Tungsten-carbide coating of heavy metals

The aim of this study was to follow the reaction between composite alloys based on tungsten, as a major component, and carbon. The varying parameters were: the composition, the volume fraction of the tungsten in the material and the experimental parameters (time, temperature, carburizing method). Four different tungsten alloys were prepared with varying concentrations of tungsten, nickel, iron and copper. The product of the sintering process was tungsten spheroid particles surrounded by a matrix which is a solid solution of the binder's elements plus tungsten. After examination of the system it was determined that the growth process is not simple diffusion process of WC on the surface, but rather a reaction between the particles dispersed in the bulk material and the carbon dissolved by the matrix. This causes tremendous differences between the kinetics of varying alloys. 5 refs., 2 tabs., 9 figs. (Author)