Carbon:Vanadium (C:V) nanocomposite filmsfor tribological applications

Nanocomposites are heterogeneous materials wherein the lateral extension of at least one component is lower than 100 nm.[1] They represent a new class of functional materials, whose properties cannot be predicted from those of their constituents alone. Among the various classes of nanocomposites, metal-containing nano-particles embedded in a carbon matrix have recently attracted considerable interest regarding their structure and properties.[2,3]
This study focuses on the structure and the mechanical properties of C:V nanocomposites. A series of C:V films with a varying vanadium concentration of 2 at.% ≤ xv ≤ 50 at.% was grown on silicon by DC dual magnetron sputtering. Depending on the metal concentration, significant structural variations were observed within both phases (dispersed phase and matrix) of the nanocomposite. At low vanadium concentrations, an amorphous metal rich and an amorphous carbon phase are formed. An increasing metal content promotes the formation of cubic VC and a graphitic carbon phase. With optimized deposition parameters, the hardness of the C:V nanocomposite films is higher then 10 GPa, and the elastic modulus achieves values of about 130 GPa. The friction coefficients for sliding conditions are as good as 0.1.

[1] P. M. Ajayan, L.S. Schadler, P.V. Braun, Nanocomposites Science and Technology, Wiley, 2005
[2] T. Hayashi, S. Hirono, M. Tomita, S. Umemura, Nature 381, 772-774 (1996)
[3] M. Krause et al., Phys. Stat. Sol. (B), 244, 4236-4239 (2007); G. Abrasonis et al. Carbon, 45, 2995-3006 (2007); M. Berndt et al., Plasma Process. Polym. 6, S902–S906 (2009); C. Adelhelm et al., J. Appl. Phys. 105, 033522 (2009); M. Magnuson et al. Phys. Rev. B, 80, 235108 (2009).