Mechanical Properties of Amorphous Hard Carbon Films Prepared by Cathodic ARC Deposition

Abstract

Cathodic arc deposition combined with macroparticle filtering of the plasma is an efficient and versatile method for the deposition of amorphous hard carbon films of high quality. The film properties can be tailored over a broad range by varying the energy of the carbon ions incident upon the substrate and upon the growing film by applying a pulsed bias technique. By varying the bias voltage during the deposition process specific properties of the interface, bulk film and top surface layer can be obtained. We report on nanoindentation and transmission electron microscopy studies as well as stress measurements of cathodic-arc amorphous hard carbon films deposited with varied bias voltage. The investigations were performed on multilayers consisting of alternating hard and soft amorphous carbon.

Heat treatment of cathodic arc deposited amorphous hard carbon films

“…The sample was either at ground potential, at -lOOV, -5OOV, or -2kV with a bias pulse duration of 2 ps and a bias pulse off-time of 6 ps. It w a s found in earlier investigations [19][20][21][22] that films deposited at a bias voltage of -1OOV show the most "diamond-like" character (Le., high sp3 fraction, density, hardness etc.) whereas films deposited at a high bias of -2kV show the most graphitic character.…”

Growth and Mechanical and Tribological Characterization of Multi-Layer Hard Carbon Films

“…In the case of 30 nm layers, the multilayer structure is clearly visible. This film was deposited with approximately equal mass densities of hard and soft material [5], rather than with equal thicknesses as in this work. Therefore, the layer thickness ratio is 4050 hard:soft.…”

“…The deposition method has been described in detail elsewhere [5,7]; only a summary will be presented here. C+ ions are extracted from a vacuum-arc plasma and passed through a…”

“…Stress is linearly correlated with hardness in these films [3,4] and appears to be an intrinsic attribute of the ion-beam growth process that leads to hard f i l m s [1,4]. Previous work in our: laboratory has shown that multilayer carbon films consisting of alternating layers of hard (-60 GPa) and softer (-30 GPa) material can have lower compressive residual stresses while retaining hardnesses above 30 GPa [5]. The wear rates of the multilayer films were found to be unusually low mm3 N-' m-') and, at high loads, tribological performance was shown to be optimized for multilayer f i l m s with an approximate 5050 harclxoft thickness ratio [a.…”

Some Vacuum-Arc-Based Plasma and Ion Beam Tools for Surface Modification

“…By adding the appropriate gas to the deposition set-up, metal oxides and nitrides (for example) can also be formed. This approach has found particularly nice application for forming DLC (diamond-like carbon) thin films, using a carbon cathode in the plasma gun [32,33]. Advantages of the approach compared to other DLC deposition methods include that the vacuum arc deposited films are inherently hydrogen-free, and the ion energy can be precisely controlled so as to form films that have a very high (in fact, optimized maximally high) sp 3 content (the fraction of diamond-bonded carbon as opposed to graphite-bonded carbon within the film).…”