Plasma-Sprayed Coatings for Solar Receivers

The European project CAPTure (Competitive solAr Power Tower, funded by the H2020 program) intends to significantly reduce costs of solar thermal electricity, paving the way for its deserved competitiveness on the power market. To this end, the solar plant efficiency needs to be optimized by improving separated relevant components. In this frame, this study was focused on the solar receiver part.

Pressure less sintered silicon carbide is of high interest for the solar receiver. SiC is characterized by high radiation absorbing properties, but also by large thermal losses. Thus, applying coatings with appropriate optical properties could significantly improve the performance and the effective cost. However, their behavior under oxidizing atmosphere has to be studied.

The plasma spray process was proposed to apply thick coatings on SiC parts. Several materials were assessed, including oxides, silicides and borides, to try to obtain both a high solar absorptance and a low emittance at high temperature, while maintaining these optical selective properties in an oxidizing atmosphere. Coatings will be presented in terms of composition, microstructure, optical properties, and aging behavior at high temperature.