Inorganic Interfacial Engineering of Hard Metals: Powder Processing and Compaction

摘要

Hard metals are commonly produced following a powder metallurgy route, which involves powder production, mixing, granulation, compaction and sintering. The inorganic interfaces needs to be engineered through the processing chain to yield a reliable, high-strength material. Recent work on the processing of WC/Co powders in aqueous media is presented and we demonstrate that a well-dispersed suspension can be obtained using polyethylene imine (PEI) as a dispersant. Spray drying colloidally stable suspensions resulted in granules with densly packed primary particles and can result in dimple formation due to an inward collapse of a dense particulate shell during drying. The soluble binder, PEG, and PEI enhanced the cohesion and strength of the granules. The low Weibull moduli were related to density gradients and internal pores of varying size.