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The FeCoCrNiMn high-entropy alloy coating reinforced with WC particles was fabricated on 45# steel using plasma surfacing technique. A comprehensive characterization was conducted to investigate the friction and wear behavior of the coating at various temperatures. Results demonstrated that this coating exhibited exceptional wear resistance at room temperature (RT). However, it experienced slight decomposition of WC particles and oxidation corrosion at 400 °C, resulting in a degradation of its wear resistance. The WC decomposition and oxidation corrosion were aggravated at 600 °C, inducing a stronger oxidation corrosion wear effect, and thus led to a more severe wear of this coating. However, these oxidation products provided considerable lubrication effect resulting in a continuous decrease in friction coefficient, from 0.49 at RT to 0.44 at 400 °C, and reached a lower value of 0.16 at 600 °C. The potential oxidation corrosion wear and lubricating mechanisms of this coating at evaluated temperatures were discussed systematically. [ABSTRACT FROM AUTHOR]

The purpose of this study was evaluating the performance of new Bis-EFMA based bulk-fill composites with common methacrylate based composites and commercial dental composites. The Bis-EFMA monomer was synthesized and the novel Bis-EFMA based bulk-fill composites were prepared. The resin composite samples were co-cultured with human gingival epithelial cells and human dental pulp stem cells to test the biocompatibility. The edge adaptation was observed under a combination of stereoscope and scanning electron microscope. The internal hardness was measured using a Vickers microhardness tester after one-time filling of cavities prepared in extracted teeth. After friction and wear test on the surface of the resin composites, the surface morphology and volume wear of each group were measured by the optical profilometer. The color stability was measured by a colorimeter. Direct contact with human gingival epithelial cells and human dental pulp stem cells did not cause significant changes in their growth density and morphology, indicating good biocompatibility of Bis-EFMA group (p > 0.05). The continuous margin proportion of the Bis-EFMA group was as good as commercial bulk-fill composites (p > 0.05). The sectional microhardness results showed that the Bis-EFMA group had the highest microhardness. After the friction and wear test, the volume wear of the Bis-EFMA group was minimal, indicating its good wear resistance and mechanical strength. Color changes in all resin groups after 28 days of immersion were within the clinically acceptable range. The addition of Bis-EFMA demonstrated excellent biocompatibility, edge adaptation and color stability comparable to commonly used clinical bulk-fill composites, along with preferable mechanical strength, friction and wear resistance. Bis-EFMA based bulk-fill composites have the potential to be employed as a bulk filling material in commercial dental composite applications. • Bis-EFMA BF-DRCs showed good biocompatibility to the pulp periodontal tissue. • Bis-EFMA BF-DRCs adapted well to cavity wall. • The rigid structure got Bis-EFMA BF-DRCs higher microhardness and anti-friction property compared with SDR™. • Bis-EFMA BF-DRCs had reliable color stability. [ABSTRACT FROM AUTHOR]

Shaft-surface friction pairs in marine equipment endure considerable wear and corrosion in seawater, particularly under cyclic loading. A friction and wear test bench was employed to replicate the conditions faced by ship stern shafts and bearings in seawater. The study aimed to assess the tribological performance of three types of polyphenylene sulfide (PPS) materials: pure PPS, PPS reinforced with 30% glass fiber (30% GF in PPS matrix), and PPS reinforced with 30% carbon fiber (30% CF in PPS matrix), against 316L stainless steel under varied lubrication conditions. Results demonstrate that all PPS variants exhibit minimal friction force and wear loss in seawater, with 30% CF in the PPS matrix displaying the least friction and wear characteristics. Friction force fluctuates within a 2.5 ~ 5 N range, and wear loss is 0.027 g. However, due to the uneven bonding of glass fiber (GF) within the PPS matrix, the addition of GF did not significantly enhance the materials’ anti-friction properties and wear resistance. The predominant wear mechanism involves severe three-body abrasive wear caused by GF detachment from the friction pairs surface. Additionally, the study explores carbon fiber’s resilience to cyclic loading, the lubricating effect of seawater mixed with carbon fiber debris, and the transfer mechanism of polymer films. These findings highlight synergistic anti-friction and wear-resisting effects between carbon fiber, seawater, and polymer transfer films, offering valuable insights for selecting effective shaft friction pairs materials in challenging seawater conditions. [ABSTRACT FROM AUTHOR]

On specific railway lines, trains are faced with the challenge of low-temperature environments. However, it is still unclear how the low-temperature service environment affects the friction-induced wear and vibration behavior at the train braking interface. Similarly, the impact of the brake pad friction block shape under low temperatures on this behavior is not well understood. This lack of knowledge adversely affects the operation, maintenance, and use of brake pads in low-temperature environments. Therefore, test samples of friction blocks were designed and processed based on several commonly used friction block shapes for trains (ellipse, triangle, and pentagon). Parking brake tests were conducted on a self-developed test bench with controllable temperature, exploring how different shapes affect friction-induced wear, vibration, and noise at the train braking interface under low temperatures (− 20 °C). The results showed that under the effects of low-temperature environments, the shape of the friction block significantly affects the friction-induced wear and vibration noise of the braking interface. Among them, the elliptical friction block has a smaller eccentric wear angle, a smaller and evenly distributed contact plateau area, relatively minor surface wear, and produces low-intensity vibration noise with small fluctuations. In contrast, the triangular and pentagonal friction blocks have larger eccentric wear angles, larger and concentrated contact plateau areas, relatively severe surface wear, and generate high-intensity vibration noise with large fluctuations. Analyzing the reasons, it is found that under the combined effects of low-temperature conditions and different shapes, the friction-induced wear on the surface of the friction block changes, thus exciting different intensities of vibration and noise. [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 work indicates that the core–shell structure is expected to meet the requirements of high friction and low wear for clutches. In the article, two types of core–shell particles are added to Cu-based friction materials for tribological testing. The results showed that as the concentration increased, the coefficient of friction showed a trend of first increasing (from 0.13 to 0.67) and then decreasing (from 0.67 to 0.57). At the same concentration, the COF of carbon coated copper (Cu@C) friction material is 0.4 higher than that of copper coated carbon (C@Cu) friction material, but the wear rate is 43.1% lower. Both materials exhibit high COF but their wear behavior are different due to the distinct components of the friction film. [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]

