Wear performance of UHMWPE based composites including nano-sized fumed silica

Abstract

Fumed silica has been utilized in various applications due to its advanced mechanical properties. In addition to this advantage, the branch-like structure of fumed silica leads to a very high specific surface area in comparison to spherical nano-sized particles. Since the major contribution of the nano-sized fillers is growing the filler/matrix interaction surface, we used the fumed silica particles in the UHMWPE matrix to enhance the wear performance of the base material. The composites were produced by using the compression molding method and in order to determine the molding parameters such as molding pressure and molding temperature, a set of experiments was carried out by using the neat UHMWPE prior to the composite fabrications. After completing the molding stage, the specimens were subjected to the wear tests in a ball-on-disk configuration against a tungsten carbide (WC) counterpart. In addition, the composites were exposed to a nitric acid attack to investigate the effect of the fumed silica on the oxidation behavior. According to this work, fumed silica provides beneficial results for the wear performance of UHMWPE based composites. However, excessive loadings of the fumed silica lead to the formation of particle clusters in the microstructure and thereby reducing the wear resistance of the composites. The anti-oxidation performance of the composites was also enhanced with the addition of the fumed silica in the UHMWPE matrix.