The Effects of Calcium Fluoride Addition on Crystallization Characteristics of Hydroxyapatite-zirconia Composite

摘要

Hydroxyapatite (HA) doped with 3% Yttria-stabilized 20vol%m-ZrO_2 composite were synthesized by solid state reaction between tricalcium phosphate (TCP) and Ca(OH)2 at various temperature(1000 to 1200°C) for 3h with adding 5~20wt% calcium fluoride (CaF_2), respectively. The effects of various amount of CaF_2 on crystallization characteristics of HA-20vol%ZrO_2 composite were investigated in details. The results show that when small amount of CaF_2 was added, the reactions of HA with CaF_2 occurs, which leads to the formation of fluorapatite (FA). With the increasing of the amount of CaF_2, the decomposition of HA to (3-TCP decreases gradually and the CaZrO_3 peaks disappear, while t-ZrO_2 increases because of the formation of thermally stable FHA solid solutions. When the sintered temperature is above 1100°C and the addition of CaF_2 is about 10wt%, the main phases are FHA and t-ZrO_ with a negligible amount of Ca_5P_8, which suppress the reaction between HA and ZrO_2. From SEM, it can be seen that with 10wt% of CaF_2 addition, the morphology of the composite powder is a mixture of spherical ZrO_2 particles embedded within agglomerated HA shaped like a small rod.