Professor Patrick Grant FIMMM FREng
Department of Materials
Tel: +44 1865 273737 (Head of Dept Office)
My research takes place at the interface between advanced materials and manufacturing, and concerns a wide range of structural and functional materials. Current applications include structured porous electrodes for supercapacitors and batteries, 3D printed materials with spatially varying electromagnetic properties for microwave devices, and advanced metallics for power generation. Recent work has also concerned X-ray imaging of microstructural evolution, especially of solidifying alloys.
The research uses variants of manufacturing techniques used in industry such as vacuum plasma spraying and field assisted sintering alongside in-house developed novel processes such as spray deposition of multi-suspensions and 3D printing of dielectric materials. We make extensive use of numerical modelling for device design, to provide insights into underlying processs physics, and to understand how heat and mass flows relate to the final microstructure. All the research work involves close collaboration with industry and other universities across the UK and the world.
Find out more: Group research page
Novel high energy density high reliability capacitors
Dr. A. Mahadevegowda, Dr. C. Johnston, Dr. H.E. Assender, Professor P.S. Grant
Current capacitor technology significantly limits the temperature capability and electrical performance of power electronics relative to the "More Electric Airframe" systems requirements, which are emerging rapidly as a key priority for both aeroengine and airframe manufacturers. Novel capacitor materials combining high dielectric ceramics and high performance polymers are being developed for aero-engine applications, particularly within the more electric aircraft concept. Investigations include characterisation of the fundamental material properties using advanced analytical instruments, clean room characterisation of the electrical properties, development of fabrication routes, and modelling of behaviour for lifetime prediction. (Funded by Technology Strategy Board, Labinal Power, ICW Ltd)
Processing and properties of tungsten coatings for fusion reactors
Dr D. Armstrong, Professor P.S. Grant
Tungsten is the key plasma facing material for use in any future nuclear fusion device due to its high melting point, good sputter resistance and low activity. However its refractory nature leads to inherent difficulties in its processing and many traditional production routes are not available. Vacuum plasma spraying is one of the most attractive methods of producing tungsten coatings for this application, but thermal mis-match between the tungsten and substrates such as steel or copper lead to the development of complex residual stresses which degrade the performance of the coating. Other challenges include microstructural control, and characterising the properties of tungsten in the coating arrangement. This project will use recently upgraded vacuum plasma spraying equipment to produce both pure and alloyed tungsten coatings on novel substrates. In-situ process data will be recorded including temperatures, deflections, etc. Coatings will be characterised using state of the art microscopy and micro-mechanical testing facilities, as well as thermal loading, and finite element analysis used to understand the evolution of the stress state. By consideration of the process conditions in manufacture, the microstructure and the properties of the coatings, optimisation will be performed to produce practical tungsten coatings for further testing and application. Funded by EPSRC and CCFE
Spray forming of Ni superalloys for high temperature applications
Dr A. Sato, Professor P.S. Grant
We are developing a novel variant of the spray forming process in order to produce Ni superalloy components with enhanced functionality for the power generation industry. Funded by Mitsubishi Heavy Industry, Japan.
The Quest for Ultimate Electromagnetics using Spatial Transformations (QUEST)
Dr D. Isakov, Dr F. Castles, Prof. C R M Grovenor, Prof. P S Grant
Recent UK-led breakthroughs in the theory of STs, such as the possibilities concerning cloaking and invisibility, have caught both the scientific and popular imagination, and have stimulated a huge growth in related research around the world. The potential of the underlying ST approaches, however, have much wider applicability than cloaking alone, in arguably more important applications that span communications, energy transfer, sensors and security. However, theory and concepts are outstripping practical demonstration and testing, leading to a mismatch in what may be theorised and computed and what can be realised for impact in society and commerce. We contend that the timing is now ideal for UK theorists, modellers, manufacturers and engineers to work together to maintain the UK strength in this field, with a clear focus on the reduction to practice and demonstration of potentially radical new concepts and devices. Collaboration with the University of Exeter, University of St Andrews, and Queen Mary, University of London.
