Growth of nanostructured TiN/NbN superlattice coatings by DC reactive sputtering process

Single layer TiN and NbN coatings were deposited on Si (111) and tool steel substrates using a reactive DC magnetron sputtering process. Process parameters were controlled in such a way that cubic phases of TiN and NbN with B1 structure were formed. Subsequently, TiN/NbN multilayer coatings were deposited at various modulation wavelengths (), that is the bilayer thicknesses. X-ray diffraction (XRD), nanoindentation and atomic force microscopy (AFM) were used to characterize the coatings. Multilayer coatings deposited at 120 Å >  > 25 Å showed satellite reflections along (111) principal reflection, thus confirming the formation of superlattice structure. The multilayer coatings exhibited hardness as high as ~4000 kg/mm2, which was about 2 times the rule-of-mixtures value. The AFM images showed that the coatings had a roughness of ~5 nm