Microstructure Control of Fiber-like TiN Particles in Hot Pressed Si₃N₄-O’SiAlON-TiN Composites

Abstract

The microstructure control of TiN particles in hot pressed Si₃N₄-O’SiAlON-TiN composites was investigated using waste-Si and sponge Ti powders, dependent upon the ball milling and attrition milling processes. The composites were composed of multi-phases, including β-Si₃N₄, O’SiAlON and TiN phases regardless milling process used. In the composite using ball milling, TiN particles kept the original shape of sponge Ti powder and included many residual pores. Many microcracks were observed at the interfaces of Si₃N₄/TiN interfaces due to the difference of their thermal expansion coefficients. However, in the composite using attrition milling, the morphology of TiN particles was changed to a fiber shape, without residual pores and microcracks.