AMORPHORIZATION AND RECRYSTALLIZATION DURING PLASMA SPRAYING OF HYDROXYAPATITE

X-ray diffraction was used to characterize the dependence of mean crys tallite size and crystallinity on the thickness of coatings. A fall in mean crystallite size but a rise in crystallinity with increased thic kness was observed. The reason might be due to the differences in cool ing rate of partially molten particles of hydroxyapatite. The thicker the coating, the longer the cooling time. The longer cooling time was beneficial to the occurrence of recrystallization. It was found that t he critical thickness of recrystallization (r(c)) was about 20 mu m.