DIAMOND METAL COMPOSITE COATINGS ON CEMENTED-CARBIDE TOOLS

The adhesion properties of diamond coatings on cemented-carbide tools have been improved by two approaches: a novel substrate pre-treatment method and a three-step process for making metal-reinforced diamond composites. (1) Diamond powders are rubbed into the voids created by cobalt removal from the cemented carbides. During subsequent diamond deposition these diamond powders consolidate to form the 'anchoring roots'' of the deposited diamond films, resulting in strong mechanical bonding between the films and substrates. (2) The adhesion can also be improved by adding reinforcing phases using a three-step process. The above two methods have effectively overcome the film delamination problems due to the considerable thermal stress associated with curvature effects.