Rheological properties of irregular-shaped titanium-hydroxyapatite bimodal powder composite moulded by powder injection moulding

Abstract

This paper presents an alternative approach in powder injection moulding (PIM) process by highlighting the advantages of using irregular-shaped and bimodal size powder in Ti6Al4V-HA composite. An investigation on the rheological behaviour Ti6Al4V-HA feedstock at a ratio of 90:10 weight percent was done using spherical and irregular shapes of Ti6Al4V powder particle, together with palm stearin and polyethylene acts as a binder system. Subsequent to the rheological results, the critical powder volume percentage (CPVP) value of the bimodal feedstock improved by 5–8 vol. %. Furthermore, an irregular-shaped Ti6Al4V-HA shows pseudoplastic behaviour and low viscosity with the values of 73–408 Pa.s which is comparable with the spherical-shaped Ti6Al4V-HA (48–305 Pa.s). The injected parts of bimodal irregular-shaped Ti6Al4V-HA also successfully produced without any cracks and distortion with high relative density of 95% after sintering. The result is supported by SEM morphological images which displays micron size porosities that will benefit the sintered part as scaffold for a good osseointegration property with cells. The findings highlight the suitability of irregular-shaped Ti6Al4V-HA during injection moulding as it had outstanding rheological behaviour as good as spherical-shaped Ti6Al4V-HA. Sintered irregular-shaped Ti6Al4V-HA with porous morphological structure, suggest a useful alternative material of irregular morphology of Ti alloy in biomedical industries especially for bone implant application.