilitated easy shearing at the contact interface. The wear mechanisms for CG at elevated temperatures were identified as adhesion, oxidation and delamination, likely exacerbated by the material's softening. In contrast, ICG exhibited superior wear resistance, attributed to its higher hardness and the formation of a protective tribo-layer containing copper and graphite. This tribo-layer offered a low-shear interface at lower PV values, reducing friction. However, at higher PV values, ICG wear increased due to abrasion and adhesion. Overall, copper impregnation offers a promising strategy to improve the wear resistance of carbo-graphite, particularly at elevated temperatures.

Microstructure, Mechanical, and Tribological Properties of Nb-Doped TiAl Alloys Fabricated via Laser Metal Deposition.

TiAl alloys possess excellent properties, such as low density, high specific strength, high elastic modulus, and high-temperature creep resistance, which allows their use to replace Ni-based superalloys in some high-temperature applications. In this work, the traditional TiAl alloy Ti-48Al-2Nb-2Cr (Ti4822) was alloyed with additional Nb and fabricated using laser metal deposition (LMD), and the impacts of this additional Nb on the microstructure and mechanical and tribological properties of the as-fabricated alloys were investigated. The resulting alloys mainly consisted of the γ phase, trace β0 and α2 phases. Nb was well distributed throughout the alloys, while Cr segregation resulted in the residual β0 phase. Increasing the amount of Nb content increased the amount of the γ phase and reduced the amount of the β0 phase. The alloy Ti4822-2Nb exhibited a room-temperature (RT) fracture strength under a tensile of 568 ± 7.8 MPa, which was nearly 100 MPa higher than that of the Ti4822-1Nb alloy. A further increase in Nb to an additional 4 at.% Nb had little effect on the fracture strength. Both the friction coefficient and the wear rate increased with the increasing Nb content. The wear mechanisms for all samples were abrasive wear with local plastic deformation and oxidative wear, resulting in the formation of metal oxide particles.

Mechanical, corrosion and tribological behavior of friction stir processed AZ31B/egg shell /WS2 hybrid surface composite

In the present work, egg shell and Tungsten disulphide particles are reinforced in AZ31B alloy using friction stir process. Initially, the ES and WS2 particles are mixed at different weight ratios (25/75, 50/50 and 75/25) then are reinforced in AZ31B plates using a taper threaded FSP tool at rotation speed of 1000 rpm, axial load of 6 kN and traverse speed of 10 mm/min in hole method. The post macroscopic analysis showed that defect free hybrid surface composite is obtained with 75wt %ES and 25wt % WS2 particles reinforced in AZ31B alloy. The grain size is reduced from 15 µm to 5 µm due to the addition of 75wt% ES and 25wt% WS2 particles through FSP. The mechanical, corrosion and tribological responses of AZ31B/75ES/25WS2 hybrid surface composite are observed and are compared with FSPed AZ31B alloy without reinforcements and AZ31B base alloy. The microhardness is improved by 66% and 83% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy. Similarly, the ultimate tensile strength is improved by 16% and 31% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy but the % of elongation is decreased by 70% and 78% in FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite respectively compared to the AZ31B base alloy. The corrosion rates of FSPed AZ31B alloy and AZ31B/75ES/25WS2 hybrid surface composite are decreased by 22% and 48% respectively compared to AZ31B base alloy. The dry sliding friction and wear responses are observed for AZ31B base alloy and AZ31B/75ES/25WS2 hybrid surface composite by varying the applied load (10 N, 20 N and 30 N) and sliding velocity (1.5 m/s, 2.6 m/s and 3.6 m/s) with constant sliding distance of 2000 m. In AZ31B base alloy, the wear mechanism is initially dominated by delamination and ploughing phenomena but at high sliding condition, the delaminated and worn out debris based tribolayer reduced the wear rate. In AZ31B/75ES/25WS2 hybrid surface composite, the wear mechanism is dominated by adhesive and delamination phenomena and the formed tribolayer decreased the wear rate at high sliding condition.

