Abstract
Calcium orthophosphates, i.e, rhenanites of a type of ACaPO_4, in which A=K, Na, or Li, were prepared and their physicochmeical properties were investigated thermomechanically, by x-ray diffraction and infrared spectroscopy in an attempt to investigated their effects on sintering of hydroxyapatite.Thermomechanical analysis suggested that of the rhenanites, NaCaPO_4 and LiCaPO_4 accelerate the sintering of hydroxyapatite, lowering the sintering temperature.As compared to NaCaPO_4, LiCaPO_4 was much more effective in lowering the sintering temperature.The differential thermal analysis suggested that its effectiveness in lowering the sintering temperature of hydroxyapatite is related to the fact that LiCaPO_4 melts to from a liquid phase at a temperature of about 840℃.At 4wt% of LiCaPO_4 added, the hydroxyapatite could be sintered at temperatures around 780℃, which is approximately 300℃ lower than that used for sintering non-additive hydroxyapatite.
