Thermal shocking resistance of AlCrNO-based solar selective absorbing coating prepared by cathodic arc plating

Abstract

Thermal shocking resistance is an important property of the solar selective absorber coating applied in solar power plant. In this paper, we reported the thermal shocking resistance of AlCrNO-based solar selective absorbing coating which was prepared by cathodic arc plating. The coating endured 100 cycles of thermal shocking test, and in each cycle, the sample was heated to 600 °C at a heating rate over 200 °C/min and then cool down to room temperature at a cooling rate over 150 °C/min. After 100 cycles, optical properties, morphologies, elements, phase structure, and surface roughness of the sample were detected by spectrophotometers, scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and atomic force microscope (AFM). According to the results, α/ε of the sample after thermal shocking test changed from 0.93/0.20 to 0.94/0.21, which expressed that the coating possessed perfect thermal shocking resistance. Similar to the sample after thermal aging test, the content of nitride of the coating increased, and threshold of reflectance shifted red. But reflectance pattern of the sample after thermal shocking test was different from it of the sample after thermal aging test because micro defects appeared on the surface of the coating after thermal shocking test.