Effect of TiC incorporation on the optical properties and oxidation resistance of SiC ceramics

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.

First principles investigations of the optical selectivity of titanium carbide-based materials for concentrating solar power applications

“…For applications in concentrating solar power (CSP) units, transition metal carbides are usually included in the form of nanoparticles in a matrix, such as SiC. 48,49 Since such systems cannot be directly investigated using density functional theory for computational reasons, we have investigated the optical properties of the nanoparticles using the scattering theory of Mie, 50,51 which we outline briefly below. When the size a of a nanoparticle is comparably smaller than the wavelength of the incident light λ , Mie theory states that the extinction, scattering, and absorption cross sections (Q ext , Q sca , and Q abs , respectively) of this particle can be calculated using the following equations:…”

Advanced nanocomposite materials made of TiC nanocrystals in situ immobilized in SiC foams with boosted spectral selectivity

“…They possess favorable properties as solar absorbers such as a very high melting point, a good thermo-mechanical properties at high temperatures and, most of them are intrinsically selective. 10–17 Among those materials, TiC and TiN exhibit an inherent spectral selectivity which can be used for delivering high-performance SSAs. 17–19 However, they tend to oxidize in the targeted operating temperature range.…”

“…10–17 Among those materials, TiC and TiN exhibit an inherent spectral selectivity which can be used for delivering high-performance SSAs. 17–19 However, they tend to oxidize in the targeted operating temperature range. 20–22 As most single-phase materials do not naturally have the required behavior (in terms of both thermal stability and spectral selectivity) as SSAs, how can we further enhance the working temperature of SSAs beyond 600 °C?…”

Influence of the oxidation on the optical properties of Mo-Si-Ti, Ta-Mo-Cr-Al and Ta-Mo-Cr-Ti-Al alloys

“…Scratches and pores could generate multiple reflexions and interferences that would affect the radiative properties for the wavelengths inferior to their average size [8]. The mechanism behind the selectivity of textured surfaces has been investigated for some regular surfaces [9] such as:…”