Excellent Wear Resistance Research Articles

Enhancement of friction and wear performance of polytetrafluoroethylene composites through the synergistic effect of hard fillers

AbstractThe Stirling engine is a high‐efficiency externally heating piston engine. The self‐lubricating properties of polytetrafluoroethylene (PTFE) are crucial for the operation of Stirling engines. Three PTFE composites filled with different contents of carbon fiber (CF), polyimide (PI) and nano‐zirconia (nano‐ZrO2) were prepared and their mechanical, friction and wear properties were investigated. The results showed that the density of CF‐containing PTFE composites was significantly reduced by 1.46% to 6.9% compared to neat PTFE. Meanwhile, the incorporation of fillers greatly enhanced the hardness by more than 21.4% over the hardness of neat PTFE. In addition, the friction coefficients of three PTFE composites were lower than those of neat PTFE, and the wear rate of these composites was three orders of magnitude lower than that of neat PTFE. In particular, the wear rate of PTFE filled with CF and PI at high pressure (2 MPa) and high velocity (4 m/s) was only 1.24 × 10–6 mm3/Nm. The wear morphology was also analyzed by scanning electron microscopy and energy‐dispersive x‐ray spectroscopy. It was found that the addition of CF and PI in PTFE has the most pronounced improvement on tribological performances. The synergistic effect of CF's mechanical reinforcement and PI's adhesive properties reduces the wear of the matrix, resulting in excellent wear resistance of PTFE composites.Highlights The compressive strength of PTFE was reinforced by CF and nano‐ZrO2. CF can lower the density and significantly enhance hardness of PTFE. Synergistic CF and PI enhance PTFE composites' friction & wear performance. Adhesive fillers & debris size key to forming uniform continuous transfer films.

Research on Mechanical Properties of High‐Manganese Steel Coating Manufactured by Coaxial Powder‐Feeding Laser Cladding

Due to the process complexity of the high‐carbon high‐manganese steel (HMnS) in casting and arc welding, this article propose the coaxial powder‐feeding laser cladding (LC) of HMnS coating using self‐developed HMnS powders. Firstly, high‐carbon HMnS coatings are prepared on the 16Mn substrate using coaxial powder‐feeding LC technology. It has a single austenite phase, without large defects such as pores and cracks. Then, ultrasonic shock peening is used to harden the HMnS coating, and the mechanical properties such as microhardness, impact toughness, wear and tensile properties are measured, which prove that HMnS coating has excellent working hardening, plasticity, toughness, and wear resistance properties. Finally, transmission electron microscopy is used to investigate the coupling effects such as dislocations, multiple twinning, and stacking faults on the HMnS coating after tensile fracture (true strain 39.2%). The deformation strengthening mechanism based on the dynamic Hall–Petch effect is revealed. The research results provide a new method for the preparation of high‐carbon HMnS coatings, and a new idea for expanding the application of high‐carbon HMnS.

An Investigation on the High-Temperature Stability and Tribological Properties of Impregnated Graphite

Impregnated graphite is a common material for friction pairs in aeroengine seals, especially at high temperatures. For the convenience of the application of graphite materials in aeroengines, an SRV-4 tribometer and a synchronous thermal analyzer are employed to study the tribological properties and thermal stability of pure, resin-impregnated, metal-impregnated, and phosphate-impregnated graphite against stainless steel from room temperature to 500 °C. The results indicate that impregnations can improve the wear resistance and thermal stability of graphite at high temperatures. Compared with other impregnated graphite materials, the resin-impregnated graphite shows a good friction coefficient and poor wear rate and thermal stability over 300 °C, due to the degradation and oxidation of the resin-and-graphite matrix. The metal- and phosphate-impregnated graphite materials exhibit excellent wear resistance and thermal stability under 500 °C as a result of the protection of the impregnations, while the average friction coefficient of the metal-impregnated graphite is much greater than the phosphate-impregnated graphite, and even reaches 2.14-fold at 300 °C. The wear rates for the graphite impregnated with resin, metal, and phosphate are 235 × 10−7, 7 × 10−7, and 16 × 10−7 mm3N−1m−1 at 500 °C, respectively. Considering all aspects, the phosphate-impregnated graphite exhibits excellent tribological properties and thermal stability.

