Improvement in sinterability and phase stability of hydroxyapatite and partially stabilized zirconia composites

摘要

Composites of hydroxyapatite with partially stabilized zirconia with MgO or MgF_2 were pressureless sintered between 1000 deg C and 1300 deg C. The reactions and transformations of phases were verified by X-ray diffraction. For the hydroxyapatite and zirconia composites with MgO, calcium from the hydroxyapatite diffused into the zirconia phase, and the hydroxyapatite decomposed to tri-calcium phosphate at sintering temperatures higher than 1000 deg C. Above about 1200 deg C, CaZrO_3 was formed. Composites containing the MgF_2 decomposed slower than the composites with MgO, which was verified by the changes in the lattice volume of the hydroxyapatite left in these composites. Fluorine ions in MgF_2 diffused into hydroxyapatite, which resulted in thermal stability at high sintering temperatures. Composites with MgF_2 had higher hardness than those with MgO. The lowest porosity was found in a composite initially containing 10 wtpercent partially stabilized zirconia and 5 wtpercent MgF_2.