Influence of Pre-Oxidation on Dual Atmosphere Effect on AISI 441 Interconnects for Solid Oxide Fuel Cell Applications

Abstract

In previous studies an extreme dual atmosphere effect on the airfacing side of AISI 441 at 600°C was observed. However indications showed that pre-oxidation of the material might have a beneficial effect on the corrosion resistance in dual atmosphere. To examine this further we pre-oxidized AISI 441 samples for 0 min, 11 min, 45 min, 180 min and 280 min and subsequently exposed these at 600 °C for 500 h under dual atmosphere conditions. Photographs of the air-facing sides were taken throughout exposure to monitor the corrosion behavior. SEM analysis was performed on all samples after exposure.

The Influence of Different Factors on the Dual Atmosphere Effect Observed for AISI 441 Interconnects Used in Solid Oxide Fuel Cells

“…What is, however, agreed upon, by different researchers in the field, is that hydrogen is the culprit (13)(14)(15). This is also supported by our recent studies on the effect that pre-oxidation has on the dual atmosphere effect (16,17). Here we showed that the pre-oxidation layer on the fuelfacing side is more important as a useful mitigation strategy against the dual atmosphere effect than the pre-oxidation layer on the air-facing side.…”

“…All coupons were ultrasonically cleaned in ethanol and acetone before pre-oxidizing them for 20 min at 800 °C in an air flow rate of 280 sml min -1 and 3 % water vapor. The pre-oxidation length was chosen because previous studies have shown that shorter pre-oxidation times result in accelerated corrosion in dual atmosphere (16,17). The other pre-oxidation parameters, i.e.…”

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

“…(10,11). Promoting the formation of a chromia scale at the fuel side through pre-oxidation treatments in air effectively delays the onset of breakaway corrosion (1,2). These findings were in line with hydrogen permeation measurements by Kurokawa et al who reported that hydrogen permeation is faster through the steel, rather than through the Cr2O3 scale (12,13).…”

“…Hence, in this study, the effect of humidity content in the fuel gas was investigated. This parameter might affect the oxidation behavior of the FSS on the fuel side(14) (chromia thickness, breakaway corrosion etc..) which in return affects the protectiveness of the airside as well (2).…”