Microstructure and Optical Properties of SS/Mo/Al 2 O 3 Spectrally Selective Solar Absorber Coating
- PDF / 1,670,291 Bytes
- 7 Pages / 593.972 x 792 pts Page_size
- 28 Downloads / 212 Views
JMEPEG DOI: 10.1007/s11665-016-2445-1
Microstructure and Optical Properties of SS/Mo/Al2O3 Spectrally Selective Solar Absorber Coating Xiang-Hu Gao, Zhi-Ming Guo, Qing-Fen Geng, Peng-Jun Ma, and Gang Liu (Submitted May 29, 2016; in revised form September 26, 2016) Surface-textured Mo thin film is fabricated by magnetron sputtering through the adjustment of deposition parameters, which exhibits a high absorptance of 0.80 and a low emittance of 0.09. The single-layer Mo deposited on stainless steel (SS) is characterized by x-ray diffraction (XRD), ultra-high resolution scanning electron microscope, atomic force microscope and optical measurement. The controlled surface roughness combined with larger aspect ratio contributes much to the high absorptance and low emittance. Based on the SS/Mo coating, a spectrally selective coating (SS/Mo/Al2O3) is designed and fabricated. The coating shows an amorphous structure and exhibits an absorptance of 0.90 and an emittance of 0.08. Tauc-Lorentz and Drude free-electron models are used to modeling the optical properties of Al2O3 and Mo layers by phase-modulated spectroscopic ellipsometry. Keywords
magnetron sputtering, microstructure, optical properties, spectrally selective solar absorber, surface-textured
1. Introduction Solar energy harvested by a spectrally selective solar absorber can be considered as an alternative route to alleviate our dependence on traditional energy sources such as fossil fuels resulting in less impact on the environment. The main requirements for the solar selective coatings are high absorptance (a) in the solar spectral range (0.3-2.5 lm) and low emittance (e) in the infrared region (2.5-50 lm) (Ref 1-3). During the past few years, much effort has been focused on the metal-dielectric composites coating. The highly absorbing metal-dielectric composite, or ceramic, consists of fine metal particles in a dielectric or ceramic matrix, or a porous oxide impregnated with metal. These films are transparent in the thermal IR region, while they are strongly absorbing in the solar region because of interband transitions in the metal and the small particle resonance (Ref 4, 5). Various combinations such as Mo-Al2O3, Mo-Si3N4, WAl2O3, W-Ni-Al2O3 and AlNi-Al2O3 have been investigated in terms of the optical performance and thermal stability of the cermet surfaces (Ref 6-10). Angelantoni ENEA (Italy) has commercialized the Mo-SiO2 high-temperature solar selective
Xiang-Hu Gao, Research and Development Center for Eco-chemistry and Eco-materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730070, China; and University of Chinese Academy of Sciences, Beijing 100049, China; and Zhi-Ming Guo, National Engineering Research Center for Technology and Equipment of Green Coating, Lanzhou Jiaotong University, Lanzhou 730070, China; Qing-Fen Geng, Peng-Jun Ma, and Gang Liu, Research and Development Center for Eco-chemistry and Ecomaterials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730070, China. Contact e-mail:
Data Loading...
