Effects of post-deposition annealing on structure and mechanical properties of multilayer Ti/DLC films

The multilayer (Ti/DLC) × 3 films were deposited using a DC arc evaporator with a titanium cathode and a pulsed cathode-spark evaporator with a graphite cathode. Following the deposition of the films, a heat treatment process was performed in air and Ar atmosphere at temperatures of 200 °C and 400 °C. The investigation of the films involved the examination of their structure, surface morphology, and chemical composition using AFM, SEM, XPS and Raman. Additionally, the mechanical properties of the films were assessed by nanoindentation, sclerometry and wear test. Changes in the structure, RMS roughness, С-sp2/С-sp3 ratio of carbon atoms in the film and the formation of Ti-C carbide were determined in relation to the heat treatment conditions. Studies have demonstrated that subjecting materials to heat treatment at temperatures of 400 °C results in a decrease in friction coefficient and an increase in hardness. The deposition of films on the working surfaces of microdrills with subsequent heat treatment leads to a reduction in wear, an extension of their service life, and an improvement in drilling accuracy as compared to microdrills without films. Furthermore, microdrills with (Ti/DLC) × 3 films annealed in air at 400 °C exhibit negligible size reduction and better drilling accuracy.