Expandable gasket, sealed joint and method of forming same

Abstract

An improved expandable gasket, sealed joint and method of forming a sealed joint which includes a gasket having at least 5% by weight unexpanded or unexfoliated graphite. The graphite material is preferably a mixture of expanded and unexpanded graphite compressed in a sheet or other shape affixed to a metal plate. The preferred composition is 5 to 70% by weight of unexpanded graphite and 30 to 95% expanded graphite, wherein the percentage of unexpanded graphite is controlled to provide the desired gasket expansion. A more preferred composition includes at least 10% by weight unexfoliated graphite or more preferably 15 to 50% by weight. The gasket is placed between the surfaces to be sealed and clamped in place. When the joint is heated, the unexpanded graphite exfoliates, causing the gasket to swell or expand, tightly sealing the joint. The expandable gasket of this invention is particularly suitable for automotive application, including head and exhaust gaskets which are subject to temperatures exceeding about 400.degree. C.

Dependencies are inferred from the claim text.