硫脲对非调质钢在HCl酸洗溶液中的缓蚀作用

Corrosion Inhibition Effect of Thiourea on Non-quenched and Tempered Steel in HCl Cleaning Solution

目的研究硫脲(TU)对非调质钢在HCl溶液中的缓蚀作用。方法通过动电位极化曲线、电化学阻抗谱研究硫脲对非调质钢在HCl溶液中的缓蚀效应,采用KH-7700型三维视频显微镜观察非调质钢的腐蚀形貌。结果非调质钢在不含缓蚀剂的HCl溶液中的自腐蚀电位(Ecorr)为-0.566 V,自腐蚀电流密度(Jcorr)为12.57 m A/cm^2。随着HCl溶液中硫脲浓度的增加,非调质钢的自腐蚀电流密度(Jcorr)逐渐减小,反应电阻(Rct)逐渐增大,界面双电层电容Cdl降低,缓蚀效率逐渐增加,阴极极化曲线几乎重合,而阳极极化曲线逐渐正移。当HCl溶液中加入5 g/L硫脲时,缓蚀效率达91.17%,效果好于市售酸洗缓蚀剂AS-30,能够有效消除非调质钢在HCl酸洗液中的腐蚀麻点。结论硫脲对非调质钢在HCl溶液中具有明显的缓蚀效应,能够有效消除非调质钢酸洗过程中的腐蚀麻点。

Objective To study the inhibition effect of thiourea on corrosion of Non-quenched and tempered steel in HCl solution. Methods The polarization curves and electrochemical impedance were measured by electrochemical workstation. The corrosion morphology of Non-quenched and tempered steel was observed by three-dimensional video microscope. Results The corrosion potential of non-quenched and tempered steel in HCl solution without corrosion inhibitor was -0.566 V, and the corrosion current density was 12.57 m A/cm^2.With increasing concentration of thiourea in HCl solution, the corrosion current density of Non-quenched and tempered steel gradually decreased, the interfacial electric double layer capacitor（Cdl） gradually decreased, the reaction resistance and inhibition efficiency gradually increased, the cathodic polarization curves almost coincided and the anodic polarization curves gradually shifted positively. When the concentration of thiourea was 5 g/L in HCl cleaning solution, the corrosion inhibition efficiency reached up to 91.17%. The corrosion inhibition effect of thioureai was better than that of the commercial inhibitor AS-30. Thiourea could eliminate the emerging of pitting in HCl solution. Conclusion Thiourea had ob-vious inhibition effect for non-quenched and tempered steel in HCl solution and could effectively eliminate the corrosion pitting.