Understanding SiC Ceramics: SSiC, RBSiC, and CVD SiC

Sintered SiC (SSiC)is produced by sintering high-purity SiC powder at high temperature, typically with sintering additives. The result is a dense ceramic body that is essentially free of residual silicon, giving it excellent hardness, Wear Resistance, corrosion resistance, and dimensional stability, along with strong high-temperature performance. Because of this combination of properties, SSiC is generally the most versatile choice for precision mechanical components, and it is widely used in mechanical seals, bearings, pump parts, nozzles, furnace components, and semiconductor equipment parts.

Reaction-Bonded SiC (RBSiC) is made by infiltrating a porous SiC/carbon preform with molten silicon, which reacts with the carbon to form additional SiC. This process results in a material that retains some free silicon. The main advantage of this method is very low shrinkage during manufacturing, which makes it well suited to producing large or geometrically complex parts at a relatively lower cost, with good thermal shock resistance and thermal conductivity. The trade-off is that the residual free silicon limits performance at very high temperatures or in certain corrosive environments. RBSiC is commonly used for furnace structures, kiln furniture, heat exchangers, large beams and tubes, and other sizable structural components.

CVD SiC (Chemical Vapor Deposited SiC) is produced by an entirely different process, in which gaseous precursors are introduced into a reaction chamber and SiC is deposited directly onto a substrate. This method produces material of extremely high purity, very low porosity, and excellent surface quality, along with outstanding chemical resistance and high-temperature performance. Because of this purity, CVD SiC is the material of choice for demanding semiconductor applications, including wafer carriers, susceptors, CVD/epitaxy chamber components, and other high-purity process parts. It is also the most expensive of the three.

In short: RBSiC offers an economical route to large and complex components but contains residual silicon; SSiC offers a dense, strong, wear- and corrosion-resistant option well suited to precision structural parts; and CVD SiC delivers ultra-high purity for semiconductor and other high-purity applications, at a higher cost.