Mo-SiO_2太阳选择性吸收涂层的空气高温热稳定性

THERMAL STABILITY OF Mo-SiO_2 SOLAR SELECTIVE COATINGS AT HIGH TEMPERATURES IN AIR

采用磁控溅射的方法制作Mo-SiO_2太阳能选择性吸收涂层,测量了涂层经过空气高温退火前后在0.34～25μm波长范围内反射曲线的变化情况。刚沉积完的涂层,太阳吸收比达到0.95,发射比为0.093。在空气中500、600℃退火1h后,涂层反射曲线基本不变。在空气中700℃退火1h后,涂层光谱选择性恶化,太阳吸收比下降到0.91,发射比上升到0.6。通过扫描电子显微镜观察了单层Mo、单层SiO_2以及SiO_2覆盖Mo的样片薄膜在空气中不同温度退火前后的形貌变化,发现以上薄膜表面不再平整,甚至出现裂纹和薄膜脱落,成为Mo-SiO_2选择性吸收特性恶化的主要原因。

Mo-SiO2 muhilayer solar selective coatings were deposited by magnetron sputtering technique. The samples were annealed in atmosphere at different temperatures ranging from 500℃ to 700℃ for 1 hour. The reflectance in the wavelength region of 0.34-25 μm of the as-deposited and annealed samples were measured with UV-VIS-NIR and FF-IR spectrometers. The solar absorptanee （ct） and thermal emittance （e） of as-deposited coatings were 0.95 and 0.093, respectively. The reflectance was nearly the same after anneal in air at 500℃ and 600℃ for lhour. The spectra selectivity of coating deteriorated after annealing in air at 700℃ for lhour, whose α and ε were changed to 0.91 and 0.6, respectively. Then Mo, SiO2 single layer and Mo/SiO2 tandem layers were deposited with the same process and annealed in air at different temperatures for 1 hour. The surface morphology of as-deposi- ted and annealed films were investigated with scanning electronic microscopy. The annealed films became rough, and cracks and peelings appeared, and was the main reason of spectra selectivity deterioration.