New technique for bonding hydroxyapatite ceramics and magnesium alloy by hydrothermal hot-pressing method

The solidification of hydroxyapatite (HA:Ca10(PO4)6(OH)2) and its bonding with Magnesium (Mg) alloys (AZ31; Mg-3Al-1Zn) were achieved simultaneously by using a hydrothermal hot-pressing method at a low temperature as low as 150 °C with no special surface treatment of Mg alloy. A mixture of calcium hydrogen phosphate dihydrate 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/Mg 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/Mg interface and propagated into the HA. The fracture toughness determined on the bonded HA/Mg specimen was close to that of the HA ceramics only (0.30 MPam1/2).