Study on the Modification Technology of Zinc Powder in Inorganic Zinc-Rich Coating

Abstract

 In order to improve the shortcomings of poor dispersibility, easy agglomeration and easy corrosion of flaky zinc powder in inorganic zinc-rich coatings, the surface of flaky zinc powder was modified by silane coupling agent KH560 and cerium nitrate, and the optimum process conditions for surface modification of zinc powder was screened by polarization curve test.The changes in physical properties and corrosion resistance of zinc powder on zinc-rich coatings before and after modification were compared.Results showed that the optimal modification conditions of silane coupling agent KH560 were 12%(mass fraction), 60 ℃ of reaction temperature, pH 8 and 60 min of reaction time.The optimum dosage of cerium nitrate modified zinc flake/zinc powder was 0.01%(mass fraction)under the process conditions of room temperature, pH 7 and 60 min of reaction time.The dispersibility of modified zinc powder in water was improved.Moreover, the workability, drying time and adhesion of the modified zinc powder changed significantly.The corrosion current of the coating prepared by modified zinc powder was reduced by about 1 order of magnitude, the polarization resistance was increased by about 1 order of magnitude, and the corrosion resistance of the coating was significantly improved.In general, the cerium nitrate modified coating had the lowest passivation current and the smallest corrosion rate, which could be recommended to use cerium nitrate modified zinc powder for long-term protection.a

Keywords

• inorganic zinc-rich coatings| flake zinc powder|modification|silane coupling agent|cerium nitrate|corrosion behavior