The Influence of Plasma-spraying Parameters on the Characteristics of Fluorapatite Coatings
This study was undertaken to evaluate the effect of plasma-spraying parameters, including spraying current and hydrogen content, on the properties of hydroxyapatite (HA) and fluorapatite (FA) coatings. It was found that FA coating displayed the less-molten to molten structure by variable spraying parameters, but the HA coatings show the molten structure in the present range of spraying parameters. By X-ray diffractometry (XRD), FA coatings showed better crystallinity than HA coatings. The index of crystallinity was found to be in the range of 65.3% to 91.1% for FA coating and 39.7% to 54.6% for HA coating. The difference of structure and crystallinity could be attributed to the thermal properties of HA and FA material. It is generally believed that amorphous phase in calcium phosphate coating would easily dissolve and lose long-term stability in clinical use. The results suggest that FA coating has the potential to show stability in long-term clinical use, and we can modify the characteristics of FA coatings by variable spraying parameters.