High Efficiency Producing Technology Applied in Metal Optical Lens by 3D Wax Printing Combined with Investment Casting

3D printing technology can easily and quickly produce small batch models and full-size parts, which has obvious and important benefits in shortening development time. Since metals exhibit excellent mechanical strength and high wear resistance, metal additive manufacturing (MAM) is a popular technology for making metal parts. However, metal powders and 3D-printing machines are costly, which increases the difficulty of achieving mass production through MAM. In this study, the 3D wax printing and investment casting (WPIC) approach was developed to manufacture high-quality metal optical lenses with high efficiency and low cost. The manufactured lenses had a diameter of 38.1 mm, two radii of curvature (15 and 90 mm), and a cooling channel. These lenses were manufactured through 3D printing by using wax patterns produced through investment casting. The manufacturing efficiency and machining accuracy of the lenses produced using the proposed method were compared with those of lenses produced through MAM and investment casting. The results indicated that the total costs of manufacturing an optical lens through MAM and investment casting were nine and eight times greater, respectively than that of manufacturing an optical lens through WPIC. In addition, the surface roughness of metal lenses manufactured through WPIC was 45% lower than that of lenses manufactured through MAM. Finally, the time required to manufacture 50 metal lenses was only 15 days when WPIC was used; the corresponding time was 25 days and 6 months when MAM and investment casting were used, respectively. According to the above-mentioned results, the WPIC process has excellent advantages in product manufacturing cost and developing schedule over MAM and traditional methods of investment casting.

Tuning the structural and mechanical properties of SiC-Li and SiC-Na alloys for aerospace application: an ab initio study

Aluminum (Al) and its alloys are popular in the aerospace industry due to their high strength-to-weight ratio, corrosion resistance, and ductility. However, these properties (extreme ductility and malleability) can compromise corrosion resistance, making them susceptible to dents and scratches. Silicon Carbide (SiC) is a promising alternative to Al and it alloys due to its higher Youngs modulus and excellent wear resistance, although it has the drawbacks of brittleness and higher density. This study investigated the structural and mechanical properties of SiC alloyed with lithium (SiC-Li) or sodium (SiC-Na) using ab initio calculations with the aim of tuning the structural and mechanical properties of SiC. Modeling was done using Burai software, which offers a friendly graphical user interface for Quantum ESPRESSO, thus facilitating the creation of input files, visualization of crystal structures and analysis of results. The results from this study showed that the addition of Li and Na lowered the density as well as the mechanical properties of SiC but still being favorably better than those of Al and its alloys, suggesting that the modeled alloys could potentially replace the traditional Al and its alloys in the aerospace industry. Further experimental studies are needed to validate these findings and to explore the possibility of simultaneous alloying of SiC with both Li and Na for enhanced performance.

Innovative transparent silk-melamine formaldehyde film with enhanced corrosion resistance and high tensile strength for surface decoration

Transparent films with reduced light reflection and excellent wear resistance are crucial for applications that require anti-reflective properties without causing environmental harm. However, the preparation process of conventional anti-reflective films is relatively complicated. This paper proposes a simple method to prepare transparent film based on silk fabrics and melamine formaldehyde (MF) resins. The silk fabric's lattice structure serves as a frame, while the MF resin provides transparency and corrosion resistance as a functional filler. The resulting composite films, produced via hot pressing, exhibit excellent tensile strength (up to 617.4 MPa), anti-abrasion properties, and improved flexibility compared to pure MF films. Importantly, these films achieve a high transmittance (>85%) and a significant haze (ranging from 71.8% to 94.9%), with the silk fiber content primarily influencing scattering and haze levels while minimally affecting light transmittance. Additionally, the films demonstrate good pollution resistance and environmental friendliness, allowing contaminants to be removed after 5 h, and exhibit a TVOC emission of <0.1 mg/m3. These findings indicate that the developed composite films are promising candidates for wood surface decoration and applications that benefit from haze, such as anti-glare products. This work not only provides a straightforward method for creating flexible, anti-reflective transparent films utilizing natural fibers but also contributes to advancing sustainable practices in material design.

