Microstructural and Mechanical Properties of Nanostructured Tungsten Nitride Thin Films Prepared by RF Reactive Magnetron Sputtering

In the present work, nanostructured tungsten nitride (WN) thin films were deposited by RF reactive magnetron sputtering technique in a mixture of N-2 and Argon atmosphere and its microstructure and mechanical properties were investigated. The Argon pressure was kept constant at 20 sccm, while the N-2 partial pressures were varied (3%, 5%, 10% and 15%). The WN thin films are deposited on SS304 stainless steel substrates at a temperature of 500 degrees C. The microstructural property was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) and mechanical properties were evaluated by nanoindentation technique. The XRD studies indicated the formation of different phases as a function of nitrogen content. The hardness and the young's modulus values were in the range 27-39 GPa and 239-280 GPa, respectively. The high hardness values correspond to the coatings with the low nitrogen content and vice-versa. The mechanical properties of the tungsten nitride coatings were strongly influenced by the microstructure.