Microstructure, chromaticity and thermal stability of SS/TiC-WC/Al2O3 spectrally selective solar absorbers

•The SS/TiC-WC/Al2O3 solar absorber coating has been prepared.•The coating exhibits a high absorptance of 0.92 and a low emittance of 0.10.•The coating is investigated by chromaticity study.•The coating exhibits an good thermal stability at 500 °C for 100 h in vacuum.

A new spectrally selective solar absorber coating of TiC-WC/Al2O3 tandem layer is designed and prepared on stainless steel (SS) substrate by magnetron sputtering. The coating consists of an absorptance layer (TiC-WC) and an antireflectance layer (Al2O3) from substrate to top. The new SS/TiC-WC/Al2O3 coating exhibits excellent selective absorbing properties with a high solar absorptance of 0.92 and a low thermal emittance of 0.11. The SS/TiC-WC/Al2O3 coating presents a purple color, which is further investigated by chromaticity study. The thermal stability of the coating is evaluated and characterized by SEM, XRD, UV-vis-NIR spectrophotometer, Fourier transform infrared spectroscopy, and Raman spectroscopy. Experimental results indicate that the coating is highly stable in vacuum at 500 °C for 100 h with a good solar selectivity of 0.92/0.11.