Research on Cloud-Edge-Device Collaborative Intelligent Monitoring System of Grinding Wheel Wear State for High-Speed Cylindrical Grinding of Bearing Rings

Aiming at the problems of grinding wheel wear during high-speed cylindrical grinding, communication delays, and slow response during data acquisition, processing, and system operation, an intelligent online monitoring technology frame for CNC manufacturing units is proposed, incorporating a real-time-perception grinding mechanism and a cloud-edge device. Based on the grinding data and grinding wheel wear mechanism, a monitoring model using multi-sensor information fusion is constructed to assess the grinding wheel wear state. In addition, edge data acquisition and online monitoring software have been developed to improve the speed of data transmission and processing. Finally, based on the proposed framework, a cloud-edge device collaborative intelligent monitoring system for assessing grinding wheel wear during high-speed cylindrical grinding of bearing rings is constructed. It improves the grinding quality and efficiency, reduces the grinding cost, and incorporates remote control functionality.

Influence of Heat Treatment on Fretting Wear Behavior of Laser Powder Bed Fusion Inconel 718 Alloy

Abstract This research paper focuses on the fretting wear characteristics of self-mated laser powder bed fusion (L-PBF)-produced Inconel 718 alloy, with the primary aim of characterizing its distinct wear-rate in relation to fretting cycles. This study investigates both the as-built and heat-treated Inconel 718 Superalloy. Experiments were conducted under aggressive contact conditions, involving a flat-on-flat contact pressure of 100 MPa (1645 N) and a temperature of 650 °C sustained over a million cycles. From the preliminary observation, the microstructure reveals that the heat-treated L-PBF alloy has denser and harder precipitates than its as-built counterpart. This indicates that heat-treated alloy is much harder (470 HV0.3) than the as-built Inconel 718 (275 HV0.3). The heat treatment process resulted in the precipitation of beneficial strengthening phases like γ′ and γ″, along with maintaining stable carbides (NbC). Notably, the heat-treated material displays an approximately two-fold lower wear-rate (0.103 μm/cycle at the end of 1000 k cycles) compared to the as-built material (0.238 μm/cycle), attributed primarily to its high strength characteristics. Additionally, the heat-treated material demonstrates a reduced steady-state friction coefficient (0.34) in contrast to the as-built material (0.37), owing to its inherent capability to form a uniform and stable lubricious glaze oxide layer. Both as-built and heat-treated systems show dominant adhesive wear mechanisms along with localized abrasion resulting from the combination of oxidation and cyclic wear processes.

Flow-induced erosion modelling of cohesive material with coupled CFD-DEM approach

Erosion is one of the continuous wear mechanisms in cohesive materials caused by the shear stress applied by the fluid flow at the liquid–solid interface. The erosion resistance of cohesive materials is significantly influenced by the strength of the cohesive bonds that hold the particles together, increasing the complexity of the mechanism. The erosion rate of cohesive materials depends on the critical shear stress (CSS) and the erodibility coefficient at the surface. The current understanding of the relationship among the inter-particle bond strength, CSS, erodibility coefficient, and their respective contributions to the flow-induced erosion process is still lacking; therefore, it cannot be adequately described mathematically. The present research offers a coupled computational fluid dynamics (CFD)–discrete element method (DEM) approach to visualize and quantitatively analyze the flow-induced erosion in cohesive materials. The capability and accuracy of the developed model were validated using experimental data available in the literature. A cohesion model was then employed to describe the strength of the cohesive bond, and the effects of the cohesion energy density (CED) on the CSS and erodibility coefficient were investigated. The analysis indicated that for cohesive materials, the non-dimensional CSS not only is affected by the particle Reynolds number but also strongly depends on CED. The simulation results indicated that by increasing the CED value from 500 to 900kJ/m3, the CSS increased by 25 %, and the erodibility coefficient decreased by 62 %. The proposed CFD–DEM approach can effectively estimate the erosion initiation and erosion rate of cohesive materials in different applications and geometries.

