Preparation Of Polyaniline Composite Coatings On Carbon Steel Surface And Their Anticorrosion Properties

In this paper,nano-polyaniline aqueous dispersions were prepared by chemical oxidation polymerization and used for the corrosion protection of carbon steel sheet.Acrylic emulsion or organic siloxane modified resin,as main film-forming materials,were blended with the stable nano-polyaniline aqueous dispersion to obtain polyaniline/acrylic emulsion composite treatment liquid or polyaniline/organic siloxane modified resin composite treatment liquid,respectively.Effects of the type and dosage of the corrosion inhibitor on the two kinds of composite anticorrosion coating were investigated.Effects of stabilizer AM-1.5,aniline monomer and phosphoric acid on the synthesis of nano-polyaniline aqueous dispersion were investigated.The results show that: when the mass ratio of AM-1.5 to aniline monomer was 2:1,stable nano-polyaniline aqueous dispersions were been obtained in the all range of aniline monomer content studied.of range.The particle size of all nano-polyaniline particles were less than 400 nm,and the particle size distribution were narrow.The optimal synthetic conditions of the polyaniline aqueous dispersion were as follows: the mass ratio of AM-1.5 and aniline was 2:1,aniline monomer content was 1%,and the content of phosphoric acid was 10%.The corrosion resistance of polyaniline composite coatings were studied by tafel curves and electrochemical impedance spectroscopy(EIS).The results are as follows:(1)In the polyaniline/acrylic emulsion composite surface treatment solution,when the content of polyaniline was 0.40%,the corrosion resistance of the composite coating is optimal.Different kinds of corrosion inhibitors were added to polyaniline/acrylic emulsion composite surface treatment solution.When the content of corrosion inhibitors were as follows: sodium metavanadate 0.08%,Ammonium fluotitanate 0.04%,sodium molybdate 0.04%,the impedance magnitude of polyaniline/acrylic emulsion composite anticorrosion coating increased and the corrosion current density decreased,indicating that the corrosion resistance of composite coating were improved.(2)In the polyaniline/ organic siloxane modified resin composite surface treatment solution,when the content of polyaniline was 1.5% of organic siloxane modified resin,the corrosion resistance of the composite coating was optimal.Different kinds of inhibitors were added to polyaniline/organic siloxane modified resin composite surface treatment solution.When the content of corrosion inhibitors were as follows: Ammonium fluotitanate 0.04%,sodium molybdate 0.06%,the impedance magnitude of polyaniline/organic siloxane modified resin composite anticorrosion coating increased and the corrosion current density decreased,indicating that the corrosion resistance of composite coatings have been enhanced.The addition of phytic acid and tannic acid lowered the corrosion resistance of the composite coating...