Densification Behavior and Mechanical Properties of Biomimetic Apatite Nanocrystals

Nanocrystalline hydroxyapatite (nHA) of 50 nm average diameter and length to diameter ratio of > 3 was synthesized by biomimetic method. Non-isothermal sintering improved densification behavior and mechanical properties of apatite to 0.88 maximum fractional density, 70MPa bending strength, 148MPa compressive strength and 2.53GPa microhardness at sintering temperature of 1250° C. Higher sintering temperatures resulted in the decomposition of the apatite and in-situ biphasic calcium phosphate HAP/TCP formation. This process lowered apatite densification and weakened mechanical properties of the sintered specimen. Transmission electron microscopy (TEM), x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) helped to elucidate the structure/property correlations.