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a-C/a-C:Ti multilayer films were deposited on medical Ti6Al4V alloy using a closed field unbalanced magnetron sputtering system with various substrate bias duty cycle. The tribological and corrosion behaviors of the multilayer films in Hank's solution were evaluated by a ball-on-disk tribometer and an electrochemical workshop. The duty cycle has a significant effect on the bonding structure, and mechanical and tribological properties of the films. The polarization resistance of the films on Ti alloy is approximately ten times more than that of Ti6Al4V which indicates that higher corrosion resistance can be achieved in Hank's solution at 37 °C. However, the polarization resistance and corrosion current do not change so much with the variation of duty cycle, implying that its influence on corrosion behavior of these a-C/a-C:Ti multilayer films is not so obvious. [ABSTRACT FROM AUTHOR]

Abstract: TiN/CN x multilayer films with bilayer periods of 4.5–40.3nm were deposited by direct-current magnetron sputtering. Layer morphology and structure of the multilayered films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The TiN/CN x multilayers exhibited coherent epitaxial growth due to the mutual growth-promoting effect at small bilayer period and some crystalline regions going through the interface of TiN/CN x . Nanoindentation tests showed that the hardness of the multilayers varied from 12.5 to 31GPa, with the highest hardness being obtained with a bilayer period of 4.5nm. The tribological properties of the films were investigated using a ball-on-disk tribometer in humid air, and the TiN/CN x multilayer with a bilayer period of 4.5nm also exhibited the lowest friction coefficient and the highest wear resistance. [Copyright &y& Elsevier]

Abstract: Thick a-C/a-C:Ti multilayer films with bilayer periods of 12–70nm were deposited on Ti6Al4V alloy substrate by means of closed field unbalance magnetron sputtering. The morphology and microstructure of the multilayer films were investigated by scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Nanocrystalline TiC was distributed in the a-C:Ti layer and at the interface between the two adjacent layers. The mechanical and tribological properties were evaluated by Rockwell and scratch tests, a nanoindentor and a ball-on-disk tribometer. The multilayer film with a bilayer period of 12nm showed the highest adhesion strength, hardness (26GPa) and elastic modulus (232GPa); it also had the lowest average coefficient of friction (0.09) and a wear rate of 8.06×10−17 m3 N−1 m−1. [Copyright &y& Elsevier]