Calcium phosphate bioceramics, such as hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP), were simply fabricated using a natural material, recycled oyster shell. The oyster shell turned to pure CaO after calcination, and phosphoric acid was mixed to the calcined CaO powders. The observed phases of the fired mixtures were dependent on the mixing ratio of the calcined oyster shell to phosphoric acid, and heating temperature. The HAp and β-TCP were stably synthesized at about 800- 900 oC in an air atmosphere and in the 1 : 1.0~1 : 1.1 and 1 : 1.3~1 : 1.4 wt% mixing ratios, respectively. The synthesized HAp and β-TCP powders, which have Ca/P molar ratios of 1.70 (HAp) and 1.48 (β-TCP), showed fine particles of about 0.5 μm in size and the powder compacts were fully densified, showing a sintering shrinkage of 18.0%, by sintering at 1200~1250 oC for 1 h.

Keywords: Hydroxyapatite, β-tricalcium phosphate, Oyster shell, Phosphoric acid, Synthesis, Densification.