Fabrication of hydroxyapatite targets in radio frequency sputtering for surface modification of titanium dental implants

Abstract

The purpose of this study was to explore the properties of sintered hydroxyapatite specimens for developing a suitable hydroxyapatite target and a fabrication process for the radio frequency sputtering of implants. Using a compound surface treatment of sand blasting and acid etching followed by hydroxyapatite radio frequency sputtering, this work planned to develop a commercial dental implant system in the near future. First, in addition to producing hydroxyapatite parts using hot isostatic pressing, this study examined the properties of hydroxyapatite parts produced through cold pressing followed by sintering in vacuum and air. The experimental results showed that the index of crystallization, density, and Vickers hardness of the parts sintered in air were more favorable than those of parts sintered in vacuum, and that the parts sintered in vacuum could crack or break. Second, hydroxyapatite sputtering was performed on the hot isostatic pressing–produced and cold pressing–produced targets on titanium dental implant surfaces at power levels of 50 and 90 W. The results showed no cracks in the cold pressing–produced hydroxyapatite targets when the sintering condition was at 1050 °C. By contrast, cracks occurred in the hot isostatic pressing hydroxyapatite targets at a relative density in excess of 93.35%. Observing scanning electron microscopy cross-sectional images revealed that the sputtering deposition rate was approximately 0.456 nm/min at the sputtering power level of 50 W and 1.139 nm/min at 90 W.