Deposition and characterization of reactive magnetron sputtered zirconium carbide films

Zirconium carbide films have been deposited on silicon (100) substrates using direct current magnetron reactive sputtering using CH4 as a carbon source. The films exhibit a typical nanocomposite structure consisting of nanocrystalline ZrCx (nc-ZrC) grains embedded in a matrix of amorphous carbon (a-C) at low carbon content. Almost no crystalline phase can be found for carbon contents above 86 at.%. The mechanical, tribological and electrical properties of the films showed a significant dependency on the amount of the a-C in the nanocomposite structure. A larger amount of a-C gives rise to reduced hardness and higher resistivity of the film. However, both friction coefficient and wear resistance are improved by increasing the content of the surplus a-C. The influence of binding state of excess a-C phase on the properties has also been investigated. A larger sp2/sp3 ratio was beneficial to relax the stress and improve the electrical properties. The Zr-based films exhibited lower friction coefficients than nanocomposites films based on e.g. Ti suggesting a potential application for this material in sliding contacts.