Modification of the Corrosion Response of Steel Substrates by Ion-Nitriding

摘要

This paper concentrates on the electrochemical behaviour of ion-nitrided coatings produced bycathodic arc plasma deposition. The corrosion of five different steel grades modified by ion-nitridingwas investigated through electrochemical polarization and electrochemical impedance spectroscopytechniques in immersion tests performed in a 0.5 M NaCl solution. Ion-nitrided and bare steelsubstrates were employed. Enhanced corrosion resistance is found for the coated steels. A porous filmis produced on the metallic substrates, which allows for electrochemical reactive areas to be developedinside the pores. Surface film breakdown results in the localised corrosion of the materials at potentialspositive to the corresponding pitting potential values for each material in the testing solution.