Rheological properties of irregular-shaped titanium-hydroxyapatite bimodal powder composite moulded by powder injection moulding
Nurul Nadiah Mahmud, Farah ’Atiqah Abdul Azam, Mohd Ikram Ramli, Farhana Mohd Foudzi, Kei Ameyama, Abu Bakar Sulong
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.