Effect of annealing on structural, mechanical and tribological properties of Cr-(CrN/TiAlN) coating.

TiAlN film was deposited with Cr-CrN interlayer (Cr-(CrN/TiAlN)) on DAC-10 tool steel using cathodic arc deposition followed by annealing in vacuum chamber at 700°C temperature. Nanoindentation and nanoscratch test were conducted on as-deposited and annealed samples. The annealed samples showcased improved hardness (8.55 %) and elastic modulus (12.21 %) attributed to the formation of larger grain size (48 nm) and diffusion of Cr atoms from the interlayer. The XRD pattern of the annealed samples revealed Cr diffusion in the TiAlN top layer along with the formation of oxide such as Al₂O₃. The annealed samples registered lower pile up, indentation depth, higher strain hardening exponent (n = 0.41) and lower plastic work (0.25). Tribological properties such as scratch hardness was improved by 8.84%, whereas coefficient of friction and wear rate was reduced by 22.92% and 35.75%, respectively, after annealing of the coating. The relation between the nanomechanical and scratch properties was indicative of the influence of hardness and strain hardening exponent on the wear properties of the annealed Cr-(CrN/TiAlN) coating. [ABSTRACT FROM AUTHOR]