Structure, hardness and thermal stability of nanolayered TiN/CrN multilayer coatings

Nanolayered TiN/CrN multilayer coatings were deposited on silicon substrates using a reactive DC magnetron sputtering process at various modulation wavelengths (Lambda), substrate biases (V-B) and substrate temperatures (T-S). X-ray diffraction (XRD), nanoindentation and atomic force microscopy (AFM) were used to characterize the coatings. The XRD confirmed the formation of superlattice structure at low modulation wavelengths. The maximum hardness of the TiN/CrN multilayers was 3800kg/mm(2) at Lambda = 80 Angstrom, V-B = -150 V and T-S = 400degreesC. Thermal stability of TiN, CrN and TiN/CrN multilayer coatings was studied by heating the coatings in air in the temperature range (TA) of 400-800degreesC. The XRD data revealed that TiN/CrN multilayers retained superlattice structure even up to 700degreesC and oxides were detected only after TA greater than or equal to 750degreesC, whereas for single layer TiN and CrN coatings oxides were detected even at 550degreesC and 600degreesC, respectively. Nanoindentation measurements showed that TiN/CrN multilayers retained a hardness of 2800 kg/mm(2) upon annealing at 700degreesC, and this decrease in the hardness was attributed to interdiffusion at the interfaces. (C) 2003 Elsevier Ltd. All rights reserved.