Structure and tribological properties of reactively sputtered Zr–Si–N films

International audienceZr–Si–N films were deposited on silicon and steel substrates by magnetron sputtering of a Zr–Si composite target in Ar–N2 reactive mixtures. The silicon concentration in the films was adjusted in the 0–7.6 at.% range by varying the surface of Si chips located on the erosion zone of the target. The films were characterised by X-ray diffraction, electron probe microanalysis, atomic force microscopy and wear tests. The structure and the tribological properties of Zr–Si–N films were compared to those of ZrN coatings. Depending on the silicon concentration, the films were either nanocomposites (nc-ZrN/a-SiNx) or amorphous. Introduction of silicon into the zirconium nitride coatings induced a change in the preferential orientation of the ZrN grains: [111] for ZrN films and [100] for Zr–Si–N ones. This texture modification was also observed for a ZrN film deposited on an amorphous SiNx layer. Thus, within our deposition conditions, the occurrence of a-SiNx enhanced the [100] preferred orientation. Friction and wear behaviour of the films were carried out against spheres of alumina or 100 Cr6 steel by using a ball-on-disc tribometer. The results showed that addition of silicon into ZrN-based coating induced a strong decrease in the friction coefficient and in the wear rate compared to those of ZrN films. These results were discussed as a function of the films structure and composition

Influence of the silicon concentration on the optical and electrical properties of reactively sputtered Zr–Si–N nanocomposite coatings

International audienceZr–Si–N films were deposited on silicon and X38CrMoV5 steel substrates by sputtering composite Zr–Si targets in reactive Ar–N2 mixture. The silicon concentration in the deposited films was adjusted by the variation of the number of Si chips located on the target erosion zone. As a function of the silicon content, the films exhibited the following structures: insertion of Si into the ZrN lattice, nanocomposite (nc-ZrN/a-SiNx) and an amorphous-like structure. Addition of silicon into ZrN-based coatings induced a lost of the golden aspect due to the decrease of the metallic behaviour. This result was confirmed by ellipsometric measurements. The films refractive index increased with the silicon concentration. On the other hand, a continuous decrease of the extinction coefficient was noticed. The effect of the silicon content on the optical properties of Zr–Si–N films was discussed as a function of the films structure and the occurrence of new optical absorptions due to the silicon chemical bonds. Finally, the evolution of the films electrical resistivity was discussed in connection to the films structure changes

Thermodynamic and experimental study of low temperature ZrB2 chemical vapor deposition

A thermodynamic study of the Zr-B-H-Cl system is realised using a cornputer-aided Gibbs energy minimisation program. Effect of the total pressure and the atomic ratio of hydrogen to chlorine (Hl / Cl) on the CVD deposition diagram is investigated. The total pressure decrease lowers the minimal temperature for ZrB2 deposition. It reaches 780 K at 100 Pa. H / Cl ratio affects the ZrB2 + B codeposition domain area. A CVD deposition diagram at 800 K with isoyield curves is also presented. Zirconium diboride films are elaborated on quartz and Zircaloy-4 substrates using ZrCl4 and BCl3 precursors. Since ZrB2 films cannot be synthesised at temperature lower than 800 K by thermal CVD, an original CVD process enhanced by Ar-BCl3 post-discharge has been developed. At 733 K, films obtained using this process are composed of ZrB2 nanograins embedded in an amorphous solid solution of zirconium and boron oxides