Mechanical and antibacterial behaviors of TaN-Cu nanocomposite thin films after multi-rejuvenation

Cu-doped TaN films were known to have good anti-bacterial and anti-wear behaviors. However, in some of the practical applications, the depletion of surfaced Cu might eventually cause the films to lose their effectiveness against wear and bacteria. This study hence was aimed at understanding the rejuvenation process for these films. The structures, morphologies, antibacterial and mechanical properties of TaN-Cu nanocomposite thin films after multi-rejuvenating processes were the focus of this study. The results revealed that the Cu particles would re-appear on the film surface after each rejuvenation cycle, which can recover the anti-wear and anti-bacterial properties. The particle size and density appeared to decrease with the increase of rejuvenation cycle. The hardness of the samples would also decrease with the number of cycles. This was due to the slow depletion of Cu atoms, which might cause the increase of porosity and the decrease of hardness. The wear rates and friction coefficients of these rejuvenated samples depend mainly on the possibility of forming lubricious Cu films, although film hardness also played a certain role. In sum, the present study confirms that the anti-bacterial and anti-wear behaviors can be rejuvenated twice or more, under the experimental conditions adopted.