To address the issues of abrasive wear, impact wear, and soil adhesion that can lead to wear failure and excessive operational resistance in agricultural soil touching parts during farming. This study focuses on UHMWPE composites, modified by filling Nano‐SiC as a hard phase filler and XNBR as an elastic filler. These fillers were dispersed into the UHMWPE matrix through melt blending technology to create a high‐performance composite material for the surface protective material of soil touching parts. The study discovered that by adding hard and elastic fillers to the UHMWPE matrix, the density, hardness, flexural modulus and thermal stability of the materials were all increased. Specifically, the density increased by 5.67% and the flexural modulus increased by 107%. In the block on ring wear test the volumetric wear rate decreased by 98%, while in the mortar wear test the mass wear rate decreased by 64.64%. Additionally, the contact angle on the surface of the specimen after mortar erosion and wear increased to 102.76°, 18% higher than that of pure UHMWPE. These results demonstrate that the modified fillers can improve the abrasion and plastic deformation resistance and hydrophobic desorption of UHMWPE. UHMWPE composite material, serving as the surface protection for soil touching parts, resolves the issues of abrasion of soil abrasive particles and excessive soil adhesion resistance on these parts. This significantly prolongs the service life of soil touching parts of agricultural machinery and improves the operational efficiency and economy. Highlights: Research on nanoparticles and elastomer‐modified composite materials.Research has shown the enhancement of UHMWPE composite materials by Nano‐SiC.XNBR improves the plastic deformation resistance of UHMWPE composites.Effects of Nano‐SiC and XNBR on the desorption behavior of composite materials.UHMWPE composites reduce soil contact wear and soil adhesion. [ABSTRACT FROM AUTHOR]

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Copyright of Bearing is the property of Bearing Editorial Office 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.)

In order to improve the wear and corrosion resistance and enhance the tribological and mechanical properties of gray cast iron, the laser surface cladding technique was employed to fabricate double-layer coatings with different Ni/WC ratios on the surface of gray cast iron. The effects of laser processing parameters and the type of Ni-based alloy on the microstructure and properties of the gray cast iron matrix and laser-clad layer were investigated. A 316L stainless steel transition layer was introduced between the gray cast iron substrate and the Ni/WC coating to prevent the cladding layer from cracking. The tribological and mechanical properties of the laser-clad coatings were characterized with various tests at the macro- and micro-scales; the residual stresses on the coating surfaces were measured, and electrochemical tests were also carried out. The microstructures of the clad layers were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the laser-clad layers exhibit excellent vibration and noise reduction performance, which is partially due to the reduction and stabilization of the coefficients of friction (COFs) and the high levels of compressive residual stress on the surface of the laser-clad layers. The wear and corrosion resistance of the laser-clad layers are significantly improved, and the maximum wear loss of the laser-clad coating was about only 5% of that of the unclad gray cast iron substrate. This research has significance for the laser surface modification of cast iron, steel, and other metals, which is an increasingly important topic, especially in the automotive friction brake industry. [ABSTRACT FROM AUTHOR]

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.)

Chromium nitride (CrN) is a promising structural and protective material with excellent mechanical properties and good wear and corrosion resistance. However, CrN tends to decompose into Cr 2 N at high temperatures, which makes the fabrication of single-phase and dense bulk CrN ceramics extremely challenging. In this work, a novel routine, ammonolysis followed by plasma activated sintering (PAS), has been proposed to fabricate single-phase and dense CrN ceramics. Single-phase CrN ceramics with a relative density of 98.2 %, higher than those in previous work, were successfully fabricated at the sintering temperature of 1200 °C. Its hardness and fracture toughness reach 11.9 GPa and 3.98 MPa m1/2, respectively, better than other CrN ceramics in literature. It exhibits friction coefficients of 0.75 to 0.45 and wear rates of 2.31 × 10−6 to 3.06 × 10−5 mm3 N−1 m−1 at the friction loads of 5–20 N. The successful fabrication of single-phase CrN ceramics can be attributed to the combined effect of the sintering atmosphere of extra N 2 and rapid densification. During densification, N 2 injected into the furnace will be encapsulated rapidly, creating a localized high nitrogen pressure that suppresses CrN decomposition and ultimately results in single-phase and dense CrN ceramic bulk. [ABSTRACT FROM AUTHOR]

