A comparative study of corrosion resistance in CrN and CrN/Cr coatings, electrodeposited chromium and epoxy paints

This work was aimed at comparing the corrosion resistance of CrN and CrN/Cr coatings deposited through unbalanced magnetron sputtering (UBM), Cr industrial coatings and epoxy paints. UBM coatings were optimised and produced at room temperature, using 400 mA discharge current. Ar and N2 flow rates were set at 9 standard cubic centimetres per minute (SCCM) and 3 SCCM, respectively. Deposition times were set to produce CrN monolayers and nanometric multilayers having 1μm total thickness and 100 nm period. Coating microstructure was determined through scanning electron microscopy as texture and crystalline phases were determined using x-ray diffraction and infrared spectroscopy. Corrosion resistance was studied with anodic polarisation tests using 0.5M H2SO4 and 0.05M KSCN solution. Nanometric multilayers improved stainless steel corrosion resistance and it was observed that coated CrN steel A36 could be an alternative for replacing stainless steel in acid environments. Corrosion mechanisms for the coatings so deposited are discussed.