The spectral properties and thermal stability of NbTiON solar selective absorbing coating

A new solar selective absorbing coating of NbTiON/SiON was prepared on Cu substrate using a reactive magnetron sputtering method. The new coating exhibits a high absorptance (alpha) of 0.95 and a low emittance (epsilon) of 0.07, and the thickness of NbTiON and SiON layers was optimized to achieve high solar selectivity. The spectral properties (alpha/epsilon) of the coating on Cu substrate are stable (0.94/0.08) even after heat-treatment at 500 degrees C in vacuum for 40 h, but decreased at 600 degrees C. If the substrate is replaced by stainless steel (SS), the coating exhibits better stability, which indicates its potential applications in intermediate temperate solar absorber. (C) 2011 Elsevier B.V. All rights reserved.