P(MMA-GMA-AM-St) as transition layer for constructing GO@pPTFE core-shell nanoparticles as hydro-based lubricant additives towards excellent friction reduction and wear resistance

P(MMA-GMA-AM-St) as transition layer for constructing GO@pPTFE core-shell nanoparticles as hydro-based lubricant additives towards excellent friction reduction and wear resistance

Low-temperature oxidation behaviors of Cu-15Ni-8Sn alloy in different aging conditions

Cu-15Ni-8Sn (wt%) alloy has been widely used in engineering applications due to its excellent mechanical strength, wear, and corrosion resistance. However, low-temperature oxidation (LTO) poses a significant challenge, restricting its further application and longevity. In this study, the low-temperature oxidation behavior of the Cu-15Ni-8Sn alloy under different aging condition was investigated using multi-scale characterization by SEM and TEM. The characterization results reveal the oxide films of the aged sample contain tri-layers at low temperature, the outermost layer is dominated by CuO and Cu2O, the middle oxide layer contains of Cu2O, NiO, SnO2 and SnO, and the inner oxide layer is composed of NiO and SnO2. In addition, the as-quenched sample has superior oxidation resistance compared to the aged samples, and the oxidation resistance of the aged samples decreases with the increase of aging time. That is, there is a trade-off between hardness and oxidation resistance in aged Cu-15Ni-8Sn alloys. Therefore, these findings provided a way to adjust the aging parameter based on specific service conditions.

Effect of heat treatment on the microstructure, mechanical properties and tribological behavior of Ti-45Nb alloy fabricated by laser powder bed fusion

To avoid stress-shielding effects between biomedical implants and human bones, low modulus heat-treated Ti-45Nb specimens fabricated by laser powder bed fusion (LPBF) after annealing heat treatment were studied in this study. The microstructure and mechanical properties of the specimens revealed that (i) the as-built specimen consisted mainly of the β-TiNb phase, and heat treatment did not affect the phase species, demonstrating the thermal stability of the LPBFed Ti-45Nb alloy. (ii) After heat treatment, all the specimens exhibited excellent yield strengths (over 1100 MPa), and low Young's moduli (approximately 80 GPa). (iii) The specimens exhibited excellent wear resistance with the main wear modes of abrasive and adhesive wear and low COF (0.353-0.394) under a load of 20 N.

EVALUATION OF PHYSICAL AND MECHANICAL PROPERTIES OF BN REINFORCED AL7079 METAL MATRIX COMPOSITES

Metal matrix composites (MMCs) are regarded as viable alternatives to conventional materials such as metals, plastics, and ceramics in structural applications due to their properties, including lightweight, high specific stiffness, elevated elastic modulus, enhanced specific strength, and excellent wear resistance. Among the many metal composites, aluminum metal matrix composites (MMCs) have emerged as sophisticated engineering materials for several prospective applications in engineering industries due to their superior qualities compared to typical aluminum alloys. Ceramic particles are the most extensively utilized reinforcements in MMCs due to their superior wear resistance, thermal stability, and exceptional bonding with the matrix. This research work has been conducted to develop ceramic particle-reinforced aluminum matrix composites and to evaluate their physical and mechanical properties. Al7079 alloy and Boron Nitride (BN) are selected as the matrix and reinforcement for the study respectively. The stir casting technique was utilized to fabricate the composites.Al7079-BN composites are prepared by varying the percentage of BN reinforcement particles from 0 to 8% by volume, with an increment of 2%. Test specimens were machined from the produced composites for the evaluation of microstructural, physical, mechanical properties according to ASTM standards. The microstructural analysis of the produced samples was conducted using scanning electron microscopy (SEM). The density of the composite was assessed empirically using Archimedes principle and theoretically through the rule of mixture. Microstructural analysis reveals a homogeneous distribution of BN particles throughout the matrix without any agglomeration, and it also demonstrates excellent bonding. The density of the composites decreased by approximately 4.6% with the incorporation of BN reinforcement up to 8%, attributed to the lower density of BN particles. The mechanical properties such as hardness, tensile strength, Youngs modulus, and compressive strength of the composite increases significantly.

