Development of Triphasic Hydroxyapatite/(α and β)-Tricalcium Phosphate Based Composites by Sintering Powder of Calcium-Apatite in the Presence of Montmorillonite

In recent years, the development of calcium phosphate/clay composites for bone tissue engineering attracted a lot of interest. In this study, novel bio-composites composed of hydroxyapatite (HAP), alpha and beta-tricalcium phosphate (alpha, beta-TCP) and sodium-montmorillonite (MNa) were developed. The composites were prepared by sintering at 900 degrees C of calcium-apatite powders in the presence of various amounts of MNa. The calcium-apatite precursors were prepared by the wet precipitation method with two desired Ca/P molar ratios (1.660 and 1.623). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to characterize the prepared composites. The results showed that during the sintering process, a surface interaction apatite/MNa led to the incorporation of clay ions into the apatite structure resulting in its decomposition and formation of composite ceramics comprising HAP, beta and alpha-TCP. The decomposition of apatite increased with increasing MNa content and with decreasing Ca/P ratio. The decomposition of stoichiometric HAP led to triphasic ceramics with substituted-HAP as the major phase while the decomposition of calcium-deficient HAP led to triphasic ceramics with substituted-alpha-TCP as the major phase. Combination of MNa-clay phase and substituted-alpha-TCP can improve both mechanical and biological properties of the prepared composites.