Microstructures, hardening and tribological behaviors of tin matrix composites reinforced with SiC and Zn particles

Abstract

In order to strengthen pure tin and improve its dry sliding resistance, Sn/SiC and Sn/Zn composites were fabricated via a powder metallurgy route. Microstructure, hardness and pin-on-disk wear resistance of pure tin and the fabricated composites were compared to those of Sn–7.5Sb–3.5Cu Babbitt alloy. The dominant wear mechanism at different applied loads was determined by analyzing worn surfaces and wear debris in each case. The results showed that the hardening effect of Zn was much higher than that of SiC. The hardening role of Zn in the tin matrix was ascribed to the direct load transfer mechanism. Microscopic studies of the worn surfaces revealed that the pure tin was susceptible to surface fatigue wear and plowing damage, depending on the normal load applied during the wear test. In the case of Sn/SiC composite and the Babbitt alloy, delamination wear mechanism resulting from subsurface crack propagation controlled the wear rate. While the highest hardness and the lowest coefficient of friction were obtained for the Babbitt alloy, the Sn/Zn composite exhibited the highest wear resistance at a constant applied load, indicating the importance of asperity contact type in the wear process.