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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. [ABSTRACT FROM AUTHOR]

Cf/SiC composites are widely utilized in the aerospace industry due to their excellent properties. However, Cf/SiC composites are notoriously challenging to machine. The substantial cutting force and severe tool wear during machining often result in poor surface quality and low machining efficiency. This paper presented a corrugated helical PCD (polycrystalline diamond) tool, featuring a helical structure and an arc array micro-groove on the primary cutting edge, and these micro-groove structures are staggered, facilitating continuous material removal during the machining of Cf/SiC composites. The study investigated the milling force variations of the corrugated helical PCD tool when machining Cf/SiC composites under different milling parameters. A comparative study was conducted on the milling force, surface quality, and tool wear of corrugated helical PCD tool and commercial PCD tools. The experiment revealed that the milling force initially decreases and then increases with rising spindle speed and increases with higher feed rates per tooth, milling depth, and width. The newly designed tool exhibited lower milling force, superior machining surface quality, and extended tool life, approximately 0.7 times that of commercial PCD tools. The cutting performance of the corrugated helical PCD tool proved superior. Additionally, it was confirmed that the primary wear mechanism for the corrugated helical PCD tool cutting Cf/SiC composites was abrasive wear. [ABSTRACT FROM AUTHOR]

The application of Inconel-718 ranges from structural components to engine parts such as turbine blades and compressor discs. Inconel-718 is an age-hardenable alloy. We are presenting a comparative tribological study on as-cast and heat-treated Inconel-718 superalloy. The wear behavior of both as-cast and aged Inconel-718 alloy was investigated using a linear reciprocating tribometer at 25 ∘ C, 225 ∘ C, and 450 ∘ C against Si3N4 ball. The heat treatment of Inconel-718 alloy resulted in the improvement of the hardness of the alloy. All the tribological tests were conducted under a constant 20 N normal load. The observed coefficient of friction was found to be decreasing with the increase in temperature. The wear tracks were characterized by a three-dimensional optical profilometer and scanning electron microscopy (SEM). The observed wear volume loss (mm3) of the aged alloy was less than that of the as-cast Inconel-718 alloy. SEM of the worn sample reveals that the main operating wear mechanism at 25 ∘ C is delamination whereas at elevated temperatures of 225 ∘ C and 450 ∘ C, the main operating wear mechanism is abrasion, adhesion, oxidation and spalling. SEM of the counter-surface was also conducted in order to understand the adhesion on its surface and it was found that the adhered oxide contained mainly Ni and Nb oxides. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Wear failure of cutting inserts is the main form of failure that occurs when cutting difficult-to-machine materials at high speeds. To obtain cutting inserts with outstanding tribological properties, multilayered cubic boron nitride (cBN) and nanocrystalline diamond (NCD) coatings (cBN/NCD) were prepared on WC-6 wt% Co tool substrates. The tribological properties of the multilayered cBN/NCD coatings were studied at different temperatures, and the results showed that the coefficient of friction (COF) and wear rate of the coatings were closely interrelated to the temperatures, and the COF gradually decrease and the wear rate gradually increase as the temperature increased from room temperature (25 °C) to 600 °C. The COF and wear rate of the multilayer coatings at 600 °C were ∼0.05 and 8.43 × 10−6 mm3/(N⋅m), respectively. The wear resistance of the cBN/NCD coatings was higher than that of TiAlN coatings and PcBN tool materials by more than 3 and 4.5 times, respectively. The high-temperature wear failure modes of the multilayered cBN/NCD coatings were abrasive wear, diamond graphitization, and BN hydrolysis. Coating wear accelerated when pores were formed on the cBN surface of a multilayered cBN/NCD coating due to the low nucleation density of diamond. These results would guide the application of cBN/NCD-coated cutting tools in high-speed cutting processes. [ABSTRACT FROM AUTHOR]

This study investigated the microstructure and tribological performance of TiO 2 coating prepared through the plasma-spraying of TiO 2 on an aluminum alloy (ZL109) surface. Box–Behnken design was employed to calculate the optimal spraying parameters (spraying current: 439 A, spraying voltage: 129 V, and Ar flow rate: 117 m3/h). High-temperature tribological characteristics (T = 120 °C) were examined under varying loads (F = 100 N, 120 N, and 140 N). The scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis results revealed that the coating porosity decreased from 3.31 % to 0.31 % with the increase in the spraying voltage from 120 V to 130 V. Both powder and coating exhibited consistent elemental composition (Ti, O) and phase composition (TiO 2 , TiO, Ti 2 O 3). During the spraying process, part of the powder was oxidized. The average coefficient of friction of the coatings varied from 0.05 to 0.08, and as the load increased, the wear mechanism of the coating changed from abrasion to adhesive wear and oxidation. [ABSTRACT FROM AUTHOR]

Difficult-to-machine materials are characterized by high hardness, strength, and anisotropy. During machining, tools can suffer from adhesion, abrasion, material detachment, and high cutting temperatures. These factors result in severe adhesive wear, abrasive wear, oxidative wear, and diffusion wear. Intense tool wear leads to more burrs, delamination, chipping, and dimensional errors in the parts. It significantly increases production costs and reduces machining efficiency. Therefore, further research into tool wear is of great importance. This paper reviews the characterization and monitoring of tool wear, the morphology and mechanism of wear, and measures for improving wear, with a focus on tool wear in the machining of difficult-to-machine materials. Through a comprehensive review of existing research findings, this work offers a perspective on the investigation of tool wear, providing an effective guide for future research. And it is of great significance to improve tool life and cutting quality. [ABSTRACT FROM AUTHOR]

