COBALT METAL POWDER, AND SINTER BEING COMPOSITE MATERIAL PRODUCED THEREFROM

摘要

PURPOSE: To produce a sintered hard tool excellent in strength by using, as a binder for hard powder, a mixture of two kinds of Co powder each with a specific quality at the time of producing a grinding tool by sintering a green compact of hard powder. CONSTITUTION: A Co powder is mixed with a hard-metal powder or an extremely high hardness powder such as diamond powder, compacting the resultant powder mixture, and sintering the resultant green compact, by which a grinding tool, and the like, are formed. In this case, the Co powder used as a binder is a mixed Co powder which, as to quality, contains 75 ppm Si, 30 ppm S, 20 ppm Mg, 30 ppm Na, and 20 ppm Al as impurities and has 1.4 g/cm3 apparent density, 98 HRB Rockwell hardness, and 0.8 m2 /g BET surface area and in which granular Co of 5-150 m formed by atomizing molten Co comprises 20 to 80% and the balance is composed of superfine particles of metallic Co of 3 m obtained by subjecting cobalt oxide to hydrogen reduction. By using this Co powder as a binder, the grinding tool excellent in strength can be produced.