Polycarbosilane Conversion Bonded Porous SiC Ceramics

Abstract

Porous silicon carbide (SiC) ceramics were fabricated by a polycarbosilane (PCS) conversion bonding technique, in which PCS was used as a binder to bond SiC particles with each other. In the preparing process, SiC particles were first coated with PCS, and then the powder compacts were heat-treated in an inert atmosphere. During the heat-treatment, the PCS decomposed and gradually converted to inorganic covalent solids composed mainly of Si-C networks. The pyrolysis process of PCS, the pore structures and flexural strength of the as-prepared specimens were analyzed and discussed. Preparing temperature as low as 1100°C was adopted in this process and the porous SiC ceramics with a flexural strength of 20 MPa at an open porosity of 43% was obtained. Since PCS was used as a binder, the critical feature of this technique was that the preparation of porous SiC body was achieved at a low temperature.