Synthesis of silicon carbide ceramics from a polysilastyrene at low temperatures

Summary The conventional route for preparation of silicon carbide ceramics is by the use of pressureless sintering, hot pressing, or hot isostatic pressing of silicon carbide starting powders. High sintering temperatures (2073–2473 K) and the addition of sintering additives are normally used to enhance densification. These sintering additives, however, form second phases at grain boundaries which impair the mechanical properties of the material, particularly at high temperatures. It is therefore desirable that new processing routes are developed that overcome these difficulties. A proposed route is to use a polymeric pressure which can provide a Silicon carbide matrix as binding agent for silicon carbide powders, thus making the requirement for high temperatures and sintering additives unnecessary. This paper reports observations of the direct transformation of a polymeric precursor into amorphous Si–C, and crystalline SiC at low temperatures, and the use of this precursor as a binder for the production of SiC powder/ex‐precursor SiC composites.