Rheological and thermal debinding properties of blended elemental Ti-6Al-4V powder injection molding feedstock

Abstract

The rheological and thermal debinding properties of a feedstock play an important role in the molding and debinding stage of powder injection molding (PIM), and can directly determine the quality of final PIM product. This work focuses on the rheological and thermal debinding properties of blended elemental Ti-6Al-4V (BE Ti64) PIM feedstock with a comparison study of pure titanium (Ti) feedstock. The effects of 60Al-40V alloy addition, on the attributes of BE Ti64 feedstock; including critical solids loading, rheological behavior, and binder decomposition behavior, were studied using torque rheometry, capillary rheometry, and thermogravimetric analysis. The critical solids loading of BE Ti64 (66vol.%) was somewhat lower value than the Ti feedstock (69vol.%), due to the different in particle characteristics. Both BE Ti64 and Ti feedstocks exhibited non-Newtonian shear-thinning behavior. The difference in flow activation energies for the two feedstocks indicates that the BE Ti64 feedstock is more sensitive to temperature compared to the Ti feedstock. During thermal debinding, both the feedstocks exhibited a dual-sigmoid, binder-decomposition behavior with only minor differences in activation energy.