Direct Fractographic Evaluation of Multilayer CNx/TiN Films by Magnetron Sputtering

In this paper, a multilayer CNx/TiN composite film on high-speed steel substrate was prepared by using a multi-arc assisted DC reactive magnetron sputtering system. The cross-section observations of the fracture surface reveal that the films show a pure cleavage fracture due to its super-high hardness, and the interfacial strength between the film and substrate is associates with the film thickness, i.e., 2µm is a critical thickness for the present deposition. That is to say, there is no disbonding or cracking at the interface when the film thickness is less than 2µm, while the interfacial failure is generated if the film thickness is larger than 2µm. This direct SEM observation of the fracture surface provides a distinct image for evaluating the mechanical property and also analyzing the failure mechanism of the films.