The effects of complex well conditions in shale oil wells on the swelling and tribological properties of high-acrylonitrile stator rubber used in screw pumps were investigated in this study. Tests were conducted considering the combined effects of immersion medium, temperature, and duration. The key parameters measured included mass change rate, volume change rate, hardness, elongation at break, tensile strength, surface micro-morphology of the rubber after thermal expansion and swelling, friction coefficient, and wear quantity. The results indicated that in the actual well fluids, the mass change rate of high-acrylonitrile rubber ranged from −1.08% to 1.29%, with a maximum volume change rate of 2.78%. In diesel oil, the greatest mass change rate of the rubber was 4.68%, and the volume change rate did not exceed ±1%, indicating superior swelling resistance. In both actual well fluids and diesel oil, the maximum decreases in hardness were 8.7% and 9.5%, respectively. Tensile strength and elongation at break decreased with increasing immersion temperature, with elongation at break in 80 °C diesel oil decreasing by over 50%, indicating a significant decline in the tensile properties of the rubber. The average friction coefficient of rubber specimens immersed in actual well fluids at three temperatures, as well as in diesel oil at 25 and 50 °C, decreased compared with the high-acrylonitrile rubber without thermal expansion and swelling. However, the average friction coefficient of rubber specimens immersed in diesel oil at 80 °C increased. The wear quantity of the rubber increased following immersion in both media. Additionally, the friction coefficient and wear quantity of the rubber increased with increasing immersion temperatures. The results of the study can offer valuable insights into assessing the durability of properties in high-acrylonitrile stator rubber under complex well conditions. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the strengthening mechanism of laser shock peening on the interfacial bonding properties between TiN coatings and TC4 titanium alloy substrates. The different surface textures were induced by LSP on a TC4 titanium alloy substrate. Subsequently, titanium nitride (TiN) coatings were deposited on the surface texture. A scratch test and reciprocating sliding wear assessment were conducted to evaluate the impact of LSP on the interfacial bonding properties and wear performance of the coatings. The experimental results demonstrated that the adhesion of TiN coatings deposited on the surface texture formed by laser shock peening was significantly enhanced. The efficacy of laser shock treatment in reducing wear rates was found to be significantly enhanced in cases of both increased spot overlapping rate and increased laser power density. The surface texture created using laser parameters of 6.43 GW/cm2 and a 50% overlapping rate was found to have the most significant effect on improving the adhesion and anti-wear properties of the coating. The laser shock texture was identified as the main contributor to this improvement, providing a large interfacial contact area and a mechanical bond between the coating and the substrate. This bond inhibited the initiation and propagation of micro-cracks caused by the concentration of internal stress and interfacial stress of the coating. [ABSTRACT FROM AUTHOR]

Current-carrying friction materials with excellent electrical conductivity and anti-wear ability are in constant demand in both academia and industry. In this work, the sliver-titanium nitride (Ag–TiN) composite ceramic coating was fabricated by an arc ion plating method. The microstructure, chemical composition, crystal structure, mechanical properties and current-carrying tribological behaviors of the Ag–TiN composite coating were systematically studied and the worn surfaces were also thoroughly investigated to analyze the possible tribological mechanisms in detail. The results showed that the Ag–TiN composite ceramic coating achieved uniformly distributed co-deposition of Ag and TiN compositions and exhibited excellent mechanical properties and electrical conductivity. The current-carrying tribological tests also revealed that the Ag–TiN composite coating exhibited exceptional friction reducing, anti-wear and conductive properties during the friction process. The analysis of the worn surface showed that the excellent current-carrying tribological behaviors of the Ag–TiN composite ceramic coating were related to the excellent electrical conductivity, the appropriate mechanical properties and the tribo-layer film formed on the worn surface. [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.)

Hybrid shell microcapsules have been incorporated into polytetrafluoroethylene (PTFE)/aramid fabric composite liners to enhance the tribological behavior of self-lubricating spherical plain bearings. PAO40/polysulfone/SiO2 hybrid shell microcapsules were synthesized utilizing a combination of Pickering emulsification technology and solvent evaporation. The modified liner with 9 wt% microcapsules exhibited the highest reduction in the average friction coefficient and wear rate, which were 31.1% and 47.9% lower than the unmodified liner. Furthermore, the tribological behavior of modified liners was investigated under different loads and sliding speeds. The friction process of the modified liner and the formation process of the transfer film were analyzed. Investigations into the friction reduction mechanism revealed that the PAO-40# released from microcapsules transitioned the friction type from dry to mixed. SiO2 particles are conducive to forming a denser transfer film by the PTFE abrasive. The results of this study have important scientific significance. [ABSTRACT FROM AUTHOR]

In this study, three types of three-layer functionally graded materials (FGMs) were designed by mainting the average content of the reinforcement constant and changing the span of the composition. The B4C particle-reinforced Al-matrix FGMs and a homogeneous composite (HC) with the same average composition were prepared using the laser additive manufacturing technique. The FGMs had a higher average secondary-phase content and grain size than the HC. Large (black) and reticulated (white) secondary phases corresponding to B4C phase, T phase, and MgZn2 were observed in the as-deposited FGM samples. The content of the secondary phase in the middle layer was generally low. The bottom layer, which was in direct contact with the substrate, exhibited the smallest grain size. The hardness and wear resistance significantly improved owing to the high B4C content in the top layer. The flexural behaviors of each layer of the FGM in different directions were systematically studied. The plasticity of the single-layer material decreased with increase in the B4C content. When the bottom layer had a high B4C content, the flexural ability significantly reduced. Among all the samples, G2 with 8% B4C particle content in the top layer exhibited the best comprehensive mechanical properties. The hardness value, wear rate of the top layer, maximum bending stress, and maximum bending strain of the FGM were 177.5 HV, 0.367 × 10−3mm3/(N·m), 585.6 MPa, and 7.36%, respectively. This study can provide a reference value for the future design and development of wear-resistant gradient materials for aerospace applications.

