New technique for bonding hydroxyapatite ceramics and titanium by the hydrothermal hot-pressing method

Solidification of hydroxyapatite (HA:Ca10(PO4)6(OH)2) and its bonding with titanium (Ti) was achieved simultaneously by using the hydrothermal hot-pressing method at temperatures as low as 150 °C with no special surface treatment of Ti. A mixture of calcium hydrogen phosphate dihydrate and calcium hydroxide was used as the starting powder material for solidifying HA. Three-point bending tests were conducted to obtain an estimate of the fracture toughness for the HA/Ti interface as well as for the HA ceramics only. The fracture toughness tests showed that the induced crack from the pre-crack tip deviated from the HA/Ti interface and propagated into the HA. The fracture toughness determined on the bonded HA/Ti specimen was close to that of the HA ceramics only (∼0.30 MPa m1/2).