Development of ZrB2-Based Single Layer Absorber Coating and Molten Salt Corrosion of Bulk ZrB2–SiC Ceramic for Concentrated Solar Power Application

Abstract

This study has dual objectives, one to develop single layer ZrB2-SiC-based ceramic absorber coating on stainless substrate, and another aim is to explore the degradation of ZrB2- SiC bulk ceramic in molten solar salt. In particular, we report the molten salt corrosion behavior of earlier developed ZrB2-SiC ceramic composite at 400 °C for 100 h. The corrosion rate in solar salt was determined to be 0.73 ± 0.09 mg h-1/cm2by gravimetric analysis. Binary and ternary oxide phases were formed due to electrochemical corrosion. The hot-pressed bulk ZrB2-SiC ceramic exhibits a high solar absorptance of 0.848 and also a high thermal emissivity of 0.66. A one-layer solar selective absorber coating without antireflection layer was developed using the ceramic disk as a sputtering target. When deposited using radio frequency (RF) magnetron sputtering technique on stainless steel substrate, a solar absorptance of 0.769 and thermal emissivity of 0.15 was obtained for an amorphous coating of thickness ~90 nm, without antireflection coating. The composition, determined by electron probe microanalyzer and X-ray photoelectron spectroscopy techniques, revealed nonstoichiometric phases in the layer with a relatively higher concentration of the lighter elements. The implication of the present work for concentrated solar power application is discussed. © 2021 American Chemical Society. All rights reserved.