Comparative study of metal /amorphous-carbon multilayer structures produced by magnetron sputtering

The present study discusses the structural and mechanical properties of metal/amorphous carbon (a-C) multilayer structures of a-C/Mo/a-C/.../Mo/substrate and a-C/W/a-C/.../W/substrate deposited by magnetron sputtering. To this end, the effects of deposition parameters on multilayered nanometric structures were examined. Samples consisted of structures with alternate metallic and a-C layers with thicknesses in the nanometric range (1-3 nm). The films were deposited on crystalline silicon and glass substrates at room temperature using two opposing magnetron sputtering heads, which allowed the alternate deposition of the metallic and a-C films on the substrates placed on a directional holder. The substrate negative bias voltage was varied between 40 and 300 V and the process was performed at Ar pressures in the range 0.2-2 Pa. The structural and morphological properties and local order of the layers and interfaces were analysed by transmission electron microscopy and X-ray diffraction. Mechanical stress, and critical load for coating failure were measured by profilometry and the microscratch technique, respectively, and the results are discussed in terms of the deposition conditions and the multilayer nanostructure. Potential applications of films based on metal/a-C multilayers include the production of hard, protective, wear-resistant coatings for corrosion-resistamt and high temperature-resistant applications. (C) 2002 Elsevier Science B.V. All rights reserved.