Ceramic seals on moving metal parts - where seal contains expansion zones providing resistance to thermal shock

摘要

Contact seal for parts which move w.r.t. each other, and where one sealing surface consists of a ceramic layer on one of the moving parts. The ceramic layer is interrupted in the axial direction of the seal by expansion zones possessing a larger coefft. of thermal expansion, and a higher thermal conductivity, than the ceramic layer. One moving part is pref. provided with an intermediate sprayed coating followed by a continuous expansion zone provided with grooves on its surface, each groove being separate and filled with ceramic. Used as seals for rotating or oscillating parts such as pump shafts, shaft liner bushes, or plungers, where the seals can now be used at high temps. The ceramic gives excellent service but has only moderate resistance to thermal shock when used on metals, the ceramic flaking off due to difference in thermal expansion. The invention permits the parts to expand or contract without cracking the ceramic.