不锈钢衬底表面形貌对AlN/AlN-Cr/Cu太阳能选择性吸收涂层光热性能的影响

EFFECT OF SURFACE TOPOGRAPHY OF STAINLESS STEEL SUBSTRATE ON SOLAR THERMAL CONVERSION OF Al N/Al N-Cr/Cu SELECTIVE ABSORBING COATING

在数值仿真计算和实验两方面研究不锈钢衬底表面形貌对AlN/AlN-Cr/Cu太阳能选择性吸收涂层光热性能的影响。在数值仿真计算中,建立一维三角形光栅结构模型对衬底表面形貌进行简化,采用严格耦合波分析(RCWA)的方法,仿真计算并分析光栅深度T_z和周期T_x对涂层的太阳吸收比α和400℃热发射比ε的影响。实验上,制备具有不同深度和间隔起伏表面的不锈钢衬底,采用磁控溅射的方法在其上沉积相同结构参数的AlN/AlN-Cr/Cu太阳能选择性吸收涂层,测定涂层性能参数,并分析不锈钢衬底形貌对其的影响。数值计算和实验结果表明:对于一个在已优化涂层组分和厚度的AlN/AlN-CdCu太阳能选择性吸收涂层,不锈钢衬底表面起伏对涂层高温光热转换将产生不利的影响。随着不锈钢衬底表面平均起伏深度的增加,涂层的太阳吸收比α基本保持不变,而400℃时的热发射比ε则明显逐渐增大。为保证涂层有效的光热转化效率,建议不锈钢衬底表面起伏的深宽比T_z/T_x≤1/20,深度T_z≤0.2μm。

The effect of the surface topography of stainless steel substrates on the solar thermal performance of A1N/A1N- Cr/Cu selective absorbing coating was studied in both numerical simulation calculation and experimental preparation. The numerical simulation calculation was based on the assumption of the one-dimensional triangular grating structure which simplified the surface topography of substrates. The effect of the substrate surface grating depth T, and grating period Tx on solar absorptance ot and thermal emittance 8 at 400 ℃of AIN/A1N-Cr/Cu coating were calculated and analyzed by rigorous coupled wave analysis （RCWA） method. Firstly, the substrates with different surface grating parameters were prepared in experiment, on which the MN/AIN-Cr/Cu coating was deposited by magnetron sputtering method. Then the solar thermal performance parameters were measured and analyzed. The numerical calculation and experimental results show that the surface ups and downs of stainless steel substrate damage the high temperature solar thermal conversion performance of the selective absorbing A1N/A1N-Cr/Cu coating. The solar absorptance a remains substantially unchanged, while the thermal emittance ε at 400 ℃ gradually increases with the increasing of grating depth T,. The aspect ratio Tx/Tx≤1/20 and the grating depth T≤0.2 μm should be reached for effective solar thermal conversion efficiency of the coating.