AerMet100钢在盐雾中的腐蚀与电化学特性

Corrosion and Electrochemical Properties of AerMet100 Steel in Salt Fog

目的对AerMet100钢在盐雾中的腐蚀和电化学特性进行研究,分析其腐蚀机理。方法通过盐雾试验,观察分析AerMet100钢的腐蚀行为和腐蚀形貌,分析腐蚀产物成分。测试盐雾试验不同时间后的极化曲线和电化学阻抗谱,并建立等效电路模型,采用Cview和Zsimp Win软件进行等效电路和极化曲线拟合,计算自腐蚀电位、自腐蚀电流和等效元件数值,定量分析其变化规律,之后通过K-K转换验证等效电路拟合的正确性。利用扫描开尔文探针(SKP)测试盐雾试验不同时间后带锈试样的表面电位,并进行Gaussian拟合,分析其电位分布和变化规律。最后,结合试验结果,对AerMet100钢在盐雾中的腐蚀机理进行分析。结果AerMet100钢在盐雾试验中的腐蚀形态由点蚀逐步发展为均匀腐蚀,其腐蚀产物分为两层:外锈层主要成分是β-FeOOH,内锈层主要成分是Fe_3O_4和γ-Fe_2O_3,内锈层较外锈层更为致密。盐雾试验9 d后,自腐蚀电位为–593.178 mV,自腐蚀电流为3.919μA,腐蚀产物层电阻为4.152?·cm^2,腐蚀反应电阻为2748?·cm^2,此时试样的腐蚀倾向性最低,腐蚀产物的积聚降低了腐蚀反应速率。未腐蚀试样表面平均电位为–842.387 mV,盐雾试验6 d后为–701.686 mV,12 d后为–575.502 mV。随着盐雾试验时间的延长,试样表面平均电位升高,电位分布分散,电位差增大,分为明显的阴极区和阳极区。结论AerMet100钢表面腐蚀产物层可有效阻止腐蚀溶液向基体的渗透和扩散,延缓腐蚀进程,对基体起到较好的保护作用。

The work aims to study the corrosion and electrochemical characteristics of AerMet100 steel in salt fog,and analyze its corrosion mechanism.The corrosion behavior and corrosion morphology of AerMet100 steel were observed and analyzed by salt spray test,and the composition of corrosion products was analyzed.The polarization curves and electrochemical impedance spectra of salt spray test after different time were tested and the equivalent circuit model was set up.The equivalent circuit and polarization curve were fitted by Cview and Zsimp Win software.The self corrosion potential,self corrosion current and equivalent element value were calculated,and the regularities of the transformation were analyzed quantitatively.The correctness of equivalent circuit fitting was verified by K-K transformation.Scanning kelvin probe(SKP)was used to test the surface potential of rusted samples after salt spray test for different time,and Gaussian fitting was applied to analyze its potential distribution and change rule.Finally,the corrosion mechanism of AerMet100 steel in salt fog was analyzed based on the test results.The corrosion form of AerMet100 steel gradually developed from pitting corrosion to uniform corrosion in the salt spray test.The corrosion products were divided into two layers:the main component of the outer rust layer wasβ-FeOOH and the main component of the inner rust layer was Fe3O4 andγ-Fe2O3.The inner rust layer was more compact than the outer rust layer.After 9-day salt spray test,the corrosion potential wasΩ593.178 mV,the corrosion current was 3.919μA,the corrosion product layer resistance was 4.152Ω·cm2,and the corrosion resistance was 2748Ω·cm2.At this time,the corrosion tendency of the sample was the lowest,and the accumulation of corrosion products decreased the rate of corrosion reaction.The surface potential of the sample without corrosion wasΩ842.387 mV,and the potential wasΩ701.686 mV after 6-day salt spray test.After 12-day salt spray test,the potential wasΩ575.502 mV.With the prolongation of the salt spray test time,the average potential of the sample increased,the potential distributed dispersedly and the potential difference increased.Cathode area and the anode area were formed obviously.The corrosion product layer on the surface of AerMet100 steel can effectively prevent the penetration and diffusion of corrosion solution to the matrix,postpone the corrosion process and play a better protective effect on the matrix.