Industrial development has led to an increase in demand for friction materials, resulting in increasingly prominent environmental issues throughout their entire life cycle, and developing green and eco‐friendly brake friction materials has become a focus in the braking field. This paper explores the mechanical and tribological properties of fly ash (industrial waste) and sisal fiber (natural fiber) as eco‐friendly components to enhance brake friction materials. Four samples containing different ratios of fly ash and sisal fiber were prepared and tested with a variable‐speed friction testing machine. The results show that the eco‐friendly alternative combination can effectively improve the friction coefficient, and reduce friction fluctuations and thermal degradation, but the wear rate will also increase accordingly. In addition, the worn morphology reveals the formation of the contact platform and wear mechanism. A hybrid integration of analytic hierarchy process (AHP) and multi‐objective optimization by ratio analysis (MOORA) was used to weigh various evaluation indicators objectively and rank the samples. The sample with 8% fly ash and 6% sisal fiber exhibited the best comprehensive tribological performance. Highlights: Development of eco‐friendly brake friction composites with natural and waste additives.Investigation of the effect of the natural wastes' ratio on prepared composites' physical, mechanical, and tribological properties.Evaluation of brake friction composites with AHP‐MOORA.Sample S6F8 exhibits the best comprehensive tribological performance. [ABSTRACT FROM AUTHOR]

By incorporating the dual ceramic elements TiB 2 /B 4 C, we investigated their impact on the mechanical properties, thermal properties, and friction performance of copper-based powder metallurgy materials, and elucidated the friction wear mechanism. Additionally, machine learning algorithms were employed to predict the friction coefficient and stability coefficient. The conclusions are as follows:With the increase in the TiB 2 /B 4 C ratio, the trend of mechanical properties initially increases and then decreases, with the optimum ratio being 5:3 for TiB 2 and B 4 C, exhibiting superior mechanical properties. Moreover, B 4 C enhances the thermal conductivity of copper-based friction materials more effectively than TiB 2. In terms of overall friction performance, the ratio of TiB 2 to B 4 C at 5:3 yields better frictional properties. The primary components of the friction surface friction film are CuO, Cu 2 O, Fe 2 O 3 , and B 2 O 3 , transitioning from a ceramic film to a metallic film as the TiB 2 /B 4 C ratio increases. The friction wear mechanism shifts from abrasive wear to severe fatigue wear as the TiB 2 /B 4 C ratio increases, accompanied by oxidative wear. Furthermore, an AdaBoost algorithm model was developed to effectively predict the friction coefficient and stability coefficient, with accuracies of 0.9993 and 0.8739, respectively. [ABSTRACT FROM AUTHOR]

AbstractThe current investigation examines the wear performance of High-Velocity Oxygen Fuel coated Colmonoy-88 coating on SS 304. An L9 orthogonal array design based on the Taguchi fractional factorial method was used to create the erosive wear tests. The impact of three parameters, such as impact velocity (100, 120, and 140 m/s), angle of impact (30°, 60°, and 90°), and test duration (10, 15 and 20 min), on wear performance was investigated by analysis of variance. Results show that the impact angle is the most vital factor for mass loss in both SS 304 and Colmonoy-88, followed by impact velocity and time duration. It was revealed that the maximum wear takes place at 30° impact angle in both specimens. The outcomes of the XRD and EDS analysis show that the Colmonoy-88 has a high chromium content, which provides it with exceptional erosion resistance. The Colmonoy-88 wear mechanism involved inter-splat micro-cutting, lips, crack initiations, and craters caused by fly ash particles at varying impact angles. [ABSTRACT FROM AUTHOR]

PA66 is a commonly used material for plastic gears due to its excellent high-temperature resistance, high strength, self-lubrication, and friction resistance. In this study, the effect of different humidity levels on the tribological properties of PA66 materials in self-mated contacts are investigated using a pin-on-disk test rig. The results show that the friction coefficient and wear rate of the PA66-PA66 sliding combination increase drastically after humidity treatment mainly due to the surface plasticization caused by water absorption and the decrease of cohesive strength and glass transition temperature. Moreover, the limiting PV value of PA66 materials decreased significantly after moisture absorption, and when the actual PV value exceeds this reduced material limit, the degree of friction and wear increases drastically. The wear mechanism of the PA66-PA66 sliding combination is mainly adhesive wear without humidity treatment. The wear mechanism is adhesive wear combined with abrasive wear after humidity treatment (50%, 70%, 90%, immersion in water) and abrasive wear is most significant at 50% humidity. Abrasive wear decreases with the increase of the moisture content, while adhesive wear increases. [ABSTRACT FROM AUTHOR]

