Oxide Scale Morphology and Chromium Evaporation Characteristics of Alloys for Balance of Plant Applications in Solid Oxide Fuel Cells

The effect of aluminium addition on the high-temperature oxidation behaviour and Cr evaporation of aluminised and alumina-forming alloys for SOFC cathode air pre-heaters

“…In the first 24 hours of Cr leakage detection, AluChrom 318 showed a higher Cr evaporation rate than the aluminised SS309. For AluChrom 318, the high Cr evaporation rate in the first 24 hours was derived from the transient Cr 2 O 3 formed in the initial stage at the gas/metal interface, leading to the slightly higher chromium evaporation before the eventual development of the continuous alumina layer takes over [3]. The rapid formation of the alumina scale on the aluminised SS309 by direct reaction between the aluminium coating and oxygen accompanied by the inward diffusion of aluminium into the alloy matrix resulted in a lack of exposure of Cr [31].…”

“…750 ˚C) by utilising the thermal energy recovered from the high temperature exhaust gas of the SOFC systems. The CAPH is the second most expensive BoP component (next to the SOFC stack itself) as limited materials can be used for the requirements imposed by high temperature operation, namely; strength, machinability, long-term creep, corrosion resistance, as well as cost effectiveness [3]. The requirements here differ from those of metallic SOFC interconnects as the necessity to match the thermal expansion coefficients (TECs) of other SOFC components and to form electronically conducting coatings does not apply to CAPHs.…”

Synthesis and Stability of SrxNiyOzChromium Getter for Solid Oxide Fuel Cells

“…8 At the SOFC operating temperatures, the presence of humidity in ambient air, however, lead to significant evaporation of Cr vapor from the surface scale due to solid-gas interactions between humid air and surface chromium oxide. 9,10 The Cr vapor, released into the air stream, subsequently poisons the cathode in the cell stack. 11,12 A schematic illustration in Figure 1 depicts the gas-solid interactions on a metallic surface with the formation of gaseous chromium vapor species followed by its transport to the cell cathode and subsequent electrochemical deactivation also called cathode poisoning.…”

Electrochemical Validation of In-Cell Chromium Getters to Mitigate Chromium Poisoning in SOFC Stack

“…18 The deposition of Cr-containing species can cause an increase in both diffusion and charge-transfer resistances, 19 reduce porosity and produce compressive residual strains, which hinder the reactant gas percolation and cause structural breakdown of the SOFC cathode. 13 To minimize and mitigate the effect of Cr poisoning, several materials modification approaches have been proposed including protective surface coating, [20][21][22][23] altering the cathode chemistry, 8,24,25 and use of Cr getter. 6 One of the successful protective coatings to date have been based on transition metal-doped and un-doped manganese cobaltite oxide ((Mn,Co) 3 O 4 -MCO), which is effective to decrease chromium evaporation rates as well as slow the oxidation kinetics of base alloy.…”

“…After a long-term exposure, the MCO layer replacement by a complex reaction product layer may lead to interfacial delamination and spallation of coating. [20][21][22][23] The long-term stability of coatings, thus, remains a major concern. Metallic protective coatings such as Co, Ni or Cu have also been identified as promising coating materials but long-term stability needs to be demonstrated.…”