2024-T3铝合金三价铬转化膜的制备及耐蚀性能

摘要

通过动电位极化曲线、电化学交流阻抗谱(EIS)及盐雾腐蚀试验研究了Cr2(SO4)3浓度、成膜温度和成膜液pH等工艺参数对2024-T3铝合金表面三价铬化学转化膜耐蚀性能的影响，采用扫描电镜(SEM)及能谱(EDS)对转化膜的表面形貌及其沉积元素进行表征，并以X射线光电子能谱(XPS)分析了转化膜中铬元素的价态。结果表明，优化的工艺条件为：Cr2(SO4)35 g/L，K2ZrF62 g/L，成膜液pH=4，成膜温度40°C。在此条件下制备的三价铬转化膜具有较好的耐蚀性能，转化膜中不含六价铬。%The influence of process parameters including Cr2(SO4)3 concentration, film-forming temperature, and solution pH on the corrosion resistance of trivalent chromium chemical conversion coating on surface of 2024-T3 aluminum alloy was studied by potentiodynamic polarization curve measurement, electrochemical impedance spectroscopy (EIS), and salt spray corrosion test. The surface morphology and deposited elements of the conversion coating were characterized by scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS). The valence of chromium element in the conversion coating was analyzed by X-ray photoelectron spectroscopy (XPS). The optimized process conditions are as follows:Cr2(SO4)3 5 g/L, K2ZrF6 2 g/L, film-forming temperature 40 °C, and pH 4. The trivalent chromium conversion coating prepared under the above conditions has good corrosion resistance and is free of hexavalent chromium.