Increasing efficiency through higher operating temperatures in innovative and sustainable energy conversion processes is a key task in improving resource efficiency. It places new demands on materials, requiring the development of new material and manufacturing concepts.
To complete the energy transition, new high-temperature material solutions and manufacturing technologies are essential for the vast majority of energy conversion technologies. The aim of the joint project is to make significant contributions to CO2 reduction, resource conservation and the increased efficiency of production units and processes through applied materials research. Three areas are addressed: Solar thermal systems, high temperature electrolyzers and hydrogen turbines In solar thermal energy systems, solar rays – which are focused using mirror systems - are used to heat molten salts that then transport the heat to a steam turbine In this process, the solar receivers, piping, pumps, and storage tanks are placed under particular stress due to corrosion by the molten salts at temperatures of 350 °C to 550 °C.
Low-cost aluminide diffusion coatings for heat storage tanks, and piping made of ferritic steels, are being investigated to provide corrosion protection as well as potential for higher operating temperatures High-temperature electrolysis is a promising technology for the production of green hydrogen Innovative and cost-effective coatings for interconnectors made of ferritic HT stainless steel – to protect against corrosion and the evaporation of volatile, toxic and function-disrupting chromium (VI) species - are being researched and further developed. MoSiB alloys for hydrogen turbines are being investigated for the highest application temperatures above 1300 °C These alloys are produced using powder metallurgical processes Both pressure-assisted sintering and SEBM are used At the same time, the forming of molded parts with tribological and process optimization is under research.
In the joint project ”HI-TEMP“, which is funded by the German Federal Ministry of Education and Research in accordance with Guideline 3004/68 501 ”Support for application-oriented research for non-university research institutions“, the Fraunhofer institutes IWM, IST, IKTS, ICT and IWU have joined forces to develop materials solutions for the addressed technologies in a complementary approach.
At Fraunhofer ICT an annealing process for aluminum slurry coatings is being developed as part of the joint project for solar thermal applications. The external heat creates aluminide diffusion layers that protect the steel from corrosion. The advantage of using this process rather than a furnace is that it is not necessary to subject the entire component to heat treatment, but only the component surface. For a digitized AI-supported approach to the targeted further development of diffusion layers, the entire system is parameterized in all process steps, and the data is structured in a computer-readable format. Electroplated coatings based on lanthanum oxide are being investigated to protect the interconnector in a high-temperature electrolyzer. The method is cost-effective and well suited for coating even more complex geometries, and it yields thin, nano-structured layers. To assess the potential for operating solid electrolyzers under pressure, the stability of interconnector coatings at 30 bar in relevant atmospheres is being investigated.
Fraunhofer Institute for Chemical Technology ICT