Effects of TiCN interlayer on bonding characteristics and mechanical properties of DLC-coated Ti-6Al-4V ELI alloy

• A TiCN interlayer between a Ti-6Al-4V ELI alloy and the DLC film was investigated.
• The TiCN interlayer enhanced hardness, elastic modulus, and interface bonding.
• The friction coefficient of the DLC coated Ti-6Al-4V with the TiCN interlayer had an extremely low value of 0.03.
• DLC thin films with the TiCN interlayer showed a favorable coating process.

The delamination of diamond-like carbon (DLC) films on titanium alloys can be prevented by using an interlayer coating. In this study, a DLC film was deposited using a filtered vacuum arc (FVA), and a TiCN interlayer was applied between the Ti-6Al-4V ELI alloy and the DLC film. The interface boundary, carbon bonding, and mechanical properties of the DLC-coated Ti-6Al-4V were investigated, and the results indicate that DLC thin films with a TiCN interlayer are suitable coating materials for Ti-6Al-4V. The coated DLC films had a crystal structure that consisted of an amorphous phase while the TiCN interlayer exhibited a crystalline structure. The TiCN interlayer was necessary in order to improve the hardness, elastic modulus, and interface bonding. The TiCN interlayer on the DLC film was observed to increase the ID/IG ratio as a result of the sp3 bonding of the carbon atoms. The resulting friction coefficient of the DLC-coated Ti-6Al-4V with the TiCN interlayer had an extremely low value of 0.03.

HR-TEM cross-sectional images and the corresponding SADP of the DLC films: (a) HR-TEM image of the DLC/TiCN interlayer and (b) TiCN interlayer/Ti-6Al-4V. Friction coefficient of the Ti-6Al-4V, Ti-6Al-4V/DLC, and Ti-6Al-4V/TiCN/DLC samples was measured using the pin-on-disk method.Figure optionsDownload as PowerPoint slide