Effects of deposition parameters on the structure and properties of ZrN, WN and ZrWN films

This paper examines optimal settings for deposition parameters for transition metal nitride (ZrN, WN and ZrWN) thin films that are deposited on tungsten carbide tools and glass substrates using direct current (DC) reactive sputtering with pure Zr and W metal targets and Ar plasma and N₂ reactive gases. Experiments using the grey-Taguchi method are conducted to study the effects of deposition parameters (substrate plasma etching time, N₂/(N₂ +Ar) flow rate, deposition time and substrate temperature) on a film that is deposited on a cutting tool that is used for dry machining and on the films’ mechanical properties. The substrates’ surfaces are etched using oxygen plasma pretreatment. It is clear that the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The results of grey relational analysis show for the dry turning AISI 304 stainless steel that the surface roughness is approximately R_a = 0.70 Μm and that the flank wear is approximately 14.02 Μm. The grey relational analysis shows that the period for which the substrate (tungsten carbide tool) is under plasma-etched pretreatment has the most significant effect on both the surface roughness and flank wear. The coated films are analysed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction and a nano-indenter. The ternary nitride (ZrWN)-coated specimens exhibit better mechanical properties than binary nitride (ZrN and WN) specimens. The optimum ZrWN coating exhibits the greatest hardness (H), elastic modulus (E) and H/E values.