Abstract
Spherical-shaped hydroxyapatite particles (Ca/P of more than 1.7) were heat-treated at 800℃, 900℃, and 1,000℃ for 60 and 300 minutes. The effects of these heat treatments on x-ray diffraction pattern, dissolved amount of Ca and P ions after 5-week immersion in a physiological saline solution, and pH value of HAP were investigated. The following conclusions were obtained.
1. The pH value of HAP changed from 7.6 to 11 after heating. The increment was larger with higher heating temperature. With longer heating time, the pH value increased. The pH value decreased by prolonging the immersion time in the physiological saline solution.
2. The dissolution amount of Ca ion from heat treated HAP particles was higher than that from the un-treated HAP particles.
3. The dissolution amount of P ion from the untreated HAP was higher than that from the heat treated HAP particles, whereas the dissolution amount tended to decrease by increasing the heat treatment temperature.
4. X-ray diffraction patterns identified CaO peaks from HAP particles heated at 1,000℃ for both 60 and 300 minutes. These diffracted CaO peaks disappeared from HAP which was immersed in the physiological saline solution for 5 weeks.
