Ho Y. Lee

Structure and properties of WC–CrAlN superlattice films by cathodic arc ion plating process

Abstract New WC–CrAlN superlattice films have been deposited on Si(100) substrate using a cathodic arc ion plating system. A substrate holder was rotated with a range from 1 to 12 rev./min to control the thickness of layered structures, and on arc power density of Al cathodes was controlled to change the Al concentration in the film. The microstructure and mechanical properties of the film depend on the superlattice period (λ) and Al concentration. The chemical composition was evaluated by glow discharge optical emission spectroscopy (GDOES). Using X-ray diffraction analysis (XRD), it is observed that the preferred orientation of microstructure is changed according to the superlattice periods (λ) and Al concentration. Through transmission electron microscope (TEM) analysis, the microstructure and superlattice period (λ) of the WC–CrAlN superlattice film were confirmed. The hardness of the deposited film was evaluated by a nanoindentation test. As a result of the nanoindentation test, the hardness of WC–CrAlN superlattice film gained approximately 40 GPa at the superlattice period (λ) of 7 nm. The structure of WC–CrAlN superlattice film was transformed from dense columnar structure to a nanocomposite structure.

Characterization of WC–CrAlN heterostructures obtained using a cathodic arc ion plating process

Abstract New WC–CrAlN heterostructure films were deposited on Si wafer and S45C steel substrate by a cathodic arc ion plating (CAIP) process. The Al concentration and bilayer repeat period (λ; 2–10 nm) were controlled to obtain a nano-layered structure. We have characterized our samples using X-ray diffraction (XRD), cross-sectional transmission electron microscopy (TEM) and electron diffraction patterns. Mechanical properties of the WC–CrAlN films were characterized using nano-indentation tests, residual stress evaluation and scratch testing. The microhardness of WC–CrAlN films was in the range of 30–43 GPa. The residual stress was reduced below 2 GPa and the adhesion strength obtained was approximately 50 N by alternative deposition of heterostructure (WC–CrAlN) and buffer (WC–Cr) layers.