ABSTRACT
This chapter concentrates on materials used for the main sealing faces of mechanical seals, the most crucial components of the seal. The main requirements for these materials are tribological, but since they are also exposed to chemical attack, by sealed and ambient fluids, corrosion resistance must also be considered. Finally, the structural behavior of mechanical seal components plays a crucial role in determining performance, due to the effects on alignment of the seal faces to one another. Silicon carbide forms a particularly important group of materials for mechanical seals. They are polycrystalline with SiC crystallites of variable size, typically 2-80 µm, which is large compared with the interfacial fluid film thickness in most mechanical seals. After tribolayer (or transfer layer) instability, the most common material failure mechanisms of the typical ceramics are forms of brittle fracture. Blistering is an important failure mode of mechanical seal carbons.
