Porous 2H‐Silicon Carbide Ceramics Fabricated by Carbothermal Reaction between Silicon Nitride and Carbon

Abstract

Porous SiC ceramics were synthesized by sintering pressed and pressed/CIPed powder compacts of α‐Si 3 N 4 , carbon (Si 3 N 4 :C = 1:3 mol as ratio), and sintering aids, at 1600°C for few hours to achieve a reaction, and subsequently sintering at a temperature range of 1750°–1900°C, in an argon atmosphere. High porosities from 45%–65% were achieved by low shrinkage with large weight loss. Formation of pure 2H‐SiC phase via a reaction between Si 3 N 4 and carbon can be demonstrated by X‐ray diffractometry. The resultant porous SiC samples were characterized by SiC grain microstructures, pore‐size distribution, and flexural strength. This method has the advantage of fabricating high‐porous SiC ceramics with fine microstructure and good properties at a relatively low temperature.