A Laser Processing Technique for Improving the Wear Resistance of Metals

Abstract

This paper describes a process whereby the surface of a wide variety of metals and alloys can be impregnated with hard, wear-resisting particles. In experiments to date, particles of TiC or WC have been injected into thin laser melted surface layers of iron, nickel, titanium, aluminum, and copper base alloys. Many other metal/particle combinations appear to be feasible, for the only fundamental limitation on the process evident to date is that the metal must not exhibit an excessive vapor pressure under the conditions of laser melting. Despite the wide range of alloy compositions experimented with, the processing conditions necessary to achieve good volume fractions of carbide are surprisingly constant. This similarity in processing conditions results in part from carrying out the carbide injection under soft vacuum conditions, thus eliminating oxidation problems without introducing problems associated with the use of shielding gases. Work in progress1 has demonstrated that several of the metal/carbide combinations produced to date exhibit good resistance to abrasive wear. It is expected that resistance to most other types of wear will also be good. Preliminary results suggest that in addition to applications involving the production of wear-resisting metal surfaces, the process may be suited to the manufacture of carbide hardened cutting tools. Furthermore, the simplicity of the process recommends it for surface alloying applications.