Performance of Cr-DLC Thin Film Annealed at Different Temperatures

Diamond-like carbon (DLC) combines a range of significant physical and chemical properties that makes it suitable for several coating applications. In this work, Cr-DLC thin film is deposited by using RF magnetron sputtering with a pure chromium target, argon (Ar), and acetylene (C2H2) gases, as potential materials for thermal solar selective absorbers. The thin film constitutes of chromium (Cr) nanoparticles deposited inside DLC matrix. After deposition, the samples were exposed to temperatures of 500 and 800 C for 2 hours in air (annealing). The deposited Cr-DLC thin film was characterized and tested in both as- deposited condition and after annealing. The microstructure and the optical properties (absorbance and emittance) of the sputtered Cr-DLC thin films were studied before and after annealing. It was found that the optical absorbance of the sputtered Cr-DLC thin film was about 97% for the first time reported. After annealing at 500C the absorbance decreased to 91% in UV, visible light and IR ranges. The microstructure of the as deposited Cr-DLC is transformed after annealing into chromium oxide, graphite oxide, graphene oxide.