Design, synthesis and thermal stability study on graded TiNxOy solar selective absorbing coating fabricated by pulsed DC reactive magnetron sputtering

Abstract

Design, synthesis and characterization of a solar selective absorbing coating based on titanium oxynitride are reported in this contribution. All the layers were deposited by reactive magnetron sputtering in a horizontal in-line sputtering system. The optical constants of individual layers were obtained by spectroscopic ellipsometry measurement and fitting. Multilayer solar selective absorbing coating including, from substrate to air interface, Al infrared reflective layer/ (TiNx/TiNx1Oy1/TiNx2Oy2) composite absorbing layer/SiO2:Al antireflective layer were then designed and and fabricated based on their optical properties and thickness optimization. A solar absorptance (α) of 94.6% and thermal emittance (ε) of 3.8% for operation temperature of 100 °C were obtained by analyzing the measured spectra data. Combined with X-ray diffraction and scanning electron microscopy, the relevance between the thermal stability and crystal structure and morphology of the film after annealed at 250 °C and 400 °C in air was explored