Electrochemical corrosion of magnetron sputtered WTiN-coated mild steels in a chloride medium

The electrochemical corrosion behaviour of WTiN coatings, of composition W 31, Ti 28 and N 40 at.% sputtered on carbon steel, chromium steel and high speed steel (HSS) has been investigated and the effect of the steel heat treatment on the steel/WTiN system performance explored. Open circuit potential measurements, polarisation curves and electrochemical impedance spectroscopy were used, together with X-ray diffraction and scanning electron microscopy to characterise the corroded and uncorroded coating/substrate systems. It was found that the influence of the substrate on corrosion resistance follows the order Carbon Steel<HSS