The effect of acid pickling pretreatments prior to cerium conversion coating process on the corrosion behavior of AA2198-T851 alloy substrates was investigated. Three acid pretreatments were employed: nitric acid (HNO₃), phosphoric acid (H₃PO₄) and sulfuric acid (H₂SO₄). The cerium conversion coating process was performed using a batch solution composed of cerium nitrate and hydrogen peroxide. Microscopic techniques, electrochemical impedance spectroscopy, polarization resistance and open-circuit potential measurements were employed to investigate the effect of each acid pretreatment. The untreated and nitric acid pretreated substrates presented more defective cerium conversion layers than the substrates treated with phosphoric and sulfuric acids. Accordingly, the corrosion resistance of the untreated and nitric acid-treated substrates was very low, while that of the substrates treated with phosphoric acid and sulfuric acids were greatly improved. The sulfuric acid pickling treatment was the best pretreatment before cerium conversion coating among the investigated pretreatments on the AA2198-T851 Al-Cu-Li alloy.

研究了铈转化涂层工艺之前酸洗预处理对AA2198-T851合金基体腐蚀行为的影响。使用了三种酸预处理：硝酸（HNO ₃），磷酸（H ₃ PO ₄）和硫酸（H ₂ SO _4））。使用由硝酸铈和过氧化氢组成的间歇溶液进行铈转化涂覆工艺。使用显微镜技术，电化学阻抗谱，极化电阻和开路电势测量来研究每种酸预处理的效果。与用磷酸和硫酸处理的基材相比，未处理和硝酸预处理的基材呈现出更多的铈转化层缺陷。因此，未处理和硝酸处理的基材的耐腐蚀性非常低，而用磷酸和硫酸处理的基材的耐腐蚀性大大提高。在研究的AA2198-T851 Al-Cu-Li合金预处理中，硫酸酸洗处理是铈转化涂层之前最好的预处理。