In this work, the effects of the gradient microstructures by surface mechanical attrition treatment (SMAT) on the corresponding tribological properties of the nanoprecipitates strengthened copper alloy was investigated. The nanoprecipitates strengthened copper alloy possesses a decent tribological properties compared with the pure copper and bronze. The SMAT-processed NP&T alloy possesses distinctly lower coefficients of friction (COF) than its coarse-grained counterpart throughout the entire frictions. In particular, under a sliding load of 2 N, NP&T alloy possesses a lower COF of 0.58 ± 0.03, approximately 15% lower than that of its homogeneous counterpart. Additionally, the wear volumes, wear rates, and worn surface roughness were approximately 45% lower in the NP&T alloy, indicating the superior tribological properties. The macro-, micro-, and atomic-scale friction and wear mechanisms in the worn NP&T alloy were systematically determined. The inherent gradient nanostructures could achieve strain delocalization, thereby suppressing surface deformation and improving wear resistance. Wear-induced substructure in the NP&T alloy comprises gradient layers mediated by twinning and stacking faults combined with nanocomposite layers, resulting in novel tribological performance characteristics. Thus, combining inherent and newly formed wear-resistant gradient nanostructures is an effective design strategy for high-performance Cu alloys.

Son yıllarda hasar görmüş makine parçalarının düşük maliyetli kaynak yöntemleri ile tamir edilip tekrar kullanılması yaygın hale gelmiştir. Bu çalışmada imalat sektöründe yaygın olarak kullanılan MIG ve ark kaynak yöntemleri ile beş farklı kaynak teli kullanılarak AISI 1050 çeliğine kaynaklı tamir işlemleri uygulanmıştır. MIG yönteminde SG2 kalite ve paslanmaz kaynak telleri, ark kaynağında rutil, bazik ve paslanmaz kaynak telleri kullanılmıştır. Tamir edilmiş numunelerin mikroyapı, mikrosertlik, sürtünme ve aşınma davranışları incelenmiştir. Mikroyapı incelemeleri optik mikroskop ile gerçekleştirilmiştir. Aşınma deneyleri ASTM G99 standartına uygun olarak kuru şartlarda pim-disk yöntemi ile yapılmıştır. Aşınma kanalları yüzey profilometresi ile ölçülerek spesfik aşınma oranları hesaplanmıştır. Aşınmış yüzeyler SEM ve EDS analizi ile incelenerek aşınma mekanizmaları belirlenmiştir. Tamir edilmiş numunelerin kaynak bölgelerinde çatlak, boşluk vb. mikroyapısal kusurlar tespit edilmemiştir. Tamir edilmiş tüm numunelerin mikrosertlik değerleri AISI 1050 çeliğinden yüksek çıkmıştır. En yüksek ortalama mikrosertlik değerleri paslanmaz kaynak teli ile tamir edilmiş numunelerde tespit edilmiştir. Tamir işlemleri sonrası numunelerin aşınma performansı yaklaşık 3 kat artmıştır. En yüksek aşınma direnci MIG yöntemi ve SG2 kalite kaynak teli kullanılan numunede tespit edilmiştir

The ZCuPb15Sn5/1045 bimetallic composites were prepared by the melt-casting composite method. The mechanical and tribological properties of the copper-steel bimetallic composites under different cooling process conditions were studied. The results showed that with the acceleration of the cooling rate, the copper layer of the copper-steel bimetallic composite became harder, the grain became finer, and the distribution of the anti-friction element Pb became more uniform. Underwater cooling conditions, the shear strength increased, and the shear fracture gradually showed the tendency of tough and brittle fracture. The cooling process had a more significant influence on the tribological properties of the material. When the cooling rate was slow, the copper layer of the bimetallic composites had a high friction coefficient and relatively serious adhesive wear and oxidation wear. For the water cooling sample with a very fast cooling rate, the friction coefficient of the copper layer was low and the wear degree was relatively light.

The cam tappet friction pair is one of the three major friction pairs in an internal combustion engine, and the surface of the tappet undergoes severe wear during operation. To improve the wear resistance of the cam tappet friction pair during operation, in this study, crescent-shaped micro-textures were prepared on the surface of the tappet material of GCr15 steel by laser machining technique, and the effects of the orientation and depth of the texture on the friction properties of GCr15 steel were studied. The processed test samples were tested and characterized by friction and wear tests, scanning electron microscopy (SEM), 3D morphometry, and EDS. The flow field simulation model of micro-texture was established by using Fluent finite element software. The simulation and experimental results show that the crescent-shaped microtexture prepared on the surface of GCr15 steel can play a certain role in reducing friction and wear resistance, meanwhile orientation and depth of the texture affect the friction performance. In the fluid simulation, the positively oriented texture can produce higher oil film pressure than the opposite texture. When the texture depth is 20 μm, it has a better friction and wear reduction effect, and the friction coefficient decreases by 65.81% compared with that of the untextured surface, and the amount of wear decreases by 74.19%. This is mainly due to the existence of texture in the friction process to reduce the contact area and the shallower depth of texture can produce a larger oil film pressure in the oil lubrication state, so it has better tribological performance. The research data provide a certain reference for the design and optimization of the cam tappet friction pair.

Complex formation structures lead to significant differences in the failure mechanisms of hobs. WC-reinforced medium entropy composite coatings exhibit excellent comprehensive properties. However, the wear mechanism of coatings in different formation structures is still unclear. In this study, FeNiCr-WCx (x = 0, 40, 50, 60 wt%) composite coatings were prepared on the surface of H13 steel using laser cladding technology. The friction and wear mechanism of FeNiCr-WC composite coatings under different friction pair conditions was discussed. The results show that FeNiCr-WC composite coatings mainly consist of reinforced phase, lamellar eutectic structure and solid solution phase. As the WC content increases, the content of M6C and carbide phases in these coatings increases. The average microhardness of 40WC, 50WC and 60WC coatings is 3.28 times, 3.61 times and 4.20 times that of H13 steel, respectively. The wear rates of 40WC, 50WC and 60WC coatings are respectively about 0.25, 0.10 and 0.06 times that of FeNiCr coating under Al2O3 friction pair conditions. Three-body wear and oxidation wear mainly occurred on the surface of FeNiCr-WC composite coatings. The wear rates of 40WC, 50WC and 60WC coatings are respectively about 0.34, 0.35 and 0.16 times that of FeNiCr coating under Si3N4 friction pair conditions. Glaze layers with high Si content were formed on the surface of 50WC and 60WC coatings. The glaze layer is prone to cracking and peeling, resulting in increased wear rates for both coatings. As the hardness of the coating increases, the GCr15 friction pair undergoes severe abrasive wear.

