WC/Co 초경합금 산화물의 환원/침탄 반응

Abstract

In the present study, the focus on the analysis of carbothermal reduction of WC/Co oxide powder. WC/Co oxide powder prepared by the oxidation using the WC-13wt.%Co hardmetal scrap as the raw material, resulting in the mixture of WO3 and CoWO4. This oxide powder was mixed with carbon black, and then this mixture carbothermally reduced under a flowing Ar atmosphere and H2 atmosphere. The change in the phase structure during carbothermal reduction was analysed using X-ray diffraction and relative intensity obtained from the X-ray diffraction. Under a Ar atmosphere, It was observed that WO3 was reduced to WO2 phase passing by through the intermediate W20O58 and W18O49 phases. Finally reduced WO2 was carburized in a WC through the W2C phase. CoWO4 was partially reduced WO2 phase, other reduced phase was not observed. WO2 was also carburized in a WC through the W2C phase, CoWO4 was carburized in WC/Co through the Co6W6C and Co3W3C phases. However, under a H2 atmosphere, WO3 was reduced to W through the intermidiate W20O58 and WO2 phases. Finally reduced W was carburized in a WC through the W2C phase. CoWO4 was reduced WO2 and Co7W6 phases. WO2 was reduced W, and then carburized in a WC through the W2C phase. Co7W6 was carburized WC/Co through the Co6W6C and Co3W3C phases. WC/Co hardmetal oxide powder was transformed through the metal phase such as W and Co7W6 phases under a H2 atmosphere. However, W and Co7W6 phases were not observed under a Ar atmosphere.