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本文介绍了用于太阳能全玻璃真空集热管中的真空沉积黑铬选择性吸收薄膜。试验了不同的工艺条件对此薄膜光学性能的影响,并进一步研制成双层的真空沉积黑铬选择性薄膜,它具有89％～91％的太阳吸收率α_s和小于5％(80 ℃)的红外法向发射率ε_n。该薄膜经一小时、300℃～400℃温度的真空烘烤后,其αS和ε_n基本没有变化。应用椭圆偏振光谱仪,在三个波长下对铝衬底及各层薄膜的光学常数进行了测定和计算,并用上述结果计算了这些波长下的整个双层黑铬薄膜的反射率,其结果与分光光度计实测的反射率相符。同时还测定了各层薄膜的透过率τ(λ)。这些结果表明,上面一层黑铬薄膜具有减反射作用,因而使双层黑铬薄膜比单层黑铬薄膜具有更高的吸收率,并仍保持其低的红外发射率。对由真空沉积双层黑铬薄膜所试制的真空集热管进行了热性能试验。结果表明,沉积双层黑铬的管子的集热性能优于单层黑铬管,其闷晒的集热性能优于同类型的国外产品。
This article describes the vacuum deposition of black chromium selective absorption film used in solar glass vacuum tube. The influence of different process conditions on the optical properties of the film was tested and the double-layer vacuum deposited black chrome selective film was further developed with 89% -91% solar absorptance α_s and less than 5% (80 ℃) Infrared normal emissivity ε_n. The film after an hour, 300 ℃ ~ 400 ℃ vacuum baking, the αS and ε_n basically no change. The optical constants of the aluminum substrate and the thin films at three wavelengths were measured and calculated using an ellipsometer. The reflectivity of the entire double-layered black chrome film at these wavelengths was calculated using the above results. The measured reflectance of the photometer matches. At the same time, the transmittance τ (λ) of each layer was measured. These results show that the above black chrome film has antireflection effect, so that the double black chrome film has a higher absorption rate than the single black chrome film while still keeping its low infrared emissivity. The vacuum performance of vacuum tube was tested by vacuum deposition of double black chrome film. The results show that the heat accumulation performance of double black chrome tube is better than that of single black chrome tube, and the heat collecting performance of the double black chrome tube is better than that of the foreign products of the same type.