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目的：提高2024-T3铝合金在中性NaCl溶液中的耐小孔腐蚀性能。方法采用动电位极化曲线测试、扫描电镜(SEM)观察并结合X射线光电子能谱(XPS)等方法，研究2024-T3铝合金在含不同浓度Na2 SnO3的0.1 mol/L NaCl溶液中的电化学腐蚀行为，分析Na2 SnO3及其浓度对2024-T3铝合金小孔腐蚀和均匀腐蚀的作用。结果电化学测试结果显示，添加一定量(0.05~0.4 g/L)的Na2SnO3可以使溶液的pH值升高(可从6.6上升至10.1)，促进铝合金表面发生钝化，使铝合金孔蚀电位Eb和自腐蚀电位Ecorr的差值增大(最大可达到600 mV)，因此降低了铝合金的孔蚀敏感性，提高了其耐小孔腐蚀的能力。但是Na2 SnO3质量浓度较大(0.2、0.4 g/L)时，会促进2024-T3铝合金的均匀腐蚀。 SEM和XPS结果显示，小孔及其附近区域Cu含量较多，并有大量的SnO2颗粒沉积。结论少量(0.05、0.1 g/L)的Na2 SnO3对2024-T3铝合金的小孔腐蚀和均匀腐蚀均具有较好的抑制效果。 Na2 SnO3对2024-T3铝合金的缓蚀作用可能源于其水解产生的SnO2优先在铝合金表面的金属间颗粒( S相)周围发生沉淀，从而屏蔽了铝合金表面的活性点。

ABSTRACT:Objective To improve the pitting corrosion resistance of 2024-T3 aluminum alloy in neutral sodium chloride solu-tion. Methods In this paper, potentiodynamic polarization curves, scanning electron microscopy ( SEM) combined with X-ray pho-toelectron spectroscopy ( XPS) methods were used to study the electrochemical corrosion behavior of 2024-T3 aluminum alloy in 0.1 mol/L NaCl solution containing different contents of sodium stannate (Na2SnO3). The influence of sodium stannate and its concentration on the pitting corrosion and uniform corrosion of 2024-T3 aluminum alloy was analyzed. Results The electrochemical test results showed that a certain amount (0. 05~0. 4 g/L) of sodium stannate addition could increase the pH value of solution (from 6. 6 to 10. 1), promote the passivation of aluminum alloy, and increase the gap between pitting corrosion potential (Eb) and free corrosion potential ( Ecor ) ( up to the maximum of 600 mV) . So sodium stannate could reduce the susceptibility of 2024-T3 aluminum alloy to pitting corrosion and improve the pitting corrosion resistance. However, further increased concentrations of sodi-um stannate (0. 2 g/L and 0. 4 g/L) accelerated the uniform corrosion of aluminum alloy. SEM and XPS results demonstrated the presence of high content of Cu element around the pits and a lot of SnO2 particles deposited on the pits and their peripheral regions. Conclusion A small amount (0. 05 g/L and 0. 1 g/L) of Na2 SnO3 had good inhibition effect on both pitting corrosion and uniform corrosion. The inhibition effect of sodium stannate on 2024-T3 aluminum alloy might be due to the preferential deposition of hydrol-ysate SnO2 on the intermetallic particles ( S phase) , so as to block the active sites on the aluminum alloy surface.