Structure, thermal stability and chromaticity investigation of TiB2 based high temperature solar selective absorbing coatings

• Published in: Solar energy 2019-03, Vol.181, p.88-94
• Main Authors: Qiu, Xiao-Li, Gao, Xiang-Hu, Zhou, Tian-Hong, Chen, Bao-Hui, Lu, Jia-Zheng, Guo, Hui-Xia, Li, Xiao-Ting, Liu, Gang
• Format: Article
• Language: English
• Subjects: Absorbers; Absorptance; Absorptivity; Aluminum oxide; Chemical composition; Chromaticity; Coatings; Emissivity; Fourier transforms; High temperature; Infrared spectrophotometers; Infrared spectroscopy; Investigations; Morphology; Organic chemistry; Photoelectron spectroscopy; Photoelectrons; Raman spectra; Raman spectroscopy; Scanning electron microscopy; Selectivity; Solar energy; Solar selective absorbing coatings; Spectroscopy; Spectrum analysis; Stainless steel; Stainless steels; Structural stability; Structure; Temperature effects; Thermal stability; Titanium; Titanium boride; Titanium diboride; Transition metals; Vacuum; X ray photoelectron spectroscopy
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2019.01.068

•The SS/TiB2/Al2O3 solar absorber coating has been prepared.•The coating exhibits a high absorptance of 0.93 and a low emittance of 0.11.•The coating exhibits a good thermal stability at 700 °C for 2 h and 600 °C for 100 h in vacuum.•The chromaticity diagram of the coating with respect to annealed temperatures is established. Transition metal titanium diboride (TiB2) is a promising material for the solar selective absorbing coatings due to its favorable spectral selectivity and thermal stability. In this research, spectrally selective TiB2/Al2O3 tandem absorber is deposited on stainless steel (SS), which exhibits a high solar absorptance (αs = 0.93) and a low thermal emissivity (ε = 0.11). In this tandem absorber, the TiB2 acts as the main absorber layer and the Al2O3 acts as an antireflection layer. The tandem absorber coating is systematically characterized by ultra-high resolution scanning electron microscope (SEM), UV–vis-NIR spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Micro-Raman techniques. The thermal stability in vacuum of the SS/TiB2/Al2O3 tandem absorber coatings is investigated in the temperature range of 400–800 °C for 2 h and 100 h, respectively. SEM and Raman spectra indicate that the change of surface morphology and chemical composition for the coating result in the degradation of optical performance. With the different annealed temperature, the SS/TiB2/Al2O3 tandem absorber coatings exhibit different color, which is further investigated using chromaticity diagram.