Effect of Direct Aging Heat Treatment on Microstructure and Mechanical Properties of Laser Powder Bed Fused Maraging Steel 300-Grade Alloy

Abstract This paper investigates the effects of a 6-hour direct aging heat treatment at 490 °C on the mechanical, tribological, and microstructure characteristics of laser powder bed fused maraging 300 steels, which is produced at various laser energy densities. After direct aging heat treatment, the grain boundaries become irregular and vague due to the residual stress releasing, squeezing of precipitates into the grain boundaries, and phase transformations. The XRD analysis reveals the reverted austenite (γ′) phase forms during aging treatment due to the inevitable reversion of metastable martensite to the stable reverted γ′ phase. The heat-treated samples' microhardness rises with rising the laser energy density (LED) from 61.41 to 92.10 J/mm3 due to a decrease in the reversed austenite phase and a further rise in LED decreases the microhardness of heat-treated samples due to a rise in the reversed austenite phase after heat treatment. The heat-treated sample produced at LED of 92.10 J/mm3 shows maximum yield, ultimate tensile strengths, and minimum elongation percentage due to its high microhardness, and the fractography results show the failure mode as a mixed brittle and ductile fracture. The wear-rate of the heat-treated additively manufactured maraging 300 steel decreases as the LED increases from 61.41 to 92.1 J/mm3 and a further rise in LED from 92.10 J/mm3 to 166.66 J/mm3, the wear-rate increases. The wear-rate rises with a rise in sliding velocity from 1.5–3.5 m/s. The dominant wear mechanism was observed as abrasion with small grooves and saplings.

Thermodynamic properties, interfacial adhesion energy and tribological properties between MCN (M = Hf, Ta, Cr, Nb) coating and Ti alloy substrates investigated by experiment and first-principles calculations

A series of MCN (M = Hf, Ta, Cr, Nb) coatings were prepared by double glow plasma surface alloying (DGPSA) as protective hard coatings for Ti60 (Ti-5.5Al-4.0Zr-4.0Sn), aiming to solve the problems of low bonding strength between the ceramic coating and the substrate as well as the poor wear resistant of ceramic alloy coatings. First principles calculation was used to study the elastic constant of MC0.5N0.5 solids, thermomechanical parameters and the interfacial adhesive strength of Ti(101)/MCN(220). The calculated results indicated the HfCN solids show excellent mechanical properties, lower thermal expansion coefficient α, lower Gibbbs values and higher values of entropy (S), superior adhesion strength Wad ∼ 5.7 J/m2. The high-temperature tribological performance tests show that the HfCN and TaCN coatings exhibited better wear resistance compared with the CrCN and NbCN coatings at 500 °C -700 °C. The wear rate of HfCN coatings at 500 °C and 700 °C is about 2 times and 5 times lower than that of CrCN, which is in accordance with the HfCN coating’s excellent thermal stability and high interfacial bonding strength with the Ti substrate. The adhesion wear mechanism of all coatings gradually intensified with increasing temperature.

Analysis of abrasive impact wear of the Mn8/SS400 bimetal composite using a newly designed wear testing rig

In this study, the abrasive impact wear behaviour of a bimetal composite made of medium manganese steels (MMSs) and low carbon steels (LCSs), i.e., the Mn8/SS400 bimetal composite, was investigated using a newly designed wear-testing rig. The need for a new rig arose from the difficulty in replicating real-world wear conditions. Our rig allows for precise control and measurement of wear, simulating harsh environments more accurately than other wear-testing rigs. The bimetal composite Mn8/SS400 demonstrated superior wear resistance, showing an improvement of up to 2.8 times compared to benchmark steels, attributed to its enhanced work hardening sensitivity. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), and electron backscatter diffraction (EBSD) analyses were employed to elucidate the wear mechanisms. After 300 h of abrasive impact wear, the subsurface microhardness of Mn8 reached 601.31 HV, significantly higher than that of the matrix hardness of 292.24 HV, indicating a substantial work hardening effect. The wear mechanism of the Mn8/SS400 bimetal composite was found to be a synergistic effect of grain refinement strengthening, dislocation strengthening, and twin strengthening. Initially, twin strengthening was the dominant mechanism up to 200 h of wear testing. However, after 300 h, contributions from all three mechanisms became increasingly significant, enhancing the overall wear resistance of the composite.

