plasma spraying of particulate thermotropic liquid crystalline polymers onto the surfaces of composite and metallic structures . the present plasma spray process employs a conventional direct current electric arc plasma spray gun in which an inert plasma gas is introduced , caused to swirl , and discharges as a rotating plasma flame having an exceptionally high temperature , above about 14000 ° k , into which the particulate liquid crystal polymer is discharged for melting and propulsion onto the target surface . the target surface preferably is preheated , and the molten particles deposit and cool to form a build up of the desired thickness . cooling is regulated by post - heating the deposit to a temperature between about 200 ° f . and 500 ° f .