Microstructure and optical properties of W/W‐W_xN/WO_x multilayer metal‐dielectric solar selective absorbing coating

Abstract

The solar spectrum selective absorption coating (SSAC), as a core component of the concentrated solar power (CSP) system, faces increasingly stringent performance criteria as concentrated solar thermal power production technology advances and becomes more industrialized. Due to atom interdiffusion at the layer border, the current traditional composition and structure of progressive absorption coatings suffer from coating property loss at high temperatures. In this work, W/W‐WxN/WOx SSACs were prepared utilizing a medium frequency reactive magnetron sputtering approach with transition metal nitride as the absorption layer and WOx film with superior intrinsic absorption as the antireflection layer. The optical properties, structural composition, and thermal stability of the coatings were evaluated and characterized using field emission scanning electron microscopy (FE‐SEM), X‐ray diffractometer (XRD), ultraviolet–visible spectrophotometer (UV‐vis), X‐ray photoelectron spectrometer (XPS), and thermal emission meter, and the coatings' failure model and failure mechanism were established and explained. The experimental results demonstrated that the coating had outstanding spectrally selective absorption performance with an absorbance of 0.90 and thermal emissivity of 0.08 under air circumstances, as well as high thermal stability at 250°C and 20 h.