Nanometric chromium nitride/chromium carbide multilayers by r.f. magnetron sputtering

Chromium nitride/chromium carbide (CrN/CrC) multilayers, with periods between 5 and 100 nm, were deposited on M2 steel and silicon substrates using a single cathode r.f. magnetron sputtering system. The target was pure chromium (99.99%) and the nitride/carbide multilayer structure was obtained in a continuous process by alternating the sputtering gas composition between Ar/N-2 and Ar/CH4 reactive mixtures. The deposition parameters were arranged to obtain optimized properties for both materials in individual coatings and then implemented in multilayered film deposition. X-Ray diffraction allowed for a detailed characterization of the different phases obtained in both CrN and CrC individual coatings and in CrN/CrC multilayers. The periodic structure of the multilayers was characterized using low-angle X-ray diffraction and transmission electron microscopy. The mechanical and tribological properties such as hardness, residual stress, sliding wear behavior and friction coefficient in multilayers were analyzed by means of nanoindentation and ball-on-disk techniques and their dependence on period thickness are presented. These properties of the CrN/CrC multilayers are compared with those of CrN and CrC individual coatings. (C) 2003 Elsevier B.V. All rights reserved.