Optical and Corrosion Studies of Spray Pyrolysis Coated Titanium Dioxide Thin Films

Abstract

In the present work, nanostructured thin films of titanium dioxide (TiO2) have been coated on the stainless steel (SS 304L) substrate by spray pyrolysis coating technique. The surface morphology and chemical constituents of the thin film have recorded using Field Effect Scanning Electron Microscopy (FESEM) and Energy Dispersive Analysis of X-rays (EDAX) respectively. The structural and optical properties of the films of as deposited were examined by Micro Raman, Photoluminescence Spectroscopy (PL) and UV-Vis absorption method. The FESEM micrograph showed the microporous nature of the film. EDAX spectrum illustrated the presence of Ti and O on the coated surface of the steel substrate. The peaks in the micro Raman spectrum indicated that the TiO2 samples of present study are in rutile phase of titanium dioxide. A strong emission peak around 350 nm was observed in the Photoluminescence spectrum of the samples. The anti-corrosion properties of the TiO2 coated samples were investigated by neutral salt spray test for 390 h. Electrochemical Impedance Spectroscopy (EIS) analysis and Tafel analysis were performed before and after salt spray test and the results suggested an increase of corrosion resistance of the titanium dioxide thin film in a corrosive environment. The positive shift of equilibrium corrosion potential (Ecorr) of bare stainless steel to thin film coated stainless steel (from −0.96 V to −0.38 V) in the electrochemical Tafel analysis implied the significant increase of corrosion resistance.