Fabrication and tribological behavior of laser cladding Cu/Ti3SiC2 reinforced CoCrW matrix composite coatings on Inconel718 surface

To satisfy the need for high wear resistance of Inconel718 alloy under harsh working conditions, laser cladding technique was adopted to fabricate the Cu/Ti3SiC2-CoCrW metal matrix composite coatings on that surface. The phase composition, microstructure, microhardness, surface energy, and tribological properties of the composite coatings were systematically analyzed by characterization methods such as XRD/ SEM/ EDS/ XPS and performance test methods such as high-temperature friction and wear test, and the wear mechanism at different temperatures was deeply discussed. The research results indicate that the microhardness of coatings is increased by 2.2–2.9 times compared to the substrate, which is mainly owing to the solid solution strengthening effect and the diffusely distributed hard reinforcing phases such as Cr7C3, WCx, and TiC. Regarding the wear resistance, the wear rate of coatings is significantly reduced by 1–2 orders of magnitude over the substrate. Among them, the Co-based coating adding 10 wt% Cu - 10 wt% Ti3SiC2 exhibited the lowest wear rates at room and high temperatures, which were 0.22 and 3.23 × 10−5 mm3/ N·m, respectively, with 98.22 % and 88.19 % reductions in comparison with the substrate. The low surface energy (27.94 mN/m) was one of the main reasons for the good tribological properties. When the friction environment changes from room temperature to 600 °C, the primary wear mechanism of coatings changes from abrasive and adhesive wear to oxidative wear.

Augmenting microstructure and tribological performance of wire arc additive manufactured PH13-8Mo stainless steel via TiC/TiB2 nano-particles incorporation

This study aimed to investigate the effect of TiC and TiB2 nano-inoculants addition on the microstructure and tribological behavior of PH13-8Mo stainless steel processed through wire arc additive manufacturing (WAAM). The incorporation of TiC/TiB2 inoculants demonstrated notable efficiency in mitigating the anisotropic wear and scratch response and enhancing wear resistance observed in the as-printed state. This improvement was ascribed to the refinement of the grain structure, disruption of the columnar structure, and increased content of the retained austenite. Notably, TiB2 inoculation exhibited superior grain refinement and achieved the highest hardness. However, the TiC-inoculated condition demonstrated the best wear resistance, attributed to its excellent combination of hardness and fracture resistance, and a higher contribution of strain-induced martensite transformation during wear testing. Additionally, the implementation of post-printing solutionizing and aging treatment was found to improve the scratch and wear resistance of the alloy, attributed to the formation of nano-sized β-NiAl precipitates. The main wear mechanism observed involved oxidation wear, adhesive wear, and three-body abrasive wear. The findings of this study highlight the significant potential of incorporating ceramic-based nano-particles for improving the wear resistance of WAAM PH13-8Mo components, particularly in demanding applications like injection molding dies where superior abrasion resistance is paramount.

A Comparison of the Tribological Properties of SiC Coatings Prepared via Atmospheric Plasma Spraying and Chemical Vapor Deposition for Carbon/Carbon Composites

The microstructure, mechanical performance, and tribological properties of SiC ceramic coatings prepared via atmospheric plasma spraying (APS) and chemical vapor deposition (CVD) method were compared to provide good anti-wear protection for carbon/carbon composites. The surface morphology of the APS-SiC coating was characterized as having a porous structure, whilst the CVD-SiC coating presented with many pyramidal-shaped crystals constituting the surface. The APS-SiC coating consists of a dominating SiC phase and a small fraction of the Si phase, while the XRD pattern of the CVD-SiC coating mainly consists of the SiC phase. The dense crystalline microstructure of the CVD-SiC coating made it possess a higher hardness and Young’s modulus at 31.0 GPa and 275 GPa, respectively. The higher H/E and H3/E2 parameters of the CVD-SiC coating implied that it exhibited better plastic resistance, which is also beneficial for anti-wear properties. The scratch test reflected the critical loads of the spallation of the APS-SiC coating and CVD-SiC coating, which were evaluated to be 25.9 N and 36.4 N, respectively. In the tribological test, the friction coefficient of the APS-SiC coating showed obvious fluctuations at high load due to damage to the SiC coating. The wear mechanism of the APS-SiC coating was dominated by abrasive wear and fatigue wear, while CVD-SiC was mainly dominated by abrasive wear. The wear rate of the CVD-SiC coating was far below that of the APS-SiC coating, suggesting the better wear-resistance of the CVD-SiC coating.