This research focuses on the development of carbide-free nanostructured bainitic steel through the process of austempering at 250°C. The selected steels are also patented at 550°C, to get fine pearlitic structure. In austempered steels, microscopic analyses encompassing optical, scanning, transmission electron microscopy and X-ray diffraction revealed the presence of nanoscale bainite, filmy and blocky austenite. In contrast, lamellar pearlite was observed in the patented steels. With increase in the austempering duration, the extent of bainite improved, while the volume percentage of blocky retained austenite (RA) decreased. The tribological performance of high-carbon bainitic steels is compared with patented one of same composition against a tungsten-carbide counter disc. The specific wear rate as well as coefficient of friction decreases with rise in load from 10 to 50 N. The hardening volume of B15VA-1 sample is greater than that of B15VA-2 and P15VA, and it is mainly due to the transformation of blocky RA to strain-induced martensite. The bainitic pins with higher hardness exhibited superior tribological response than the pearlitic ones. SEM analysis of worn surfaces confirmed that at lower load (10 N), abrasive wear occurs, but at higher load (50 N), wear mechanism changes to adhesive along with abrasive in bainitic steel and oxidative wear along with adhesive and abrasive wear in pearlitic steel. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tribological behaviors of SiCp/Al–Mg–Mn–Cu aluminum matrix composites under solid solution (labeled as SS sample) and aging treatment (labeled as SA sample) were systematically investigated. The microstructures, tribological properties and wear mechanisms of worn surfaces were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and wear testing machine, respectively. The microscopy study showed the uniform distribution of reinforcements in the SiCp/Al–Mg–Mn–Cu composites. And a large number of fine CuMgAl2 phases were observed in the untreated sample but dissolved in the SS sample to some extent. It can be confirmed that the size and number of some new precipitates and CuMgAl2 phases were in the suitable state for the SA sample resulting from its excellent integrated mechanical properties. A good combination of strength and plasticity in SA sample was corresponding well with its much lower coefficient of friction (COF) and well abrasion resistance, with a COF of 0.25. The wear mechanisms of the untreated and SS samples have found to be the combination of abrasive and adhesive indicated by the presence of some wear debris and delaminated flakes, whereas the wear mechanism is changed to adhesive dominantly with slight delamination in case of SA sample. [ABSTRACT FROM AUTHOR]

In fields such as industrial engineering and healthcare, additive manufacturing technology is a focal point for researchers. Wear represents a significant challenge for additive manufacturing technology, increasingly emerging as a research hotspot in recent years. This review categorizes and summarizes wear issues in additive manufacturing technology, providing a comprehensive overview of wear mechanisms, materials, and the effects of additive manufacturing processes on wear. Research indicates that different wear mechanisms result in varying wear characteristics. The inherent properties of the materials significantly influence wear during the manufacturing process. Modifying material compositions and optimizing microstructures can enhance the wear properties of additive manufacturing products. Additionally, the study of additive manufacturing technology in repair and maintenance is a current and anticipated research hotspot for the coming decades. In the research of additive manufacturing processes, the effective regulation of process parameters and their post-processing play a positive role in enhancing the wear characteristics of products produced via additive manufacturing. Lastly, the challenges and recent advancements concerning wear issues in the field of additive manufacturing technology research are summarized. [ABSTRACT FROM AUTHOR]

Our previous study (Polymer Composites 2023, 44: 1252–1263) revealed the positive role of rubber in modifying the tribological properties of polymer composites. This concept was applied here by incorporating synthetic Eucommia rubber (TPI) to 3D printed polyether ether ketone (PEEK) skeletons with different infill densities. The formation of TPI/PEEK composite improved the friction and wear of PEEK matrix with some reduction in mechanical performance. The composite with 70% infill density is recommended in terms of its overall performance. Based on the morphological and chemical analysis, the composite's wear mechanism was discussed. The findings of this present study could pave a new route to modify friction‐reduction and anti‐wear performance of PEEK. Highlights: Novel composites were successfully prepared from thermodynamically incompatible synthetic Eucommia rubber (TPI) and polyether ether ketone (PEEK).The tribological properties of TPI/PEEK composites were studied in association with the infill density of PEEK.The TPI rubber helped improve the friction and wear properties of PEEK thanks to its role in enhancing the formation of transfer films on the counter steel surface. [ABSTRACT FROM AUTHOR]

The AISI M2 coatings were prepared on H13 die steel substrates by laser cladding technology. The effects of MoS2 addition on the microstructure and wear resistance of the coatings were investigated. The results showed that adding MoS2 can reduce the wear rate of M2 coating, enhance the hardness of the coating, and affect the wear mechanism of the coating. The wear rate of the M2 coating is 3.33 × 10−5 mm3/N·m, mainly consisting of oxidative wear and abrasive wear. When the MoS2 addition reached 7 wt%, the wear rate is only 1.88 × 10−5 mm3/N·m, and the wear mechanism is mainly oxidative wear. The microstructure of the coatings was analyzed using X-ray diffraction techniques and scanning electron microscopy techniques, and its mechanism was thoroughly studied. MoS2 can refine grains and promote fine grain hardening. The average grain size of the M2 coating is 3.42 μm, but the average grain size of the coating containing 7 wt% MoS2 decreases to 1.40 μm.

As a typical age-strengthened alloy, Cu–Cr–Zr alloys have high strength, good electrical conductivity, and excellent wear resistance. In this work, the Cu–Cr–Zr–Nb alloys were in different aging states after the aging process. After aging at 460 °C for 4 h, the alloy was peak-aging. The common effect of the existence of the FCC Cr particle, which was coherent with the Cu matrix, and the increase in hardness improved the wear property of the alloy. The results of the wear test showed that the optimal wear parameter was a speed of 300 rpm and a load of 5 N. Under these wear parameters, the alloy had the lowest mean coefficient of friction (COF) value and the least mass loss, having the best wear resistance. Furthermore, the wear mechanism of the alloy was mainly adhesive wear and abrasive wear.

