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A novel solar selective absorbing MoSi2-Al2O3 multilayer coating deposited on Cu or stainless steel (SS) substrate by magnetron sputtering is reported. The coating consists of an infrared reflective metal layer using Mo or Cu, an absorption MoSi2-Al2O3 bilayer, and an anti-reflection Al2O3 layer from substrate to top. With the help of computer simulation, we obtain the optimal metal volume fraction and thickness of each layer on Cu substrate. And then a good optical performance (α/ε) of 0.94/0.06 for the all-layer coating on Cu substrate is obtained. On the other hand, the influence of the deposition parameters for the infrared reflective Mo layer on the emittance is discussed. The emittance decreases with the decrease of sputtering pressure and the increase of the target power. The lowest emittance of the SS (substrate)/Mo is 0.047 after optimization. The optical performance (α/ε) of the all-layer coating on the optimized SS/Mo substrate is 0.95/0.07. The thermal stability of the all-layer coating on SS substrate is evaluated, and it is found to have a good thermal stability at 400 °C, due to the choice of MoSi2, which means a good candidate of solar selective absorbing coating for parabolic trough concentrated solar power (CSP). [ABSTRACT FROM AUTHOR]

Highlights: [•] We first proposed to use a AlNi alloy to fabricated cermet absorption coating. [•] We obtained an excellent optical property AlNi–Al2O3 absorbing coating. [•] Preliminary thermal stability tests show AlNi–Al2O3 coating is promising for CSP. [ABSTRACT FROM AUTHOR]

Abstract: A new solar selective absorbing coating of NbTiON/SiON was prepared on Cu substrate using a reactive magnetron sputtering method. The new coating exhibits a high absorptance (α) of 0.95 and a low emittance (ε) of 0.07, and the thickness of NbTiON and SiON layers was optimized to achieve high solar selectivity. The spectral properties (α/ε) of the coating on Cu substrate are stable (0.94/0.08) even after heat-treatment at 500°C in vacuum for 40h, but decreased at 600°C. If the substrate is replaced by stainless steel (SS), the coating exhibits better stability, which indicates its potential applications in intermediate temperate solar absorber. [Copyright &y& Elsevier]

In this work, the NbTiSiN and NbTiSiON layers are used instead of NbTiN and NbTiON layers to further improve the thermal stability of Al/NbTiN/NbTiON/SiO 2 multilayer solar selective absorbing coating. The thermal stability of Si-doped individual layers and multilayer coatings are investigated. The X-ray diffraction (XRD) results show that Si incorporation into NbTiN (NbTiSiN) layer does not change its preferred orientation, and the Si-doped NbTiON (NbTiSiON) layer remains in amorphous phase. On the other hand, by introducing Si into NbTiN and NbTiON layers induce significant improvement of the oxidation resistance at 500 °C in air. After ageing in air at 500 °C for 2 h, the absorptance and emittance (at 400 °C) of Al/NbTiN/NbTiON/SiO 2 and Al/NbTiSiN/NbTiSiON/SiO 2 multilayer coatings change from 0.934/0.13 and 0.931/0.12 to 0.538/0.14 and 0.922/0.13, respectively. Meanwhile the surface roughness increases from 18.3 and 7.9 to 41.5 and 14.7 respectively, as atomic force microscopy (AFM) shows. The Al/NbTiSiN/NbTiSiON/SiO 2 coating still has a high absorptance (0.910) and low emittance (0.13, at 400 °C) after ageing at 550 °C in vacuum for 100 h. It displays that Si-doping play an important role in the improvement of the thermal stability. [ABSTRACT FROM AUTHOR]

Abstract: Mo–Al2O3 solar selective absorbing coating was deposited on stainless steel substrate by magnetron sputtering. The evaluation of high temperature stability indicates that the degradation of the optical properties is due to the diffusion and oxidation of single metal Mo in the ceramic Al2O3. Mo diffuses easily in Al2O3 layer and the interface between the double Mo–Al2O3 layers when aging temperature is above 400°C, which was observed by SEM and AES with etching depth. The thermal stability was improved significantly when a denser Mo–Al2O3 layer was obtained by optimizing the deposition parameters. [Copyright &y& Elsevier]