Preparation And Study Of Black Nickel & Chrome Solar Selective Absorbing Coatings

In recent years, Solar thermal utilization in industry application have gain more and more attention as the energy and environmental problems been getting more and more serious, and solar spectrum selective absorbing coatings are the key technology in solar thermal utilization. This thesis summarized the basic types of solar spectrum selective absorbing coatings, their absorption mechanism and preparation methods and introduce the research work and new results of many scientific groups at home and abroad. Furthermore, this thesis studied on black nickel & chrome solar selective absorbing coatings by plating method, and discussed their absorption mechanisms.According to the five basic absorption mechanisms, combined with the practical preparation conditions, this thesis designed the structure of black nickel & chrome selective coating and chosen the proper material for the selective coating (silver). The brief experimental process is to plate black nickel & chrome on H85 copper alloy, and study the effects of Plating time/Current density/Bright silver bottom-coating's presence or absence on the two coating's solar selectivity and finally a reasonable processing parameters of black nickel selective coating was proposed.This thesis characterized these selective coatings by surface SEM & EDS, XRD and the solar selectivity (α/ε), studied the effect of thickness on the coating's selectivity through cross-section SEM and meanwhile discussed the difference between the two coating's absorption mechanisms.The creativity of this thesis lies in:(1) Bright silver was adopted as the reflecting bottom for the solar selective coating, because of its advantage in Heat resistance,Corrosion resistance and excellent spectral reflection, plus the good combination with the substrate, the simple and stable processing parameters and the simplicity of cleaning-up of the residual solution; (2) one reasonable and stable processing parameters of black nickel selective coating was proposed(α=0.90,ε=0.06,α/ε=15); (3) the absorption mechanisms of black chrome selective coating was proved (Interference-structured selective coating & Surface-structured selective coating), and some reasonable schemes to prove the selectivity were proposed.