| Summary: | 碩士 === 龍華科技大學 === 化工與材料工程系碩士班 === 103 === In all metal materials, magnesium and its alloy have mechanical property closed to human bone tissue. Magnesium and its alloy also have ability of degradable and biocompatible. Magnesium ions are harmless. But poor corrosion resistance properties resulting in the problem of excessive vivo degradation rate has restricted the clinical application. Calcium and phosphorus is essential ingredients in the body's bone tissue, apatite by the calcium and phosphorus constituted can promote the growth of bone tissue.
Therefore, this study attempts to use micro-arc oxidation for preparing films on magnesium alloy in order to increase the corrosion resistance. We add calcium acetate and sodium hexametaphosphate in the electrolyte, and use different power (unipolar pulse, micro-arc oxidation with cathode reduction and bipolar pulse) to prepare films containing calcium and phosphorus, as well as doing detection of corrosion resistance and hydrogen evolution rate.
The results showed, using micro-arc oxidation with cathode reduction can prepare more calcium and phosphorus on the micro-arc oxidation film. When the reducing voltage is 30V and reducing electrolyte have 5 g/L calcium acetate, we can prepare the film containing calcium 9.04％, and its calcium to phosphorus ratio is 2.02, which is close to human bones. Under these conditions, corrosion current density is 3.595×10-7 A/cm2. The corrosion resistance of the ceramic coating is superior to the substrate and the corrosion rate may be retarded up to three orders or more, and hydrogen evolution rate is 7.977×10-3 mL/hr．cm2, which is superior to the substrate. It is slower 100 rate than that on the substrate.
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