Microstructural control of Al alloys using intrinsic oxides
A. Verma, Dr. K.A.Q. O'Reilly, Professor P.S. Grant
The world produces 37 million tons of Al every year. All of this metal will have grain refiner additions made to it to promote the nucleation of a fine primary Al grain size. Oxide particles exist in nearly all liquid metals and alloys exposed to air or even under protective atmospheres. Oxide particles are often considered harmful inclusions since they reduce castability of alloy melts, deteriorate ductility and fatigue strength of castings and cause severe difficulties in down stream processing of continuous cast feedstock. As a result, considerable effort is expended to prevent oxide formation and to clean the melt by expensive melt filtering. However, recent research work at Brunel has demonstrated that by liquid metal engineering they can not only eliminate the harmful effects of the oxides but also make positive use of them for effective enhancement of nucleation for structural refinement of the Al grains, so reducing the need for grain refiner additions. Work in Oxford has demonstrated that grain refiner additions not only nucleate the Al grains, but also control intermetallic selection in Al alloys, hence modifying mechanical properties. This project is investigating the potency of oxide particles for heterogeneous nucleation of intermetallics. The nucleation sequence of various intermetallic phases due to unavoidable oxides and their control is being studied during solidification of Al-alloys. A phase extraction technique is being used to facilitate the detailed characterisation of intermetallic phases and their interaction with extrinsic and intrinsic alloy additions. Special reference is being made to inclusions and impurity elements in recycled materials.
Processing of oxide dispersion strengthened alloys for fission and fusion power
Z. Hong, M. Gorley, Dr. H. Zhang, Professor S.G. Roberts, Professor P.S. Grant
Oxide dispersion strengthened alloys comprise a metallic alloy with a dispersion of sub-micron oxide particles. The fine scale dispersion of the ceramic particles gives rise to strain fields around the particles, which can confer strength and other properties by interaction with dislocations in a manner similar to that of fine scale precipitates produced by ageing heat treatments in conventional metallurgical alloys. The particles also have the potential to stabilize microstructural features such as grain size at intermediate temperature. A further potential benefit of these particles in steels for nuclear applications is that they or the interface between the particles and the matrix may act as a 'sink' for vacancies and He induced by a neutron flux environment, partially mitigating otherwise severely damaging effects such as embrittlement. It is known that the type (size, volume fraction, chemistry, etc) of particles and the homogeneity of their dispersion in the matrix is influential on the final ODS alloy properties and the extent to which potential benefits are realised in practice. However, there are few systematic studies that allow the detail of the oxide particle mixing/dissolution and re-precipitation behaviour to be reconciled in terms of the processing parameters of practical interest. In part, this derives from the long times associated with the design-make-characterise-irradiate-test cycle. In this project we combine in-house processing of high quality ODS steel powders by mechanical means, the subsequent manufacture of consolidated ODS alloys. The study focusses on the dynamics of the critical metallic-ceramic mixing process and aims to develop ideas for identifying and assuring the "quality" of milled powders so that downstream properties are evolved optimally. Alternative processes to mechanical mixing are also being explored. Funded by EPSRC.
Liquid Metal Engineering (LiME) EPSRC Manufacturing Hub - Oxford spoke
S. Feng, A. Lui, Dr. E. Liotti, Professor P.S. Grant
The group is a partner in a new Engineering and Physical Sciences Research Council (EPSRC) funded £10 million Manufacturing Research Hub, which started in November 2015. The EPSRC Manufacturing Hub in Future Liquid Metal Engineering is led by Brunel University with major research activities at Oxford, Leeds, Manchester and Imperial College London, and involves a large number of industrial partners who will invest a further £45 million over the next 7 years. The UK metal casting industry adds £2.6bn/yr to the UK economy, employs 30,000 people, produces 1.14 million tons of metal castings per year and underpins the competitive position of every sector of UK manufacturing. However, the industry faces severe challenges, including increasing energy and materials costs, tightening environmental regulations and a short supply of skilled people. The group research will develop new approaches to X-ray imaging of solidification, including machine-learning techniques for automated image analysis. These techniques will be used to understand how impurities in liquid metals control microstructural evolution and how solidification conditions can be manipulated, for example by a pulsed magnetic field, to improve the tolerance of processes to impurities and so enable the increased re-circulation of metals in the manufacturing economy.
