铝表面聚苯胺的电化学合成与性能研究

Electrochemical Synthesis and Properties of Polyaniline on Aluminum Surface

目的提高铝在含氯离子介质中的耐腐蚀性能。方法在含有0.4 mol/L苯胺的1 mol/L硫酸中,采用恒电位法和循环伏安法在铝表面电化学合成聚苯胺,用红外光谱、紫外光谱和扫描电镜对聚苯胺的结构和形貌进行表征。通过动电位极化曲线和电化学交流阻抗测试,研究聚苯胺在0.6 mol/L NaCl、0.6 mol/L HCl、0.3 mol/L H2SO4和0.3 mol/L H2SO4+0.6 mol/L NaCl几种腐蚀介质中对铝的防护性能。结果红外光谱表明,合成的是硫酸掺杂态聚苯胺。紫外-可见光谱表明,不同电化学方法合成的聚苯胺吸收峰位置相近。扫描电镜观察显示,恒电位法制备的聚苯胺为纳米短棒状结构,而循环伏安法制备的聚苯胺呈现出颗粒状结构。聚苯胺涂层铝在各种腐蚀溶液中的自腐蚀电位都比铝正移,在0.3 mol/L H2SO4中,恒电位法和循环伏安法制备的试样自腐蚀电位分别提高了769、894 m V。相比于恒电位法,循环伏安法制备的聚苯胺涂层具有更好的防腐蚀性能,在0.3 mol/L H2SO4+0.6 mol/L NaCl中的保护效率高达91.69%,在0.6 mol/L HCl和0.6 mol/L NaCl溶液中的保护效率分别为80.40%和6.54%。结论聚苯胺涂层在酸性溶液中比在中性溶液中具有更明显的腐蚀防护效果,在0.3 mol/L H2SO4+0.6mol/L NaCl强腐蚀性溶液中能对铝基体起到良好的防腐蚀作用。

Objective To improve the anti-corrosion performance of aluminum in medium containing chloride ion. Methods Polyaniline was electrochemically synthesized on aluminum in the solution of 1 mol / L sulfuric acid containing 0. 4 mol / L aniline by potentiostatic method and cyclic voltammograms. The structure and morphology of polyaniline were characterized by the infrared spectrum（ IR）,UV-VIS spectra and scanning electron microscope（ SEM）. The anticorrosion performance was tested by the polarization curves and electrochemical impedance in four kinds of corrosive medium including 0. 6 mol / L NaCl,0. 6 mol / L HCl、0. 3mol / L H2SO4 and 0. 3 mol / L H2SO4＋0. 6 mol / L NaCl. Results IR and UV-Vis spectra showed that polyaniline synthesized by different electrochemical methods was SO4^2--doped structure and had similar absorption peak position. SEM indicated polyaniline had a structure of granular,nano-short rod. Polyaniline coatings shifted the corrosion potential to more positive values in all kinds of corrosive medium,the corrosion potentials of polyaniline prepared by potentiostatic method and cyclic voltammograms in 0. 3 mol / L H2SO4 were positively shifted by 769 m V and 894 m V,respectively. Compared to the potentiostatic potential method,the polyaniline coating prepared by cyclic voltammetry had better anticorrosion performance,its protection efficiency was as high as 91. 69%in 0. 3 mol / L H2SO4＋ 0. 6 mol / L NaCl,and its protection efficiencies in 0. 6 mol / L HCl and in 0. 6 mol / L NaCl solution were80. 40% and 6. 54%,respectively. Conclusion The corrosion protection effect of polyaniline for Al in the acidic solution was more obvious than in the neutral solution; the polyaniline coating on aluminum could play a good corrosion protection role in the aggressive environment of 0. 3 mol / L H2SO4＋ 0. 6 mol / L NaCl.