In this study, SiO2 containing PAO6 microcapsules were endowed with surface active groups by polydopamine (PSPMS). Then the modified microcapsules were in situ grafted into phenolic resin (PF@PSPMS) to control the dispersion and bonding in high viscosity resin. Further, the tribological properties of the PF coating and the prepared liner were analyzed. The results show that the life of PF@PSPMS-coating is 73 times longer than that of PF-coating, the friction coefficient (COF) is reduced by 78%. Meanwhiles the COF of the corresponding liner is reduced from 0.11 to 0.06, and the wear amount is reduced from 64.07 μm to 23.07 μm. The wear mechanism shows that the breakage of PSPMS release lubricating oil at the friction interface, forming a coordinated solid-liquid lubrication effect with PTFE. At the same time, the presence of lubricating oil can remove the debris on the surface of the friction pair and improve the quality of the transfer film. In addition, the dispersion of silica fragments at the friction interface is conducive to improving the hardness and wear resistance. This work provides a new method for the dispersion of microcapsules in the liner and further explains the anti-friction and wear mechanism of silica microcapsules in the liner system, confirming the effectiveness of microcapsules in the liner system.

In the wastewater treatment device, the core moving parts (such as the check valve in the pump body) are prone to failure due to wear and corrosion. There is an urgent need to develop high-performance self-lubricating materials suitable for moving components in electroplating wastewater. Therein, the tribological properties of Si 3 N 4 (silicon nitride) based composites with the addition of hBN (hexagonal boron nitride) against 2507 duplex stainless steel in electroplating wastewater were investigated using a Pin-On-Disc (POD) tribometer. The results show that the addition of hBN to the ceramic matrix could effectively improve the tribological properties of Si 3 N 4 materials. The friction coefficient and wear rate of Si 3 N 4 are lowered to 0.14 when the hBN content reaches 30 wt%, which is attributed to the formation of a lubricating films (containing hBN, Si(OH) 4 and Cu and its oxides) on the worn surfaces. A segmental test results indicate that the lubricating film undergoes processes such as formation, spalling, and regeneration during the friction process. Meanwhile, hBN and Si(OH) 4 , due to their inherent structural characteristics, can lubricate and protect the worn surfaces. The molecular dynamics simulation results indicate that Cu and its oxides are prone to slip under normal and transverse forces, and have a positive effect on reducing friction. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of different substrate surface roughness on the friction and wear properties of amorphous carbon films, and improve the tribological properties of the 2Cr13 sample surface under 601EF lubricating grease lubrication, the methods such as machining, polishing and other techniques were employed to prepare different surface roughness on the surface of 2Cr13 samples. Subsequently, amorphous carbon thin films were prepared on the surface of samples with different roughness by magnetron sputtering. The friction and wear properties of amorphous carbon films and silicon nitride balls under 601EF lubricating grease lubrication were investigated through ball-disc contact friction and wear tests, and the wear places were analyzed by optical microscopy. Results showed that the Si3N4 balls that rubbed against the substrate surface all presented a clear platform, while the substrate surface did not display any obvious grinding marks. The samples with the Ra range of 0.20～0.75 μm on the coupling ball had the smaller wear amount, the wear spot area range was 0.152～0.165 mm2, and the wear form was adhesive wear. By contrast, the samples with the Ra range of 0.95～3.19 μm had more wear amount on the coupling ball, the wear spot area ranging from 0.228～0.275 mm2, and there were furrow-like wear marks, which indicated more serious wear. Under the same operating conditions, as the surface roughness of the substrate increased, the starting and average friction coefficients between the two friction pairs, as well as the wear amount of Si3N4 balls, all showed a trend of first decreasing, then increasing, and then decreasing. When the Ra was 0.56 μm, the tribological performance of the amorphous carbon film was the best, and the friction curve was relatively stable, with an average friction coefficient of 0.162, and the wear amount of its coupling ball was the smallest, 0.152 mm2. In general, the surface roughness of the substrate affected the tribological performance of amorphous carbon films, and the surface with good anti friction properties could be obtained by preparing appropriate roughness on the substrate surface via the means of machining, polishing, etc.

In the mass-production of microfluidic devices through micro hot embossing/injection moulding, the longevity of mould inserts is influenced by elevated adhesion and friction between the polymer and the mould. Thus, accurate prediction of mould lifespan requires a comprehensive understanding of surface wettability and tribological performance during polymer contact. The current study addresses this gap by characterizing fabricated micro-structured Ni, Ni-WS2, and Ni-PTFE nanocomposite moulds (surface morphologies, crystal structures and microhardness) to investigate inherent lubrication mechanisms. Surface wettability of mould material was systematically studied by measuring the contact angles with eight different polymer melts. Pin-on-disk tests with polymer pins made of cyclic olefin copolymer (COC 8007), polypropylene (PP), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were conducted to elucidate the wear resistance of the nanocomposite moulds. Pressure-dependent friction coefficient and wear resistance were further explored under increasing external loads, simulating the actual moulding processes where contact pressure may vary considerably depending on the part shape. Results indicate that Ni-WS2 exhibits the highest microhardness (532 Hv), followed by Ni-PTFE (465 Hv) and Ni (198 Hv). Notably, Ni-PTFE demonstrates exceptional hydrophobicity against all polymer melts, signifying low surface energy during polymer contact. Moreover, both nanocomposite moulds exhibit reduced friction coefficients and enhanced wear resistance across various polymers. Counterintuitively, despite its lower hardness, the Ni-PTFE mould displays superior wear resistance against the COC pin under higher loads, while the Ni-WS2 mould experiences severe adhesive wear, as observed from wear morphology and profile analysis. This finding establishes the Ni-PTFE as a promising alternative as a mould insert material for precision manufacturing.

