Ti-6AI-4V合金被廣泛地使用在航空工業和化學工業，由於此種材料具有低密度、高強 度、以及耐蝕等特性之故。但是Ti-6AI-4V合金的表面層容易生成氧化膜，會影響此材料廣泛地被應用。因此在基材表面披覆一層厚度為lOooA的Si02或Ta20S'阻止氧的吸附和維持相當高的抗蝕性是值得研究的方式。本實驗探討Si02及Ta20S披覆層在3.5%NaCI水溶液中的腐蝕行為，利用電化學之直流測試與交流阻抗法，藉由電極表面所產生的電容與電阻變化，繪製Nyquist圖評估Si02及Ta20S披覆層其耐蝕性與吸附性。由實驗數據得知:Si02披覆層有較佳的極化電阻，較低的腐蝕電流及腐蝕速率， Ta20S披 覆層的耐蝕性較差，而Ti-6AI-4V合金基材的腐蝕性是介於Si02及Ta20S鍍層之間。

The Ti-6AI-4V alloy is widely used on the space and chemical industry due to its lower density， higher strength and corrosion resistance properties， and so on. Unfortunately， the surface of the Ti-6AI-4V alloy is facilitated to oxidize and affect its application. An attempt was made to coat Si02 or Ta20S films (lOOOA)on the substrate to prevent the surface oxidation and to improve its corrosion resistance. This corrosion properties of the coated Si02 and Ta20S alloys were explored in 3.5% NaCI aqueous solution. Electrochemical data of ac construct the Nyquist diagram to evaluate the corrosion resistance and adhesion of the coated film of Si02 and Ta20S' Resulting from experimental data， the Si02 coated film on the Ti- 6AI-4V alloy shows better polarization resistance， lower corrosion current and corrosion rate. However， the Ta20S coated alloy has worse corrosion resistance than the uncoated Ti-6AI-4V alloy.