The gear friction pairs in RV reducer always withstand a broad range of temperature, sliding velocity and heavy load. In the research, three types of heat treatment methods (carburizing + quenching, nitrocarburizing and high concentration nitrocarburizing) are applied on the 20CrMo (cycloidal gear material) disc to study the tribological behavior and wear mechanism. The friction coefficient, wear depth and wear rate of the three types of friction pairs under various temperature (−20 °C, 25 °C, 50 °C, 100 °C) are measured and the microstructure characteristics are analyzed by SEM and EDS. The results reveal that high temperature can dramatically decrease the wear scar dimensions and wear rate due to the more active lubricant. Although the lubricant lost its activity at −20 °C, the friction coefficient and maximum wear depth for GCr15/20CrMo (carburizing + quenching) and GCr15/20CrMo (high concentration nitrocarburizing) are relatively less than 0.1 and 4 μm. The wear rate of GCr15/20CrMo (carburizing + quenching) and GCr15/20CrMo (high concentration nitrocarburizing) are 14.49 μm3/N·m and 17.20 μm3/N·m, which are only 28.7% and 34.1% of GCr15/20CrMo (nitrocarburizing). With the temperature increases to 25 °C, tribofilm is more likely to form on the 20CrMo specimen after nitrocarburizing, leading to better wear resistance. At high temperature (50 °C and 100 °C), GCr15/20CrMo (high concentration nitrocarburizing) system presents excellent tribological behavior by the combination of good lubricant activity, formation of tribofilm and refined nitrides. The wear rate even reaches 0.45 μm3/N·m and 0.43 μm3/N·m at the sliding velocity of 300 mm/s and 562 mm/s under 100 °C. Overall, specimen with high concentration nitrocarburizing process exhibits exceptional wear performance under full operating conditions of RV reducer.

As one of the main problems in the processing of carbon fiber reinforced polymer (CFRP), tool wear affects the quality and efficiency of hole making. As a new CFRP hole making process, the suction-type internal chip removal method can effectively slow down the tool wear rate. In order to further clarify the reasons for this method to slow down the tool wear, this study investigates the wear mechanism of the internal chip removal tool. The main contents include: first, the experimental parameters such as drilling axial force, drilling temperature, and tool wear are obtained through the experimental method, and the drawing of the drilling temperature change curve of internal chip drilling is completed; second, the polar analysis method is used to study the influence of the drill parameters on the drilling axial force and the tool wear, and the basis for the selection of the structure of the internal chip drill is given; finally, the method of comparative experiments of the internal chip drilling process and the non-internal chip drilling process is used to conclude that the use of the internal chip drilling process can effectively slow down the tool wear rate. Finally, the method of comparing the internal chip removal and non-internal chip removal processes is used to conclude that the use of internal chip removal processing method can effectively reduce the axial force, drilling temperature, and slow down the tool wear.

Grinding process monitoring is key to assessing the intelligence of grinding processing and ensuring manufacturing quality of the intended product. The grinding force in the grinding process is an important characteristic, and the grinding force signal has a close relationship with the degree of wheel wear, grinding heat, grinding wheel and workpiece contact state, and other entities. Therefore, the analysis of the grinding force signal using the time domain and frequency domain analysis methods can effectively reveal the grinding characteristics and wheel wear evolution mechanism in the gear grinding process. In this study, the microcrystalline corundum grinding wheel was used to conduct the profile grinding test on 20CrMnTi steel gears installed in vertical machining centers. A high-performance general-purpose dynamometer was used to collect the discrete time series data of the grinding force in real time; a confocal laser microscope and scanning electron microscope were used to observe the wear characteristics of the microcrystalline wheel surface; finally, a micrometer was used to measure the thickness of the wheel’s end-top surface to assess the degree of wheel wear in a quick and simple way. To improve the precision, automation, and intelligence level of the gear grinding process considering the microcrystalline corundum grinding wheel, online monitoring of the grinding process and wear mechanism of the grinding wheel was performed. The intrinsic correlation between the time-frequency domain signals of the grinding force, the contact status of the grinding wheel and workpiece, and the wear degree of the grinding wheel was established. Thus, in this study, a new online monitoring method for monitoring the grinding process of the grinding wheel was proposed based on real-time force signals. Meanwhile, the wear mechanism underlying the morphology of microcrystalline corundum grinding wheels was characterized and analyzed using laser confocal microscopy and scanning electron microscopy. The results showed that the distribution pattern of waveform characteristic indicators such as kurtosis, waveform index, peak index, and pulse index in the time domain spectrum of the grinding force showed a distinct trend of varying cutting depth grinding state ≥ steady-state grinding state of a significantly worn grinding wheel ≥ steady-state grinding state of a lightly worn grinding wheel > noncontact state. However, the variation of the two waveform characteristic values of the grinding force, amplitude spectrum and pulse indicator under different grinding states is completely opposite to that of the time domain signals. After assessing the three-dimensional roughness of the working surface of the grinding wheel, it is observed that there is a slight decrease and a subsequent rapid increase in the roughness of the working surface of the wheel with the evolution of wheel wear. The polycrystalline structure of the microcrystalline corundum abrasive particles gives them the ability to update and sharpen along the microcrystalline interface, showing layer-by-layer cleavage peeling.

Ultralow-wear polyethylene (ULWPE) was proposed to replace conventional UHMWPE as an artificial joint material. Different molecular weights of ULWPE, ULWPE-200, ULWPE-300, and ULWPE-700 were examined against CrCoMo compared to conventional UHMWPE in multidirectional motion. The wear mechanism was elucidated from the perspective of macroscopic wear behavior and microscopic wear debris characterization. It was found that the morphologies of the ULWPE worn surface were similar to that of UHMWPE, with scratches, burnishing, and protuberances. ULWPE-700 possessed the lowest wear loss at all loading conditions, and the wear loss was 40.3% lower than that of UHMWPE at 3 MPa. Furthermore, wear debris was consistent in morphology and size range but showed differences in quantity, size distribution, and shape distribution. Combined with the wear surface morphology and wear debris analysis, it showed that plastic deformation was the main cause of wear debris formation and the wear mechanisms were adhesive wear and abrasive wear. Moreover, the FBA of ULWPE-700 was 64% lower than that of UHMWPE at 3 MPa, suggesting that ULWPE-700 wear debris had the lowest potential osteolysis. This study provides deeper insight into the bio-tribological behavior and the potential biological activity of ULWPE as an artificial joint material. [ABSTRACT FROM AUTHOR]