Nanostructures for energy storage applications
C.A. Huang and Professor P.S. Grant
Nano-structured materials are attractive for some energy related applications because they can provide very high surface areas per unit mass, leading to high energy densities in various storage applications. A supercapacitor (electrochemical capacitor) stores electrical energy either in the form of ions at an electrode/electrolyte interface (electrical double-layer capacitor, EDLC) or by faradic redox reactions at the electrode (pseudo-capacitors). Both types offer high power density (rapid discharge), excellent reversibility, and long cycle life. Supercapacitors usually use activated (meso-porous) graphite for their electrodes, but alternatives with higher power capability are being studied intensively, including entangled, meso-porous carbon nanotube (CNT) films - an application that makes use of the "natural" tendency of the CNTs to entangle and percolate current at low volume fractions. We are fabricating comparatively large amounts of both multi-walled CNTs (by chemical vapour deposition) or single wall CNTs (by arc discharge) in-house, purifying them, functionalizing their surface to improve their ion storage capability, and then processing them into large area films or buckypaper - on a variety of flexible or stiff substrates. In some cases, other process steps can add nanoparticles to provide a superimposed pseudo-capacitance. Our goal is to demonstrate the potential benefits of this approach over existing materials at the laboratory scale, and also to ensure that we develop processing technologies that at all stages offer the potential for cost-effective scaling to the near-industrial, and then full industrial use. The ability to process and characterize fully these materials in-house is key to this strategy. Funded by EPSRC Grant: Supergen Energy Storage.
Powder of dispersion strengthened copper alloys for fusion applications
A. Morrison, Professor P.S. Grant
Nanostructured oxide dispersion strengthened (ODS) copper alloys with a high density of nano-sized dispersoids exhibit high thermal conductivity, excellent irradiation resistance, high temperature microstructural stability, which makes them promising candidates as heat sink materials in nuclear power generation. Processing plays an important role in determining performance because the stabilising, fine-scale nano-clusters of ceramic particles are developed during the early stages of processing and cannot be subsequently manipulated. The objectives of our work are to develop an in-house manufacturing capability for Cu ODS alloys, in which powder metallurgy and spray forming will be two key processing techniques. These primary processing approaches are being developed as an alternative to the commercial in-situ oxidation route during casting and heat treatment. The primary processing will be complemented by spark plasma sintering consolidation processing to ensure full density. At each stage the nano/micro-structure will be investigated using a range of microstructural techniques, both in Oxford and at the new Materials Research Facility at CCFE. This information will be used to rationalise the mechanical response of alloys assessed by a combination of conventional and micro-mechanical testing, with the aim identifying the process-material combinations that provide optimum mechanical properties and microstructural stability. Funded by CCFE and EPSRC.
9 public active projects
Solid-state supercapacitors with rationally designed heterogeneous electrodes fabricated by large area spray processing for wearable applications, C. Huang, J. Zhang, N.P. Young, B. Chen, H.J. Snaith, I. Robinson and P.S. Grant,Sci. Rep., 6 (2016), 25684.
Preparation, microstructure and microwave dielectric properties of sprayed PFA/barium titanate composite films,Q. Lei, C. Dancer, P.S. Grant and C.R.M. Grovenor, Comp. Sci. Tech., 129 (2016), 198–204.
