Superhard and tougher SiC/diamond-like-carbon composite films produced by electron beam physical vapour deposition

SiC/diamond-like carbon (DLC) composite films have been produced on metal substrates via electron beam physical vapour deposition process with various substrate temperatures. The films deposited at 700 °C contain a DLC matrix and nanocrystalline 3CSiC. However, the films deposited at 900 °C contain a 3CSiC matrix and DLC plus nanocrystalline diamond. Both nanoindentation and Hysitron testing have shown that the Young’s moduli and hardnesses of the films increased with the substrate temperature. The hardness could reach ∼60 GPa in some parts of the films produced at 900 °C. Meanwhile, the fracture toughness, measured using a micro-beam bending technique, reached 9.2 ± 2 MPa1/2 for such a composite film. Both high hardness and toughness could be explained by the unique microstructure of the composite film.