The effect of shot peening treatment on dry sliding wear behavior of medium manganese steel in as-hot rolled and solution-aging states were studied. The results show that before shot peening, the wear resistance of the solution-aging sample was better than that of hot-rolled steel. The excellent wear resistance was due to the synergistic effect of Ti (C, N) particle precipitation strengthening and grain refinement in the matrix, resulting in high strain hardening ability. After shot peening, different microscopic evolution mechanisms caused great contrast in properties. The as-hot rolled sample released internal stress by generating deformation twins (DTs) during shot peening. With the increased shot peening time, the DTs thickened and interacted with dislocations, effectively reducing the free dislocation path, releasing residual stress, and significantly improving wear resistance. However, solution-aging steel generated many dislocations, resulting in residual stress concentration at Ti (C, N) particles, promoting crack initiation and propagation, and deteriorated wear resistance.

Zr-Y modified silicide coating was deposited on TC4 alloy by the pack cementation process. The microstructure， friction and wear performance， and wear mechanisms of the coating were investigated. The results show that the Zr-Y modified silicide coating has a multi-layer structure， an outer layer consists of TiSi2 and a small amount of ZrSi2， a thin middle layer is TiSi， and an inner layer is a mixture of Ti5Si4 and Ti5Si3. The micro-hardness of the coating is much higher than that of the TC4 substrate and exhibits an obvious decrease tendency from the surface to the interior. The Zr-Y modified silicide coating possesses good anti-wear performance when wearing against GCr15 and Al2O3 balls at a high-temperature of 600 ℃. When wearing against GCr15， the wear rate of the coating is about 3.59×10-5 mm3/（N·m）， which is about 36.6% of that of the TC4 substrate， and the main wear mechanisms are characterized by the adhesive of GCr15 on the coating surface and oxidation wear. When wearing against the Al2O3 ball， the wear rate of the coating is about 9.75×10-5 mm3/（N·m）， which is about 18.9% of that of the TC4 substrate， and the wear mechanisms are fatigue wear， oxidation wear， and adhesion wear.

During the drilling process of large displacement wells, due to the high horizontal-vertical ratio, the movement of the drill string underground is complex, resulting in severe wear on the casing wall and a reduction in casing strength, greatly affecting subsequent drilling and production operations. A casing wear efficiency model based on energy transfer was applied. The segmented method was used to determine the lateral force on the pipe string, and the crescent-shaped wear of the casing was analyzed. Based on the API (American Petroleum Institute) minimum wall thickness method, the crescent-shaped casing wear was simplified, and a method for predicting casing wear and calculating residual strength was established. Using this model, calculations were performed on a large displacement well in the South China Sea. The results show that lateral force is the main factor affecting casing wear, and reverse circulation drilling has a significantly greater effect on casing wear than normal drilling. The most severely worn section of the entire wellbore is the section with the greatest dogleg severity, where the risk of casing failure is highest, making it the critical section for implementing anti-wear measures. After the completion of the four-stage operation in this well, the depth of casing wear at the location of the maximum dogleg severity is 1.15 mm, and the casing strength has decreased to 58. 24% of its original strength, but still meets strength requirements. The research outcome provides a basis and reference for the prevention and control of casing wear in highdisplacement wells in the South China Sea. [ABSTRACT FROM AUTHOR]

Samples of AISI 52100 bearing steel were treated by using laminar plasma quenching methods with three optimized process parameters: input power, scanning speed, and scanning distance. The influence of process parameters on the surface morphology and quenching depth of AISI 52100 bearing steels was explored, as well as the influence on their microstructure and microhardness. Furthermore, the surface wear resistance was tested by using a reciprocating wear testing machine. The results showed that samples with a lower surface roughness and a deeper hardened layer could be obtained by treating with the combination of input power 10.6 kW, scanning speed 500 mm/min and distance 20 mm. Microstructure analysis indicated that finer acicular martensite formed at the surface layer. The microhardness analysis shows that the hardness was improved by 20%, and the wear volume was reduced by 37.7%. The treated AISI 52100 bearing steel sample only had some furrow-like abrasive wear, while the untreated sample had more spalling pits in addition to furrow-like wear. The excellent anti-wear performance could be attributed to the hardness of cryptocrystalline martensite, which formed a hardened layer on the surface of the material. Therefore, the plasma quenched AISI 52100 bearing steel exhibited excellent wear resistance, which could effectively improve the service life of the bearing steel and has broad prospects in the field of surface modification. [ABSTRACT FROM AUTHOR]

High-temperature wear tests on molybdenum–tungsten–vanadium steel were conducted using a universal mechanical high-temperature friction and wear testing machine. The experimental results reveal the evolutionary mechanism of high-temperature friction in the oxide layer of the steel. The oxidation wear of the test steel occurred at 700 °C with the evolution of characteristic monolayer tribo-oxidation layers on the frictional surface. The frictional oxide underwent oxide initiation - lateral growth of massive oxide - formation of frictional oxide layer - local intrusion of oxide layer into substrate - local penetration of oxide lateral growth contact. The frictional oxide evolutionary process was accompanied by a shedding of the frictional oxide surface. Carbides in the test steel prevented the tribo-oxidation layer from invading the matrix. The unique evolutionary characteristics of the tribo-oxidation layer are essential factors affecting the mechanism of maintaining slight oxidative wear. [ABSTRACT FROM AUTHOR]

