Microstructure mechanism of the hydroxyapatite densification process

Abstract

Hydroxyapatite (HA) is a well-known materials used as biomaterials in various applications. Numerous studied had been done for unlocking the pros and cons of this material. Sintering process has been used for extraction of pure HA that have similar Ca/P ratio to human bone mineral. This study aims to investigate the effect of sintering temperature on the properties of synthetic HA as well as to develop the mechanism of this densification process. Synthetic HA powder (Sigma-Aldrich #04238) was mixed together with binders, namely polyvinyl alcohol (PVA) and polyethene glycol (PEG) in wet mixing condition using ball mill. Pressed HA (15 g, 65 mm x 12 mm) was sintered with temperature ranging from 1000°C to 1200°C with heating rate and cooling rate of 10°C/min. It has been found that, pure HA was obtained when the HA was sintered with temperature ranging from 1000°C to 1200°C. The thermogravimetric analysis showed that there are there were two mass loss stages on the heating process from room temperature to 1250°C; 100-500°C (dehydroxylation) and 680-1080°C (decomposition). From the microstructure data, the mechanism of the densification process of HA was developed.