Compatibility of SiC--and MAX phase-based ceramics with a KNO3-NaNO3 molten solar salt

Abstract

In this work, several ceramic materials were exposed together with two reference structural materials (i.e., 316L stainless steel and Inconel 600) to a molten solar salt (40 wt% KNO3 and 60 wt% NaNO3) for 1000 h at 600°C to investigate the compatibility for their use in concentrated solar power (CSP) applications. The exposed ceramics included different SiC grades (solid statesintered, liquid phase-sintered, and silicon-infiltrated) and MAX phase-based materials (Maxthal ® 211 & 312 (nominally, Ti2AlC & Ti3SiC2, respectively), Cr2AlC, Nb4AlC3, (Nb,Zr)4AlC3, and a cermet comprising 40 vol% Fe and 60 vol% (Nb,Zr)4AlC3). All SiC grades were chemically stable in the molten salt, whereas all Nb-containing MAX phase ceramics were severely oxidized. Comparing the two Maxthal ® grades showed that the 312 was chemically more stable than the 211, and both grades formed a Na-based oxide scale. Interestingly, Cr2AlC showed practically no interaction with the molten salt during the performed exposure and formed a submicrometer stable Cr3C7 layer. Hence, it may be considered as promising structural (coating) material candidate for the targeted CSP application.

Compatibility of 3D-Printed Oxide Ceramics with Molten Chloride Salts for High-Temperature Thermal Energy Storage in Next-Generation CSP Plants

“…Oxide ceramics like Al 2 O 3 and ZrO 2 are attractive construction materials for hightemperature applications such as in the field of conventional power generation [8] and Energies 2021, 14, 2599 2 of 11 molten salt TES/HTF technology [9] due to their excellent corrosion resistance, good mechanical strength at high temperatures and low material costs. The ceramics generally have a better chemical compatibility with corrosive media like molten salts than metallic materials [10].…”

Multifunctional performance of Ti2AlC MAX phase/2D braided alumina fiber laminates

“…4 In particular, Ti 2 AlC is the most studied and promising composition thanks to the combination of the properties described above, the oxidation cubic kinetics up to temperatures around 1300℃, and availability, non-toxicity, and low cost of the chemical precursors. 5 Based on these features, Ti 2 AlC and other Al-MAX phases have been proposed to operate under aggressive environments in different applications such as high-temperature structural material, 6 protective coatings, 7 bond coats in thermal barrier coatings, 8 accident-tolerant fuel cladding in nuclear light water reactors, 9 solar receivers and external walls of the storage tank in concentrated solar power units, 10,11 and as catalyst, 12 among others. 13 However, although Al-MAX phases might be considered for these applications, the aggressive environments demand a unique combination of properties and high degree of reliability in long-term operation, which in some cases Ti 2 AlC cannot withstand.…”

Degradation of Al2O3f/SiO2 composites exposed to Na2SO4 environment and MMH/N2O4 bipropellants test

“…The impurities sucked in from the environment or introduced by the fuel might react to form low‐melting point salts such as Na 2 SO 4 , NaCl, Na 2 CO 3 , NaVO 3 , KCl, and/or volcanic ash. The molten salts could accelerate the corrosion of CMCs composites 24‐30 . The corrosion behavior of Al 2 O 3f /SiO 2 composites in a molten salts environment has rarely been studied.…”