Rheological properties of titanium-hydroxyapatite with powder space holder composite feedstock for powder injection moulding

Abstract

Metal-ceramic composites such as titanium-hydroxyapatite have been extensively studied as a new generation of implant material in medical application. The powder injection moulding (PIM) process is one the viable processing method in producing the titanium-hydroxyapatite composite which offers extreme geometry part at a lower cost of production. The final powder injection moulding (PIM) product was influenced by the feedstock rheological and thermal properties that related to the binder selection and the critical solids loading. The emphasis of this study was towards the rheological and thermal properties of Ti6Al4V-hydroxyapatite composite feedstock with the powder space holder using a low-density polyethene and palm stearin binder system. The critical solids loading for 90:10 of Ti6Al4V-hydroxyapatite with 20% of the space holder was selected for capillary rheometer tests. The solids loading was obtained at 73 vol.% with optimal solids loading in the range of 2–5% below the critical solids loading which were 68, 69 and 70 vol.%. All feedstocks exhibited shear thinning behaviour, with the shear rate and viscosity values in the range of the PIM feedstock. The work in this study found that the feedstock of 68 vol.% solids loading possessed the best rheological properties with a higher flow behaviour index.