EXPERIMENTAL AND ANALYTICAL STUDY ON THERMOCRACKING OF ALUMINA CERAMIC RING IN A MECHANICAL SEAL

A mechanism of thermocracking, which occurs in an alumina ceramic ring of a mechanical face seal, is proposed based on experimental and anal ytical results. Methods for its prevention are also discussed. The exp eriments were conducted using an external type mechanical face seal co mposed of a carbon ring and three kinds of alumina ceramic rings, with distilled water as the liquid to be sealed. By using a layer of gold vacuum deposited onto the surface of the ceramic ring as a part of a D C circuit, the moment of crack initiation was identified. The thermal stresses produced in the ceramic ring by frictional heating were calcu lated using finite element analysis.