Abstract
A silicon nitride ceramic with uni-directionally aligned β-Si3N4 grains (UA-SN) was fabricated, and the effect of anisotropy in microstructure on tribological properties was investigated. The plane normal to the grain alignment exhibited the highest wear resistance, and the worn surface of this plane was quite smooth, in contrast to the sliding planes (directions) whose surfaces were irregular owing to grain dropping. It is considered that the high wear resistance in this plane is attributable to the inhibition of crack propagation along the sliding surface by the stacked elongated β-grains normal to the sliding surface. In addition, α-Si3N4 ceramics with various amount of in-plane aligned β-Si3N4 grains were also produced and the relationship between β content and tribological and mechanical properties was investigated. The results are discussed in comparison of the wear behaviour of UA-SN.
