Chemical Composition and Stability of Hydroxyapatite Film Coated by Sputtering Technique

Abstract

The chemical composition and stability of hydroxyapatite (HA) film coated on pure titanium screw implants and plates by a sputtering technique were investigated by chemical and physical analyses. The surfaces of the titanium screw implants and plates were sandblasted to an average roughness Ra 2.69±1.1 μm using sintered fluoroapatite particles. The sputtering conditions were 100～500 W and 0.2～2 Pa of argon gas pressure using a radio frequency magnetron sputtering instrument. The HA film thickness was determined as 1.48±0.21 μm by energy dispersive X-ray fluorescence spectrometer (EDX) measurement. The crystal structure and composition were identified as crystalline HA by an inductively coupled plasma-optical emission spectrometer, X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR).
The stability of crystal structure, chemical composition, thickness, surface structure and pH values in ultra-pure water of the HA film were investigated by a long-term stability test for 24 months under 25℃ ± 2℃and 60%±5%RH, and an accelerated stability test for 6 months under 40℃±2℃ and 75±5%RH using XRD, FTIR, ICP, EDX, SEM and pH meter.
No change was observed in crystal structure, chemical composition,and properties of the HA film by these stability tests.