Influence of sintering atmosphere on the performance of porous silicon carbide ceramics

The core-shell structure precursor powder was fabricated by coat-mix process in different fabrication conditions with various aging pH value. The porous silicon carbide ceramics were prepared through molding, carbonization, and sintering in argon atmosphere and vacuum, respectively. Morphology, physical phase, weight loss rate, density, porosity, bending strength and thermal shock resistance of porous silicon carbide ceramic samples were analyzed and the results show that the aging pH values of ceramic samples sintered in both of atmospheres have the consistent influence on the performance of the samples. The ceramic samples sintered in vacuum have a better bending strength and porosity, while ceramic samples sintered in Ar atmosphere have a better purity and toughness. When the pH value of aging process ranges from 3 to 5, the porous SiC ceramic samples sintered in Ar atmosphere have a stable thermal expansion coefficient.