Electron beam deposited tantalum carbide film on titanium

Tantalum carbide (TaC) thin films were electron beam deposited on a roughened surface of pure titanium using a hot-pressed TaC ceramic target. The as-deposited film retained the stoichiometry of the TaC target, but after exposure to 750°C in vacuum the TaC film transformed to Ta2C and developed cracks. The intrinsic hardness of the as-deposited film was obtained via mathematical extrapolation from the multiple hardness measurements of the film/substrate system under varying indentation loads. The hardness thereby obtained is 12.4 GPa - somewhat lower than the hardness reported for bulk TaC. The degree of the reduction of hardness was significantly lower than that revealed for titanium carbide EB deposited films. Possible reasons of the hardness lowering are discussed. TaC films could find a potential application to protect titanium parts of orthopedic devices.