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The friction and wear of water-lubricated bearings has always been an engineering problem that we need to solve urgently. To investigate the influence of SiO 2 particle size and dispersion on the friction and wear properties of nitrile rubber. The friction and wear performance of rubber compounds (SiO 2 (nano) /NBR, SiO 2 (micr) /NBR and SiO 2 (TESP) /NBR) was tested by American Rtec multifunctional friction and wear test machine under the conditions of water lubrication and constant temperature. The results showed that the particle size of SiO 2 has a great impact on its dispersion in nitrile rubber, and the surface modification of SiO 2 can significantly improve its dispersion. SiO 2 (TESPT) /NBR showed a good friction coefficient under low-speed and high-load conditions. The wear of SiO 2 (nano) /NBR and SiO 2 (micr) /NBR, which was mainly the fatigue wear, was relatively serious. In contrast, the modified SiO 2 had a smaller particle size, better dispersion and stronger interfacial bonding with the nitrile rubber matrix. This significantly reduced the wear of SiO 2 (TESPT) /NBR, which was mainly the abrasive wear, and improved its wear resistance. • TESPT was used to modify the hydroxyl groups on the surface of nano-silica. • The escape and disintegration of SiO 2 (micr) and SiO 2 (nano) agglomerates during the wear process were characterized. • The effect of particle size and dispersion of SiO 2 on tribological properties of nitrile rubber was revealed. [ABSTRACT FROM AUTHOR]

Purpose: Ultra-high molecular weight polyethylene (UHMWPE) is adopted in water-lubricated bearings for its excellent performance. This paper aims to investigate the tribological properties of UHMWPE with a molecular weight of 10.2 million (g mol‐1) under different molding temperatures. Design/methodology/approach: The UHMWPE samples were prepared by mold pressing under constant pressure and different molding temperatures (140°C, 160°C, 180°C, 200°C, 220°C). The friction and wear tests in water were conducted at the RTEC tribo-tester. Findings: The friction coefficient and wear loss decreased first and rose later with the increasing molding temperature. The minimums of the friction coefficient and wear loss were found at the molding temperatures of 200°C. At low melting temperatures, the UHMWPE molecular chains could not unwrap thoroughly, leading to greater abrasive wear. On the other hand, high melting temperatures will cause the UHMWPE molecular chains to break up and decompose. The optimal molding temperatures for UHMWPE were found to be 200°C. Originality/value: Findings are of great significance for the design of water-lubricated UHMWPE bearings. [ABSTRACT FROM AUTHOR]