Fabrication of Porous Reaction-Bonded Si₃N₄-SiC Composites

Abstract:

Porous reaction-bonded Si3N4-SiC composites were fabricated by using potassium chloride(KCl) as pore-forming agent. Green bodies with 20% SiC and 30% KCl in mass were subjected to presinter in Ar atmosphere at 1000~1200 and then reaction-sintered. The results indicated that Si₃N₄-SiC composites which with about 58.5% porosity could be prepared, and the main phase compositions were α-Si3N4 and SiC. After presintered, the porosity of composites had small decrease, but bending strength increased obviously and little amounts of Si₂N₂O had been found. The distribution of pores of porous ceramics was homogeneous and SiC grains were surrounded by Si3N4 grains and fibres. Lots of needle-like α-Si₃N₄, especially in the high porosity ceramics, could be observed.

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