| Summary: | 碩士 === 明志科技大學 === 機械工程系機械與機電工程碩士班 === 102 === This study conducted RF-sputtering process to deposit the HA films with three separate HA targets, which were manufactured in-lab via three different process types including cold pressing and sintering (CPS), hot isostatically pressing (HIP) and atmospheric plasma spraying (APS). This study not only evaluates the properties of the HA films but also wants to find an appropriate manufacturing process of the HA sputter target for a sake of developing a compound surface modification technique of HA sputtering in combination with SLA-like treatment for titanium dental implants. The experimental results showed that the APS process is a promising way to fabricate the HA sputter target with a longer lifetime and had a density about 2.83 g/cm3. Furthermore, the APS target not only can withstand a high discharge power of 300 W in sputtering but also obtain a HA film with partially crystalline phase present. In contrast, the HIP target with a density of 3.1 g/cm3 would be easily broken during sputtering even at a low sputtering power of 50 W, and thus not being suitable; the CPS target with a density of 1.43 g/cm3 could endure a power only below 70 W. The HIP and the CPS targets contained nearly a pure HA phase, whereas the phase composition of the APS target had α-TCP, β-TCP, TTCP, crystalline HA, and amorphous HA. The CPS films with an amorphous phase via sputtering at power 70 W had deposition rate 0.578 nm/min and Ca/P ratio 1.83; the APS films with partially crystalline phase via sputtering at power 250 W had deposition rate 4.675 nm/min and Ca/P ratio 2.48. Subsequently, for the sputtered HA films onto the surface-treated Ti plates (arithmetic average mean roughness Ra: CP Ti, commercially pure titanium, accompanied by sandblasting at 4.0 μm > CP Ti accompanied by acid etching at 2.4 μm > CP Ti accompanied by grinding at 0.4 μm). The results showed that the HA films on the lower surface roughness substrate at high discharge power had some crystalline phase, but the higher roughness substrates had no crystalline phase. Furthermore, the HA films on substrates of the different roughnesses did not affect the Ca/P ratio. The present study also performed the post-annealing in air for the sputtered HA films onto SLA-like treated Ti plates. The experimental results indicated that the amorphous HA films would be nearly transformed into a crystalline phase when annealed at temperature 800oC for 120 min, but the oxide (TiO2) on the Ti plate surface might break within temperature from 400oC to 800oC. Therefore, the post-annealing treatment is not suitable for the sputtered HA films onto the SLA-like treated Ti plates. Subsequently, the work conducted the in-vitro test of bioactivity by soaking in simulated body fluids (SBF) for the sputtered HA films onto SLA-like treated Ti plates for immersion periods of 1, 2, 3, and 4 weeks. The results presented that some bone-like apatite (calcium-phosphate precipitation) formed on the Ti plate surfaces after immersion for 4 weeks, the Ca/P ratio (1.63 - 1.71) of which is close to 1.67 of the stoichiometric HA phase. ICP-OES analysis revealed that the Ca and P ion concentrations in the SBF solution would decrease after immersion of 28 days. Finally, carried out the sputtering process to deposit the HA onto a SLA-like treated dental implant. To begin with a titanium rod was machined into screw-shaped dental implants by using a Swiss-type CNC lathe, next blasting and acid-etching were conducted on the as-machined Ti implants, and then the HA sputtering was performed under the condition of sputter working distance 50 mm and implant-holder rotating speed 15 rpm. In this stage, we found that the external thread whirling and the internal screw tapping processes in CNC lathe will enhance the processing performance, compared to conventional threading process. Also it was discovered in the HA sputtering that the HA film thickness decreased approximately by 20% and 60% for the top and the bottom of the screw-shaped implant thread respectively.
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