Thermal stability investigation of the SS/MO/Al₂O₃ spectrally selective solar absorber coatings

ABSTRACT

A novel Mo/Al₂O₃ spectrally selective solar absorber coating is deposited onto stainless steel (SS) substrates using magnetron sputtering method, which exhibits a high absorptance (α) of 0.90 and a low emittance (ε) of 0.08. In order to investigate the thermal stability, the SS/Mo/Al₂O₃ coatings are annealed in air and vacuum at different temperatures. The surface morphology, microstructure, composition distribution, diffusion and optical properties before and after high-temperature annealing are characterised by scanning electronic microscopy (SEM), atom force microscopy (AFM), X-ray diffraction (XRD), micro-Raman spectroscopy, UV–vis spectrophotometer and emissometer. Experimental results indicate that the coatings are stable in air at 350°C. The values of solar absorptance and emittance below 350°C are 0.87–0.90 and 0.06–0.08, respectively. The coatings remain stable after annealed at 600°C in vacuum for 2 h with a good spectral selectivity (α/ε) of 0.89/0.06.

KEYWORDS:

• Spectrally selective coating
• thermal stability
• microstructure
• annealing

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Ling-Hua Jin http://orcid.org/0000-0001-6036-6969

Additional information

Funding

This work was financially supported by Major Subject of State Grid Corporation of China [Grant Number 5216A01600W0].