engleski

Electrochemical investigation of thermally modified steel surfaces

Abstract In this work, the influence of the metal surface modification on its corrosion resistance is investigated by two different electrochemical methods: potentiodynamic polarisation measurements and electrochemical impedance spectroscopy. The surface of the carbon steel samples has been modified by thermal processes: nitrocarburisation and oxidation at high temperatures. These processes change only the shallow surface region of the metal sample while the core metal is almost unchanged. This enables the improvement of the metal corrosion resistance as well as its mechanical properties. The results of the electrochemical investigations performed in this work showed that the nitrocarburised surface layer strongly enhanced the carbon steel corrosion resistance. Iron oxides formation at the surface layer had not significantly improved the performance of the nitrocarburised one. Even though the corrosion resistance of the nitrocarburised samples is much higher than that of the non-treated carbon steel, it had not reached that of the stainless steel. Further development of the surface modification processes is required to obtain a surface layer on the carbon steel with a corrosion resistance similar to that of the stainless steel.

carbon steel ; corrosion ; nitrocarburisation ; oxidation ; EIS

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