| Fabrication and Characterization of Hydroxyapatite/Mullite and Tricalcium Phosphate/Al2O3 Composites Containing 30 wt% of Bioactive Components |
| Jung-Soo Ha |
| School of Materials Science and Engineering, Andong National University |
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| ABSTRACT |
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Mullite-matrix and $Al_2O_3$-matrix composites were fabricated with 30 wt% hydroxyapatite (HA) and tricalcium phosphate (TCP), respectively, as additives to give bioactivity. A diphasic gel process was employed to lower the densification temperature of the mullite matrix to $1320^{circ}C$. A polymer complexation process was used to synthesize a TCP powder that was fully densified at $1250^{circ}C$, for application to the matrix. For the HA/mullite composite, HA decomposed during sintering by reactions with the matrix components of $Al_2O_3$ and $SiO_2$, resulting in a mixture of $Al_2O_3$, TCP, and other minor phases with a low densification of less than 88% of the theoretical density (TD). In contrast, the TCP/$Al_2O_3$ composite was highly densified by sintering at $1350^{circ}C$ to 96%TD with no reaction between the components. Different from the TCP monolith, the TCP/$Al_2O_3$ composite also showed a fine microstructure and intergranular fracture, both of which characteristics are advantageous for strength and fracture toughness. |
| Key words:
Hydroxyapatite, Mullite, Tricalcium phosphate, $Al_2O_3$, Composites |
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