Influence of Ar/N2 flow ratio on structure and properties of nanoscale ZrN/WN multilayered coatings

ZrN/WN multilayered coatings with nanoscale bilayer periods have been synthesized with different Ar/N2 flow ratio in an ultra-high vacuum rf magnetron sputtering system. The extensive measurements were employed to investigate the influence of Ar/N2 flow ratio on microstructure and mechanical properties of the coatings. A well-defined composition modulation and layer structure of the multilayered coatings were proved. Almost all multilayered coatings revealed higher nanohardness than the rule-of-mixture values of the monolithic ZrN and WN coatings. At Ar/N2 flow ratio (FAr:FN2 = 5), the X-ray diffraction (XRD) pattern showed strong intensity of W2N (111), W2N (200) and W2N (311). The multilayered coating at this condition possessed excellent hardness, residual stress, reduced elastic modulus and fracture resistance, compared to those synthesized at other Ar/N2 flow ratios.