A double-absorbing layer solar spectrum selective absorption coating and its preparation method

Abstract

The invention relates to the field of solar light selective absorption coatings, in particular to a double absorption layer solar spectrum selective absorption coating and a preparation method thereof. The preparation method comprises the following steps: cleaning the base layer; preparing an infrared reflection layer on the base layer by a coating method; preparing a double-structure absorbing layer on the infrared reflection layer by a coating method; An anti-reflection layer is prepared on the absorbing layer; the absorbing layer includes a high-refractive-index absorbing sublayer and a low-refractive-index absorbing sub-layer from bottom to top, and both the high-refractive-index absorbing sub-layer and the low-refractive-index absorbing sub-layer are made of Coating methods are prepared sequentially. The absorbing coating is prepared by the above-mentioned preparation method. The coating preparation method has simple process and low requirements for coating equipment, and is suitable for large-scale and low-cost production.

Description

technical field [0001] The invention relates to the field of spectrally selective absorption coatings, in particular to a double-absorbing layer solar spectrum selective absorption coating and a preparation method thereof. Background technique [0002] The solar spectrum selective absorption coating is the core material to realize the conversion of solar energy to heat. On the one hand, it has a high absorption rate in the solar light band (0.3μm-2.5μm), absorbing sunlight energy and converting it into heat energy, and the other On the one hand, it has a low emissivity in the infrared thermal radiation band (2.5μm-50μm), which can effectively suppress radiation heat dissipation. One of the important indicators to measure the selective absorption performance of the coating is the ratio of the solar spectral absorptivity α to the infrared radiation rate ε(T), α / ε, the larger the value of α / ε, the more suitable for medium and high temperature applications above 200°C. [0003]...

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Problems solved by technology

Al(Mo, W, Ni, Co, NiO x , TiN)-Al 2 o 3 、Al 2 o 3 -Mo-Al 2 o 3 The common feature of cermets and thin metal interference film systems is that the high absorptivity and low emissivity of the coating are achieved by strictly controlling the composition of the composite material, the size and shape of the metal or metal nitride particles, or the continuous growth of the metal film. or discontinuous islands or other morphological structures, the manufacturing process is complicated, and the process stability has a great influence on the coating performance, it is not easy to obtain a coating with excellent performance, resulting in a high solar spectral absorptivity α at the same time ( Generally higher than 90%), the infrared radiation rate ε(T) is also high (generally higher than 5%, 80°C), and the transition zone from sunlight absorption to infrared reflection is wide, and the infrared radiation rate ε(T) varies with The temperature rises rapidly (more than 10% in the middle and high temperature zone), and α / ε is generally less than 20

Therefore, when the coating is applied to a collector with a relatively low focus, there is generally a problem of low photothermal conversion efficiency of the collector when the working temperature is above 200 °C.

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