Pulsed DC magnetron sputtered tantalum nitride hard coatings for tribological applications

Transition metal nitride coatings are used in electronics industry as a diffusion barrier coating. In the present study, tantalum nitride thin films were coated at room temperature (300 K) on various substrates, such as cemented carbide milling inserts, glass and stainless steel, using pulsed DC magnetron sputtering technique. Optical emission spectroscopy (OES) was employed to analyze the sputtering plasma to understand the reaction kinetics of tantalum nitride formation. The properties of the films were evaluated by various techniques, including X-ray diffraction (XRD), scratch adhesion test, ball-and-crater method and atomic force microscopy (AFM). The deposition rate was found to increase with an increase in sputtering power. The coatings were amorphous at low sputtering power, and showed development of crystalline structure, with (111) orientation. The initial results show that the film structure and adhesion needs to be improved further for tribological applications.