Vickers and knoop hardness of electron beam deposited ZrC and HfC thin films on titanium

Submicron thickness films of zirconium and hafnium carbides were electron beam deposited on the sandblasted surface of a metallic titanium substrate. The films were characterized by scanning electron microscopy, and the hardness of the composite film-substrate systems was measured by both Vickers and Knoop microindentation methods in the wide indentation loading range. The intrinsic hardness of the film was separated out from the composite hardness using an area law-of-mixtures approach and taking into account the indentation size effect. Measured with Vickers (Hf0V) and Knoop (Hf0K) indenters, the hardness was evaluated to be of about 26 and 24 GPa, respectively, for ZrC, and 19 and 21 GPa, respectively, for HfC films, being somewhat higher compared to published data for bulk carbides.