Hydrogen trapping and permeation in metallic and ceramic coatings for fusion powerplant applications

Future fusion powerplants must maintain tritium inventory to ensure safe and sustainable plant operations. Structural materials in the breeder blanket and tritium extraction systems will be exposed to tritium and lithium. This means that with the materials themselves must be able to withstand Li corrosion and how low tritium retention, or alternatively coatings can be used to inhibit tritium permeation and enhance the corrosion resistance of the structural materials.

Ceramic coatings, such as erbium oxide and yttrium oxide, have acceptable lithium compatibility and high permeation reduction factors, making them good candidates for tritium permeation barrier applications. They can be used in conjunction with a corrosion resistant topcoat, such as tungsten, to form a multilayer coating system that resists tritium permeation and Li corrosion.

There is currently limited information on the behaviour of tritium in fusion-relevant ceramics. A combined experimental and modelling approach is needed to identify trap types for hydrogen-isotopes in as-received ceramic systems, along with their relative strengths and stability. Building upon this, studies on the interaction with an understanding of the role of the substrate-coating interface in hydrogen trapping and permeation.

While trapping in metallic systems is better understood than for ceramic systems, hydrogen isotope inventory measurements are essential as an early screening tool for new alloys and metallic coatings, and will facilitate the development of improved material systems for enhanced properties in the future.

The project will conduct experimental investigations of the trapping and permeation behaviour of various substrate-coating systems, using materials characterisation techniques to link the microstructure to the hydrogen isotope trapping and permeation behaviour observed. This characterisation will include the use of Thermal Desorption Spectroscopy (TDS) and ion beam analysis and additional microstructural characterisation techniques.