Structure and compression strength of hydroxyapatite/titania nanocomposites formed by high energy ball milling

Hydroxyapatite/titania (HA/TiO2; TiO2 = 0, 5, 10, 15, 20, 25 wt.%) nanocomposites were produced by high energy ball milling (HEBM) at 50 Hz for 1 h from starting materials particle sizes of HA <100 μm and TiO2 <25 μm. X-ray Diffraction and Field-Emission Scanning Electron Microscopy results indicated that hydroxyapatite and Anatase were the major phases after mechanical milling with particle size less than 100 nm. After 1 h of convenient thermal treatments at 1000-1200 °C, beta-tricalcium phosphate and calcium titanium oxide phases were the main crystalline phases irrespective of the sintering temperature. While Rutile phase was observed at 1200 °C, the presence of Rutile as a secondary phase in the microstructure of the composites has led to an increase of the compressive strength up to 330 MPa in the nanocomposites containing 25% TiO2. Longer sintering time (3 h) at 1200 °C has not increased the compressive strength. The produced nanocomposites have showed a moderate deformability where a reduction in height (strain) ranging between 1% and 5.6% was attained at the point of the highest compressive stress.