抄録
It is one of the most important factors to control the carbon content severelyin manufacturing the cemented carbides. Even in the region where neither the phase nor free carbon phase appears, the mechanical properties of the cemented carbides are affected by the change of the Co phase. Therefore a very precise control of carbon content, (less than ±0.05%), is required.
Since the starting powders have a large specific surface, an oxidation on the surface appears to be easily occured. This oxidation causes the decarburization during sintering, and so it is also very important to keep the degree of oxidation below a certain level. In this paper the oxidation mechanism of such powders is studied.
First, the corrosion mechanism in atmosphere of the block metal and some reports on the powder oxidation were reviewed. Investigation on the Co, WC and WC-Co mixed powders, which are usually used for producing commercial cemented carbides, were shown. As a result, the oxidation mechanism on such powders was considered the same as that of the block metal. This is to say, the hydroxide formation (corrosion reaction) is presumed on the surface of the powders.
