2A96铝合金表面含三价铬转化膜制备 及其电化学性能研究

通过调整Cr_2(SO_4)_3浓度和K_2ZrF_6浓度,在2A96铝合金表面制备了含三价铬转化膜;采用极化曲线和交流阻抗谱研究了所制备含三价铬转化膜的电化学性能,利用金相显微镜和扫描电镜(SEM)对铝合金成膜前后的表面形貌进行观察和分析。结果表明,在单因素试验中,质量浓度分别为5 g/L Cr_2(SO_4)_3和2.0 g/L K_2ZrF_6溶液中制备含三价铬转化膜的自腐蚀电位最大,交流阻抗谱的相位角最大,阻抗弧长也最大,耐腐蚀性能最好;显微形貌分析得出成膜后的2A96铝合金表面覆盖了一层转化膜。

Preparation and Electrochemical Properties of 2A96 Al Alloy Surface Conversion Coating Containing Trivalent Chromium

The conversion coating containing trivalent chromium was prepared on the surface of 2A96 Al alloy by adjusting the solution of different concentration of Cr2(SO4)3 and K2ZrF6. The electrochemical corrosion properties of the conversion coating containing chromium trivalent were studied by polarization curves and AC impedance spectroscopy. The surface morphology of aluminum alloy before and after coating formation was observed by metallographic microscope and scanning electron microscope (SEM). The results showed that in the single-factor test, the self-corrosion potential of the conversion coating containing trivalent chromium was the highest when the mass concentration was 5 g/L Cr2(SO4)3 and 2.0 g/L K2ZrF6 solution, the maximum phase angle of the AC impedance spectrum was the highest, while the impedance arc length was the largest, and the corrosion resistance of the conversion coating containing trivalent chromium was the best. The results of the microstructure analysis indicated that the surface of 2A96 aluminum alloy was covered with a conversion coating after the conversion test.