论文部分内容阅读
通过正交实验得出在铝硅合金表面制备铈转化膜的最佳工艺参数为:Ce(NO3)3为14 g/L;KMnO4为1.5 g/L;K2S2O8为1.0 g/L;NaF为0.8 g/L;转化液pH值为2;室温成膜时间为60 min。SEM、EDS、XRD分析结果表明,铝硅合金表面的Ce-Mn转化膜由基膜和粘附的大小不一的颗粒组成;膜层厚度大约10μm~15μm,主要由Ce和Mn的氧化物、氢氧化物组成;由动电位极化、交流阻抗、浸泡实验等测试结果表明,经Ce-Mn转化膜处理后,自腐蚀电位正移210 mV;腐蚀电流密度降低90%;电荷传递电阻增加一个数量级,具有较高的膜层电阻、较低的膜层电容与双电层电容、较高的弥散指数。
The optimum technological parameters for the preparation of cerium conversion coating on the surface of Al-Si alloy were obtained through orthogonal experiment: Ce (NO3) 3 was 14 g / L, KMnO4 was 1.5 g / L, K2S2O8 was 1.0 g / L, NaF was 0.8 g / L; the pH value of the conversion solution is 2; the filming time at room temperature is 60 min. The results of SEM, EDS and XRD show that the Ce-Mn conversion coating on the surface of Al-Si alloy consists of the basement membrane and the adhering particles of different sizes. The thickness of the membrane is about 10μm ~ 15μm, which is mainly composed of oxides of Ce and Mn, The results of potentiodynamic polarization, AC impedance and immersion test show that the self-corrosion potential shifts 210 mV and the corrosion current density decreases by 90% after Ce-Mn conversion coating treatment. The charge transfer resistance increases by one Orders of magnitude, higher sheet resistance, lower sheet capacitance and double layer capacitance, higher dispersion index.