Synthesis and characterization of Cr-B-N coatings deposited by reactive arc evaporation

Abstract

Nanocomposite Cr-B-N coatings were deposited from CrB0.2 compound targets by reactive arc evaporation using an Ar/N2 discharge at 500 °C and -20 V substrate bias. Elastic recoil detection (ERDA), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) were used to study the effect of the N2 partial pressure on composition and microstructure of the coatings. Cross-sectional scanning electron microscopy (SEM) showed that the coating morphology changes from a glassy to a columnar structure with increasing N, partial pressure, which coincides with the transition from an amorphous to a crystalline growth mode. The saturation of N content in the coating confirms the formation of a thermodynamically stable CrN-BN dual-phase structure at higher N2 fractions, exhibiting a maximum in hardness of approximately 29 GPa. © 2008 Materials Research Society.