Tungsten And Base Metal Powder Injection Molding Feedstock Preparation And Evaluation

The tungsten based metal powder injection molding feedstock with wax-based multi-polymer (EVA, HDPE) binder has been prepared to study the interaction of polymer and powder. By adding different additives, the rheological properties, thermal properties have been studied and the micro-mechanism of the additives have been analyzed through infrared spectrum.The crystal lattice has been applied in the interaction of powder and polymer, which can give some theoretical principle in the determination of powder size and concentration. The rheological behavior can be described as psedoplastic fluid with a shear thinning effect. Additives can improve the uniformity and decrease the viscosity, especially the modified DBP (dibutyl phthalate) can improve the properties in a greater extent. The visco-activation energy E is 21.58kJ/mol, and the shear rate sensitivity factor n_F2 is 0.27, which is useful in the injection procedure.When the concentration of modified DBP is 2% and the loading is 50%, the feedstock has the best viscosity and uniformity. The agglomeration will happen with larger loading, or the idea density cannot be got with smaller loading in the sinter process. The modified DBP can decrease the association of the molecular in the feedstock to decrease the viscosity thus to improve the rheological behavior. Through DTA, TG analyze, the additives will not do harm to the thermal-decomposition, and the binder has a good performance in the sinter stage.