Abstract
This work describes a high temperature corrosion kinetics study of ∼30 % porous Fe22Cr alloys. The surface area of the alloy (∼0.02 m2 g−1) has been determined by tomographic microscopy. The weight gain of the alloys was studied by isothermal thermogravimetry in the air for 100 h at 700–900 °C. Breakaway oxidation was observed after oxidation at 850 °C (∼100 h) and 900 °C (∼30 h). The lifetime prediction shows the investigated porous alloy can be used for >3000 h at temperatures <700 °C. At temperatures ≥700 °C, the lifetime of the porous alloy is limited by the available chromium reservoir.
Highlights
High temperature reactors and devices such as supercritical reactors, superheaters, turbines, and engines [1] rely on advanced alloys
The presented porous metal sheet has a thickness of ~400 μm, similar to the ceramic/cermet sup ports used in traditional solid oxide cells [3]
Image analysis of the cross-section scanning electron microscopy (SEM) image revealed a porosity of 31 % (±2%), which is in agreement with the Archimedes method
Summary
High temperature reactors and devices such as supercritical reactors, superheaters, turbines, and engines [1] rely on advanced alloys For these applications, the most important properties of metallic alloys are their relatively low cost (in comparison to advanced ceramics), manu facturability, and the possibility to form complex shapes. Porous ferritic stainless steels have been proposed as support structures for high temperature ceramic fuel cells [14,15,16] and gas separation membranes [17]. The existing studies point to rela tively fast corrosion of porous alloys at high temperatures (≥800 ◦C), but the specific effects of the particle size, porosity, and surface area still remain open. The results were used to propose a simple approach for the lifetime prediction of the porous alloy
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