Corrosion Behavior of SiC Laminate Under Decomposed Sulfuric Acid at 850°C

Abstract

In view of the possible application of SiC‐based ceramic laminates as critical components of hydrogen generation plants based on sulfur‐iodine or hybrid‐sulfur thermochemical cycles, the effect of corrosion on this kind of ceramics has been investigated. For this purpose, the material was exposed for 1000 h at 850°C to the corrosive action of a gaseous atmosphere simulating the environment of a sulfur‐based thermochemical hydrogen generation plant (a gaseous mixture containing several aggressive species: O2, H2O, SO2, SO3, and H2SO4, with relative concentrations representative of the inlet of an SO3 decomposer reactor). Specimens of multilayer SiC were prepared according to the following processing path: tape casting of a SiC‐based slurry, building of the green multilayer by stacking 11 sheets, final de‐binding and sintering treatments. The material microstructure and its flexural strength and modulus were studied before and after corrosion to investigate degradation phenomena. The microstructure was investigated by XRD, SEM‐EDS, XPS, and density measurements. Flexural strength and modulus were measured by four‐point bending test. The corrosive atmosphere displayed an oxidizing effect that resulted in the formation of silica, oxycarbides, and gaseous products of carbon oxidation. Nevertheless, the corrosion was hindered by the formation on the sample surface of a passivating silica layer. Bending strength and modulus were found unchanged or even improved after corrosion.

Temperature Dependence of Electrical Resistivity (4–300 K) in Aluminum‐ and Boron‐Doped SiC Ceramics

“…Silicon carbide (SiC) has been recognized as an important material with a wide range of industrial applications. SiC ceramics with good thermal conductivity, mechanical strength, and oxidation resistance have been applied to fusion reactors, gas turbines, filters, optical mirrors, and structural parts . SiC‐based materials can also be processed into various semiconductor devices that are more reliable than the existing Si‐based devices at extreme operating conditions such as high temperature, high power, and high frequency .…”

Control of Electrical Resistivity in Silicon Carbide Ceramics Sintered with Aluminum Nitride and Yttria

“…As a IV–IV binary semiconductor, silicon carbide (SiC) has received considerable attention due to its excellent thermal conductivity, mechanical strength, superior corrosion, and oxidation resistance . Such properties have led to the implementation of SiC in gas turbine components, fusion reactors, heat exchangers, hot‐gas filters, and optical mirrors.…”

Thermophysical Properties of Short Carbon Fiber/SiC Multilayer Composites Prepared by Tape Casting and Pressureless Sintering

“…Therefore, this kind of composite layers could be integrated into a multilayer thermal protection system. 25 The outer dense SiC layers are expected to grant excellent oxidation resistance 18,19,25 and fairly good heat conductivity in the plane. 26 The C sf /SiC composite layers in the middle of the multilayer architecture could also grant acceptable thermal conductivity in plane and provide decreased thermal conductivity through the TPS thickness.…”

“…17,18 SiC multilayer with self-passivating behavior has been proposed as an oxidation-resistant component of TPS. 19,20 Meanwhile, besides the mechanical and oxidation properties, thermal properties, especially thermal conductivity property, are very fundamental for application in thermal protection system. 21,22 However, the effect of fiber addition on thermal conductivity, to the authors' knowledge, has not been reported yet.…”