Performance and Structural Analysis of Vanadium Composite Electrogalvanized Steel Sheets

Abstract

Vanadium composite electrogalvanized (Zn-V hydroxide) steel sheets were prepared by electroplating using a horizontal flow cell. The structure of Zn-V plating layer depended on the flow rate of electrolyte and the current density, and the performance of Zn-V steel sheets depended on the structure of plating films. The Zn-V plating films composed of two-phase structure without cracks showed the high corrosion resistance and high adhesion. The two-phase layer consisted of the field oriented fiber and non-field oriented texture. The field oriented fiber phase was mainly composed of metallic Zn, and the non-field oriented phase was mainly formed from the amorphous V compound. The V compound in the non-field oriented phase seems to be formed by the hydrolysis reaction of V ions due to pH increase in cathode layer according to hydrogen evolution during Zn-V plating. The Zn-V steel sheets had a black and low-gloss appearance compared to the conventional electrogalvanized steel sheet (EG). Since the V compound in the non-field oriented texture was black and the field oriented texture formed the surface roughness, the lightness and gloss of the Zn-V steel sheets decreased with increasing V content in plating films.