Ti-6A1-4V/HA composite feedstock for injection molding

Mixing is a crucial step in the powder injection molding (PIM) process, as mixing deficiencies cannot be eliminated by subsequent processing steps such as injection molding, debinding and sintering. The feedstock (mixture of powder and binder) should therefore be homogeneous and moldable. In addition, it should contain the maximum powder loading, so as to minimize shrinkage during sintering and to avoid introducing defects in subsequent processing steps. In this study, titanium alloy-hydroxyapatite (Ti-6A1-4V/HA) composite powder was mixed with a multi-component binder, PAN-250S in a Haake Rheocord 90 Mixer. Tests were performed to assess the homogeneity and moldability of the feedstock at different powder loadings of 55, 60 and 65 vol.%. The tests conducted were density, binder burn-out and rheology. It was found that feedstock with powder loading of 60 vol.% was the most suitable as it gives a homogeneous and moldable feedstock. Characterization of the feedstock was also conducted to establish guidelines for molding and debinding.