Abstract
In concentrating solar power (CSP) technologies, the absorber material should be spectrally selective under severe operating conditions, i.e. ~1000°C under air atmosphere. SiC-TiC nanocomposites could be good candidates for this application due to their spectral selectivity at room temperature, but their behavior under CSP operating conditions is unknown. Therefore, the spectral selectivity and oxidation resistance of TiC-SiC composites were studied up to 500 °C, under air, for various compositions. During heating, the emittance increased with the temperature. After heating, the TiC grains at the surface were oxidized into TiO2, while SiC grains showed good behavior. However, despite little oxidation, the spectral selectivity of the nanocomposites remained interesting after heating. Specific oxidation tests up to 9 days at 1000°C under air showed an increase of the oxidation resistance with the amount of SiC. This result is the consequence of the formation of a protective layer of SiO2 preventing the oxidation of the TiC grains. The composition 30 at% TiC-70 at% SiC seems to be a good compromise between low oxidation and good selectivity.