SiO2及Ta2O5披覆層在Ti-6Al-4V合金上的腐蝕行為

The Corrosion Behavior of the SiO2 and Ta2O5 Coatings on the Ti-6Al-4V Alloy

Ti-6Al-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-6Al-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1000 Å的SiO2或Ta2O5、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SiO2及Ta2O5披覆層在3.5% NaCl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SiO2及Ta2O5 披覆層其耐蝕性與吸附性。由實驗數據得知：SiO2披覆層有較佳的極化電阻，較低的腐蝕電流及腐蝕速率，Ta2O5披覆層的耐蝕性較差，而Ti-6Al-4V合金基材的腐蝕性是介於SiO2及Ta2O5鍍層之間。

The Ti-6Al-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-6Al-4V alloy is facilitated to oxidize and affect its application. An attempt was made to coat SiO2 or Ta2O5 films (1000Å) on the substrate to prevent the surface oxidation and to improve its corrosion resistance. This corrosion properties of the coated SiO2 and Ta2O5 alloys were explored in 3.5% NaCl aqueous solution. Electrochemical data of ac construct the Nyquist diagram to evaluate the corrosion resistance and adhesion of the coated film of SiO2 and Ta2O5. Resulting from experimental data, the SiO2 coated film on the Ti-6Al-4V alloy shows better polarization resistance, lower corrosion current and corrosion rate. However, the Ta2O5 coated alloy has worse corrosion resistance than the uncoated Ti-6Al-4V alloy.