Suitability of layered Ti₃SiC₂ and Zr₃[Al(si)]₄C₆ ceramics as high temperature solar absorbers for solar energy applications

Layered Ti₃SiC₂ and Zr₃[Al(Si)]₄C₆ ceramics were prepared by hot-pressed sintering. The spectrally selective absorption properties of these layered carbides have been investigated and compared with those of TiC and ZrC. It is found that the Ti₃SiC₂ ceramic exhibits a solar absorbance of 0.70 and a thermal emissivity of 0.19, yielding spectral selectivity (absorbance divide by emissivity) of 3.7, while the spectral selectivity of Zr₃[Al(Si)]₄C₆ is 2.8 (0.71/0.25). To evaluate the suitability of these ceramics as high-temperature absorbers for solar radiation, the investigation on the thermal stability and temperature dependent emittance was performed in air. Compared with TiC and ZrC, both Ti₃SiC₂ and Zr₃[Al(Si)]₄C₆ show better thermal stability. Meanwhile, Ti₃SiC₂ and Zr₃[Al(Si)]₄C₆ exhibit a low emissivity in the investigated temperature range, benefiting from their metal-like electrical conductivity.