Corrosion Resistance Study of Nanostructure Zirconium Carbide Coatings

In this study, zirconium carbide (ZrC) coatings are electrodeposited on zirconium substrate by electrolysis from molten salt at 772 oC. Electrodeposition is carry out at 120 and 380 mA/cm2 as electrolysis current densities. The coatings have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) methods. Corrosion resistance of coatings are investigated using potentiodynamic polarization test in a solution containing boric acid (H3BO3) and lithium hydroxide (LiOH) at pH= 6.85. The production of zirconium carbide coatings has been confirmed by XRD, FTIR and EDX analysis methods. The results show that zirconium carbide coatings improve the corrosion resistance of zirconium. Moreover, the passivation zone has been expanded by ZrC coatings. The electrodeposition current density shows incredible effect on electrocrystallization, nanostructure and consequently corrosion resistance of ZrC coatings. As the coating electrodeposited at 120 mA/cm2 shows lower corrosion rate. Nanostructure, coherency of ZrC particles, and absence of cracks in the coating are affected this behavior of zirconium carbide coatings.