Investigation of the corrosion behavior of carbon steel coated with zinc electrochemically at different current densities in chloride solutions

Authors : Behçet Kağan Bölük, Sibel Demirel

Pages : 1257-1269

Doi:10.17714/gumusfenbil.1780519

View : 64 | Download : 178

Publication Date : 2025-12-15

Article Type : Research Paper

Abstract :In this study, the surface of high carbon steel (0.83 % C) was electrolytically coated in Zn coating solution at constant current densities of 1 A/dm², 2 A/dm², 3 A/dm², 4 A/dm² and 5 A/dm² for 30 minutes. The corrosion resistance of zinc-coated carbon steel in 3.5 % NaCl solutions was determined by Tafel polarization measurements. According to the Tafel polarization results, the corrosion current density was 105 µA/cm2 for uncoated carbon steel, while this value was 85.7 µA/cm2 with Zn coating at 1 A/dm², and the decrease in corrosion current density was determined as 10.8 µA/cm2 with 5 A/dm² coating. A 90 % decrease in corrosion current density was observed in the Zn coating to which 5 A/dm² current was applied. Accordingly, as the coating applied constant current density increased, the corrosion current density decreased. In addition, the changes that occur over time on the surfaces of Zn-coated and uncoated steel exposed to a constant current of 5 A/dm² in a 3.5 % NaCl solution for 0, 4, 24, 48, and 120 hours were investigated by SEM images and EDS analyses. The experimental results indicated that the Zn coating was denser and more homogeneous coating under the 5 A/dm² constant current application conditions. After 240 hours, 5 A/dm2 constant current, the coating maintained its corrosion protection in corrosive environments such as chlorides, and the surface coating remained relatively intact. Additionally, coating thicknesses were determined using an optical microscope. The thickness of the Zn coating was determined as 2 µm at a constant current of 1 A/dm2, while this ratio was determined as 14 µm at 5 A/dm2. Accordingly, the coating thickness increased homogeneously with the increase in the constant current density applied in electroplating. As a result, it was observed that the Zn coating at a constant current of 5 A/dm² was effective in preventing the corrosion of high carbon steel in aggressive environments containing chlorides.
Keywords : Karbon çeliği, Korozyon direnci, Akım yoğunluğu, Elektrokimyasal çöktürme, Çinko kaplama

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