Chromium Tungsten Carbide, 3Cr₃C₂.W₂C

Chromium Tungsten Carbide, 3Cr₃C₂.W₂C, is formed by heating a mixture of chromic oxide, tungstic acid, and carbon in a carbon crucible in the electric furnace for five minutes with a current of 400 amperes under 75 volts, and treating the product with warm hydrochloric acid, and then with concentrated ammonia solution; or by heating a mixture of chromium, tungsten, carbon, and copper in a carbon crucible, and dissolving the copper from the product by washing with nitric acid. The double carbide is obtained in small, hard, crystalline grains, of density 8.41 at 22° C.; it is not magnetic. It is attacked by chlorine at 400° C.; bromine acts only slowly at 500° C., while iodine at that temperature does not affect it. When heated in air it does not burn. It is not attacked by acids; fused potassium hydroxide or alkali carbonates react only slowly; fused alkali nitrates or potassium chlorate rapidly decompose it, giving a mixture of chromate and tungstate. When heated in hydrogen chloride, chromic chloride, tungsten chloride, hydrogen, and methane are formed.