Si Doped and Un-Doped CrN Thin Films Produced by Magnetron Sputtering: Structural and Mechanical Properties
Chromium nitride and silicon doped chromium nitride thin films have been deposited by r.f. reactive magnetron sputtering. The effect of processing parameters on the properties of chromium nitride films and the correspondent influence of the addition of silicon on the chromium nitride matrix in the films structure and mechanical properties have been investigated. The characterization of the coatings was performed by X-ray diffraction (XRD), and nano-indentation experiments. These studies allow analyzing the crystalline phases, crystal orientation/texture, crystallite size, mechanical properties and the relations between the characteristics of the films. The increase of the nitrogen partial pressure in the working atmosphere produces changes from a body-centered cubic (bcc) Cr structure, to hexagonal Cr2N to face-centered cubic (fcc) CrN structure, with CrN (111) preferred orientation. For the films with a dominant Cr2N phase the hardness has a relative maximum (42 GPa). The highest hardness was measured for a coating with dominant CrN phase (45 GPa) with a crystallite size around 18 nm. The addition of Si, in the films with CrN dominant phase, maintains the CrN (111) preferred orientation and produced variable changes in films hardness, depending on deposition conditions.