Influence of Additives on High Temperature Damping Properties of WC-Co Cemented Carbides by Impulse Excitation Technique

摘要

In order to support the need of the cutting tool industry to fabricate harder tools withstanding higher temperatures, cemented carbides are studied by the impulse excitation technique (IET). IET is a wellestablished non-destructive technique for the determination of the elastic modulus and the damping behaviour of materials as function of temperature. Damping spectra contain information on the microstructure and the mechanisms controlling the mobility of dislocations and grain boundaries in the material. In the present work, comparative IET studies were performed on various WC-Co cemented carbide grades with 10 or 12 wt % Co binder and varying amounts of grain growth inhibitors such as Cr3C2 and VC. The elastic behaviour and damping of the material were investigated up to 1150°C under inert atmosphere. In addition, damping spectra of pure WC and Co were studied to reveal the influence of the binder on relaxation peaks in the cemented carbides. With increasing effectiveness of the grain growth inhibitors, a more pronounced relaxation peak was observed at temperatures between 650 and 1000°C. The grades without grain growth inhibitor display only weak peaks in this temperature range.