Magnetron sputtered NbN films with electroplated Cr interlayer

NbN films were deposited on SS substrates by reactive DC magnetron sputtering at various N 2 flow rates and substrate biasing. Coatings were studied for their thickness, structure, hardness and adhesion aspects. Process parameters were optimized for deposition of NbN coatings. NbN coatings were then extended on to MS substrates with Cr interlayer in three different thicknesses of 2, 4 and 10 μm. Cr was deposited by electroplating. The duplex coatings have been studied for the improvement with respect to surface hardness by Knoop micro indentation, adhesion by scratch testing and corrosion performance by potentiodynamic polarization technique. Open circuit potentials were also measured. ► NbN films are deposited by reactive DC magnetron sputtering. ► Effect of N 2/Ar flow ratios and substrate biasing was studied. ► Coatings were studied for thickness, structure, hardness and adhesion. ► Coating was extended on to MS substrate with various Cr interlayer thickness. ► Duplex coating has been studied for hardness, adhesion and corrosion improvement.