Manufacturing, Microstructure and Corrosion Resistance of Electrophoretically Deposited SiO2 and Ni/SiO2 Coatings On X2CrNiMo17–12–2 Steel

Abstract

The SiO 2 and Ni/SiO 2 coatings were electrophoretically deposited on X2CrNiMo17-12-2 steel using ethanol-based suspensions of the SiO 2 and Ni powders. The influence of the zeta potential and concentration of the suspensions, the applied voltage and deposition time on the quality of the coatings was studied. Microstructure of the plan-view and cross sections of the coatings was investigated using scanning electron microscopy. The plan-view images revealed the uniform microstructure of the coatings with sporadically observed cracks, pores as well SiO 2 and Ni agglomerates. On the cross-sections, the Cr 2 O 3 layer, resulted from oxidation of the substrate during sintering of the coatings was observed. The polarization tests have shown that SiO 2 and Ni/SiO 2 coatings improve the corrosion resistance of the X2CrNiMo17-12-2 steel in 3.5% NaCl aqueous solution.