The Effect of Variable Binder Content and Sintering Temperature on the Mechanical Properties of WC-Co-VC/Cr3C2 Nanocomposites

摘要

WC powders with an average crystallite size of 10nm were successfully prepared by ball milling of micron-sized tungsten carbide powders. Grain growth inhibitors (VC and Cr3C2) with concentrations of 0.6wt% each were added to nanocomposites of WC-9Co and WC-12Co, in both as-received and milled WC. Powder mixtures were then consolidated using spark plasma sintering technique at 1200 and 1300 degrees C for 10min under high vacuum and pressure of 50MPa. The influence of WC crystallite size, Co content, and sintering temperature over microstructure and mechanical properties of the resulting composites were studied through XRD and FESEM. Densification and attained grain sizes of the sintered products were measured by Archimedes principle and Scherrer procedure, respectively. Moreover, microhardness (H-v30) and fracture toughness were measured and compared for each composition to comparatively assess the individual effect. It was observed that the addition of VC and Cr3C2 resulted in decreased densification of the synthesized composites. These grain growth inhibitors were found to limit grain sizes to 131nm with an average hardness of 1592H(v30) and fracture toughness of 9.23 Mpam(1/2).