Effect of groove textures on wear of friction pair between groove side and scraper under different factor combinations

Three-body wear is the primary wear mechanism in friction pair between groove side and scraper. This study quantitatively investigates the effect of groove textures on three-body wear under different factor combinations through abrasive wear experiments. The results indicate that groove textures significantly reduce wear of samples. The wear reduction rate of sample reaches 41% under the optimal factor combination. Width, depth, and tilt angle of groove textures significantly influence wear loss. Among these factors, width exhibits a negative effect on the change of wear loss, while depth and tilt angle show positive effects. Additionally, there are interactive effects on the change of wear loss between width and depth, as well as width and tilt angle. The effect process of groove textures to three-body wear was qualitatively analyzed by discrete element method (DEM) simulation. Combined with wear morphologies, the wear-resistant mechanism of groove textures was explored. The results indicate that groove textures can mitigate the severity of three-body abrasive wear, reduce the contact area between particles and samples, alter particles movement and enhance wear resistance. Meanwhile, groove textures can serve as a guiding mechanism to modify particles movement and direction and transform the sliding motion of coal particles into rolling motion, converting the continuous “face-face” contact of three-body wear into intermittent “point-face” and “line-face” contacts. This study provides novel study ideas and theoretical foundations for wear-resistant designs in mining machinery and three-body wear equipment.

The Microstructure and Properties of Ni60/60% WC Wear-Resistant Coatings Prepared by Laser-Directed Energy Deposition.

Ni60/60% WC composite coatings with a good surface roughness and high mechanical properties were successfully prepared on 316L stainless steel substrate by laser-directed energy deposition (LDED) technology. The effects of laser power on the microstructural evolution and mechanical properties of the Ni60/60% WC composite coating were investigated. The relationships between the chemical composition, the microstructure, the hardness, and the friction wear resistance of the composite coatings were characterized and investigated. The results show that the laser power had a significant effect on the energy input, which determined the melting extent of the Ni60 phases around the WC particles and the bonding strength between the reinforcements and the matrix, as well as the bonding strength between the substrate and the coatings. With an increase in the laser power from 800 W to 1400 W, the average hardness of the coating surface increased due to the increased densification of the deposited coatings and then decreased due to grain coarsening under a high energy input. The average coefficient of friction of the coatings decreased gradually to 0.383 at 1000 W, showing a minimum wear of 0.00013 mm2 at 1200 W. The main wear mechanisms on the coated surfaces were adhesive wear and abrasive wear. Moreover, the coatings deposited at 1200 W exhibited better forming quality and wear resistance. This work suggests that the processing parameters during LDED can be optimized to prepare Ni60/60% WC wear-resistant coatings with excellent mechanical properties.

Wear behaviour analysis of thermo-mechanically processed AA7075 and AA7075/SiC/Graphite composite

The current work focuses on investigating the tribological performance of AA7075 alloy and AA7075 hybrid composite with SiC and graphite reinforcements of 2 and 0.5 wt percentages, respectively. The alloy and hybrid composite are fabricated through stir casting and thermo-mechanically processed through hot rolling routes. Dry sliding wear characterization has been carried out using a pin-on-disc wear testing setup for alloy and composite under various processing conditions using experiments designed according to Taguchi's L9 orthogonal array. The technique for order preference by similarity to ideal solution (TOPSIS) method has been adopted to achieve a single multi-response index (MRI) considering the minimization of multiple objective functions for specific wear rate (SWR) and coefficient of friction (COF). The analysis of variance (ANOVA) results of the MRI indicated that sample processing condition and load were the most significant parameters. The wear mechanism at different experimental conditions was studied using Scanning electron microscope (SEM) micrographs, energy dispersive spectroscopy analysis and 3D surface profile of wear track. The AA7075 composites are found to be comparatively good in all experimental conditions compared to the base alloy due to load-bearing SiC particles and solid lubricant graphite as reinforcing elements. The mechanically mixed layer (MML) formation in hybrid composites helped achieve good tribological properties. The AA7075 alloy and hybrid composites cross rolled at 350 °C yielded better results than other samples. The wear mechanism was abrasive and adhesive at low temperature and low load conditions in both alloy and hybrid composites. Whereas, at higher temperatures and high loads oxidative wear mechanism with delamination was prevalent. The transition of SWR from mild to severe value occurs at 250 °C in all experimental cases. The specific wear rate was improved by 85.64 % between worst and best conditions, i.e., annealed alloy and cross rolled composite.

