Pressureless sintered silicon carbide (S-SiC) is produced by pressureless sintering of super-fine-grain or SiC powder. Carbon and boron, beryllium, beryllium compounds or aluminium are used as sintering agents. The powder mixture is compressed to form machinable green compacts. Depending on the initial powder these compacts are sintered at temperatures between 1900 and 2200 °C, the sintering agent causing the SiC particles to melt on the surface with compression of the material. With shrinkage amounting to as much as 20 %, the parts must be finish-machined. Because there is no free silicon, it is possible to use S-SiC across the entire pH-value range. S-SiC is more brittle than reaction-sintered silicon carbide. For material characteristics see materials for seal faces and stationary seats. The microstructure is fine-grained and uniform.

Structure of a S-SiC sliding face