High-performance materials for particles and supercritical CO2 heat exchangers of next-generation concentrated solar power plant systems

Abstract High-temperature heat exchangers for concentrated solar thermal systems operating at up to 750°C and 250 bar face challenges, including creep, oxidation, corrosion, thermal cycling, and particle-driven erosion. The COMPASsCO2 project explored Cr-based superalloys as cost-effective alternatives to conventional Ni-based alloys. Two novel material systems were developed: Cr-NiAl alloys with Fe additions that reached homogeneous microstructures and stable NiAl precipitates, enhancing high-temperature strength, and Cr-Si alloys showing exceptional hardness and erosion resistance. Although high ductile-to-brittle transition temperatures limited the use of Cr-Si as bulk materials, they proved effective as protective slurry coatings. A novel Cr-Si diffusion coating process was developed and validated through oxidation and erosion testing. Laboratory-scale testing under simulated conditions was supported by computational wear modeling, thermodynamic simulations, and machine-learning-based microstructural analysis. These findings highlight material solutions applicable to the particle/sCO 2 use case and relevant to other high-temperature, chemically aggressive industrial environments. Impact statement Decarbonizing high-temperature process heat and power demands materials that survive >750°C, high pressure, and particle flows. This study introduces new chromium-based alloys and protective coatings designed for the next generation of concentrated solar thermal power plants that use supercritical carbon dioxide and solid particles to convert heat into electricity more efficiently. The research combines advanced materials development with computer simulations and machine learning to predict how these materials perform over time. The newly developed chromium–nickel–aluminum and chromium–silicon materials show excellent resistance to heat, corrosion, and particle erosion at temperatures up to 900°C. A new, low-cost coating method provides durable surface protection and could extend the lifetime of heat exchanger components by a decade. Beyond solar energy, these findings are relevant for any high-temperature industry, such as gas turbines, hydrogen production, or chemical processing, where materials failure limits efficiency and sustainability. By improving durability and reducing maintenance costs, this work supports more affordable and reliable renewable energy systems and offers a pathway toward cleaner, longer-lasting technologies for high-temperature industrial applications. Graphical abstract