The Investigation of the Enhancement Mechanisms of the Oxide Treatment on Cemented Carbide Tools

The mechanisms responsible for enhancement of the metal cutting properties of cemented carbide tools during oxide treatments are investigated. The reaction of individual phases present in cemented carbide tools with various oxides was analyzed experimentally under temperature-pressure conditions previously employed for the oxide treatment. The change in the surface structure and the formation of new phases were determined by means of X-ray diffraction, oxidation experiments, and thermodynamic analyses. The experimental results show that during the oxide treatment such carbides as TiC and ZrC, which are chemically more stable than WC, form on the surface of WC. It was also found that a small percentage of oxides mixed in the eutectic phase of Co-WC stabilizes the eutectic phase, thus preventing its adhesion to a solid piece of oxides.