Preparation of reaction-bonded porous silicon carbide with denser surface layer in one-pot process

Abstract

Macro-porous silicon carbide with high porosity around 70 vol%, comprising micrometer-sized spherical porosities and a relatively denser surface layer, was fabricated by a direct blowing and reaction bonding method. The macro-porous Si/phenolic composites with the denser surface layer were prepared through a one-pot process of blowing of novolac resin which changes to the phenolic resin by thermal curing to form macro-porous body and forming the denser surface layer. The composite was then converted into porous SiC by reaction bonding at 1450°C under vacuum. It was found that the bending strength of the macroporous silicon carbide increased by 30% due to the denser surface layer. This study proposed a novel fabrication method to provide macro-porous ceramics with high porosity and improved strength in simple one-pot process.