| 摘要 |
<p>Hard metals contg. metal carbides are made, starting from a powder mixt. contg. (a) metal powders; and (b) carbonaceous material; and opt. also (c) inorganic and/or organic cpds. The loose mixt. or a pressing made from the mixt., opt. with a binder(d), is heated, and then sintered and cooled to obtain a hard metal (2) contg. carbides and/or borides, nitrides and silicides in mixed crystals, and/or hard metal-oxides. The carbon required may be used as such, or be present in binder(b). When an organic binder is used, gradual and/or stepwise heating is pref. employed so gases formed by decompsn. of the binder can diffuse out of the mixt. without causing internal pressure. Decompsn. of any organic cpds. present pref. occurs below 800 degrees F. Mixt. may also contain catalysts, e.g. halogen salts, which promote the formation of carbides. Hard metals are suitable for all types of industrial use, e.g. tools drills, dies. The need for expensive metal carbide powders is obviated.</p> |
