Effect of precursor concentration on corrosion resistance and microstructure of ZnO thin films using spray pyrolysis method

This paper presents the preparation and characterization of ZnO at various molarities deposited on glass and 316L stainless steel (316L SS) substrates via spray pyrolysis technique (SPT) for multifunctional applications such as anti-corrosion of various types of steel in oil and gas companies , marine industry, and optoelectronic applications. Zinc acetate solution was employed as precursor. The X-ray diffractometry (XRD) result showed no significant effect on crystal size and microstrain when the molarity of ZnO increased from 0.1 M to 0.2 M, but with 0.3 M, the crystal size increased from 17.33 nm to 23.10 nm, while the microstrain of the film varied from 0.13 nm to 0.10 nm. The coated films’ particles were observed to adhere suitably to the 316L SS substrate and were evenly distributed across the substrate surface. The results of the energy dispersive X-ray spectroscopy (EDX) and XRD affirm the presence of Zn and O in the deposited samples. The percentage of elements in the 316L SS are Fe = 70.10%, Ni = 10.10%, and Cr = 16.20% but on deposition of thin films. The signals of the Fe, Cr and Ni contents of the 316L SS were suppressed with increased ZnO concentration. The transmittance at the ultraviolet visible (UV-visible) region of (300 – 900 nm) showed that ZnO is highly transparent to visible light. The coated ZnO thin films improved the corrosion resistance of the 316L SS as seen from the electrochemical test result. Molarities were observed to increase with corrosion potential, which is related to corrosion resistance.The results show that the deposited ZnO coatings has a viable transparent oxide thin layer suitable for metal corrosion resistance.