CMCs based on silicon carbide fibres and silicon carbide matrix with a boron nitride interlayer are being developed for a range of applications in next generation aerospace engines. Deployment of these composites will allow more efficient operation of engines reducing environmental impact. However use in service is hampered by a lack of mechanistic understanding of the degradation processes. In particular there are two areas of interest 1) the reaction with BN and steam in service. This controls mechanical behaviour through modification of the mechanical properties of the interface. 2) The reaction of BN with environmental barrier coatings based on rare earth silicates. In both cases understanding the reactions will lead to important information for predicting service lifetimes.
This project will use state of the art energy electron loss spectroscopy (EELS) with HR-TEM to understand the local chemical environment in degraded samples. This will include simulated service samples from industrial collaborators and samples degraded in Oxford using our new steam degradation rig –recently installed. To interpret the EELS spectrum, density functional theory (DFT) modelling will be carried on a range of potential structures using existing software. This will allow full chemical and structural understanding of reactions products. The project will be well suited to a candidate interested in both high resolution microscopy and atomistic modelling.
The description above outlines a possible new research project being offered to prospective new postgraduate students.