Effect of the Composition and Structure of Silicon Carbide Composites on Wear Mechanisms

Abstract

The tribotechnical characteristics of SiC–Al₂O₃ and SiC–Al₂O₃–ZrO₂ ceramic composites are studied during plane-on-plane friction without lubrication in a wide range of speeds (2–7 m/sec) and loadings (1–7 MPa). This testing pattern allows modeling the performance of composites as sealing elements for centrifugal pumps. The influence of 20, 50, and 80 wt.% aluminum oxide in silicon carbide on the wear rate and mechanisms is analyzed. It is shown that higher alumina content of the SiC–Al₂O₃ ceramics changes the wear regularities: oxidative–adhesive wear takes place for materials containing 20 wt.% Al₂O₃ and mechanochemical wear for SiC–80 wt.% Al₂O₃. The tribotechnical characteristics of SiC–Al₂O₃–ZrO₂ (SIAL-Z) ceramics have been studied. The ratio of aluminum and zirconium oxides in this material is eutectic, which substantially decreases the hot pressing temperature and promotes a fine-grained structure. Oxidative wear takes place during friction of the SIAL-Z ceramics against a steel counterface. This composite has the highest tribotechnical characteristics among the materials of interest.