Hovsepian, P. E., Ehisarian, A. P., Purandare, Y. P., Biswas, B., Pérez, F. J., Lasanta, M. I., De Miguel, M. T., Illana, A., Juez Lorenzo, M., Muelas, R., Agüero, A. 2016. Performance of HIPIMS deposited CrN/NbN nanostructured coatings exposed to 650 degrees C in pure steam environment. Materials Chemistry and Physics 179, 110-119, DOI: 10.1016/j.matchemphys.2016.05.017
In the current work, 4 mu m thick CrN/NbN coating utilising nanoscale multilayer structure with bi-layer thickness of Delta = 2.9 nm has been used to protect 9 wt% Cr steels such as P92 widely used in steam power plants. The uniquely layered coatings have a combination of nitrides of chromium and niobium which are not only resistant to aqueous corrosion and corrosion-erosion and have excellent tribological properties, but also have oxidation resistance in dry air up to a temperature of 850 degrees C. The novel High Power Impulse Magnetron Sputtering (HIPIMS) deposition technology has been used to deposit CrN/NbN with enhanced adhesion (critical load of scratch adhesion L-C2 = 80 N) and a very dense microstructure as demonstrated by Transmission Electron Microscopy (TEM) imaging. These superior coating properties are achieved due to the unique high metal ion content (up to 90%) in the HIPIMS plasma, which allows particle acceleration and trajectory control by external electrical and magnetic fields thus delivering highly energetic material flux on the condensing surface.