(152209)Preparation of a novel TiN/TiN_xO_y/SiO_2 composite ceramic films on aluminum substrate as a solar selective absorber by magnetron sputtering

摘要

Advanced technology for solar energy collection is increasingly demanded in many applications. In this study we report a reactive magnetron sputtering technique to prepare a TiN/TiN_xO_y/SiO_2 ceramic composite film on aluminum substrate as a solar selective absorber. Aluminum substrate, TiN/TiN_xO_y and SiO_2 layers act as the IR-reflective metallic base layer, double interference absorber layers and ceramic anti-reflection layer, respectively. The structure of TiN, TiN_xO_y and SiO_2 layers,was investigated by XRD, SEM and XPS. The ceramic composite films exhibited high absorptance of 95.20% in the solar spectrum range (0.3-2.5μm) and low emittance of 5.45% (80 °C) in the infrared spectrum range (2.5-25μm). This represents an improvement of the solar absorptance by a factor of 23.16 when compared with the bare aluminum substrate. When the films were tested by a heat-treatment at 400 °C for 240 h in air, the photo-thermal conversion rate showed a slight reduction at the initial stage but soon stabilized, maintaining a reasonably high conversion rate in the rest of the heat-treatment. Extensive tests at elevated temperatures indicate that the composite ceramic film is a potential candidate in concentrated power solar absorber applications for up to 400 °C.