Stress in tungsten carbide-diamond like carbon multilayer coatings

Tungsten carbide-diamond like carbon (WC-DLC) multilayer coatings have been prepared by sputter deposition from a tungsten-carbide target and periodic switching on and off of the reactive acetylene gas flow. The stress in the resulting WC-DLC multilayers has been studied by substrate curvature. Periodicity and microstructure have been studied by transmission electron microscopy. It has been observed that compressive stress in the multilayers decreases when the bilayer thickness is reduced. Results show a minimum compressive stress for bilayer thickness of around 5?nm. This behavior is discussed in terms of interface stress and mixing between layers.