TiAl6V4 is widely used in the medical and aerospace industry due to the good corrosion resistance and mechanical properties. In this work, single-layer TiN and multi-layer Ti/TiN coatings are deposited on TiAl6V4 by high-vacuum magnetron sputtering and the phase, structure, and morphology are investigated by GIXRD, XPS, FE-SEM, and AFM. The tribological properties are determined by pin-on-disk tests with a tungsten carbide pin (WC). The 1.4 µm thick coating contains TiN, TiOxNy, and TiO2 phases. The friction coefficients, hardness, and elastic modulus of the TiN and Ti/TiN coatings are 0.43 and 0.49, 19.744 and 22.462 GPa, and 192.709 and 183.565 GPa, respectively. The tiny cracks along the scratch path on the TiN coating arise from the lower toughness compared to the Ti/TiN multilayered coating. The larger friction coefficient in the presence of the Ti interlayer may be due to network failure at the Ti and TiN boundaries which show different crystalline structures and the stress formed at both layers prohibits dislocation movement in the Ti layer. More brittle cracks are observed from the TiN monolayered coating and larger plastic deformation occurs on the multilayered coating, indicating that the latter is more resistant to delamination. The adhesion mechanism is dominated by the Ti intermediate layer and can be exploited to improve the effectiveness of TiN coatings in applications such as biomedical implants.
