Modulation, characterization and bioactivity of new biocomposites based on apatite

The present study is focused on preparation of hydroxyapatite (HA)/calcium aluminate (CA) composites and studying the effect of CA content on their mechanical and bioactivity properties. HA/CA composites containing varying CA content (5, 10, 15 and 20 wt.%) were fired at 1250 and 1350 °C to evaluate the extend the stability of HA at high temperatures. The composites were assessed by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Vickers micro-indentation (Hv) and cold crushing strength (CCS). Bioactivity testing study was carried out for these composites in simulated body fluid (SBF) for 7 days to confirm the formation of apatite layers onto the surfaces. The results confirmed that the addition of CA to HA improve the thermal stability and the mechanical properties of the composites, especially those composites fired at high temperatures. Also, FT-IRRS and SEM confirmed the formation of bone-like apatite layer on the surface of the composites especially those containing high CA content at both firing temperatures. The stability of HA at high firing temperatures was improved via the addition of CA content. Also, the surface reactions of the composites having high CA content at both firing temperatures were higher than those having low CA content post-immersion for 7 days. Conclusions prove that the HA matrix containing 20 wt.% of CA as in C4 composite could be studied in vivo study in the future for using it as bone substitutes, especially in load bearing sites.