Effect of Cr-addition on Mechanical Properties and Corrosion Resistance of Hardmetal Grades with medium-to-high Metallic Binder Content

摘要

Chromium is a traditional additive in the fabrication of hardmetal (HM) for two main reasons: it inhibits Ostwald ripening phenomena of WC particles and it improves notably corrosion resistance of hardmetal grades with ultrafine-to-fine WC grain size and low-to-medium binder content. In the framework of studies aimed at developing more performing and inert hardmetal compositions, the present investigation targets the effect of increasing chromium contents on: mechanical properties, wear and corrosion resistance of hardmetal grades with a medium-to-high binder content. After evaluation of Chromium effects on microstructure, hardness and mechanical resistance, an extensive characterization of corrosion, wear and tribocorrosion behaviour has been performed using electrochemical methodologies and abrasion testing (ASTM B611) on a wide range of cobalt- and nickel-base hardmetal grades. Optimized compositions of the binder have been highlighted, that open up attractive opportunities of improved service behaviour and deployment in new applications.