In this work, the tribological properties of a novel iron‐based self‐lubricating composite as the tribopairs of a plunger pump were systematically studied on an end‐face tribometer, and the tribological mechanism was also revealed. The results show that the wear mechanism of the composite can be ascribed to adhesive wear when the sliding speed is lower than 1.5 m/s. As the sliding speed increases from 1.5 to 2.0 m/s, the wear type transforms to oxidative wear due to the increase of tribo‐oxidation. In addition, the failure criteria of the tribopair composite materials are summarised. When the average coefficient of friction is greater than 0.04, or the wear rate is greater than 9.66 μm3/(N m), the tribopair fails. This offers a valuable reference for industrial application of the tribopairs made from the iron‐based self‐lubricating composite. [ABSTRACT FROM AUTHOR]

Carbon-based materials (e.g., carbon/carbon [C/C] and carbon/carbon-silicon carbide [C/C-SiC] materials) are considered promising brake disk materials for high-speed trains to replace cast or forged steels. Investigating the braking behavior of copper-based composites paired with various counterpart materials is helpful in advancing the development of high-speed and lightweight brake systems. In this study, the braking behavior and wear mechanisms of a novel copper-based composite mated with cast steel, C/C and C/C-SiC materials were investigated. The average coefficients of friction for the copper-based composite against C/C and C/C-SiC materials are increased by approximately 16.5% and 6.7%, and the wear rates of the copper-based composite against C/C and C/C-SiC materials are reduced by about 25.9% and 33.9% in comparison to those of the copper-based composite against cast steel. Additionally, compared with that of cast steel, the wear rate of the C/C material is increased by more than 3 times, and the negative value of the wear rate of the C/C-SiC material is noted. The dominant wear mechanisms of the copper-based composite mated with cast steel, C/C and C/C-SiC materials are adhesive wear combined with oxidation, graphite loss combined with oxidation as well as exfoliation of the material near graphite, and the material transfer combined with oxidation, respectively. [ABSTRACT FROM AUTHOR]

As a crucial part in micro-electromechanical manufacture, local ultra-precision processing of highly ductile copper is expected to be realized by fluid jet polishing (FJP), which widely utilized in optical elements. Since copper exhibits different wear behavior from stiff and brittle material, there is currently no abrasive wear prediction model applicable for copper to investigate the polishing mechanism. This research reveals that the copper material removal is dominated by deformation wear rather than cutting wear through abrasive jet impact experiments and localized wear scars analysis. A three-dimensional gas-liquid-particle triphasic wear model for copper in FJP is developed by considering impact energy and wear mechanism simultaneously. Ultimately, validation assessments at various working pressures and impingement angles achieve the goodness-of-fit up to 0.92–0.97 in quantitative comparison between simulations and experimental measurements, which demonstrate the wear prediction ability of the proposed model. This investigation facilitates a better understanding of copper wear mechanism and provides theoretical guidance for FJP process optimization. [ABSTRACT FROM AUTHOR]

Poly Ether Ether Ketone (PEEK) is a kind of special engineering plastic with excellent properties such as high-temperature resistance, self-lubrication, wear resistance, and high mechanical strength. However, its blending or composite modification applications still face numerous challenges. The primary objective of this research was to evaluate the friction and wear performance of a three-layer self-lubricating bearing bush, which was made from a modified material containing short carbon fiber and Poly Ether Ether Ketone (SCF/PEEK). The bearing bush is used as a surface contact layer on the pistons of a hydraulic motor in the interface with the cam roller. The bearing bush was processed using a 15% SCF-modified PEEK material, and the friction and wear test was conducted using a self-built friction test machine. This study aimed to assess the frictional and wear characteristics of the SCF/PEEK-modified material in the bearing bush. The results show that as the experimental pressure rises from 15 MPa to 25 MPa, the friction coefficient of the SCF-modified bearing bush experiences a significant decrease from 0.420 to 0.296. Furthermore, the stability of the frictional morphology of carbon fibers indicates its effective adaptability to low speed and high load conditions. [ABSTRACT FROM AUTHOR]

Working conditions exert an important influence on the tribological properties of protective coatings, thus affecting the wear resistance of workpieces. In this work, a TiAlSiN hardness-modulated multilayer coating with a good match of strength and toughness was deposited on WC-Co substrates. The adhesive wear played a predominant role under the condition of a larger normal load and lower velocity, leading to the formation of a third body layer composed of compressed and lubricating oxides. As a result, the wear rate of the coating tested at 20 N reduced by 23% of that tested at 5 N. Instead, abrasive wear was more manifest, leading to the formation of big-size abrasives, and thus the wear rate increased by 2.8 times while the velocity elevated from 4 mm/s to 16 mm/s. A full factorial analysis of the wear behaviors, including the nanohardness and roughness of the wear track, and the friction coefficient and wear rate of the coating, offered good guidance for the comprehension of the wear form of the TiAlSiN multilayer coating. The results demonstrated the optimization of multilayer structures for TiAlSiN coatings to attain better wear resistance under coupling conditions of normal load and velocity: harder or more lubricated sublayers. [ABSTRACT FROM AUTHOR]

Nanolubricants are dispersions of nanomaterials in a lubricating base. In this work, polyethylene glycol (PEG) was modified with graphene (G) and copper oxide (CuO) to obtain a nanolubricant (NL). The nanolubricants were prepared and their physicochemical and tribological properties were evaluated. The base and the nanomaterials were evaluated using Fourier-transform infrared spectrometry (FTIR), field-emission scanning electron microscopy coupled with energy dispersive spectroscopy (FE-SEM-EDS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Raman spectroscopy (Raman). Rheology and Tribology tests were also performed using a four-ball tester according to ASTM 2783. The results showed that nanolubricants have a Newtonian behavior and the viscosity was not significantly modified with the additives. The weld point obtained for the nanolubricants was 160 kgf. In addition, when compared to the PEG, the size of the wear scars was reduced by 9.6% (PEG with 0.01% w/w of CuO) and 35.3% (PEG with 0.05% w/w of CuO and G). The wear protection provided by G is higher than the protection provided by CuO. When the two additives were added, the wear protection increased, and a synergistic effect was observed. Two protection mechanisms were observed in the SEM: rolling bearing/ball effect (CuO) and deposition of G at valleys and peaks of the surface roughness. This article shows novel results related to a laboratory evaluation of nanolubricants in a typical tribological test (four-ball). A novel result was observed in the synergistic effect between the two additives (graphene and CuO) determined by the wear mechanism observed in the tests. [ABSTRACT FROM AUTHOR]

