Hydrothermal Synthesis and Sintering of Hydroxyapatite Powders with Si₃N₄ Whiskers Dispersion

Abstract

Hydroxyapatite (HAp) powders with Si₃N₄ whiskers dispersion were synthesized hydrothermally at 200°C under 2MPa for 10h. The transmission electron microscopy (TEM) demonstrated that the homogeneous mixture of ultra-fine HAp single crystals and Si₃N₄ whiskers was obtained by this technique. The mixture was hot-pressed at 1000°C under 30MPa for 1h in Ar, and then post-sintered by HIP at the same temperature under 200MPa of Ar for 1h. The product had almost pore free microstructures consisting of HAp and TCP matrix and Si₃N₄ whiskers. The value of K_IC was 3.1MPa⋅m^1/2, and was 3 times as high as that of the transparent HAp ceramics.