SiC-TiC nanocomposite for bulk solar absorbers applications: Effect of density and surface roughness on the optical properties

In this study, the potential of SiC-TiC nano-composites as solar absorbers has been studied. For solar thermal applications, materials with high solar absorptance and low emittance are ideally sought for (spectral selectivity). A semi-molecular sol-gel synthesis route leading to nanometric homogenous composites was described. The resulting SiC-TiC nanocomposite powder was sintered at different temperatures to produce samples with various relative densities (from 57% to 96%). The samples morphology and composition were characterized by several techniques including Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD), carbon and oxygen elemental analyses. The link between the surface roughness and the relative density was precised and the effects on the optical properties (0.25–25 µm wavelength range) were studied. Comparisons were made with pure SiC and pure TiC samples with various relative densities.