PhD in Chemistry

Aviation is one of the most carbon-intensive forms of transport and realising hydrogen-powered jet engines is seen as the most viable solution to completely decarbonise long-haul aircraft. Using hydrogen as aviation fuel does not produce CO2 from combustion, with water vapour and small (controlled) NOx traces being the main by-products. However, hydrogen is known to cause a range of deleterious effects in structural materials that can lead to dramatic reduction in a component’s lifetime. Understanding the long-term impact of the new hydrogen-rich environments on aeroengine alloys is therefore critical to enable the safe deployment of hydrogen-powered technologies. This PhD project will run in collaboration with Rolls-Royce and is aimed at exploring the interaction of hydrogen and high temperature Ni-based superalloys in hydrogen-rich combustion environments. The research will address the mechanisms of hydrogen dissociation, diffusion and microstructure interactions in combustor and turbine alloys that could lead to material damage and sudden failure. The research will also include investigation into the role of oxides, stress and barrier coatings on the rate of hydrogen ingress and its resultant effects on the mechanical properties. The research will involve undertaking various experimental activities including: 1. Material exposure to hydrogen flames (flame charging) using a state-of-the-art combustion rig, including additional factors like coatings and mechanical loadings; 2. Thermal Desorption Spectroscopy to measure hydrogen within flame-charged materials and understand the role and mechanisms of hydrogen diffusion; 3. Scanning Electron Microscopy (SEM) and advanced techniques including, EBSD, EDS and in-situ tensile testing, to evaluate oxide structure and chemistry, microstructural changes, localised deformation and fracture; and 4. Mechanical testing to assess loss of ductility/damage in H-containing materials against H-free counterparts. The project will also offer the possibility to conduct targeted modelling work to support the experimental findings. The outcomes of the project will support Rolls-Royce on their strategy for alloy selection, lifing and component design for hydrogen.