Advanced protective coatings that could let widely available ferritic steels replace specialist alloys as interconnects in solid oxide cell stacks.
This site presents the Gdańsk Tech contribution to AltCoat. The project is coordinated by the Institute of Power Engineering in Warsaw.
In a solid oxide cell stack the metallic interconnect carries current between cells and keeps the fuel and air atmospheres apart. It is normally made from a specialist ferritic stainless steel such as Crofer 22 APU or Crofer 22 H — alloys developed specifically for this duty. They work well, but they are expensive, available from few suppliers, and account for a meaningful share of stack cost.
Generic ferritic steels such as AISI 430 and AISI 441 cost a fraction as much and are produced worldwide. Left unprotected, however, they oxidise too quickly at operating temperature: the chromia scale grows to electrically resistive thicknesses, volatile chromium species escape and poison the oxygen electrode, and silicon in the steel migrates to the interface to form an insulating silica layer.
AltCoat asks whether coating can substitute for alloy design — whether the right multilayer architecture can make a generic steel behave like a dedicated interconnect alloy over thousands of hours of operation.
Each layer in the architecture addresses a different degradation path, and the layers have to work together under dual-atmosphere conditions.
A reactive sublayer deposited directly onto the steel is designed to capture silicon before it can form a continuous, insulating silica film at the metal–scale interface. Material selection for this layer is an open question the project addresses directly.
Manganese–copper oxide spinel layers slow chromia scale growth and block outward chromium transport. Reactive-element additions are used to reduce the oxidation rate further and to improve scale adhesion.
Electrospun perovskite nanofibres and low-temperature processing are explored as alternatives to conventional deposition, aiming at dense, conductive coatings that can be applied without high-temperature sintering steps.
The work moves from coating development, through long-term oxidation testing, to validation in reversible cell stacks.
Developing the multilayer stack: sublayer material selection, spinel layer composition, and deposition routes suited to generic ferritic steel substrates, with process parameters established for each layer.
A screening campaign that compares generic steels against reference interconnect alloys under isothermal exposure. Mass-gain kinetics, scale morphology and area-specific resistance are tracked throughout the exposure.
Electrospinning of perovskite nanofibre layers and low-temperature processing routes, evaluated against the conventionally deposited coatings on the same substrates.
Dual-atmosphere testing and integration into reversible solid oxide cell stacks. A central goal is to compare coated generic steel against Crofer 22 APU over 1 000 hours of operation.
| Material | Role | Temperatures | Exposure |
|---|---|---|---|
| Crofer 22 APU | Reference interconnect alloy | 650 / 700 / 750 °C | up to 5 000 h |
| Crofer 22 H | Reference interconnect alloy | 650 / 700 / 750 °C | up to 5 000 h |
| AISI 430 | Generic ferritic steel, 2–3 producer variants | 650 / 700 / 750 °C | up to 5 000 h |
| AISI 441 | Generic ferritic steel, 2–3 producer variants | 650 / 700 / 750 °C | up to 5 000 h |
The project target is an area-specific resistance below 100 mΩ·cm² for a coated generic steel after long-term exposure. This is a stated project target, not a reported result.
Coating development, deposition and the long-term oxidation campaigns run at Gdańsk Tech. The project is coordinated by the Institute of Power Engineering in Warsaw.
Department of Functional Materials Engineering, Faculty of Electronics, Telecommunications and Informatics
Warsaw, Poland · Coordinating institution
Peer-reviewed articles and conference contributions from the project will be listed here as they appear.
Warsaw · Coordinator
Gdańsk · Partner
Funding. AltCoat — “Alternative to Alloying: Advanced Protective Coatings for Low-Cost Alloys for Solid Oxide Cell Stack Technology” — is funded by the National Science Centre, Poland (Narodowe Centrum Nauki) under the OPUS 25 call, grant agreement UMO-2023/49/B/ST8/03265.
For research collaborations, sample exchange, or questions about the project, get in touch with the Gdańsk Tech team.