Preparation By Sol-gel And Properties Of Mid-to-High Solar Absorber Coating

Solar spectral selective absorber coatings have low reflectance in UV-VIS-NIR band and high reflectance in IR band,so it can translate the solar radiation into thermal energy maximumly and radiation energy to the outside,this is a major significance to improve the efficiency of solar-thermal conversion.At present,the researches on solar selective absorber coatings at home and abroad are mainly concentrated in the field of mid-to-low temperature,recently the development and optical properties of mid-to-high temperature solar selective absorber coatings have become the focus of attention.In this paper,we study the preparation and radiation characteristics of mid-to-high temperature solar selective absorber coatings.The content of this thesis includes the following parts:1.Studies on the radiation characteristics of the Ni-Al2O3 solar absorber coatingFirst,we designed the Ni-Al2O3 solar absorber coating,and then we studied the influence rules of the Ni volume fraction,thickness of coating,double-layer structure on the radiation characteristics of coating to provide the reference and guidance for experimental research.We prepared the Ni-Al2O3 solar selective absorber coating by sol-gel method,studied the effects of heat treatment temperature,Ni content,incidence angle,polarized light and double-layer structure on the radiation characteristics of coating,and we also test the thermal stability,weatherability and corrosion resistance of Ni-Al2O3 solar absorber coating.The results show that when the heat treatment temperature is 600 ℃,the Ni-Al2O3 coating has formed the cermet structure.Increase the Ni content can improve the spectral selectivity of Ni-Al2O3 coating,when the content of Ni is 80%,the spectral selectivity is best,a=0.92,ε=0.19.We also find that reduce incidence angle is beneficial to improving the spectral selectivity of Ni-Al2O3 coating,while the polarized light has no effect on the radiation characteristics of the coating.The high temperature stability of the coating is poor,but the weatherability and corrosion resistance are stronger.2.Studies on the radiation characteristics of the CuCoMnOx solar absorber coatingWe prepared the CuCoMnOx solar absorber coating by sol-gel method.We study the effects of heat treatment temperature,incidence angle,polarized light on the radiation characteristics of coating too,we also test the thermal stability,weatherability and corrosion resistance of CuCoMnOx solar absorber coating.The results show that when the heat treatment temperature is 500 ℃,CuCoMnOx solar absorber coating formed the spinel structure,and its spectral selectivity is best,a=0.91,ε=0.148.With the increase of incidence angle,a of the coating decreased and ε increased,while the polarized light has no effect on the radiation characteristics of the coating.We also find that the thermal stability,weatherability and corrosion resistance of CuCoMnOx solar absorber coating are all better.