TiO_2/PVB-PANI/PVB双层涂层对不锈钢的防腐机理研究

Corrosion Protection of TiO_2/PVB-PANI/PVB Hybrid Coating on Stainless Steel

目的制备一种新型绿色环保的Ti O2/PVB-PANI/PVB双层复合涂层,研究复合涂层对不锈钢在Na Cl溶液中的防腐作用机理。方法使用原位化学氧化法合成聚苯胺(PANI),以PVB为粘合剂,甲醇为溶剂,用浸渍提拉法和刮涂法在不锈钢表面制备Ti O2/PVB-PANI/PVB双层涂层。通过傅里叶变换红外光谱(FT-IR)、紫外可见漫反射(UV-Vis DRS)、X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线能谱(EDS)等方法对材料的官能团、光吸收性能、结构和形貌组成等进行了研究,用电化学方法和划痕浸泡实验对比了Ti O2/PVB-PANI/PVB双层涂层和PANI/PVB涂层的耐蚀性能,并分析探讨了相应的防腐蚀机理。结果 Ti O2/PVB-PANI/PVB双层涂层光响应电流为250 nA/cm2,与PANI/PVB涂层相比,其光电位下降0.12 V。电化学测试表明,Ti O2/PVB-PANI/PVB双层涂层试样相对不锈钢的自腐蚀电位升高,自腐蚀电流密度减小,容抗弧半径增大,光照时,其界面处电化学反应速率明显增加。划痕浸泡实验表明,有无光照下,Ti O2/PVB-PANI/PVB双层涂层的耐腐蚀性能均优于PANI/PVB涂层,而光照下两种涂层的耐蚀性能对比更为明显。结论 Ti O2/PVB-PANI/PVB双层涂层依靠物理屏蔽、聚苯胺的防腐作用和光致阴极保护的协同作用为不锈钢提供优异的防腐蚀效果。

The work aims to prepare a new type of green TiO2/PVB-PANI/PVB hybrid coating to study the anti-corrosion mechanism of hybrid coating on stainless steel in NaCl solution.Polyaniline(PANI)was synthesized by in-situ chemical oxidation.PVB was used as binder and methanol was used as solvent.The TiO2/PVB-PANI/PVB hybrid coating was prepared on the surface of stainless steel by dip-coating method and knife coating method.Functional groups,light absorption properties,structure and microstructures were analyzed by Fourier transform infrared(FT-IR),UV-vis diffuser reflectance(UV-Vis DRS),X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS).The anti-corrosion mechanism and corrosion resistance of TiO2/PVB-PANI/PVB hybrid coating and PANI/PVB coating were compared and analyzed by electrochemical method and scratch immersion test.The photoresponse current of TiO2/PVB-PANI/PVB hybrid coating was 250 nA/cm^2,and its photovoltage decreases by 0.12 V compared with stainless steel.From the electrochemical tests,compared with stainless steel,the self-corrosion potential of the TiO2/PVB-PANI/PVB hybrid coating rose,the self-corrosion current density decreased and the radius of the capacitive anti-arc increased.The electrochemical reaction rate at the interface obviously increased during illumination.The scratch immersion test showed that the corrosion resistance of the TiO2/PVB-PANI/PVB hybrid coating was better than that of the PANI/PVB coating in the presence or absence of light.The contrast between the two coatings in the light was more obvious.TiO2/PVB-PANI/PVB hybrid coating provided excellent corrosion protection for stainless steel by virtue of physical shielding,anti-corrosion of PANI and photocathodic protection.