Evolution of Fe bearing intermetallics during DC casting and homogenization of an Al-Mg-Si Al Alloy, S. Kumar, P.S. Grant and K.A.Q. O'Reilly, Mat. Trans. B, 47A (2016), 3000-3014.
Microwave dielectric characterisation of 3D-printed BaTiO3-ABS polymer composites, F. Castles, D. Isakov, A. Lui, Q. Lei, C.E.J. Dancer, Y. Wang, J.M. Janurudin, S.C. Speller, C.R.M. Grovenor and P.S. Grant, Sci. Rep., 6 (2016), 22714.
Gap corrected thin film permittivity and permeability measurement with a broadband coaxial line technique, Y. Wang, I. Hooper, E. Edwards and P.S. Grant, IEEE Trans. Microwave Theory Techn., 64 (2016), 924-930.
Production of hollow and porous Fe2O3 from industrial mill scale and its potential for large-scale electrochemical energy storage applications, C. Fu, A. Mahadevegowda and P.S. Grant, J. Mat. Chem. A, 4 (2016), 2597-2604.
3D printed anisotropic dielectric composite with meta-material features, D.V. Isakov, Q. Lei, F. Castles, C.J. Stevens, C.R.M. Grovenor and P.S. Grant, Materials & Design, 93 (2016), 423–430.
Mapping of multi-elements during melting and solidification using synchrotron X-rays and pixel-based spectroscopy, E. Liotti, A. Lui, T. Connolley, M. Wilson, M. Veale, K. Sawhney, I. Dolbnya, A. Malandain and P.S. Grant,Sci. Rep., 5 (2015), 15988.
Fe3O4-carbon nanofibre bead-on-string electrodes for enhanced electrochemical energy storage, C. Fu, A. Mahadevegowda and P.S. Grant, J. Mat. Chem. A, 3 (2015), 14245–14253.
Processing and microstructure characterization of oxide dispersion strengthened Fe–14Cr–0.4Ti–0.25Y2O3 ferritic steels fabricated by spark plasma sintering, H. Zhang, K. Dawson, H. Ning, C.A. Williams, M. Gorley, C.R.M. Grovenor, S.G. Roberts, M.J. Reece, H. Yan and P.S. Grant, J. Nucl. Mat., 464 (2015), 61-68.
Real-time synchrotron X-ray observation of equiaxed solidification of aluminium alloys and implications for modelling , A. Prasad, E. Liotti, S.D. McDonald, K. Nogita, H. Yasuda, P.S. Grant and D.H. StJohn, MCWASP, IOP Conf. Series: Mat. Sci. Eng., 84 (2015), 012014.
Characterisation of the residual stresses in spray formed steels using neutron diffraction, T.L. Lee, J. Mi, S.L. Zhao, J.F. Fan, S.Y. Zhang, S. Kabra and P.S. Grant, Scripta Mat., 100 (2015), 82-85.
Enhancing the supercapacitor behaviour of Fe3O4/FeOOH coaxial nanowire-carbon nanotube hybrid electrodes in aqueous electrolytes, L. O'Neill, C. Johnston and P.S. Grant, J. Power Sources, 274 (2015), 907–915.
X-ray video imaging and machine learning based analysis to understand alloy solidification
Prof Patrick Grant / Dr Enzo Liotti
We have developed X-ray imaging equipment and experimental approaches to record real-time videos of the solidification of alloys with high temporal and spatial resolution. This technique is providing new information to help understand and resolve long-standing and important issues in solidification science, including the role of grain refiners, impurities, external fields and many other important practical parameters. The particular novelties developed in the group include: (i) the ability to apply a highly controlled and reproducible pulsed electromagnetic field during solidification to break-up dendrites and to mimic industrial processes; (ii) the use of new multi-element detector (with STFC) that allows the investigation of more complex composition, realistic alloys; and (iii) a range of image analysis techniques including state-of-the-art pattern recognition machine learning algorithms (with Engineering Science) that allow quantified data to be extracted from videos automatically. This project will exploit and further develop these capabilities to study and quantify the nucleation and growth behaviour of equiaxed grains during commercial casting practices. The work will involve X-ray imaging solidification experiments, microstructural analysis and computer programming for automated analysis of images and videos. The project will also require travel and stays of typically 5 days to X-ray synchrotron sources around the world, particularly the Diamond Light Source (UK), ESRF and Soleil (Grenoble and Paris, France) and the Swiss Light Source (Geneva, Switzerland).
