Effects of the sintering process on the different properties of alumina/hydroxyapatite nanobiocomposites

In this work, nanocomposites were prepared with different percentages of alumina (Al2O3) and carbonated hydroxyapatite (CHA) using the mechanical alloying method. Then, the effect of sintering temperatures, up to 1300 degrees C, on their structure, molecular structure, microstructure and mechanical properties was investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and ultrasonic techniques, respectively. Furthermore, the in vitro bioactivity of these nanocomposites was assessed by XRD and SEM. Moreover, physical and shrinkage measurements were performed for all sintered samples. The results obtained showed that increasing the sintering temperature to 1300 degrees C enhanced the hardness value, porosity content, and shrinkage of CHA-free sample from 12 to 14 GPa, 14 to 11% and 1.2 to 2.5%, respectively. However, at the same temperature, the sample with the highest CHA content showed a significant decrease in the hardness and porosity values from 9.3 to 8 GPa and from 8.5 to 6.5%, respectively. On the other hand, the shrinkage value of this sample increased from 8.8 to 16.5%. Finally, the increase in CHA contents was responsible for giving the sintered nanocomposites a good bioactivity behavior. Graphic abstract