Micro-powder injection molding of cemented tungsten carbide: feedstock preparation and properties

Abstract Micro-powder injection molding (μPIM) is an advanced net-shaping process for manufacturing metal, ceramic and carbide complex micro-components. The hardmetal ceramic-metal composite cemented tungsten carbide (WC–Co) is known for its high hardness, reasonable toughness, and high abrasion and wear resistance in various applications. This study focused on the characterization and evaluation of WC–Co powder as a feedstock through μPIM. A WC–10 wt.% Co powder was mixed with a paraffin wax (PW) and low density polyethylene (LDPE) binder to obtain the feedstock. The powder-binder mixture was prepared in 49–51 vol.% powder loadings to investigate the effects of the powder content on the feedstock properties. Differential scanning calorimetry and thermogravimetric analysis were conducted to determine the mixing, injection molding, and de–molding stage temperatures. The flow behaviors of the feedstock were evaluated using a capillary rheometer. Finally, the mechanical properties and density of the molded and sintered components were evaluated. This experimental work reveals that the as-received WC powder requires de-agglomeration using sufficient ball milling to achieve an acceptable level of powder loading. The green parts were successfully molded using feedstocks with 49 and 50 vol.% powder loadings. The results indicate that the WC–10 wt.% Co feedstock with a 50 vol.% powder loading provides a sufficient compromise between moldability, green density and stiffness. After debinding and sintering, the findings indicate that a micro part can be successfully fabricated through the μPIM process using the WC–10 wt.% Co feedstock.