Abstract
In concentrating solar power technology, the absorber transfers the energy from the solar radiations to a thermal fluid which will produce electricity. To maximize its efficiency, the absorber should be spectrally selective while maintaining good mechanical, physical and chemical properties under severe operating conditions.Due to its good oxidation resistance, SiC is the material commonly used as the absorber, however, it is not spectrally selective. To improve its optical properties we propose to associate it with TiC, an Ultra-High Temperature Ceramic, in a nanocomposite material.In most studies concerning the optical properties of UHTCs, densified or porous pellets are obtained from commercial powders, and composites are made by mechanical mixing. To improve the homogeneity of the final material, we designed a synthesis route where Si and Ti alkoxide precursors copolymerize, in the presence of sucrose, leading to interpenetrated networks of the two oxides with enclosed carbon source particles. The carbothermal reduction produces a homogenous SiC-TiC nanocomposite with small size crystallites. The powder is then sintered by SPS to produce pellets with various densities. The effects of the TiC-SiC proportion and of the pellet density on the optical properties were studied.