本研究在探討鋁合金7175在三極式電化學系統在除氧環境下對不同種類、濃度及溫度的化學溶液中之腐蝕影響，主要包含鋁合金7175經過電化學腐蝕後的表面形態變化與極化曲線(孔蝕電位(Epit))的探討，化學溶液內的氟離子與氯離子對於孔蝕有明顯的影響，所以更進一步探討溶液內氟離子、氯離子及其他效應對孔蝕(pitting)影響。
在實驗過程中，利用不同濃度的化學溶液，分別為0.01、0.05跟0.1M的氯化鈉、氯化銨及氟化鈉三種不同鹽類的溶液，然後再以不同溫度在固定的電解液濃度下，分別測量鋁合金7175的極化曲線，可得知不論在何種溶液與濃度中，鋁合金7175皆在室溫就有孔蝕的現象，且當溫度越高所得的孔蝕電位(Epit)越低；藉由SEM圖結果可以得知，化學溶液內的金屬離子、氟離子與氯離子濃度越高，鋁合金7175的孔蝕破壞程度越明顯，由此可知Na+、NH4+、F－與Cl－對鋁合金7175的腐蝕影響具有重要的關係。
This study investigated the corrosion effects of aluminum alloy 7175 in aqueous solutions containing three different salts. Experiments were conducted on electrochemical three-electrode system. Surface morphology and the anodic polarization curve (pitting potential ,Epit ) were obtained. Experiment result showed that fluoride and chloride ions had significant effect on pitting corrosion. Therefore, more further explore the phenomenon of fluoride ions、chloride ions and other effects on pitting corrosion.
Three different solutions containing 0.01, 0.05 and 0.1M NaCl、NH4Cl and NaF were used. The effect of temperature on polarization was also measured for aluminum alloy 7175 in these solutions. The results indicated that aluminum alloy 7175 was pitting at room temperature, in the condition of any concentrations and solutions about this investigation. Lower pitting potential (Epit) were found for all solutions as the temperature was controlled higher than room temperature. From SEM graphs, we could see that the higher concentration of ions dissolve in the solutions, the more counts and deeper damage of pitting corrosion were found. Therefore, it is concluded that the concentration of Na+、NH4+、F－and Cl－ plays a significant role on pitting corrosion of aluminum alloy 7175.
