日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 80, No. 2 (2016),
pp. 157-164

Effect of Electrolysis Conditions on the Morphology and Corrosion Resistance of Polyaniline Films Formed on Iron by Electropolymerization

Hiroaki Nakano1, Keiichi Hayashi2, Satoshi Oue1 and Shigeo Kobayashi3

1Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395
2Department of Materials Process Engineering, Kyushu University, Fukuoka 819-0395
3Department of Applied Chemistry and Biochemistry, Kyushu Sangyo University, Fukuoka 813-8503

Abstract:

Polyaniline films were formed on an Fe substrate using the oxidative electropolymerization technique at 288 K in aqueous solutions of pH 2 to 10 containing aniline and p-toluenesulfonic and oxalic acids as supporting electrolytes, and the effect of conditions of electrolysis on the morphology and corrosion resistance of the films was investigated. Although the polyaniline films were formed partially in solutions of pH 2 to 4, the formation of films completed and the surface became smooth in solutions of pH 7 to 10. Polyaniline films with a smooth surface and good corrosion resistance were obtained at 8 to 30 A· m-2, while the films obtained at current densities above 50 A· m-2 showed a non-uniform surface morphology and the insufficient corrosion resistance. Films obtained at anode potentials of 0.4 and 0.8 V vs. NHE were not formed completely, and the films formed at an anode potential of 2.0 V exhibited very rough surfaces. Films formed from the solution containing p-toluenesulfonic acid as a supporting electrolyte exfoliated from the Fe substrate following immersion in a 3 mass% NaCl solution for 3 h. Although the films obtained from the solution containing oxalic acid as a supporting electrolyte showed the good adhesion to the substrate, they possessed many defects and pores, and as a result, the improvement in the Fe's corrosion resistance was less. In the solution containing both p-toluenesulfonic and oxalic acids as supporting electrolytes, the Fe coated with polyaniline films showed the good improvements in both corrosion resistance and adhesion.

[doi:10.2320/jinstmet.J2015048]


(Received 2015/7/30)

Keywords:

electropolymerization, polyaniline, iron, corrosion resistance, p-toluenesulfonic acid, oxalic acid


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