Hydrogen trapping and permeation in metallic and ceramic coatings for fusion powerplant applications- materials strand project

Supervisors: Philip Edmondson (University of Manchester), Hazel Gardner (UKAEA).

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. [4-6] 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 prospective student 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 aadditional microstructural characterisation techniques. It is also anticipated that the successful candidate will spend at least 6 months at IPP Garching in Germany, conducting collaborative experiments under the guidance of Dr Thomas Schwarz-Selinger and gaining experience of working in a large laboratory. The incumbent will also collaborate with the first-principles modelling teams at UoM and UKAEA to aid in the interpretation of the experimental findings.

UKAEA will supply the uncoated and coated steels and vanadium alloys. A subset of promising oxide coated samples would also have a tungsten topcoat applied to form a multilayer coating system, such as would be required for use in the breeder blanket. The student would expose samples to deuterium via low energy plasma using the DELPHI-II facility at UoM and the PLaQ facility at IPP Garching. Both as received and ion irradiated materials would be exposed, with ion irradiations being conducted using accelerators based at UoMs DCF using relevant ions and energies. Subsequent testing would make use of IPP Garching’s TDS and ion beam analysis (Nuclear Reaction Analysis (NRA), Rutherford Back Scattering (RBS), and UoMs world-class characterization facilities. The experimental data collected (deuterium inventories, trap energies, deuterium depth profiles) will inform and validate hydrogen isotope trapping and permeation modelling, enabling prediction of tritium inventory over time. Once a downselection of promising coated systems has been made, this subset of samples will undergo permeation testing at UoM gas-driven permeation system (GDPS) and concurrently exposed to tritium at UKAEA, with subsequent TDS and modelling enabling study of isotope effects and prediction of tritium inventory over time.

This project will be based in Manchester, but will include an extended period of time of up to 6 months at IPP Garching (Germany) to conduct experiments. Collaborative visits for meetings and experiments at UKAEA will also be expected.

This project is offered by University of Manchester. For further information please contact: philip.edmondson@manchester.ac.uk