PRODUCTION OF SINTERED HARD ALLOY HAVING SHEET-LIKE TUNGSTEN CARBIDE AND COATED SINTERED HARD ALLOY

摘要

PURPOSE: To easily obtain the sintered hard alloy by specifying the composition of starting material and manufacturing conditions and particularly performing the control of the grain size of WC just before heating and sintering in a WC-(cubic system compound)-Co sintered hard alloy. ;CONSTITUTION: A starting material having a composition consisting of, by weight, 1-25% of powder of Co and/or Ni, 3-40% of cubic system compound forming powder of one or more kinds among the carbides and nitrides of the group IVa, Va, and VIa metals of the periodic table and mutual solid solutions thereof, and the balance WC powder is prepared. This starting material is subjected to respective stages of mixing and crushing, compaction of a green compact, and heating in a nonoxidizing atmosphere, by which the sintered hard alloy can be formed. In this method, the average grain size of WC after the mixing and crushing stage is regulated to ≤0.5μm and also heating temp. is regulated to ≥1450°C. Further, ≥15% of the WC existing in the sintered hard alloy is constituted of a laminar WC where the maximum grain size is regulated to 1-10μm and the maximum size is regulated so that it becomes two or more times the minimum size. By this method, the necessity of the use of a solid solution supersaturatedly containing WC difficult to be formed can be obviated.;COPYRIGHT: (C)1993,JPO&Japio