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Purposes 38CrMoAl steel is often used as pistons in a hydraulic pump, its surface performance is especially important for long-life safe working. Wear is the main failure mode of pistons in a hydraulic pump. With surface strengthening treatment, it is able to break through its performance limit and realize high performance and reliable operation of a hydraulic pump. Methods In this work, the pattern and performance on the surface of 38CrMoAl steel has been regulated by a duplex treatment of surface texturing (ST) and active screen plasma nitriding (ASPN), aiming to achieve strengthening on its surface. Dimple texture with different shapes were first prepared on 38CrMoAl steel surface by laser processing technology. 38CrMoAl steel samples with and without textured surface have been treated by ASPN. A ball-on-disc friction and wear testing machine was employed to investigate the effect of surface texture-active screen plasma nitriding duplex treatment on the tribological behavior of 38CrMoAl steel. Findings The results show that ASPN layer is mainly built up by the phases of ε-Fe2-3N, γ′-Fe4N and CrN. The ASPN layer is compact, and free of obvious cracks and holes. Meanwhile, it is found that the uniform and continuous ASPN layer consists of a white bright layer and a diffusion layer. The hardness across surface to the inside of the ASPN layer has demonstrated a gradient distribution, where the highest hardness value is detected on the surface, and the hardness decreases as the distance from the surface increases. According to the dry sliding friction results of 38CrMoAl steel related samples against Al2O3 balls, the coefficients of friction of 38CrMoAl steel and ST＋ASPN-38CrMoAl steel are 0.40 and 0.36, respectively. The ST＋ASPN-38CrMoAl steel presents a 92.5% reduction in mass loss, as compared with 38CrMoAl steel. It can be concluded that surface texturing-active screen plasma nitriding duplex treatment endows the working surface of 38CrMoAl steel with enhanced tribological performance.

The rapid development of aerospace industry has made more and more machinery parts of equipment working at high temperature. Due to the lubrication failure of lubricating oil and grease at high temperature, solid lubricant coatings are almost the only effective method to achieve super low friction at high temperature. In recent years, the tribological properties of diamond-like carbon (DLC) films have been extensively studied at high temperature. The present study reviews the microstructure of DLC films and the influence of doping different elements on the structure of DLC films. Second, the mechanical properties and thermal stability of pure DLC films and DLC doped with different elements are also described. DLC films have different microstructures and tribological properties by different preparation methods. Finally, the high-temperature lubrication failure mechanism of DLC films and the tribological properties of DLC films when doped with different elements are discussed from the macro and micro perspectives.

In the context of limited energy resources in the World energy resources, improving energy utilization and finding new energy has always been the goal of the scientific community. In addition, new opportunities brought by the production of new quality productive forces have made it a new pursuit for scientists to find a small energy source that can provide disorderly dispersion for micro/nano electromechanical systems and self-driving devices. Solid–liquid triboelectric nanogenerator (SL-TENG) is based on the contact electrocution (CE) and electrostatic induction (EI). It has attracted much attention with its benefits such as exquisite structure, convenient manufacturing, low cost and unparalleled advantages in collecting droplet energy. Since its discovery, it has gradually become a new research direction for TENG. This paper first elaborates on the electrification mechanism of SL-TENG and introduces its main working modes. Subsequently, a review is focused on the influencing factors and latest research of SL-TENG. Then, the commonly used manufacturing methods to improve the performance of frictional power generation were introduced, and the practical applications of SL-TENG were summarized and analyzed, as well as the relevant technological progress and research directions. Finally, the significance and challenges of SL-TENG are summarized, and its future development trend is prospected. In this article, we reviewed the theoretical foundation of the Solid-Liquid Triboelectric Nanogenerator (SL-TENG), detailed four classic working modes of SL-TENG, pointed out the main factors affecting the output of friction nanogenerators, summarized the latest progress of SL-TENG, and demonstrated several exciting research results in the fields of self-powered sensors and energy collection. The article showcases broad potential applications, and finally, we discuss future prospects for SL-TENG. [ABSTRACT FROM AUTHOR]

The thermal stability of the γ-Fe2O3@SiO2 nanocomposites and super low friction of the γ-Fe2O3@SiO2 nanocomposite coatings in ambient air at high temperature are investigated in this paper. X-ray diffraction, scanning electron microcopy, transmission scanning electron microcopy, high-temperature tribometer, thermogravimetric analysis and differential scanning calorimetry were used to investigate the microstructure, surface morphology and high-temperature tribological properties of the γ-Fe2O3@SiO2 nanocomposite coatings, respectively. The results show that the γ-Fe2O3@SiO2 nanocomposite with the core–shell structure has excellent thermal stability because the SiO2 shell inhibits the phase transition of the γ-Fe2O3 phase to the α-Fe2O3 phase in the nanocomposites. The temperature of the phase transition in γ-Fe2O3 can be increased from 460 to 829 °C. The γ-Fe2O3@SiO2 nanocomposite coatings exhibit super low friction (0.05) at 500 °C. A high-temperature super low friction mechanism is attributed to γ-Fe2O3 and the tribochemical reactions during sliding. [ABSTRACT FROM AUTHOR]

Due to the unique properties of titanium (Ti) and its alloys, it has a particularly wide range of applications in aerospace, automotive, medical and other fields. However, the problems of low surface hardness, high friction coefficient and low wear resistance of Ti alloys limit its development to a certain extent. The destruction of Ti and its alloys often occurs on the surface of materials such as wear damage, corrosion, and oxidation resistance. Therefore, the exploration and application of surface strengthening technology is particularly important. The cathodic plasma electrolytic deposition (CPED) technology, as a surface modification technology, can achieve better adhesion and facilitate the material to achieve better comprehensive performance. This paper briefly introduces the basic concepts, principles and development progress of CPED. Starting from the preparation of ceramic coatings, metal coatings, diamond-like carbon films and composite coatings, it summarizes the application of CPED in Ti and its alloys. Applications in alloys to improve thermal oxidation resistance, wear resistance, corrosion resistance, and film-based adhesion. At the end, its development in the new era environment is prospected. [ABSTRACT FROM AUTHOR]