Crystallization Characteristics and Microstructure of Yttria-Stabilized Zirconia/Hydroxyapatite Composite

Good crystallized Hydroxyapatite was synthesized using H(3)PO(4) and Ca(OH)(2) as raw materials by wet chemical method and sintered at 800 degrees C for 3h. The as-prepared HA powders were mixed with 15%, 20%, 25% yttria-stabilized m-ZrO(2), respectively, and sintered at 900 degrees C- 1200 degrees C for 1 h, respectively. The main phases and rules of phases changing with the content of yttria-stabilized m-ZrO(2) and sintered temperature was investigated by XRD and the microstructure features of the composite powders were analysed by scanning electron microscopy. The results show that when the temperature is at 1000 degrees C, HA starts to decompose to beta-TCP and CaO, the m-ZrO(2) is then partly converted into t-ZrO(2) by partial consumption of CaO, which in turn results in a mixture of beta-TCP and HA further. The CaO produced reacts further with m-ZrO(2) generating a mixture of t-ZrO(2) and CaZrO(3) in different proportions. The microstructure of the HA-ZrO(2) composite further indicates that when sintered at 1000 degrees C for 1 h, gray slice area represent a mixture of HA and a small amount of beta-TCP. While in the white area, some spheric ZrO(2) mixed with a negligible amount of CaO. When sintered at 1200 degrees C, distinguished reduced spherical ZrO(2) particles embed within mixed HA and beta-TCP, which change from slice to agglomeration. As a result, when the sintered temperature is about 1000 degrees C and the addition of m-ZrO(2) reaches 20wt%, superior main phases are HA and t-ZrO(2), which improves the combination of mechanical and biological properties.