Effects of Filled Nano-Al2O3 and Its Contents on Friction and Wear Properties of Hydrogenated Nitrile Butadiene Rubber

A new hydrogenated nitrile butadiene rubber (HNBR) material filled with silane-modified nano-Al₂O₃ is developed in this work. Influence of the nano-Al₂O₃ and its contents on friction and wear performances of the HNBR materials is investigated. The nano-Al₂O₃ particles with different contents are added into the HNBR composites. Then, friction and wear tests are conducted using a pin-on-disk tribometer. Scanning electron microscope (SEM) is used to observe wear topography of the HNBR composite surfaces. Attenuated total reflection–Fourier transform infrared (ATR–FTIR) spectroscopy is used to investigate mechanism of nano-Al₂O₃ reinforcing HNBR. Results show that the filled nano-Al₂O₃ and its contents significantly affect friction and wear performances. Presence of the nano-Al₂O₃ obviously decreases friction coefficient and volume wear rate. Friction coefficient and volume wear rate of the composites reduce initially with the increase of nano-Al₂O₃ content and then increase with further increasing the nano-Al₂O₃ content. The HNBR material filled by the nano-Al₂O₃ with the content of 15 phr shows better antifriction and wear performances. SEM results indicate that the HNBR material filled by the nano-Al₂O₃ of 15 phr presents the best topography of wear surface compared with the HNBR materials filled by other nano-Al₂O₃ contents in this study. ATR–FTIR results show that mechanism of the nano-Al₂O₃ reinforcing HNBR for wear resistance is due to the graft reaction between the modified nano-Al₂O₃ and HNBR to form cross-linking networks around the Al₂O₃ nanoparticles, and self-polymerization of unsaturated groups on the surface of the nano-Al₂O₃ to form interpenetrating polymer networks with the HNBR molecular main chains.