A study on wear and erosion of sialon-Si₃N₄ whisker ceramic composites

Sialon-based ceramic composite materials containing 0-20 wt.% Si₃N₄ whiskers were hot pressed and their mechanical properties and microstructural characterization were investigated. The specimens were subjected to ball-on-reciprocating plate type wear tests at temperatures between room temperature and 1073 K. A gas blast type erosion tester was employed to examine erosion behavior of the composite at room temperature and 773 K. Si₃N₄ whiskers caused formation of large elongated grains in the microstructure. The specimen with the higher content of Si₃N₄ whiskers exhibited higher fracture toughness and lower flexural strength resulting from the larger grain size. Wear test results showed that a higher wear rate was obtained as whisker content and test temperature increased. Scanning electron microscopy observation on the wear track of specimens containing O and 20 wt.% Si₃N₄ whiskers tested at 1073 K revealed that the one with 20 wt.% of Si₃N₄ whiskers had deeper grooves inside the track than that with O wt.% Si₃N₄ whiskers. Erosion test results showed a tendency similar to that of the wear test results. The higher the test temperature and the more whiskers the specimen contained, the higher the erosion rate.