Development of stable supports consisting of SiC---Si composite for high temperature combustion catalysts

SiC-Si composite, that is stable in oxidizing atmosphere at 1300°C and has thermal shock resistance, was prepared from a powder mixture of porous β-SiC, which was prepared from rice hulls, and Si metal. To use an SiC-Si composite as a structural support for a high temperature combustion catalyst, the foaming SiC-Si composite form with continuous bubbles was prepared from foaming SiC form and the mixture of the porous β-SiC and Si metal. The foaming SiC form was prepared from the foaming polyurethane form and a β-SiC fine particles. The β-SiC fine particles having an average diameter of 0.3 μm was coated on the foaming polyurethane form. The polyurethane part of the form was burned out and the coating β-SiC was sintered to form the foaming SiC form. The SiC form was coated on the porous SiC and Si metal powder mixtures and was heated at 1500°C in argon to prepare the foaming SiC-Si composite. The foaming composite was stable in an oxidizing atmosphere at 1300°C and was highly resistance to thermal shock. The compression stress of the foaming SiC-Si composite form (175 kg/cm²was about twice that of the a-axis of honeycomb-shaped cordierite (> 85 kg/cm²).