The characteristics and properties of hydroxyapatite prepared by spark plasma sintering (SPS)

Dense hydroxyapatite (HAp) compacts was fabricated by spark plasma sintering (SPS) using spray dried HAp (SDHA) powders as feedstock. The sintering behavior of the HAp compacts was investigated with variations in powder size range, sintering duration and sintering temperature. Heat treatment of HAp powders was also carried out to study the influence of pre-heat treatment on the sinterability of HAp powders. Results showed that spark plasma sintering resulted in rapid densification to near theoretical density. The HAp compact was homogeneously sintered at 950°C in a short sintering duration of 20 minutes, while maintaining high quality and high relative density (99.9%). Small amount of β-TCP could be observed at sintering temperatures higher than 950°C. It was also found that the particle size of the starting powder played an important role in the SPS process. The smaller the particle size, the higher the relative densities under the same SPS condition. The sinterability of the powders in the SPS without pre-heat treatment was found to be greater than for the powders that received pre-heat treatment. Superior mechanical properties of the HAp compacts were obtained which showed that SPS was an effective method for the preparation of HAp compacts.