In recent years, the number of studies focusing on the additive manufacturing has increased seriously to elucidate the critical points such as physical, chemical, and mechanical properties. Contrary to common trends and for the first time in the literature, this experimental endeavor aims to comprehend the combined impact of reinforcement type and heat treatment on the wear features of additively manufactured polyamide 6 (PA6) composites. As reinforcement materials, glass, and carbon fibers were utilized and all samples were created through the fused filament fabrication. Half of the samples were subjected to annealing treatment after the main production, and characterization works were performed using a fused emission scanning electron microscope, differential scanning calorimetry, and dynamic mechanic analysis. From the outcomes, it is seen that heat treatment has a positive effect on the hardness, and wear resistance of the composites. Besides, glass fiber‐reinforced samples display lower friction coefficient and lower volume loss results than other samples. For all samples, secondary annealing causes a positive impact on wear endurance in most cases. On the other side, the wear mechanism of the tested samples changes with the test force level and reinforcement type. At lower test forces, abrasive wear‐induced debris parts are detected on the deformed surfaces of PA6 and carbon‐added samples, but this case is opposite for the highest force of 40 N. Highlights: Additive manufacturing was underlined as a promising way to create polymer composites with high dimensional accuracy.The combined effect of secondary annealing and reinforcement type on the wear resistance of 3D‐printed PA6 composites was examined for the first time in the literature.Carbon and glass fibers were compared to explore their effect on friction coefficient and wear behavior of polymer composite samples produced via FFF technology.Hardness and surface roughness measurements were used to comprehend the dry sliding wear results.Depending on the increasing test force levels and reinforcement type, deformation, and abrasion mechanisms were analyzed. [ABSTRACT FROM AUTHOR]

The fretting wear behaviors of silicone rubber under dry friction and different lubrication conditions are studied experimentally. Water, engine oil, dimethyl silicone oil (DSO), and dimethyl silicone oil doped with graphene oxide (DSO/GO) are selected as lubricants. Under the liquid lubrication conditions, the silicone rubber samples are always immersed in the same volume of lubricant. The contact model of a 440C steel ball and silicone rubber sample is the sphere-on-flat contact. The reciprocating fretting wear experiments are carried out using the reciprocating friction wear tester. A scanning electron microscope and three-dimensional white-light interference profilometer are used to detect the surface wear morphology and obtain the wear volume, respectively. The influences of normal force, lubrication condition, and displacement amplitude on fretting wear behavior are discussed. The fretting wear performances of silicone rubber under different fretting states and lubrication conditions are compared. The results show that for a small normal force, silicone rubber has the best wear resistance under DSO/GO lubrication. While for a large normal force, silicone rubber has the best wear resistance under engine oil lubrication. [ABSTRACT FROM AUTHOR]

Ti3C2Tx MXene with an ″accordion″ shape was prepared using hydrofluoric acid as an etching agent from the MAX phase (Ti3AlC2) powder. The Ti3C2Tx epoxy resin coatings were prepared using aqueous epoxy resin, aqueous epoxy resin curing agent and Ti3C2Tx as raw materials. The coefficients of friction and wear rates of the coatings were tested by a reciprocating abrasion tester and an optical digital microscope. The morphology and phase composition of the worn surfaces were analysed by scanning electron microscopy, micro confocal laser Raman spectroscopy and X-ray diffractometer to investigate the wear mechanism of coatings. The corrosion resistance of the coating in artificial seawater environment was evaluated by electrochemical workstation. It was shown that Ti3C2Tx epoxy coatings have lower coefficients of friction under artificial seawater environment compared with that under deionized water environment. At the same time, the addition of Ti3C2Tx significantly improves the corrosion resistance of the epoxy resin coating. Ti3C2Tx addition significantly improves the tribological properties of epoxy resin coatings in artificial seawater environments. With the increase of Ti3C2Tx content, both the friction coefficient and wear rate of the coating showed a tendency of decrease firstly and then increase. The lowest friction coefficient and wear rate of the epoxy resin coatings under artificial seawater environment were 0. 13 and 4. 99 × 10-5 mm~3/Nm respectively which were 65. 8% and two orders of magnitude lower than those of the pure epoxy resin coating respectively when the content of Ti3C2Tx was 1. 0 wt% [ABSTRACT FROM AUTHOR]

