Colored selective absorber coating with excellent durability
The colored solar thermal collectors can provide advantages of architectural integration over energy performance. The colour appearance of the solar thermal collectors can be achieved by increasing the number of layers. W/WAlN/WAlON/Al2O3 coating, fabricated by DC and RF magnetron sputtering showed a high solar absorptance of 0.948 and the low thermal emittance of 0.08 with a sky blue color appearance. The tandem absorber exhibited excellent long term thermal stability at 500 degrees C in air for 150 h. The absorber deposited on SS substrates showed high solar selectivity (alpha/epsilon) of 0.918/0.11, even after heat treatment in air up to 500 degrees C for 100 h. The selective performance of the coating can be stable more than 25 years. The humidity test confirms the significant moisture resistant of the coating. In summary, the new W/WAlN/WAlON/Al2O3 based coating with its colourful appearance is appropriate to be used in solar thermal collectors. (C) 2016 Elsevier B.V. All rights reserved.