| 摘要 |
1,173,109. Making tungsten carbide-cobalt. E.I. DU PONT DE NEMOURS & CO. April 8, 1968 [April 10, 1967], No. 16812 / 68. Heading C7D. An intimate mixture of tungsten carbide and cobalt is made by reducing a source of tungsten in a molten salt bath in the presence of enough carbon to convert all the tungsten to tungsten carbide and introducing a source of cobalt into the bath before during or after the formation of the tungsten carbide. Suitable tungsten sources are cobalt tungstate and para-tungstate (suitable also as cobalt sources), tungstic oxide and compounds which yield tungstic oxide on heating such as tungstic acid and its salts including calcium and cobalt tungstate, tungsten chlorides and finelydivided tungsten metal. Suitable cobalt sources are the tungstates already specified, cobalt metal, cobalt oxide and compounds which yield cobalt oxide on heating such as cobalt carbonate and formate, cobalt sulphide and cobalt chloride. Suitable carbon sources are carbon black and calcium carbide. The latter is suitable as a reducing agent owing to its calcium content: other suitable reducing agents are metallic calcium (preferred), and gaseous hydrogen. Suitable molten salts are calcium chloride, and sodium, potassium and lithium chlorides. In the example, co-precipitated tungstic oxide-cobaltic oxide are added with fine carbon and calcium metal to molten calcium chloride under argon, and the product then washed. The products may be hot-pressed to form cutting tools. |
