铈转化膜在烟气冷凝液中腐蚀行为

Corrosion Behavior of Ceriume Coverson Coating in Flue Gas Condensate

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。

This paper indicates the optimum techniques parameters of rare earth cerium conversion coating on the aluminum silicon alloy surface by orthogonal as follows：Ce（NO3）3：14g/L;KMnO4：1.5 g/L;K2S2O8：1.0 g/L;NaF：0.8 g/L;pH value of solution：2.0,immersing 60 min at room temperature.Results of the SEM,EDS and XRD show that Ce-Mn conversion coating,which is close to the matrix,is composed of a matrix film and particles of different sizes adhesive on the film;the coating thickness is about 10 ~ 5 μm,consisting essentially of oxide or hydroxide of Ce and Mn.The coating is amorphous structure,with the same direction,can inhibit the generation of micro-battery electrolyte.The polarization curve,electrochemical impedance spectroscope（EIS） and soak test results have the following findings：1） the Ce-Mn conversion coating corrosion potential increases 210 mV;2） the corrosion current density decreases to 1 /10 compared with the previous;3） it has higher layer resistance and charge transfer resistance,the lower layer capacitor and electric double layer capacitor,higher dielectric constant.Ce-Mn conversion coating is more compact and has less surface defect and uniformly covers the surface of aluminum silicon alloy.It has a good protective effect on flue gas condensate.