HARDFACING WITH COATED DIAMOND PARTICLES

摘要

Hardfacing to protect wear surfaces of drill bits and other downhole tools having coated diamond particles (44) dispersed within and bonded to a metallic matrix deposit (20). The coating (42) on the diamond particles (44) may be formed from materials and alloys such as particles of tungsten carbide, and tungsten carbide/cobalt and cermets such as metal carbides and metal nitrides. The coated diamond particles (40) are preferably sintered and have a generally spherical shape. The coated diamond particles (40) are pre-mixed with selected materials such that welding and cooling will form both a metallurgical bond and a mechanical bond within the solidified metallic matrix deposit (20). A welding rod (70) is prepared by placing a mixture of coated diamond particles (40), hard particles such as tungsten carbide/cobalt (30), and loose filler material (74) into a steel tube (72). A substrate (24) is hardfaced by progressively melting the welding rod into a selected surface of the substrate (24) and allowing the melted material to solidify, forming the desired hardfacing with coated diamond particles (40) dispersed therein on the substrate surface (22).