High temperature oxidation of AISI 441 in simulated solid oxide fuel cell anode side conditions

This study investigates the corrosion of AISI 441 in simulated anode conditions of solid oxide fuel cells (SOFCs). Several parameters such as temperature, humidity, surface condition, pre-oxidation temperature and environment, were investigated. Samples pre-oxidized at 800 \ubaC were protective at 550–900 \ubaC, while as-received samples showed protective behavior only at 900 \ubaC. Additional exposures performed at 600 \ubaC revealed the negative effect of increasing steam concentration, the beneficial effect of grinding, while pre-oxidation at 600 \ubaC did not improve the protectiveness. The role and the interplay of the aforementioned factors are discussed

The effect of hydrogen on the breakdown of the protective oxide scale in solid oxide fuel cell interconnects

In this study, the effect of hydrogen, on the degradation of AISI 441 interconnect, under solid oxide fuel cell operating conditions was investigated between 500−800 \ub0C for 336 h. As a new hypothesis, it is concluded that, hydrogen impedes Cr diffusion, probably in the grain boundaries, leading to the breakdown of the protective oxide scale. This effect is most severe at 600 \ub0C, while at lower or higher temperatures the effect is attenuated. Cr diffusion is enhanced at high temperatures, whereas protective scales can be obtained at low temperatures with a lower amount of Cr

The effect of additive manufacturing on the initial High temperature oxidation properties of RE-containing FeCrAl alloys

The effect of additive manufacturing on the high temperature oxidation properties of FeCrAl materials was investigated. For this purpose, additively manufactured Kanthal AM100 cut parallel and perpendicular to the building direction and hot-rolled Kanthal AF as a reference were exposed to air at 900 and 1100 \ub0C for 168 h. AM100 performed slightly better than AF in terms of mass gain. Nevertheless, an oxide scale with local differences in thickness formed on AM100 due to the bimodal grain structure of the underlying metal, which was composed of coarse-grained cuboidal repeating units (100 μm wide), separated by fine-grained rims

High-temperature oxidation behavior of additively manufactured IN625: Effect of microstructure and grain size

High-temperature oxidation of additively manufactured (AM) Ni-base alloy IN625 has been studied in air and Ar-5%H2-3%H2O at 900–1000 \ub0C. AM material is found to oxidize faster than the conventionally manufactured (CM) IN625 due to severe intergranular oxidation observed in the former. The AM IN625 was heat treated at 1100–1250 \ub0C and hot rolled at 980 \ub0C in order to modify the AM microstructure, primarily grain size, and analyze its role in alloy oxidation behavior. Grain size is shown to affect overall oxidation kinetics but not the intergranular oxidation morphology

The Influence of Humidity Content on Ferritic Stainless Steels Used in Solid Oxide Fuel Cell under Dual Atmosphere Conditions at 600 C

In Solid Oxide Fuel Cells (SOFC), interconnects are simultaneously exposed to dual atmosphere conditions in a range of temperature between 600 and 900 C. The presence of dissolved hydrogen in the steel can cause accelerated corrosion on the side exposed to air compared to exposures in air only. Moreover, the interconnect is subject to different humidity levels on the fuel side depending on fuel utilization. It has been already observed that a protective layer of chromia (Cr2O3) at the fuel side can mitigate the dual effect at the airside acting as a barrier for hydrogen permeation into the material. In this work, AISI 441 and Crofer 22 APU samples were exposed to dual atmosphere at 600 C under controlled humidity levels at the fuel side (20% vs. dry). Analysis performed showed how the humidity content on the fuel side largely affects the breakaway corrosion of the samples at the airside