How are silicon carbide refractories made by reaction bonding?

Reaction-bonded silicon carbide (RBSC) is produced through a specialized process distinct from the traditional Acheson furnace method used for bulk silicon carbide production.12

To create RBSC components, a finely divided, intimate mixture of silicon carbide powder, carbon, and a plasticizer is first prepared. This mixture is formed into the desired shape, after which the plasticizer is burned off. The resulting porous body is then exposed to liquid or vapor silicon at high temperatures.12

During this stage, the silicon reacts with the carbon within the mixture to form additional silicon carbide, which serves to bond the original particles together. Any residual open pores are also filled by the silicon. This "net shape" process is highly valued in industrial applications because it results in minimal dimensional change during sintering, allowing for excellent dimensional control and reducing the need for extensive post-firing machining. The final product exhibits high-temperature strength and dimensional stability, making it an effective material for demanding refractory environments.123