With the development of deep-sea exploration technology, the technology of fire-retardant hydraulic fluid (HFC) has played an important role in the power transmission of exploration equipment. However, the mechanism of the influence of seawater content on the tribocorrosion behavior of HFC remains unclear. In this study, the effects of different seawater contents on the tribological and corrosive properties of HFC were systematically investigated. The results showed that when the seawater concentration exceeds 30 wt%, a soft Mg-containing reaction film is formed in the friction contact area owing to seawater corrosion, thus effectively improving the sintering load and wear resistance to some extent. By contrast, with increasing seawater concentration, the lubricity declines, the wear intensifies, and the extreme pressure characteristics decrease significantly. The comparative analysis shows that the composition of the wear and corrosion reaction films significantly differs under high-concentration seawater conditions, which is also a key factor affecting the friction and corrosion behavior of HFC. This study provides a direction for the research and development of wear- and corrosion-resistant materials and coatings on the surface of deep-sea exploration equipment.

Ni–Cr–MoS2-based composite’s microstructure and wear behavior were examined in relation to compacting pressure and sintering temperature. The tribological performance of Ni-Cr–MoS2 composite against En32 martial is examined in this research in relation to the nodule count, particle count, and average area depending on the compacting pressure and sintering temperature. The green pallets were cylindrical in shape and had a diameter of 12.5mm × 30mm. They were pressed at room temperature (28∘C) with axial pressures of 220MPa, 275MPa, and 330MPa, then sintered in two batches at different sintering temperatures of 900∘C and 1000∘C. By using Image analysis, the amount of nodules, their size, particle counts, particle sizes, and lubricant flakes of developed composite are investigated. The typical nodule size ranges from 46 μm to 60 μm, and the average nodule percentage is between 67 and 79 present in Ni–Cr–MoS2-based composite. Particle counts ranged at present from 29 to 516 depending on the sintering temperature and compacting pressure. Up to 1.1472 μm, lubricant flake lengths were nearly the same for composite for the different compacting pressure and sintering. With varying compacting pressures and sintering temperatures, the coefficient of friction and wear rate varied for the developed Ni–Cr–MoS2 composite. The impact of the nodule, nodule counts, particle and particle size is also present on the developed composites for friction and wear. Minimum wear rate observed for composite sintered was under 1000∘C temperature, and maximum wear rate was 7.55E−8 mm3/Nm for low compacting pressure and 900∘C sintering temperature. [ABSTRACT FROM AUTHOR]

Aiming to solve the problem of thermal decay of resin-based friction materials at high temperatures, rare-earth-lanthanum-oxide-/cerium-oxide-reinforced resin-based friction plates were prepared using a hot-pressing molding process. The effect of lanthanum/cerium oxide with different contents on the mechanical and tribological properties of the resin-based friction of materials was studied, and its mechanism was explored. The result shows that lanthanum/cerium oxide improves the mechanical and tribological properties of materials so that the coefficient of friction of the specimen is more stable on adding lanthanum/cerium oxide at 5% and 1%. Lanthanum/cerium oxide improves antidegradation properties of resin-based material and reduces the high-temperature wear rate by enhancing the interfacial effect so that the wear form of the specimen changes from predominantly adhesive wear to predominantly abrasive wear. [ABSTRACT FROM AUTHOR]

Ceramic particle reinforced medium entropy alloys (MEAs) coatings have attracted considerable attention because of their excellent hardness and wear resistance. In this study, (CoCrNi) 94 Al 3 Ti 3 MEA coating and (CoCrNi) 94 Al 3 Ti 3 -cBN MEA composite coating were prepared by high-speed laser cladding. The phase constituents, microstructure，hardness and wear mechanisms of the two coatings were investigated using XRD, Raman spectra, SEM, EDS, and TEM. Results show that (CoCrNi) 94 Al 3 Ti 3 comprises only simple FCC phase because of the high-entropy effect. However, the addition of cBN transforms the phase from FCC to FCC + BCC, but also generates micron-scale TiN and CoCr, as well as nanoscale TiN and CrB. In addition, part of the cBN is converted to hBN with lubricating effect under high energy laser. As for the properties, compared with (CoCrNi) 94 Al 3 Ti 3 coating, (CoCrNi) 94 Al 3 Ti 3 -cBN coating exhibits increased hardness by 2.2 times, increased wear resistance by 5.6 times, and decreased friction coefficient from 0.58 to 0.47. It is expected that this research will provide research ideas for the preparation coating of friction reduction and wear resistance performances on titanium alloy surfaces. [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.)

