Antimicrobial copper-containing titanium nitride coatings Co-deposited by arc ion plating/magnetron sputtering for protective and decorative purposes

The experimental results obtained herein reveal that Cu-TiN coatings with a thin amorphous TiNxOy layer and TiCxNyOz layer promoted the apparent hardness, wear resistance and corrosion resistance over those of pre-electroplated Cu-35Zn material. First, the appearance of Cu-TiN coatings with a thin TiNxOy layer varied noticeably from golden yellow through red and blue eventually to purple, as the purging time increased (10-60 s) in a constant oxygen flow. Then the Cu-TiN coating with a thin TiCxNyOz layer, formed in a constant mixed flow of oxygen and acetylene, also exhibited a series of graded colors. With respect to protective performance, the enhancement of the Cu-TiN, Cu-TiNO60 and Cu-TiNOC60 coatings improved their apparent hardness at least 62.0% higher than that of pre-electroplated Cu-35Zn substrate. Notably, the apparent hardness is correlated with the wear resistance due to the existence of outermost TiNxOy and TiCxNyOz layers, in which flowing O2 + C2H2 generates TiCxNyOz on top of the Cu-TiN layer, providing a higher wear resistance than those of TiNxOy synthesized in flowing O2. Cu-TiN, Cu-TiNO60 and Cu-TiNOC60 ceramic coatings provide greater corrosion resistance than that of a pre-electroplated Cu-35Zn substrate and finally reach a stable current density in the passive region to 3.5 wt.% NaCl solution. In summary, a Cu-TiN coating can be both modestly protective and have tunable colors because of the nature of golden yellow and hard coating for TiN ceramic and the existence of the outermost TiNxOy and TiCxNyOz layers.