A COMPARISON OF THE CORROSION BEHAVIOR AND HARDNESS OF STEEL SAMPLES (100CR6) COATED WITH TITANIUM NITRIDE AND CHROMIUM NITRIDE BY DIFFERENT INSTITUTIONS USING DIFFERENT DEPOSITION TECHNIQUES

Deposition of hard coatings may influence the mechanical properties of the bulk material and its corrosion resistance. In this work we study the hardness of the coated and the back side of 100Cr6 steel plates. Electrochemical corrosion tests were performed in O2-saturated acetate buffer of pH 5.6 at 25-degrees-C. Chromium nitride and titanium nitride coatings prepared by different physical vapour deposition processes, such as are, thermionic are evaporation, magnetron sputtering and ion-beam-assisted deposition (IBAD) were compared. The results show that, for sufficient corrosion protection, chromium nitride layers have to be thicker than 500 nm. An increased nitrogen partial pressure in the evaporation chamber of the IBAD process improves the corrosion resistance significantly. The hardness of the substrates was reduced in the case of thermionic are evaporation only, indicating a deposition temperature of more than 250-degrees-C. For this process, however, we obtained the best corrosion results.