Effects of thickness ratio on phase structures, mechanical properties, and oxidation resistance of CrSiN/WSiN bilayer films

Abstract

The high oxidation resistance of CrSiN films and the high hardness of WSiN films inspired the fabrication of CrSiN/WSiN bilayer films to combine both advantages. This study deposited CrSiN/WSiN bilayer films of approximately 1 mu m with various thickness ratios through direct current magnetron cosputtering. Cr, Si, and W targets were used to deposit WSiN and CrSiN sublayers. The thickness ratios of the WSiN to the CrSiN sublayer were 1.3, 2.4, 3.2, and 4.2, respectively, by regulating the deposition times. The influences of the sublayer thickness ratio (WSiN/CrSiN) on the bilayer film's characteristics were explored. The monolithic CrSiN and WSiN sublayers had FCC and amorphous phases, respectively. The CrN (111) intensity of CrSiN/WSiN bilayer films becomes more pronounced with increasing the CrSiN sublayer thickness and decreasing the sublayer thickness ratio. The hardness of the CrSiN/WSiN bilayer films increased from 11.3 to 17.7 GPa with decreased CrSiN sublayer thickness, whereas the elastic modulus increased from 234 to 266 GPa. The wear resistance of these CrSiN/WSiN bilayer films was evaluated through the pin-on-disk tests. The oxidation resistance of these CrSiN/ WSiN bilayer films was examined after annealing at 600-800 degrees C. The CrSiN sublayers advanced the oxidation and wear resistance of the bilayer films.