COATING OF GRAPHITE FIBERS WITH TUNGSTEN CARBIDE USING SOLID AND LIQUID COPPER AS A TRANSFER MEDIUM

An attempt was made to coat graphite fibers with tungsten carbide. Solid and liquid copper were used as a diffusion medium for tungsten to migrate to the surface of the graphite fibers at elevated temperature to form carbides. It was found that it is possible to electrophate Cu-1 pct W alloy on graphite fibers. It was established that this alloy contained tungsten in atomic dispersion. It was further discovered that tungsten was not in an equilibrium condition in copper and upon heat treatment formed fine percipitates instead of diffusing to the surface of the fiber to form tungsten carbide. However, it was also found that tungsten has a certain solubility in liquid copper and thus it was possible to obtain carbide coatings on graphite fibers by using liquid copper as a transfer agent for tungsten.