Composite disk brake rotor and method of making

Abstract

A method of making and the resulting product for a disk brake rotor with a self-lubricating, thermally conductive coating thereon that enhances the friction wear life of a disk brake assembly within which it is used, comprising: (a) controllably toughening at least the outside braking surfaces of a lightweight metal disk brake rotor, said roughening being carried out to promote mechanical adhesion of coatings applied thereover; (b) thermally spraying one or more coatings onto the roughened outside braking surface, the exposed coating being electric arc sprayed using a codeposit of iron-based material and powdered graphite to form an iron matrix composite coating; and (c) surface heat treating essentially the exposed coating to dissolve and precipitate graphite and form a simulated cast iron and also to densify the coating and remove residual stresses resulting from deposition. To inhibit heat transfer, the method may further comprise forming the lightweight metal rotor to have a pair of annular ring walls supported by a hub, the ring walls being separated by a plurality of vanes for inducing air cooling as the rotor rotates, and interposing a thermally sprayed metallic-based heat barrier coating between the rotor and exposed coating. The barrier coating may be comprised of a nickel-based material which preferably includes graphite codeposited therewith. The cooling vanes and intermediate coating cooperate to protect the rotor against extreme heated conditions.