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In the present paper, the corrosion behavior of 1020 carbon steel in commercial gasoline-ethanol blends was investigated. The composition of each gasoline-ethanol blend was evaluated by infrared spectroscopy, and the ethanol content was determined by the ABNT 13992 reference method. Electrochemical Impedance Spectroscopy (EIS) and polarization methods were employed to evaluate corrosion resistance and penetration rates. Statistical analyses revealed that the gasoline’s solution resistance governs the corrosion process, the RON (Research Octane Number) and MON (Motor Octane Number) numbers as well as the olefin content being more related to the corrosion rates. The polarization resistance had minor impact on the corrosion process.

Herein, the corrosion behaviour of coated 304 stainless steel in 3.5 wt-% NaCl solution was investigated. Thin films, composed of NbN and Nb x Al y N with different Al contents, were synthesized by magnetron sputtering. The microstructural investigation involved testing in energy-dispersive X-ray spectroscopy, scanning electron microscopy and grazing incidence X-ray diffraction, revealing films with a thickness of 165-200 nm composed of an NbN-δ cubic phase. Corrosion resistance was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy tests. According to the present results, in the proposed the experimental conditions, the addition of Al to NbN coatings is detrimental to the corrosion resistance of coated 304 stainless steel. The Nb 0.90 Al 0.10 N sample shows the lowest corrosion protection and the highest porosity among the studied samples.