Optimal Design And Performance Of AlCrNO-Based Solar Selective Absorbing Coating

The solar selective absorption coating can improve the solar selective absorption performance of materials and realize the efficient utilization of solar energy.In order to improve the selective absorption performance and high temperature resistance of solar selective absorption coating at the same time,and promote the application of solar selective absorption coating,this project starts from the structural design,and obtains the solar selective absorption coating with good performance through the preparation of infrared reflection layer and barrier layer（BL）.Through the study of the selective absorption mechanism of the coating,the general law is obtained,which provides a reference for the optimal design of the solar selective absorption coating.According to the results of the previous research in the laboratory,the AlCrN/AlCrNO/AlCrO coating was selected as the absorption coating by using multi arc ion plating as the preparation process.In order to reduce emissivity,Cu layer was prepared as infrared reflection layer between the absorption coating and the substrate.In order to meet the needs of solar selective absorption coating in non vacuum high temperature environment and prevent the coating failure caused by Cu diffusion,CrN layer,alcrfemnvn layer and timnwcrvn layer are used as the isolation layer between infrared reflection layer and absorption layer.The overall structure of the coating is Cu/BL/AlCrNn/AlCrNO/AlCrO.The selective absorption properties of the coating and the oxidation performance at 600°C in atmospheric environment were studied.The results show that the optical properties（α/ε）of Cu/CrN/AlCrN/AlCrNO/AlCrO coating,Cu/AlCrFeMnVN/AlCrN/AlCrNO/AlCrOcoatingand Cu/TiMnWCrVN/AlCrN/AlCrNO/AlCrO coating are 0.876/0.125,0.861/0.196 and0.857/0.151 respectively.After the high temperature oxidation test at 600°C for 100 h,the PC（Performance Criterion）values of three groups of coatings are less than 0.05,and the coatings have no failure,showing excellent solar selective absorption performance and non vacuum high temperature oxidation resistance.In the control group,the absorptivity and emissivity of Cu/AlCrN/AlCrNO/AlCrO coating were 0.827 and 0.103 respectively.After high temperature oxidation at 600°C for 100 h,the absorptivity decreased to 0.759 and the emissivity increased to 0.138,and the PC value was 0.077.Scanning electron microscope,energy dispersive spectrometer and grazing incidence X-ray diffraction were used to analyze the microstructure,composition and phase structure of the coating.The surface of Cu/CrN/AlCrN/AlCrNO/AlCrO coating is compact,and there are no obvious holes,cracks and other defects.There is no obvious boundary between the coatings,and the coating bonding is good.The surface of the coating consists of metal nitrides and oxides,and a large number of metal particles are distributed on the surface.After high temperature oxidation,the surface of the coating has no obvious change,and the increase of metal particle size leads to the increase of the surface roughness of the coating,and the"optical trap"appears on the surface of the coating,which strengthens the light reflection and increases the absorptivity.Cu/AlCrN/AlCrNO/AlCrO coating has no isolation layer.Cu diffuses directly into the absorption layer at high temperature and reacts with O₂in the air to form Cu O,which destroys the coating structure and leads to coating failure.The experimental results show that the selective absorption performance and high temperature oxidation performance of the coating can be improved by designing the infrared reflecting layer and isolation layer reasonably.It provides a reference for the optimization of solar selective absorption coating.