Plasmochemical investigations of DLC/WCx nanocomposite coatings synthesized by gas injection magnetron sputtering technique

Abstract

Nanocomposite coatings of tungsten carbide incorporated into amorphous carbon (a-C/WCx) were synthesized with a varying amplitude of pulse pressure oscillation (0,4–0,8 Pa) on the silicon substrates through the Gas Injection Magnetron Sputtering (GIMS) technique. Hence, energy distribution manner followed by changing density (pressure) of plasma molecules was discussed in terms of two possibilities of a tungsten-carbon phase formation; clusters synthesis, within plasma ionized flux and the Lifshitz model of the surface nucleation. For this purpose, the morphology and the surface topography of deposited layers were studied by the atomic force microscopy (AFM), optical emission spectroscopy (OES) and the scanning electron microscopy (SEM). Further, pronounced structural analysis provided via transmission electron microscopy (TEM) and X-ray diffraction (XRD), presents, that spherical shaped WCx nanoclusters (1–4 nm) were dispersed in the amorphous‑carbon-like host matrix. More detailed chemical bonding state circumstances attained, that these nanocrystallites consist primarily of metastable γ-WC1−x, and the small amount of β-W2C phase; embedded within the diamond-like carbon (DLC) structure, referring to the engaged X-ray photoelectron spectroscopy (XPS) and the Raman spectroscopy examinations. Accordingly, an application issue of the unique bonds dependence of DLC/WCx coatings, deposited onto high speed steel substrate (SW7M) substrate, was emphasized by means of Vickers measurements, as a sensing microhardness feedback.