Effect of the composition and structure of silicon carbide composites on wear mechanisms

The tribotechnical characteristics of SiC–Al₂O₃ and SiC–Al₂O₃–ZrO₂ ceramic composites are studied during dry plane-on-plane friction in a wide range of velocities (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 wear mechanisms is analyzed. It is shown that higher alumina content of the SiC–Al₂O₃ ceramics changes the wear mechanisms: oxidative–adhesive wear takes place in materials containing 20 wt.% Al₂O₃ and mechanochemical wear in 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 in friction of the SIAL-Z ceramics against a steel counterface. This composite has the highest tribotechnical characteristics among the materials of interest.