Effect of aluminum hydroxide content on porosity and strength of porous mullite-bonded silicon carbide ceramics

Porous mullite-bonded silicon carbide (SiC) ceramics were prepared from SiC and aluminum hydroxide [Al(OH)(3)] powders. The Al(OH)(3) content was varied from 14.5 to 47.3 wt To, and porous SiC ceramics were fabricated via reaction sintering at 1450-1550 degrees C for 2 h. The microstructure showed large SIC grains embedded in a matrix of small and loosely packed mullite/alumina particles. It was demonstrated that the porosity decreased and flexural strength increased with increase in Al(OH)(3) content. The porosity varied from 46 to 54%, and flexural strength varied from 3 to 14 MPa with the variation in Al(OH)(3) content and sintering temperature. Typically, porous mullite-bonded SiC ceramics of 14 MPa strength and 47% porosity were obtained when SiC and 47.3 wt % Al(OH)(3) powders were sintered at 1500 degrees C. (C) 2011 The Ceramic Society of Japan. All rights reserved.