Optical Properties of Al_xO_y/Ni/Al_xO_y Multilayered Absorber Coatings Prepared by Reactive DC Magnetron Sputtering

摘要

Al_xO_y/Ni/Al_xO_y multilayered absorber coatings were deposited on stainless-steel substrates using reactive direct-current (DC) magnetron sputtering. Al_xO_y films with different morphologies, structures, and optical transmittances were obtained by varying the DC power and oxygen flux. The Al_xO_y films were characterized using field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectrometry, grazing-incidence x-ray diffraction, and ultraviolet/visibleear-infrared spectrophotometry. The effect of the thickness of the Al_xO_y films on the optical properties of Al_xO_y/Ni/Al_xO_y coatings was also investigated. Experimental results show that the thermal emittance of the Al_xO_y/Ni/Al_xO_y multilayered absorber coatings decreases as the thickness of the Al_xO_y top layer is decreased. The Al_xO_y/Ni/Al_xO_y multilayered absorber coating with 70-nmthick Al_xO_y top and bottom layers showed the best optical properties. The thermal stability of the Al_xO_y/Ni/Al_xO_y multilayered absorber coating in which the Al_xO_y films were deposited at conditions of 150 W and 8 sccm O_2 was at least 12 h when the multilayered absorber was annealed at 400℃ in air.