Metal-ceramic composites in fusion reactor environments
Name: Sam Humphry-Baker
Mentor: Dr Luc Vandeperre
Sponsor: Imperial College Research Fellowship
Powder-processed composites based on the carbides and borides of tungsten are used extensively in manufacturing tools and mining applications, however they have been recently identified as promising materials for nuclear fusion reactors1. In both applications, these materials are exposed to very high temperatures, mechanical stresses and oxidation, while in fusion devices irradiation damage poses an additional challenge.
This project is focussed on tailoring these materials to enhance their performance in extreme environments. Our strategy is based on developing enhanced metal-ceramic composites, whereby ceramic particles are combined with a small amount of ductile metallic alloy to improve the overall mechanical properties and manufacturability. The defining microstructural feature of these composites is their high density of metal-ceramic interfaces. These interfaces control heat transport, vacancy diffusion, and dislocation motion – and are therefore key to understanding their interesting properties. By engineering the density and chemistry of these interfaces using advanced processing techniques, we will design materials that can be employed in more demanding conditions.
The work can be divided into several complimentary work streams. First, materials will be processed at Imperial, using advanced powder consolidation equipment such as the vacuum hot-press. Sintering studies will be aided by the state-of-the-art thermal analysis facilities within CASC. Once synthesised, materials will be studied under oxidation2 and mechanical stresses at Imperial – predominantly using the thermogravimeter and temperature creep tester. Complimenting this work, irradiation studies will be conducted at external facilities and brought back to college for post-mortem characterisation. The work benefits from on-going collaboration with Tokamak Energy Ltd and their supporting of a PhD studentship within the Nuclear-CDT.
1. Modelling the power deposition into a spherical tokamak fusion power plant. C.G. Windsor, J.G. Morgan, P.F. Buxton, A.E. Costley, G.D.W. Smith, A. Sykes Nucl. Fusion. 57 , 36001, 2016.
2. Oxidation resistant tungsten carbide hardmetals. S.A. Humphry-Baker, K. Peng, W.E. Lee, Int. J. Refract. Met. Hard Mater. 66, p: 135–143, 2017.