Low temperature chemical vapor deposition method for forming tungsten and tungsten carbide

摘要

An improved highly erosive and abrasive wear resistant multi- layered coating system on a substrate which provides protection against impact of large particles is disclosed comprising a plurality of composite layers. In each of the composite layers, the first layer closest to the substrate comprises tungsten of sufficient thickness to confer substantial erosion and abrasion wear resistance characteristics to the coating system and a second layer deposited on the first layer comprises a mixture of tungsten and tungsten carbide and the tungsten carbide comprises W.sub.2 C, W.sub. 3 C, or a mixture of both. Because the resulting coating system has enhanced high cycle fatigue strength over the substrate, the coating system is especially useful on such structures as turbine blades and similar articles of manufacture where such chemical vapor depositing the first and second layers at a temperature in the range of about 300° to about 550° C. and then repeating the chemical vapor deposition steps to achieve the multi- layered coating system such that the overall thickness of the system is at least about 20 &mgr;m.