(1. 中南大學粉末冶金國家重點實驗室，長沙 410083；
2. 中南大學材料科學與工程學院，長沙 410083)
摘 要: 采用靜態(tài)失重法與電化學阻抗譜評價4種氨基酸對7B50超高強度鋁合金在1 mol/L NaCl+0.1 mol/L HCl溶液中的緩蝕行為，并通過腐蝕形貌表征氨基酸的緩蝕機理。結果表明：氨基酸濃度越高、溫度越低，氨基酸對鋁合金的緩蝕效率就越高。添加氨基酸后，溶液中鋁合金的表觀活化能均增大，其中，半胱氨酸(Cys)和蛋氨酸(Met)的表觀活化能最高，這歸因于—SH或—SCH3基團對鋁合金表面優(yōu)良的吸附作用。在4種氨基酸中，0.05 mol/L半胱氨酸(Cys)中含—SH基團的緩蝕效率最高，室溫下高達94.7%；Met的次之，主要是由于—SCH3的空間位阻效應所致；苯丙氨酸(Phe)的緩蝕性能較差；低濃度的組氨酸(His)緩蝕能力相對不佳，而高濃度的His在較高溫下仍保持著較高的緩蝕效率，這說明His的緩蝕效率受溫度的影響較小。因此，His相應的表觀活化能也較低。浸泡實驗后的金相結果表明：添加氨基酸后會不同程度地抑制鋁合金的晶間腐蝕和點蝕。
關鍵字: 氨基酸；緩蝕劑；電化學阻抗譜；7B50鋁合金
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The inhibition behavior of four amino acids for 7B50 aluminium alloy was investigated using the mass loss measurement and electrochemical impedance spectroscopy technique. The corrosion mechanism of amino acid was characterized by corrosion morphologies. The results show that the inhibition efficiency increases with the increase of concentration and the decrease of temperature. The apparent activation energies of aluminium alloys in the presence of amino acids are larger than that of the sample immersed in the blank solution. The apparent activation energies of cysteine(Cys) and methionine (Met) are highest due to the excellent adsorption ability of —SH or —SCH3 groups on the surface of aluminium alloy. The inhibition efficiency of 0.05 mol/L Cys at low temperature is best among these four studied amino acids, e.g., the inhibition efficiency of Cys is 94.7% at room temperature. Met is also S–containing amino acids, but its inhibition efficiency is lower than that of Cys due to the steric hindrance effect. In addition, relatively lower inhibition efficiency is achieved for phenylalanine (Phe). Histidine (His) with low concentration has very bad inhibition performance, however, at higher temperatures, relatively good corrosion inhibition capability of His with high concentration is shown up gradually. The effect of temperature on the inhibition efficiency of Histidine (His) is little. Consequently, the apparent activation energy of Histidine (His) is lower than other amino acids. The corrosion morphologies show that the intercrystalline corrosion and pitting corrosion of aluminium alloys are inhibited in the presence of amino acids.
Key words: amino acids; corrosion inhibitor; electrochemical impedance spectroscopy; 7B50 aluminium alloys
