Investigation of Zinc metallic coating properties formed on low carbon steel in alkaline and sulfate electrolytes by plasma electrolytic saturation

Authors

• F Momeni
• M Mousavi Khoee

Abstract

Electrolytic plasma galvanization is one of the newest methods for corrosion protection of steels. In this research, Plasma electrolytic (PE) method  were used for zinc deposition on st12 steel. Work-Pieces were connected to the cathode of  high voltage direct current source and were  placed inside electrolyte. Sodium hydroxide alkaline solution including 3 wt% zinc dissolved in saturated HCl acid and 30 wt% ZnSO4 solution were used as electrolytes and NaCl were added to increase the electrical conductivity. Surface morphology and composition of coatings was analyzed by SEM and EDAX. Corrosion behavior was also evaluated by DC polarization in 3.5 wt% NaCl.Results showed that zinc deposition formed broccoli type morphology coating because of the plasma spark actions. Corrosion resistance of steel increased by zinc coating to the more active potential and changing of electrolyte type from ZnSO4 to alkaline (zinc ion saturated) solution increased electric conductivity and so PE process current increases to 3A and initial spark generation voltage decreases to 50 V.
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Keywords

• Zinc Metal Coating
• Plasma Electrolytic Saturation
• Polarization
• Corrosion Resistance

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