Abstract
Changes of carbon and oxygen in the compacts of WC-5% and 13%Co mixed powders during heating in the temperature range, 300-1400°C, in H2 atmospheres were investigated by means of chemical and gaschromatographic analysis. Hydrogen gases used were as-received H2 including 0.4mol% H2O and 0.03% O2 and treated H2, in which the impurities were converted into CO by reaction with graphite at 1000°C. The following reactions were observed. (a) Reduction by H2 occurred over all temperatures. (b) Interaction of carbon and oxygen in the powders occurred at above 900°C and it increased with increasing the temperature rose. (c) Decarbonization by H2 was observed at the temperatures ranging from 600 to 1300°C, and had a maximum at about 1000°C. (d) In the as-received H2, decarbonizing reactions with H2O and O2 were remarkably observed at above 700°C, Reactions (a) and (c) occurred rapidly in the beginning of heating and almost finished within 1 hour. Reactions (b) and (d) were observed throughout the heating, but decarbonization by the reaction (b) was comparatively small.
