Effects of Copper Content on the Microstructural, Mechanical and Tribological Properties of TiAlSiN–Cu Superhard Nanocomposite Coatings

Abstract

The effects of the Cu content on the microstructural, mechanical and tribological properties of the TiAlSiN–Cu coatings were investigated in an effort to improve the wear resistance with a good fracture toughness for cutting tool applications. A functionally graded TiAlSiN–Cu coating with various copper (Cu) contents was fabricated by a filtered cathodic arc ion plating technique using four different (Ti, TiAl2, Ti4Si, and Ti4Cu) targets in an argon-nitrogen atmosphere. The results showed that the TiAlSiN–Cu coatings are a nanocomposite consisting of (Ti,Al)N nano-crystallites (~5 to 7 nm) embedded in an amorphous matrix, which is a mixture of TiOx, AlOx, SiOx, SiNx, and CuOx phase. The addition of Cu atoms into the TiAlSiN coatings led to the formation of an amorphous copper oxide (CuOx) phase in the coatings. The maximum nanohardness (H) of ~46 GPa, H/E ratio of ~0.102, and adhesion bonding strength between coating and substrate of ~60 N (LC2) were obtained at a Cu content ranging from 1.02 to 2.92 at.% in the TiAlSiN–Cu coatings. The coating with the lowest friction coefficient and best wear resistance was also obtained at a Cu content of 2.92 at.%. The formation of the amorphous CuOx phase during coating growth or sliding test played a key role as a smooth solid-lubricant layer, and reduced the average friction coefficient (~0.46) and wear rate (~10 × 10−6 mm3/N·m).

Technologies of Coatings and Surface Hardening: Industrial Applications

“…The most advanced and recently developed coating and surface-hardening technologies make it possible to obtain almost the full range of physical-mechanical and crystalchemical properties of the metalworking tool surface and electronic component surface for a wide range of applications to enlarge product operational life for working under the most extreme mechanical and thermal loads [1][2][3]. The scientific attitude to improving the surface layer parameters of the product made of traditional industrial materials or new advanced composites and nanocomposites requires budget material and time investments [4,5]. It hinders the industrial introduction of innovations and slows down the progress of the transition to the technological level associated with the concept of nanoindustry [6][7][8].…”