Effects of Pressure and Reaction Time on Bonding of Hydroxyapatite Ceramics and Titanium by Hydrothermal Hot-pressing

Solidification of hydroxyapatite (HA) and its bonding with titanium (Ti) was achieved simultaneously by using a hydrothermal hot-pressing (HHP) method at the low temperature as low as 150 deg C. A mixture of calcium hydrogen phosphate dihydrate(DCPD) and calcium hydroxide was used as a starting powder material for solidifying HA. 3-point bending tests were conducted to obtain an estimate of the fracture toughness for the HA/Ti interface. Application of pressures greater than 20MPa was necessary for bonding, and the interface strength increased with the increasing applied pressure. However, the degree of HA formation was lower when the pressure was increased. Excessively long term HHP treatment was shown to be ineffective for the bonding and there was an optimal treatment time. The optimal pressure and treatment time for bonding were estimated to be 40MPa and 12hrs, respectively.