Diamond films were prepared on silicon nitride and zirconia ceramic substrates using hot filament chemical vapor deposition (HFCVD). The surface morphology, friction, and wear properties of the diamond films prepared with different methane concentrations (2%, 4%, and 6%) were compared using scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and friction and wear testing machines. The results showed that, with an increase in the methane concentration, the diamond particles gradually changed from micro- to nanodiamonds, and the grain size first increased and then decreased. The diamond films on silicon nitride substrates were of excellent quality, with good wear resistance, strong adhesion, and wear rates of 2.857 × 10−8 mm−3•m−1•N−1, 5.151 × 10−8 mm−3•m−1•N−1, and 1.334 × 10−7 mm−3•m−1•N−1, respectively. The diamond films on zirconia substrates had more impurities on the surface, higher internal stress, poorer wear resistance, and weaker adhesion, with wear rates of 3.789 × 10−8 mm−3•m−1•N−1, 5.899 × 10−8 mm−3•m−1•N−1, and 2.074 × 10−7 mm−3•m−1•N−1, respectively. Hence, the deposition of diamond films on ceramic substrates significantly reduced the friction coefficient, and the performance of diamond films on silicon nitride substrates was excellent. [ABSTRACT FROM AUTHOR]

High-nickel titanium-based alloys (TiNi) have the advantages of low density and high specific strength, and are widely used in mechanical engineering and other fields. The poor wear resistance of TiNi alloys limits the development and application of TiNi alloys in related fields. In order to improve the wear-reducing and wear-resistant performance of TiNi alloy, a fish scale-like surface texture was designed and prepared on its surface using a laser marking machine, as well as filled with a composite solid lubricant SnAgCu-Al2O3 (S-A/TiNi). The effects of different speeds on the tribological properties of the S-A/TiNi composites were investigated under the surface texture angle parameter of 70°. The results showed that the temperature rise on the abraded surface of S-A/TiNi-70° improved the plasticizing properties of the solid lubricant at a speed of 0.037 m/s. The solid lubricant was extruded from the weave under stress, promoting lubricant film generation and obtaining optimum tribological properties. At higher velocities (>0.037 m/s), the temperature rise of the friction surface was fast, resulting in enhanced plastic properties of the solid lubricant. Damage to the lubrication film under stress results in reduced tribological performance. At lower velocities (<0.037 m/s), more heat was generated on the friction surfaces, making the plastic deformation of the solid lubricant excessive. The lubricant film was prone to spalling under cyclic stress, leading to a reduction in the tribological properties of the substrate. [ABSTRACT FROM AUTHOR]

In this study, Fe/TiC composite coating was fabricated on the surface of 65Mn steel using substrate preheating combined with laser cladding technology. In order to characterize the impact of various preheating temperatures, four coatings were fabricated on a 65Mn substrate using laser cladding at different temperatures (ambient temperature, 100 °C, 200 °C, and 300 °C). The microstructures and properties of four Fe/TiC composite coatings were investigated using SEM, XRD, EDS, a Vickers microhardness meter, a wear tester, and an electrochemical workstation. The research results show that the cladding angle of the Fe/TiC composite coating initially increases and then decreases as the substrate preheating temperature rises. The solidification characteristics of the Fe/TiC composite coating structure are not obviously changed at substrate preheating temperatures ranging from room temperature to 300 °C. However, the elemental distribution within the cladding layer was significantly influenced by the preheating temperature. An increase in the preheating temperature led to a more uniform elemental distribution. Regarding the comprehensive properties, including hardness, wear characteristics, and corrosion resistance, the optimum substrate preheating temperature for the cladding layer was found to be 300 °C. [ABSTRACT FROM AUTHOR]

Hydrogels have received extensive attention as functional lubricants because of their excellent anti-friction and anti-wear properties, tunable tribological performances, and effectiveness in alleviating lubrication failures caused by the creeping or leakage of conventional liquid lubricants owing to their semi-solid nature. This review summarizes the current research advances in hydrogel lubricants fabricated with various organic and/or inorganic gelators, including organic polymeric or supramolecular hydrogels, inorganic particles-based hydrogels, and organic polymer-inorganic particle hybrid hydrogels. We illustrate not only the design strategies for constructing high-performance hydrogel lubricants but also the tribological behavior and mechanism of different types of hydrogel lubricants and their potential applications in industrial and biomimetic fields. Corresponding outlooks and suggestions for future studies have also been proposed. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office 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.)

This study investigates the enhancement of wear resistance in CuCrZr rails through the plasma cladding of CuCrZr-GO coatings with a varying graphene oxide (GO) content. The microstructure, phase composition, and mechanical properties of CuCrZr coatings containing 0%, 0.2%, 0.4%, 0.6%, and 0.8% GO were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), ESD surface scanning, friction and wear tests, and hardness analysis. The findings indicated that increasing the GO content from 0% to 0.6% results in a transition in the coating microstructure from columnar to equiaxed crystals, leading to an improved density. However, at 0.8% GO, numerous porosity defects were observed. The coating containing 0.6% graphene oxide (GO) exhibited a superior performance, with a hardness of 75, a friction coefficient of approximately 0.7, and a wear mass of 2.84 mg under a 10 N load. In comparison to the CuCrZr coating lacking GO, the hardness showed an increase of around 4.8%, the friction coefficient decreased by approximately 5.1%, and the wear mass diminished by 59.4%. These findings hold significant implications for extending the operational lifespan of electromagnetic railguns. [ABSTRACT FROM AUTHOR]

As a typical form of damage, wear greatly affects the service properties of products, and non-destructive evaluation of the degree of wear is urgently needed. In this paper, the wear degree of AISI 1045 steel was evaluated by magnetic Barkhausen noise (MBN) testing. The root mean square (RMS) and full width at half maximum (FWHM) of MBN were extracted to establish the quantitative relationships between the tribological indicators and the stress state. The results indicate that the RMS decreases linearly and the FWHM increases quadratically with increasing tribological indicators, which can distinguish among different wear stages, including abrasive, adhesive and fatigue wear. However, the RMS shows a complicated nonlinear relation with the residual stress during the wear process. In addition, the MBNenergy parameter is also calculated to reveal the features of the hysteresis loop at the wear scar. Both the coercivity Hc and the maximum magnetic permeability μmax are linearly related to the tribological indicators and quadratically related to the stress, which reflects the effect of tribo-magnetisation on the MBN signals. The variation mechanism of MBN under different wear stages is attributed to the combined effect of plastic deformation and the stress state by microstructure observations. [ABSTRACT FROM AUTHOR]

