Properties and Rheological Behavior of Nano-Sized Cemented Carbide Injection Molding Feedstocks with Different Percentages of Grain Growth Inhibitor

Abstract

— A homogenous distribution of powder particles and binders in metal injection molding (MIM) feedstock, and good flowability, are important characteristics as these help to reduce powder-binder separation and achieve isotropic reduction after sintering. To avoid problems in these areas, this paper focuses on determining feedstock properties and studying the effect of TaC powder as a grain growth inhibitor on the rheological behavior of MIM feedstock. A raw material of WC-6%Co, together with palm stearin and a polyethylene binder system, was used as feedstock, tailored with different TaC loadings of 0.4%, 0.8%, and 1.2% by weight. The homogenous feedstock, mixed by ball milling and with a Brabender mixer, was subjected to rheology testing at different temperatures. The results indicated that all feedstock formulations exhibited good pseudoplastic behavior within acceptable ranges in MIM, with a TaC content of 0.8 wt% giving the optimum rheological properties. 