Also see homepages: Patrick Grant
Layer-by-layer manufacture of improved materials and devices for energy storage
Prof Patrick Grant
New ideas for manufacturing the electrodes used Li ion batteries, electrochemical supercapacitors and permeable fuel cell membranes are being investigated to produce improvements in one or more of energy density, power density, cycle life, safety and reduced cost. The research involves developing new ideas and equipment for layer-by-layer fabrication of the various parts of these devices, with each layer optimised for its specific function and location in the device - and is quite different for the very productive but simplistic and constraining processes used currently in industry. For example, in this project LbL processing will be used to adjust the electrode microstructure progressively during fabrication to improve ion mobility from place to place in the electrode, to reduce charge and discharge times for electric vehicle applications. LbL processing will also be investigated for its ability to transform cheap, safe but previously considered unpromising materials into efficient electrochemical storage materials for very large, grid scale storage applications. The project will involve a combination of processing and equipment development, microstructural characterisation and energy storage measurements.
Also see homepages: Patrick Grant
Spray forming of high entropy alloys
Professor Patrick Grant
High entropy alloys is a term applied to a new type of metallic alloy system that comprises near equi-atomic concentrations of at least three alloying elements, and frequently more. Since their discovery simultaneously in Oxford and Japan in 2004 a large number of alloys have been developed at small scale. A key and potentialy attractive aspect of these alloys is that despite their apparent compositional complexity, they may form extremely simple microstructures, including stable solid solutions. More recently, some alloys have been shown to offer exciting but sometimes puzzling mechanical properties. To advance these alloys and to understand their potential for commercial applications requires the manufacture of high quality alloys at larger scale, and the development of critical process-structure know-how. This project will make use of the range of leading spray forming and casting equiment available at Oxford for the manufacture of high temperature, complex composition alloys of up to 30 kg billets. The as-sprayed microstructure and its development in downstream processes will be carefully studied, and mechanical properties studied in collaboration with investigators in Oxford, China and the US.
Also see homepages: Patrick Grant
3D printing and additive manufacturing approaches for microwave metamaterials
Prof Patrick Grant
Meta-materials are artificial materials that have properties unavailable from single material classes or composites and have been demonstrated in the lab to enable physical phenomena as cloaking, invisibility, advanced communications, energy transfer, sensors and security. Many of the novel properties of meta-materials involve their unusual interactions with electromagnetic radiation such as light and microwaves. However, theorectical designs with meta-materials are outstripping practical demonstration and testing, and there is an urgent need and exciting opportunity to develop new processing approaches to fabricate new, practical meta-materials for engineering applications.
This project focuses on new processing approaches to build active meta-materials with graded dielectric and magnetic properties using 3D printing. An active meta-material is one that can be switched or controlled using an external stimulus such as electricity, magnetism, light, etc, and are at the early stages of development. The project will develop a number of active meta-material ideas suitable for our in-house 3D printing facility, and then design novel arrangements of these materials to make functioning demonstrators at the 5 - 15 cm scale for measurement. The work will involve interaction with designers using simulations and specialists in measurements in the mega-gigahertz range. At all stages, a key aspect will be to characterise the microstructure and performance of the feedstock materials you have developed. The project will also involve developing novel implementations of the additive manufacture process itself in order to allow 3D active devices to be fabricated.
Also see homepages: Patrick Grant
Also see a full listing of New projects available within the Department of Materials.