Reactive plasma spraying of wear-resistant coatings

A method for producing wear-resistant, carbide-reinforced coatings has been investigated. A conventional low-pressure plasma gun has been modified with a downstream reactor into which carbon-containing gases are mixed, heated, and disassociated. The disassociated gas ions - H* and C* - are subsequently brought into contact with heated, molten metal matrix powders. Experiments with NiCr/Ti blends and W powders have shown that uniformly dispersed carbides such as TiC, Cr(x)C(y), WC, and W2C were formed in situ on the metal precursor powders during deposition. The in situ formed particles, being formed directly from the matrices, show excellent matrix cohesion and lead to high and uniform deposit microhardnesses. The process is described, and several evaluations of materials, reactive gases, and spray conditions are reported. Microanalysis of the coatings are presented, microhardness values are reported, and XRD identifies the in situ formed phases. 14 refs