Influence of carbon incorporation on the microstructure, morphology, hardness, Young modulus and corrosion resistance of TiAlCN coatings deposited via reactive-HiPIMS

TiAlCN coatings, designed as advanced alternatives to TiAlN for enhanced tribological performance, were deposited via reactive high-power impulse magnetron sputtering (HiPIMS) with acetylene flow rates varying between 0 and 10 sccm. The carbon content, ranging from 1 at.% to 58 at.%, significantly influenced the microstructure, hardness and Young modulus properties of the coatings. At lower carbon concentrations (up to 17 at.%), carbon atoms substituted nitrogen in the TiAlN lattice. However, higher levels of carbon led to the formation of TiAl(CN) nanocrystals and amorphous carbon phases. These structural changes resulted in a shift in the coating’s growth orientation from (1 1 1) to (200) and the presence of amorphous carbon at grain boundaries, which contributed to a steady decline in hardness and Young’s modulus. Additionally, the increased carbon content reduced the coatings’ corrosion resistance. These findings highlight the complex interplay between carbon content, microstructure, and performance, providing insights for optimizing TiAlCN coatings.