Using extreme high‐speed laser cladding technology, Ni60 coatings are laser cladded onto stainless‐steel, 20# steel, and 45# steel substrates. The effect of substrate material properties on the cracking behavior, microstructure, and tribological properties of the Ni60 coating is systematically studied. The results show that as the difference of the coefficient of thermal expansion between the substrate and cladding material decreases, the tendency for crack generation in the cladding layer is reduced. In addition, the difference of the thermal physical properties of the substrate has an important effect on the temperature gradient during the cooling process of the coating, and then affects the growth rate of the grain in the coating and the overall mechanical properties of the coating. Finer grain size, fewer macroscopic coating cracks, and the evenly distributed hard phase in the Ni60 coating on the 20# steel substrate lead to better wear resistance. [ABSTRACT FROM AUTHOR]

This research uses a rotary pin-on-disc tribometer to explore the friction and wear behaviour of a copper-free semi-metallic friction composite over various operating temperatures, 25 °C, 150 °C, 250 °C, 350 °C, and 450 °C. The tribological performance of copper-free semi-metallic specimens is significantly affected by heat degradation. It was found that at 450 °C, severe wear of the pin specimen occurred. The friction layer coverage gradually decreased at ≥ 250 °C. The composite pin's wear rate was found to increase 13.26 times from 450 °C to 25 °C, whereas the disc wear rate at 450 °C was 0.86 times the wear rate at 25 °C for the loading condition of 60 N load, 2.09 m/s sliding velocity and 6283 m sliding distance. Micro-ploughing was the primary wear process below and at 150 °C, whereas groove development, delamination, and severe adhesion dominated above 150 °C. Friction tests were conducted under dry sliding conditions at room temperature (25 °C) and high temperatures (150 °C, 250 °C, 350 °C, and 450 °C). Severe wear of the pin specimen was observed at 450 °C, with 13.26 times increase in wear rate compared to 25 °C. Thermal degradation of the binder material significantly impacts the tribological performance above 350 °C. Micro-ploughing is predominant below and at 150 °C, while groove development, delamination, and severe adhesion dominate above this temperature. [ABSTRACT FROM AUTHOR]

Frictional wear of brake discs is an important cause of disc brake failure in high-speed trains, and the arrangement of friction blocks is an important factor affecting the maximum wear depth of brake discs. In order to study the influence of the arrangement of friction blocks on the maximum wear depth of the brake disc, the change of friction temperature, contact stress and relative slip speed in the braking process were considered, based on the Archard wear model for modification, using ANSYS finite element simulation software, the three-dimensional transient model of the brake disc-brake pads was established, the train through the No. 42 turnouts in the emergency braking situation was adopted, the maximum wear of the brake disc friction surface under different friction block arrangements was simulated calculation. The maximum wear depth of the friction surface of the brake disc was calculated under different friction block arrangements. The maximum contact stress was analyzed, and the parameter “ stress wear factor” was proposed to characterize the effect of stress on the maximum wear depth. The radial nodal wear depth was extracted, the wear morphology of the friction surface was analyzed, and the influence of different arrangements of friction blocks on the wear depth of the brake disc was given. The research results provide the theoretical basis and new ideas for improving the wear of brake discs and provide a reference for the design of the brake pad structure of railway braking systems in the future. [ABSTRACT FROM AUTHOR]

In order to explore the influence of textured sawteeth on saw blade cutting and wear performance, linear micro textures perpendicular to the chip flow direction were fabricated on the rake face, main flank face, and secondary flank face by laser machining, respectively. The cutting tests were carried out on sawing platform with different cutting speeds under lubrication conditions. The cutting forces, noise, temperatures, machined surface quality, and sawtooth wear were investigated. The results indicated that textures fabricated on the secondary flank face can effectively reduce friction with the machined surface and improve the surface quality, and the roughness Ra decreased about 2.5 ~ 12.5% compared with traditional saw blade. The improvement of saw blade cutting performance by machining micro textures on the main flank face was greater than the textures fabricated on the rake face. Due to the synergistic action of textures on different cutting faces, the cutting force, noise, and temperature of saw blades with textures prepared on all cutting surfaces were the lowest. The main wear forms of sawteeth were tip wear, surface adhesion wear, and oxidation wear. Although the derivative cutting phenomenon occurred, the micro textures were not completely filled, which signified that the micro textures still played the role of stored cutting fluids, reduced contact area, and formed lubrication film. [ABSTRACT FROM AUTHOR]

ABSTRACT As an emerging two‐dimensional material, black phosphorus (BP) has excellent tribological properties, but the poor dispersion of BP in oil inhibits its application in friction to some extent. Surface modification is one of the effective methods to solve the dispersibility of BP, and the use of nano‐Fe3O4 dotted on the surface of BP improves the dispersion stability of BP in soybean from 3 days to about 15 days. Compared with pure soybean oil, friction coefficient and wear rate of the addition of 0.12 wt% BP/Fe3O4 are reduced 65% and 78%, respectively. To elucidate the excellent tribological mechanisms of BP/Fe3O4 as additives in soybean oil, the compositional and structural characterisation of the abrasion mark surface was studied accordingly. On the one hand, soybean oil reacts with BP/Fe3O4 to form a composite tribo‐film during the scraping process. This tribo‐film composed of amorphous carbon, iron oxide and phosphorus oxide nitrides prevents direct contact between the sliding interfaces. On the other hand, BP and Fe3O4 nanoparticles form a mechanical rollerball structure, which can further reduce interfacial friction and wear through synergistic lubrication. The results provide new insights into the design of additives in biomass lubricating oils and propose new application prospects for BP in the field of lubricating additives. [ABSTRACT FROM AUTHOR]