| 摘要 |
Hardfacing to protect wear surfaces of drill bits and other downhole tools having coated cubic boron nitride particles or coated particles of other ceramic, superabrasive or superhard materials dispersed within and bonded to a matrix deposit. The coating on the ceramic particles or particles of other hard materials may be formed from materials and alloys such as tungsten carbide, and tungsten carbide/cobalt and cermets such as metal carbides and metal nitrides. The coated particles are preferably sintered and have a generally spherical shape. The coated particles are pre-mixed with selected materials such that welding and cooling will form both metallurgical bonds and mechanical bonds within the solidified matrix deposit. A welding rod may be prepared by placing a mixture of selected hard particles such as coated cubic boron nitride particles, hard particles such as tungsten carbide/cobalt, and loose filler material into a steel tube. A substrate may be hardfaced by progressively melting the welding rod onto a selected surface of the substrate and allowing the melted material to solidify and form the desired hardfacing with coated cubic boron nitride particles dispersed within the matrix deposit on the substrate surface. |