Aluminum-Modified Plasma Nitriding with High Efficiency and Enhanced Performance

Aluminum-modified plasma nitriding was developed in this research by the addition of a few FeAl particles around samples of 42CrMo middle carbon alloy steel during plasma nitriding. The goal of this study was to enhance nitriding efficiency and the combined performance of the steel. The research results show that nitriding efficiency was greatly enhanced, by about 6 times, with the effective hardening layer rising from 224 μm to 1246 μm compared with traditional plasma nitriding at 520 °C/4 h. More importantly, the compound layer increased just a little bit, from 11.64 μm to 14.32 μm, which remarkably reduced the ratio of the compound layer’s thickness to the effective hardening layer’s thickness, thus being quite beneficial to decreasing the brittleness level, making the brittleness level decrease from Level 4 to Level 1. Also, extremely high surface hardness and excellent wear resistance were obtained by aluminum-modified plasma nitriding due to the formation of hard phases of AlN and FeAl in the nitrided layer, with the surface hardness rising from 755 HV0.025 to 1251 HV0.025 and the wear rate reducing from 8.15 × 10−5 g·N−1·m−1 to 4.07 × 10−5 g·N−1·m−1. In other words, compared with traditional plasma nitriding, wear resistance was enhanced by two times after aluminum-modified plasma nitriding. Therefore, this study can provide comprehensive insights into the surface characteristics and combined performance of aluminum-modified plasma nitriding layers.

The Elevated Temperature Tribological Performance of Tough and Superhard TaMoN-Ag films with Solute and Nanocomposite Structures

Abstract Films have been prepared with not only high hardness to guarantee excellent wear resistance but also high toughness to prevent brittle fracture at low to middle-high temperatures. On the basis of ternary transition metal nitrides with significantly improved hardness and toughness, TaMoN-Ag films with solute and nanocomposite structure were prepared by DC magnetron sputtering technology. Friction wear tests were performed between room temperature (RT) and 700 °C. When doping with trace amounts of Ag atoms (∼1.12 at.%, 4 W), TaMoN-Ag films maintain solid solution structure. TaMoN-Ag films with the Ag target power is 4 W show the highest hardness (H∼62.1 GPa), which is 58% higher than TaMoN film and 44% better than that of TaMoN films. Meanwhile, a lower wear rate (KIC∼5.87×10-7 mm3/N·m) is obtained. The tribological properties of TaMoN-Ag films at room temperatures are related to the H3/E2 and lubricious Ag phase, while the tribological properties at high temperatures are mainly due to the formation of lubricating binary metal oxides (AgxTMyOz (Magnéli phases)). The composite films generally have good resistance to plastic deformation.

Mechanisms of hardness enhancement in CrB2 thin films with varying VB2 concentrations

Transition metal borides are well-known for their high hardness, excellent wear resistance, chemical inertness, and electrical conductivity, making them promising for a wide range of applications. Understanding the interconnections between material structure, composition, and mechanical properties is essential for designing and synthesizing effective coatings. This study systematically investigates the structural and mechanical properties of CrB₂ thin films with varying concentrations of VB₂ (0–10 wt%), focusing on structure, hardness, elastic behavior and deformation characteristics mechanisms through atomic force microscopy and nanoindentation measurements. The results show that increasing VB₂ content leads to the formation of island cluster structures, which significantly strengthens atomic bonds and, in turn, enhances the hardness of the thin films. As particle size decreases, the higher proportion of surface atoms and increased surface energy have a more pronounced effect on the mechanical properties. In particular, the addition of VB₂ up to 10 wt% in CrB₂ thin films results in a marked improvement in superhard properties. 26 % increase in hardness value is also influenced directly by the changes in Young's modulus and Poisson's ratio that depend on the VB₂ concentration.

