Influence of Ag contents on structure and tribological properties of TiSiN-Ag nanocomposite coatings on Ti-6Al-4V

TiSiN-Ag nanocomposite coatings with different Ag contents were deposited on Ti-6Al-4V using reactive co-sputtering in multi-arc ion plating system. Influence of Ag contents on structure and tribological properties of TiSiN-Ag nanocomposite coatings was investigated. The TiSiN-Ag coatings were found to have unique nanocomposite structures composed of nanocrystallite and amorphous nc-TiN/nc-Ag/a-Si3N4. When the silver content was 1.4 at.%, the coating exhibited high hardness (36 GPa), but poor wear resistance. When the silver content was increased from 5.3 to 8.7 at.%, the coatings possessed homogeneous distribution and small variation in hardness. Although these coatings revealed obvious decrease in hardness, significantly reduced in the friction coefficient and possessed excellent tribological properties, besides, the coating with the Ag content of 5.3 at.% showed best wear resistance in artificial seawater and the coating (7.9 at.% Ag) revealed the best wear resistance in ambient air. However, with a further increased incorporation of Ag into the TiSiN-Ag coating (17.0 at.%) resulted in the formation of a large volume fraction of metallic silver, which caused a decrease both in hardness and wear resistance. The coating containing highest Ag concentration (21.0 at.%) exhibited low friction coefficient both in ambient air and artificial seawater, although possessing low hardness. (C) 2016 Elsevier B.V. All rights reserved.