A Gaschromatographic Study of the Behavior of Carbon and Oxygen Gontained in WC+Co Mixed Powders when Heated in Hydrogen Atmosphere

Abstract

It has been observed that the change in the content of carbon and oxygen occurs when the WC+Co mixed powder or compact is heated in a hydrogen atmosphere. In this paper, the behavior of carbon and oxygen was studied and the mechanism was also considered, by heating WC+5% and 10% Co ball milled powders in the hydrogen atmosphere under various conditions. The changes of carbon and oxygen content after heating were estimated by chemical analysis. The gases generated in the atmosphere were measured by using a gaschromatograph and a dew point meter.
The results are as follows:
(1) Decarburization and deoxygen occurred slightly even at low temperatures such as 200°C.
(2) Below about 600°C, only CH₄ gas was generated as the result of decarburization. At higher temperatures CO gas was generated, and with an increase of temperature the amount of CO gas increased while that amount of CH₄ gas decreased.
(3) Below about 600°C, H₂O gas was generated as the result of deoxygen.
(4) Below about 600°C, the H₂O content in hydrogen did not affect decarburization but at higher temperatures the moisture in hydrogen increased decarburization greatly.
(5) These phenomena (1-4) can be explained by thermodynamical treatment.