Method of coating carbon bodies.

摘要

Described is a way of sealing a carbon body such as monolithic graphite tooling so that it retains its vacuum integrity through numerous thermal cycles typical of thermoplastic processing. This is accomplished by (a) applying to the body surface a coating formulation composed of a carbon-filled solution of a polyamic acid formed by reaction between pyromellitic acid dianhydride and a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane, and (b) heat curing the coated body to cause the polyamic acid to imidize into a thermally cured polyimide.