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The influence of the ratio of TiN powder, graphite powder, and Ni60 powder on the phase composition, microstructure, microhardness, and wear properties of the TiCN Ni‐based coating on H13 steel is investigated. The findings indicate that varying proportions of TiN powder, C powder, and Ni60 powder have a minimal impact on the coating's phase composition. The diffraction peak intensity of TiC0.3N0.7 increases with the addition of (C + TiN) in the blended powder, while the crystallinity of TiC0.3N0.7 in the Ni‐based coating with a 30% (C + TiN) mass fraction decreases. The grain structure of the 20% Ni‐based coating is fine and uniform, while the microstructure of the 30% Ni‐based coating is characterized by a large polymerization phase‐containing Ti elements, with the TiCN‐reinforced phase exhibiting irregular grain morphology. The microhardness HV0.5 of the coating with a 20% (C + TiN) mass fraction ranges from 725 to 772, with an average hardness of 747.8 HV0.5, which is 3.4 times the hardness of the substrate material and 1.3 times the hardness of the Ni‐based coating. As the mass fraction of (C + TiN) in the hybrid powder increases, the friction loss mass of the coating tends to decrease and then increase. The average wear of the Ni‐based coating with a 20% (C + TiN) mass fraction is ≈22.4% of that of the substrate and 50% of that of the Ni‐based coating, demonstrating excellent wear resistance. The wear mechanism is primarily characterized by brittle spalling and abrasive wear. [ABSTRACT FROM AUTHOR]

The high-temperature mechanical properties and tribological behavior of the Al0.5CoCrFeNb0.5Ni high-entropy alloy (HEA) were investigated. The results show that Al0.5CoCrFeNb0.5Ni HEA consists of FCC, BCC and (Cr–Co–Fe)2Nb-type Laves phases. The hardness is about 572 HV at room temperature and decreases slightly at high temperatures, still maintaining a high value (>350 HV) at 900 °C. The yield strength is nearly 2000 MPa at room temperature and tends to decrease with rising temperature (800–1200 °C). The observation of the microstructure after the hot compression tests and the evaluation of the true stress-strain curves illustrate that the softening mechanism is primarily dynamic recrystallization, which occurs mainly in the FCC and BCC phases. The degree of wear increases and then decreases from 200 °C to 800 °C. The best wear resistance was observed at 800 °C, showing the maximum friction coefficient and the minimum wear rate, which was attributed to the increased oxidation that formed oxide layers mainly consisting of Cr2O3 to protect the wear surfaces. The wear mechanism of alloys is affected by temperature. Below 400 °C the wear is mainly abrasive and adhesive wear, at temperatures above 600 °C, the wear transitions from abrasive to oxidative wear, and at 800 °C the wear changes to oxidative wear.

Significance Impregnated diamond bits (IDBs) have been widely used in various hard rock drilling activities, especially deep drilling. Drilling process with IDBs relies on diamond edge wrapped by metal matrices to break the rock formation, which means the wear pattern of the diamond bit reflects the interaction between bits and rock, as well as the existence form of broken particles, which directly determine the drilling efficiency and service life of the drilling tools. But up to now there have not been so much in-depth study on its wear mechanism and analysing method in geological drilling. Progress and Analysis Therefore, this paper reviews the research literature on IDBs wear in the field of geological drilling, summarizes the abnormal bit wear problem according to engineering project experineces and industrial standards. Firstly, based on the experiences of geological drilling activities and industry standards, different types of abnormal bit wear of drill bits were summarized. Then, the evaluation methods of drill bit wear were introduced from the aspects of wear images and drilling signals. The wear mechanism and influencing factors of the drill bit in the drilling process were sorted out from three aspects: The overall drill bit, diamond, and metal matrix. In addition, mainstream methods of controlling drill bit wear performance were listed, and the research progress of wear analysis equations was introduced, besides, how machine learning methods can assist in the study of drill bit wear was discussed. Conclusion and Prospect Thus, IDBs have great potentials in deep hard rock drilling, and their wear performance is the key influnencing the whole drilling activity. To this end, research directions such as artificial intelligence assisting data analysis, microscale computational simulation, additive manufacturing, and material processing modification were analyzed and discussed, aiming to explore advanced methods for monitoring, analyzing, and regulating the wear of diamond drill bits, so as to meet the needs of remote monitoring and controlling in drilling activities such as geological deep drilling and extraterrestrial drilling.

Water-lubricating bearings made of polymer-matrix composites have provided a new approach to prolong the service lifetime of key component in marine propulsion system. However, it was still crucial to find a convenient and effective material to manufacture the water-lubricating bearing with ultralow friction. Herein, a new kind of polyetheretherketone (PEEK) composite with ultralow coefficient of friction (COF), high mechanical strength and thermal stability has been developed. An 80.7% decrease in the COF of PEEK was achieved by incorporating the fillers. A possible mechanism between the heterogeneous nucleation and mobility hindrance of PEEK chain segment caused by different fillers was proposed. The ultralow COF endowed the water-lubricating bearing with low running noise and reduced energy consumption. The high mechanical strength and thermal stability caused the superior carrying capacity and reliability. Therefore, the prepared PEEK composites can be a possibility to realize the water-lubricating bearing with high durability and long service lifetime.

Three kinds of circular spline materials are studied for harmonic reducers, stainless steel 2Cr13, medium carbon alloy steel 40Cr, carbon 45 steel. Through the analysis of microstructure, hardness, three-dimensional and two-dimensional morphology in microwear and friction coefficient, the differences in wear resistance of different materials are attained. The results show that the microstructures of 2Cr13 and 40Cr are tempered sorbite, and the microstructure of 45 steel is ferrite and pearlite. The hardness of the 2Cr13 and 40Cr is similar and much larger than that of the 45 steel. The morphology of 2Cr13 is adhesion and spalling, and the wear mechanism is adhesion wear. The morphology of 40Cr and 45 steel is furrow and spalling, furrow and adhesion, and the wear mechanisms are abrasive wear. The friction coefficients' differences of the three materials are negligible, and the area of wear of 2Cr13, 40Cr and 45 steel are 5 008 μm2, 1 645 μm2 and 6 535 μm2. 40Cr exhibits better wear resistance than 2Cr13 with similar hardness. The hardness difference between 45 steel and the friction pair material is the largest, and the wear resistance of the 45 steel is the worst.