| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 99 === Titanium, a kind of light metal material, is widely applicated in biomedical field, mainly because of good bio-compatibility and chemical stability. Generally various applications of titanium depend on the characteristic such as surface property, oxide structure, thickness of oxide layer and chemical composition. The oxide layer of the material surface or coated hydroxyapatite of titanium often was modifies for the purpose of usage in implantation. By this kind modification, not only the bonding process could be strength between the titanium materials and also speed up the osteointegration of bone tissue.
Plasma electrolytic oxidation (PEO) is an oxidation technology that was developed since the 1930s. Light metal material was more and more broadly used in the different industries, including material industry, aerospace engineering and biomedical industry. Thus the application of PEO in light metal surface modification technology was widely used recently.
PEO is a fast film-forming process with simple device. Metal surface could induce local spark and plasma reactions by hundreds voltage in suitable electrolytic solution. Under this condition, the formation of dense and porous oxide layer was induced shortly on metal surface. This oxide layer has excellent characteristics of good bonding strength, large contact area, high temperature tolerance, high durability, better corrosion resistance and so on. It is very suitable in biomedical field due to its excellent properties.
Titanium metal using the calcium acetate （Ca(CH3COO)2), β-glycerophosphate (C3H7Na2O6P • 5H2O) as the electrolyte for plasma electrolytic oxidation, and we can rapidly get specimens which coated with titanium dioxide films dope calcium and phosphorous. Greatly bioactivite materials will complete after suitable thermal process. In this study, we perform PEO process under three levels of each factor (electrolyte composition, reaction time, reaction voltage factor) by using Taguchi method, and measured roughness of the sample and the relative intensity of anatase. We implement PEO reaction by some optimal reaction parameters which from L9 orthogonal array table in Taguchi method and is for the purpose of applicability of biomedical. Specimen after the reaction without under hydrothermal treatment, the sample immersed in 2 M of K2HPO4 solution for 10 minutes, and then soaked specimen is performed some in vitro tests. In vitro studies are analyzing the specimens immersed in Simulate body fluid (SBF) for 1-15 days. Hydroxyapatite-containing coatings on titanium substrates were formed after 3 days’ immersion. And the sample surface covered with hydroxyapatite after 7 days’ immersion. The microstructures and compositions of the obtained films were analyzed by field-emission scanning electron microscopy and X-ray diffraction. The chemical states were also analyzed by Fourier transform infrared spectroscopy.
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