Research on microstructure, mechanical property and wear mechanism of AlCoCrFeNi/WC composite coating fabricated by HVOF

In this study, HVOF spraying technology was utilized to prepare AlCoCrFeNi/WC composite coatings with varying WC content on 40CrMnMoA steel substrate. The microstructure, elemental distribution, phase structure and chemical valence states of wear scratches of the composite coatings were analyzed using the SEM, EDS, XRD and XPS. Microhardness was measured using single-point digital microhardness tester, while nanohardness and elastic modulus were determined using a nano-indenter. The bonding strength of the composite coatings was evaluated using a tensile tester. Friction and wear tests were conducted to assess the wear behavior of the composite coatings. The results indicated that the microstructure, microhardness, nanohardness and elastic modulus of AlCoCrFeNi HEA coating increased with the addition of WC, attributed to the hard phase effects of WC. However, the bonding strength first decreased and then increased. Compared to the W 0 coating, the wear rates of the other composite coatings decreased by 30.5 %, 46.1 %, 65.3 %, and 82.1 %, respectively, which demonstrating that the effect strengthening of WC. After the friction and wear tests, the wear mechanism of the W 0 and W 1 coatings represents adhesive wear, abrasive wear and severe oxidation wear. In contrast, the W 2 and W 3 coatings exhibited slight adhesive wear, slight abrasive wear and slight oxidation wear, while the W 4 coating showed the slightest abrasive wear, the slightest adhesive wear and the slightest oxidation wear.

Frictional stability of pumice-reinforced lightweight magnesium composite in ambient and elevated temperature environments

Lightweight materials with better resistance to sliding wear are prominent candidates for automobile brake drums, clutch pads and cylinder block applications to facilitate fuel economy. This attempt is reserved to cater to materials with higher tribological quality needs. Less dense foamy pumice stone particles were involved in three different percentages (5, 10, and 15 wt%) to reinforce lightweight AZ31 Mg alloy. A stir-assisted squeeze casting technique was pursued to process the composite and refine the grain structure. A phase detection, elemental mapping and microstructure study were done through X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), respectively. An experimental dry sliding wear scrutiny was administered using a pin-on-disc apparatus by considering: (i) ambient and elevated temperature environments and (ii) three different levels of loads. The results reveal a significant drop in wear loss and a frictional coefficient for 15% pumice-loaded composite than the base alloy. Post-wear examination acknowledges the fact that the ambient temperature wear is governed by adhesive-abrasive wear and high temperature is by abrasive wear mechanisms. Worn-out scrutiny authenticates the presence of oxide layers and their role in lubrication. A comparative study with previous works upholds the novel magnesium composite is the right candidate for the mentioned automobile applications.

Cutting performance and wear mechanism of submicron and ultrafine Ti(C, N)-based cermets

The complex thermal-mechanical coupling among Ti(C, N)-based cermet tool, workpiece and chip affects immensely the tool life, machining quality and costs during high-speed cutting, which makes the investigation on wear mechanisms of tools quite important. In this work, submicron and ultrafine Ti(C, N)-based cermet tools were prepared by vacuum sintering technology, and the cutting performance of the tools was evaluated by continuous dry cutting. The aim of this work is to unravel the wear mechanisms of submicron and ultrafine Ti(C, N)-based cermet tools based on the cutting performance and wear characteristics of both the cutting tools and chips generated during high-speed cutting. The Vickers hardness, flexural strength and tool lifespan of ultrafine Ti(C, N)-based cermets are significantly superior to those of submicron Ti(C, N)-based cermets because of grain refinement strengthening and the improved distribution of metal phases. Tool wear depends to a large extent upon the contact states and heat transfer ability at different locations of the tool edge, which are characterized by simultaneous action and mutual transition from abrasive, adhesion, surface fatigue and oxidative wear. Overall, ultrafine Ti(C, N)-based cermet tools with excellent comprehensive properties exhibit a distinctly reduced tool wear at different wear regions.