In-depth molecular dynamics analysis of crack evolution in polycrystalline chromium under uniaxial tensile deformation

Because of its excellent wear resistance and high hardness, chromium is widely used in coating materials. Under external load, micro-cracks on the surface of electroplated chromium coating will cause crack propagation and reduce the performance of the material. Therefore, in this study, the crack evolution process of polycrystalline chromium under uniaxial tension was studied using molecular dynamics. The effects of average grain size, strain rate, and crack location on crack propagation behavior were analyzed, which provided a scientific basis for optimizing the performance of chromium materials. The results show that cracks in polycrystalline chromium tend to fracture along grain boundaries and that stacking faults and holes are the main factors for crack propagation. As the grain size decreases, the crack passivation becomes more pronounced and the rate of crack expansion slows down. As the strain rate increases, the crystal structure of polycrystalline chromium changes more sharply, and the ultimate stress increases. At high strain rates, the direction of crack propagation changes. The degree of crack tip passivation is affected by the initial crack location, and the crack tip can be effectively passivated when it is located at the grain boundary, thus hindering crack propagation. The results of these studies reveal the influence of multiple factors on the crack propagation mechanism of polycrystalline chromium and provide theoretical guidance for the reduction of chromium coating damage.

Fabrication of Cu-Infiltrated Journal Bearing by Binder Jetting Additive Manufacturing

In this study, considering the economic feasibility of products that can be produced through the binder jetting additive manufacturing process, 316L stainless steel, a widely used material with a wide particle size ranging from 15 to 106 μm, was used. The lubrication effect was increased by internal patterning through design for additive manufacturing, and journal bearing parts with excellent load resistance and wear resistance were implemented by using wear-resistant Cu as an infiltration material. In addition, to investigate the amount of Cu infiltrated as a function of porosity, the parts were pre-sintered from 1423 K to 1573 K, and the best performance was obtained when Cu was infiltrated after pre-sintering at 1473 K. As a result of rig testing of Cu-infiltrated journal bearings, mechanical properties were obtained that were more than 50% improved compared to those of mass products.

Study on wear state of ultrasonic-assisted grinding of glass-ceramics with diamond tools based on DBO-BiLSTM

With the development of precision manufacturing technology, diamond tools play a vital role in industrial machining because of their high hardness and excellent wear resistance. However, tool wear can seriously affect machining accuracy and efficiency. In order to ensure the efficient and high-quality machining, it is of paramount importance to monitor the state of the tools used with the utmost accuracy. First, the fixed area of the diamond tool after machining was observed. The ratio of the number of abrasive particles falling off and the presence of scratches in the matrix were used as the evaluation indexes of the wear state of the diamond tool. The vibration signal was used as a monitoring signal to identify the wear state of the diamond tools. To obtain a feature set sensitive to the tool wear state, the vibration signal was analyzed in the time domain, frequency domain, and wavelet packet. The dimensionality of the sensitive feature set is reduced through the application of principal component analysis (PCA). The tool wear state was identified using the dung beetle optimizer bidirectional long short-term memory (DBO-BiLSTM) model and the bidirectional long short-term memory (BiLSTM) model. The results demonstrate that the DBO-BiLSTM has a higher accuracy in wear state identification, showing an improvement of 10.05% over the BiLSTM. Moreover, optimizing feature dimension reduction can enhance the model’s identification accuracy.

Unraveling the Subsurface Damage and Material Removal Mechanism of Multi-Principal-Element Alloy FeCrNi Coatings During the Scratching Process

Multi-principal-element alloys (MPEAs) exhibit superior strength and good ductility. However, tribological properties of FeCrNi MPEAs remain unknown at nanoscale and complex environments. Here, we investigate the effects of scratching speed, depth, and temperature on microstructural and tribological characteristics of FeCrNi using molecular dynamics simulations combined with an elevated temperature tribological experiment. The scratching force experiences the increase stage, the undulated stage, and the stable stage due to chip formation. Compared to traditional alloy coatings, low force enhances the useful life. With increased speed, the friction coefficient decreases, agreeing with previous work. High speed impacting includes severe local plastic deformation, from dislocation to amorphization. As the scratching depth increases, the average scratch force and friction coefficient increases owing to material accumulation in front of the abrasive particles. The surface morphology and dislocation behavior are significantly different during the scratching process. In addition, we revealed a temperature-dependent friction mechanism. FeCrNi MPEAs have excellent wear resistance at an intermediate temperature, which is attributed to the high Cr content promoting the formation of the compact oxide layer. This work provides atomic-scale mechanistic insights into the tribological behavior of FeCrNi, and would be applied to the design of MPEAs with high performance.

