Properties and characterization of multilayers of carbides and diamond-like carbon

Metal containing diamond-like carbon (Me-DLC) coatings are widely applied i n industrial applications. Normally, the coatings are produced with small i nclusions of carbide forming elements like the 3d, 4d or 5d metals, or Si o r B. The small carbide islands have sizes of approximately 2-20 mn. The eff ect of the nano inclusions is a reduction of internal compressive stress, a lowering of Young's modulus, a lower hardness, and a higher coefficient of friction as compared to pure diamond-like carbon (DLC). The contents of me tallic elements are typically between 10 and 20 at.%; for B containing diam ond-like carbon a higher percentage is observed (up to 50% B). In this work the effect of replacing the nano inclusions by a stack of extremely thin c arbide layers, separated by carbon layers, is tested. Properties like adhes ion, hardness, E-modulus, fatigue resistance, coefficient of friction and w ear resistance were studied. Furthermore, detailed high resolution TEM was performed to observe the effects of layer integrity. The results show a cle ar difference in wear and fatigue behavior when the multilayer structure wa s altered. Short periods within the multilayer structure of W-C:H promotes the wear resistance, while long periods promote the fatigue resistance. (C) 2001 Elsevier Science B.V. All rights reserved.