Investigation on the Influence of Nano Structured Zirconia Coating on the Corrosion Inhibition of SS 304 Stainless Steel

Abstract

Corrosion is the gradual destruction of metals through chemical or electrochemical reaction with their environment. Prevention of corrosion is necessary for the safe and fail-free working of any machine component. Stainless steel, though having an inherent corrosion resistive nature, is prone to corrosion in environments like sea water containing chloride ions. In this paper, the effect of depositing nano structured ZrO2 on the corrosion inhibition of SS304 austenitic stainless steel is reported. The coating was achieved using the sol-gel dip coating technique. The Taguchi methodology of design of experiment was adopted to conduct the experiments. The structural and morphological characterization of the coating was carried out through X-Ray diffraction and scanning electron microscopic analyses respectively. The thickness of the coating was measured using a coordinate measuring machine. The evaluation of corrosion performances of the coating in 0.5 M NaCl was done by electrochemical impedance spectroscopy and polarization measurements. The results indicated an improvement in corrosion resistance by as much as 84% for the coated specimens compared with the uncoated specimen. The coating process parameters such as molar concentration of the sol, dipping time and annealing temperature influenced the morphology and thickness of the resultant coating and hence the corrosion resistance. An increase in homogeneity and thickness of the coating was found to improve the corrosion resistance. Further, signal to noise ratio was found out to identify the optimum parameter combination yielding the highest corrosion resistance.