Dual-Mode cellulose acetate@Al2O3/MWCNTs Janus fabric with radiative cooling and solar heating for personal thermal management

Personal thermal management (PTM) textiles with heating and cooling functionalities are highly appealing due to their potential to offer personalized comfort while also contributing to decrease energy consumption. However, most PTM fabrics are static and unable to meet the human body’s thermal comfort needs during seasonal and ambient temperature fluctuations. Herein, this work presents a dual-mode Janus Metafabric to provide radiation cooling and solar heating. The cooling side of Metafabric (cellulose acetate@Al2O3 porous coating) offers high solar reflectance (92.12 %), infrared emissivity (83.22 %), and net cooling power of 55.85 W·m−2. The heating side (multi-walled carbon nanotubes) exhibits a high solar absorption rate (88.4 %). Compared with raw fabric, it can achieve an additional cooling of 4.58 °C and heating of 38.02 °C. In addition, Metafabric also have excellent ultraviolet resistance, wear resistance, and washing properties, making it suitable for practical wearing. By flipping the Janus fabric, it is easy to switch between the cooling and heating modes to adapt to dynamic ambient temperature changes, which have great potential for maintaining human thermal comfort and alleviating the energy crisis.

Microstructural and Performance Analysis of (TiAl)95−xCu5Nix Coatings Prepared via Laser Surface Cladding on Ti–6Al–4V Substrates

In this study, the surface of (Ti-6Al-4V)TC4 alloy was modified via laser cladding. The elemental composition of the coating was (TiAl)95−xCu5Nix, with Ni as the variable (where x = 0, 3, 6, and 9 at.%). Multi-principal alloy coatings were successfully prepared, and their constituent phases, microstructures, and chemical compositions were thoroughly investigated. The hardness and wear resistance of the coatings were analyzed, and the compositions and interfacial characteristics of the different phases were examined via transmission electron microscopy. The analysis revealed that Ni formed a solid solution and a eutectic structure in the Ti(Al, Cu)2 phase. These findings provide valuable insights into the coating properties. Moreover, reciprocal dry sliding friction experiments were conducted to investigate the wear mechanism. The results revealed a significant increase in wear resistance owing to the formation of a Ni solid solution and changes in the coating structure. Additionally, tensile tests demonstrated that the tensile strength of the coatings initially increased and then decreased with varying Ni content. By combining these results with various analyses, we determined that the coating exhibited optimal properties at a Ni content of 6 at.%. Overall, this study comprehensively investigated the microstructure and phase transition behavior of these coatings through various analytical techniques. These findings provide valuable guidance for further optimizing both the preparation process and the performance of the coatings. The coatings exhibit excellent wear resistance and could inspire the design of more advanced protective surfaces.

Multiple covalent modification enables nylon fiber biosensor with robust scrub-resistant and signal-capture ability for multiscenario health monitoring and security warning

Nylon fibers have great potentials in smart textiles due to excellent wear resistance, resilience, and chemical stability, whereas poor combination between fibers and conductive materials causes discontinuous signal capture. In this work, nylon fibers/di-aldehyde cellulose nanocrystals/polypyrrole (NFACP) biosensors with robust scrub-resistant and signal-capture ability were fabricated by interfacial multiple covalent reactions. The best NFACP0.2 biosensor exhibited high conductivity (354 S/m), robust mechanical strength and stretching-releasing dynamic durability. Especially, its textile sensors still possessed high sensitivity and excellent sensing performance after repeated washing and friction. Moreover, NFACP0.2 biosensor was designed into various multifunctional health monitoring and security warning systems for “stress reducing exercise” enthusiasts, high-altitude activities, and deep-sea exploration, demonstating great potentials of conductive nylon fiber biosensor in flexible electronics.