Superabrasive diamond based material with protective tungsten based coating

摘要

A coating on mono- or poly-crystalline diamond or diamond-containing material comprises a first adhesive layer formed directly on the diamond or diamond-containing material, the first layer comprising a tungsten and tungsten carbide composite alloyed with fluorine in an amount of 0.001 to 0.12wt% calculated on the total weight of the first layer. The coating further comprises a second protective layer formed on the first layer, the second layer comprising at least tungsten alloyed with fluorine in an amount of 0.001 to 0.12wt% calculated on the total weight of the second layer. The first and second layers are preferably chemically deposited. The first layer may be formed by placing the substrate in a powder medium comprising tungsten powder and fluorides and heating, with the tungsten carbide being formed from reaction between the tungsten powder and carbon within the diamond or diamond-containing material. Alternatively, the first layer may be formed using CVD. The second layer is preferably formed using CVD, and may include tungsten carbide nanoparticles dispersed in a matrix of tungsten metal. The adhesive layer provides excellent bond strength to diamond, while the protective layer provides good protection against oxidation and molten metals which are used for attaching the coated diamonds to tools.