Effect of aluminum source on flexural strength of mullite-bonded porous silicon carbide ceramics

Abstract

In the present work, four aluminum sources (Al/AlN/Al2O 3/Al(OH)3) were used to fabricate mullite-bonded porous SiC ceramicsvia reaction sintering in air at 1450°C and 1550°C for 1-6 h duration, and the role of aluminum source on microstructure and strength was estimated. The microstructures revealed a variation in necking and adhesion characteristics of SiC/mullite/silica grains. The porosity decreased and strength increased with sintering temperature or time for all specimens, except for the one prepared with Al2O3. Amongst the investigated, SiC ceramics prepared with Al2O3 exhibited the lowest porosity of 17% and highest specific strength of 19 kN.m/kg, while the usage of AlN rendered a combination of the highest porosity of 42% and lowest specific strength of 5 kN.m/kg. An attempt has been made to qualitatively explain the strength variation of prepared ceramics on the basis of contributing oxidation reactions towards mullitization. © 2010 The Ceramic Society of Japan. All rights reserved.