Thermal stability of CrCO–Ti compound coating

A series of chromium-based coatings were fabricated by unbalanced magnetron sputtering technique. Their structures were characterized by X-ray diffraction (XRD), their adhesion by a scratch tester, their wear rate by a pin-on-disk wear tester, surface energy by surface contact angle goniometer, and their thermal stability by annealing at high temperatures under atmospheric argon gas. All as-deposited coatings are amorphous-like. The coatings' structures, contact angles, nano-hardness and wear rate changed after annealing at 400 °C. XRD revealed that amorphous-like CrCO–Ti (titanium doped CrCO) coatings consist of Cr2O3, Cr7C3 and TiO phases while both Cr2O3 and Cr7C3 phases coexisted in amorphous-like CrCO coating. The preferential orientation of all amorphous-like Cr-based coatings changed upon the increase of the annealing temperature. These coatings have excellent wear resistance with wear rates as low as 10− 8 mm3/Nm and low surface energy. It was found that both Ti doping and the introduction of a radio frequency power supply improved the coatings' ductility. The coating CrCO–Ti has a higher loading capacity compared to the undoped CrCO coating and was able to withstand a normal 8.9 N load in pin-on-disk wear test with a sliding velocity of 0.25 m/s and a distance of 4000 m.