A new strategy based on thermodiffusion of ceramic nanopigments into metal surfaces and formation of anti-corrosion coatings

•Synthesis and characterization of Cr1.3Fe0.7O3 ceramic nanopigments.•Characterization of the ceramic nanopigments by XRD, EDX, SEM and TEM techniques.•A new strategy based on thermodiffusion of Cr1.3Fe0.7O3 into metal surfaces.•Formation of a novel anti-corrosion coating by Cr1.3Fe0.7O3 thermodiffusion.•Characterization of the anti-corrosion coatings using various techniques.

The present paper is the first report about preparation of anti-corrosion coatings based on thermodiffusion of ceramic nanopigments into metal surfaces. At first, Cr1.3Fe0.7O3 ceramic nanopigments have been synthesized by simple and environmentally benign sol–gel method. Annealing of the gels at different temperatures ranging from 600 to 1000 °C yielded the pure rhombohedral structure. The structural evolutions and microstructural characteristics of the synthesized nanoceramics were investigated through different methods containing X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Then Cr1.3Fe0.7O3 ceramic nanopigments were coated on mild steel surface via thermodiffusion method. The surface morphology and the corrosion behavior of the Cr1.3Fe0.7O3 coatings were evaluated using atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss measurements in a solution of 2.0 M HCl. It is found that morphology of diffusion coatings affects the protective properties of mild steel. On the other hand, in extra-corrosive HCl media Cr1.3Fe0.7O3 nanoceramic coatings provide mild steel with high protective properties.

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