Solar Selective Absorption Coating At Medium And High Temperature

In recent years, the solar heat as a clean and energy has received more and more attention, the key device in the solar heat energy utilization is the collector, the solar selective absorption coating is one of the key techniques for sufficient absorption of the collector. As the working temperature of the solar selective absorption coating generally is above 200℃, therefore improve the working temperature of the coating becomes particularly important. In this paper, research the absorptance and emittances of the solar selective absorption coating on medium-high temperature(200℃～500℃).This paper research the absorption principle of the solar selective absorption coating、 coating structure、material selection and preparation process. The main research the optical constants of metal ceramic coating by effective medium theory, design the film system of the solar selective absorption coating, preparation of the solar selective absorption coating by DC magnetron sputtering. In the use of effective medium theory of metal ceramics, discussed the metal fill factor is not the same time as Maxwell-Gamett theory and Bruggeman theory to calculate the optical constants of metal ceramic, the optical constants of two composite metal ceramic and three kinds of composite metal ceramic were calculated. Film system are designed for metal ceramic and multi-layer structure selective absorbing coatings by TFC software, through the calculation of the absorptance and emittances indicates that the design results to achieve the desired effect. Using by the JGP500 type high vacuum multifunctional magnetron sputtering equipment, to obtain the process parameters of Al2O3 and Mo singly-layered, tests the optical constants of Al2O3 and Mo materials by ellipsometer. Prepare solar selective absorption coating of MO-Al2O3 six-layered, after the test and calculation show that this absorption coating at room temperature are absorptance α≥95% and at 300℃ emittances ε≤12%.