Thermal stability of Cr-doped diamond-like carbon films synthesized by cathodic arc evaporation

Cr-doped diamond-like carbon (DLC) films were synthesized using a cathodic arc evaporation (CAE) process. The thermal oxidation behavior of Cr-doped DLC films was investigated using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The phase identification and microstructural examinations were conducted by X-ray diffraction, scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) in order to understand the characteristics of Cr-doped DLC films. The as-deposited Cr-doped DLC film exhibits a lamellar structure observed by TEM. A significant weight loss of film results from the thermal oxidation of carbon occurred at 290 to 342 deg C. At the temperature higher than 342 deg C, slight weight gain of specimen was observed due to the thermal oxidation of the underlying CrC xN y and CrN interlayer. By heat-treated specimens from 200 to 400 deg C, Raman spectra reveal the increase of I D/I G value conforming to the graphitiation process of the Cr-doped DLC films. Finally, surface reactions of the annealed films using XPS analysis were discussed