The presented investigations demonstrate the corrosion behavior and protective ability of two composite systems obtained on low-carbon steel in model corrosive medium of 5% NaCl solution.These systems consist of Zn-Co(3 wt.%)or Zn-Ni(10 wt.%)alloy coatings as an under-layer and very thin ZrO2 sol-gel film as a top-layer.The surface morphology of the samples was studied with scanning electron microscopy(SEM).Their corrosion resistance was investigated by application of potentiodynamic polarization(PDP)curves,polarization resistance measurements(Rp)for a definite period of time(10 days)and electrochemical impedance spectroscopy(EIS).The results obtained were compared with the corrosion characteristics of an ordinary zinc coating with the same thickness.The experimental data present the positive influence of the newly developed composite systems for the enhanced protective properties of low-carbon steel in the test aggressive chloride-containing environment.
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