Corrosion behavior of TiO2–NiO nanocomposite thin films on AISI 316L stainless steel prepared by sol–gel method

TiO2–NiO nanocomposite thin films were deposited on the 316L stainless steel using sol–gel method by a dip coating technique. Different techniques such as differential thermal analysis, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and scanning probe microscopy were carried out in order to characterize the structure of the coatings. The corrosion resistance of the coatings was evaluated by using Tafel polarization and electrochemical impedance spectroscopy tests of uncoated and coated specimens in a 3.5% NaCl solution at room temperature. It was found that to obtain desirable structure in coatings, the coatings should be calcined at 600 °C for one and half hour. NiTiO3, anatase and rutile were the phases obtained in different calcination conditions in air atmosphere. The results of corrosion tests indicated that with increasing the dipping times from 2 to 4, the corrosion current density first decreases but when increasing the dipping times to 6, it increases. Also the corrosion current density decreased from 186.7 nA.cm− 2 (uncoated steel) to 34.21 nA.cm− 2 (80%TiO2–20%NiO) and corrosion potential increased from − 150.2 mV (uncoated steel) to − 107.3 mV (67%TiO2–33%NiO).

► TiO2–NiO thin films were deposited on the 316L stainless steel using sol–gel method.
► Different compositions, annealing times and temperatures resulted in various phases.
► Films having different compositions showed various surface morphologies.
► Films having a composition of 80%TiO2–20%NiO showed a good corrosion protection.