Two-Step Sintering of Dense Nanostuctured Hydroxyapatite/Titania composite

Two-step sintering (TSS) has been applied to suppress the accelerated grain growth of Hydroxyapatite (HA) and Titania (TiO2) nanoparticles in the HA-TiO2 composites in the last sintering stage. Application of this method showed that the final grain size of HA-15wt.%TiO2 is maintained lower than 100nm, while through conventional sintering it reaches higher than 100nm. To find how important the temperatures at sintering steps might be, several TSS regimes were conducted. The results showed that the temperatures were critical at both sintering stages. The optimum regime consisted of heating the green bodies up to 1150˚C in the first step of sintering and then holding at 1050˚C for about 25h in the second step. This yielded the finest microstructure with no exaggeration in grain growth. The specimens prepared by optimum TSS regime resulted in no pernicious α-TCP phase

Keywords:

Nano structured Composites , Two Step Sintering , Hydroxyapatite , Scanning Electron Microscopy