Eledctrodeposition Of Organic Biocide Composite Zinc / Zinc Alloy Coatings And The Research On Their Microbial Corrosion Resistance And Antifouling Properties

In this research, a novel organic biocide composite zinc/zinc alloy coating was electrodeposited by adding organic biocide into the electrolytes. By electrochemical impedance spectroscopy, polarization curves, X-ray crystalline diffraction, scanning electron microscope, infrared absorption spectroscopy and energy dispersive spectroscopy, the mechanism of the electrodeposition process was researched. Sulfate reducing bacteria and Escherichia coli were employed in this research to detect the coatings anticorrosion and antifouling property. The specific results of the research are as follows:(1) The 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one-zinc composite coating was electrodeposited from 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one added sulfate electrolytes. By the adsorption effect on surfaces and chelation with zinc, 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one significantly influenced the electrodepositing process, altering coatings structure and morphology. The organic biocide inhibited the sulfate reducing bacteria corrosion and restrained the Escherichia coli attachment. The optimum adding concentration in the electrolyte was determined to be 1 mmol L-1, which could lead to a 5% mass fraction in the composite coating.(2) The chitosan-zinc composite coating was electrodeposited in gradient concentrations of chitosan added sulfate zinc electrolyte. Chitosan could chelate with zinc and adsorbed on the electrodepositing surfaces, which lead to a significant change in the electrodepositing process. The crystalline structure and morphology were altered by a serious of chitosan addition concentration. Chitosan-zinc composite coating obviously inhibited the sulfate reducing bacteria growth and metabolism, resulting in high corrosion resistance. Under Escherichia coli exposure, the attached concentration of chitosan composite coating could reach an 80% decrease. The optimum adding concentration of chitosan in the sulfate electrolyte was determined to be 0.6 g L-1.(3) Two kinds of organic biocide Zn-Ni composite alloy coating was electrodeposited from 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one and chitosan added Zn-Ni electrolytes, respectively. 4,5-Dichloro-2-N-octyl-4-isothiazolin-3-one increased the Ni content in the alloy coating, while chitosan decreased it. The two biocides both altered the coating structure and morphology significantly. 4,5-Dichloro-2-N-octyl-4-isothiazolin-3-one-Zn-Ni composite coating showed better corrosion resistance in sulfate reducing bacteria and better antifouling property in Escherichia coli medium, and the optimum adding concentration in the electrolyte was determined to be 2 mmol L-1.