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 | Professor Patrick Grant Cookson Professor of Materials |
[ Quicklinks: Research Summary Current Research Projects Recent Publications D.Phil. Projects Available ]
Summary of Research Interests
Research interests concern developing fundamental understanding of the complex underlying physics during materials processing in order to manipulate microstructure, extract maximum economic benefit and impose process control. Much of the research is focused on detailed investigations of novel manufacturing routes and materials utilising liquid droplets, using a combination of experimentation on near industrial scale, on-line process diagnostics, numerical simulation, and close collaboration with industry.
Current Research Projects
Novel high energy density high reliability capacitors
X. Zhao, Dr. A. Cook, Dr. C. Johnston, Dr. H.E. Assender, Professor P.J. Dobson*, Professor M. Johnson**, 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 IeMRC and MoD/dstl) (*Academic Director of the Oxford University Begbroke Science Park, **University of Nottingham)
Advanced electronic packaging for harsh environment applications
D. Shepherd, M. Sousa, Dr. C. Johnston, Professor P.S. Grant
Down oil and gas well temperatures of 250ºC and pressures of >1,000bar provide the harshest environment that electronics must endure. Even though the very expensive electronics placed down-well are protected by thermal barriers and other technologies, the time that the electronics can spend down hole is limited. This project seeks to develop new technology so that electronics may operate under these extreme conditions for up to 10 years. The project forms part of a larger project, and brings together specialists in electronic materials, high reliability assembly and a well-logging instrumentation manufacturer. The project is making use of both in-house and industrial manufacture, assembly, testing and microstructural examination of novel multi-material combinations. Finite element modelling is being used to predict and understand behaviour under extreme environments. Materials under investigation include novel insulated metal substrates and various high temperature die attach and interconnect materials and processes. (Funded by the UK Technology Strategy Board and an industrial consortium).
Materials Knowledge Transfer Partnership - Transport
Dr. C. Johnston, Dr. R.M.K. Young, Professor. P.S. Grant
As part of the Materials KTN, we are running a comprehensive network and business programme focused future lightweight and high temperature materials for low pollution, high efficiency transport. New materials, their manufacturing technologies and their integration into engineering systems are critical if UK aerospace, automotive rail and marine sectors are to meet global technical drivers. We are helping UK transport and technology businesses to meet these requirements through a range of scientific and technical products and services focused on: lightweight materials, materials technologies for reduced emission, end of life technologies (disassembly, re-use, recycling), and more electric technologies. (Funded by UK Technology Strategy Board)
Spray formed Al-Li-Mg-Zr(Sc) alloys for lightweight transport applications
Dr. J. Mi, Professor P.S. Grant
A state-of-the-art 80kg Al spray forming plant is being used to manufacture low density Al-Mg-Li-Zr(Sc) alloys for light-weight extrusions requiring minimum post-processing but providing an attractive balance of specific strength and stiffness, ductility and corrosion resistance. (Funded by the UK Technology Strategy Board and an industrial partnership)
Smart Composites: EPSRC/GE Aviation Strategic Partnership
Dr. H. Zhang, Professor P.S. Grant, Dr. S.R. Duncan*
EPSRC and GE Aviation have established jointly a 5 year Strategic Partnership with Oxford and Bristol Universities, in the area of smart composites. The focus for the research concerns two themes: (i) low cost manufacture of advanced structural composites; and (ii) novel embedded actuation materials and the associated systems technology. The research at Oxford concentrates on (1) the processing of smart composites; (2) the characterisation of their microstructure including actuation materials, interfacial properties and lifetime behaviour; and (3) modelling and control of actuation. (Funded by GE Aviation and EPSRC, * Department of Engineering Science)
Spray forming of novel aluminium alloys
C. Banjongprasert, Professor P.S. Grant
The potential of the spray forming process to manufacture a range of novel Al-based alloys is under investigation. These include new Al-Cu-Li-Mg-Zr-X alloys for strong and tough aerospace alloys and Al-Mg-Si-Li alloys for ultra low density, high stiffness application. In each case, precise compositions have been chosen to take best advantage of the unusual solidification conditions during spray casting to obtain large scale billets for microstructural and mechanical assessment that cannot be obtained by any other process. Microstructural response during downstream processing such as extrusion, and where appropriate, ageing heat treatments is being studied by analytical electron microscopy, phase extraction, X-ray diffraction, calorimetry and mechanical property testing. (Funded by Royal Thai Scholarship)
Toxic metal replacement in aerospace applications
V. Marques, Dr. C. Johnston, Professor P.S. Grant.
Current environmental legislation restricting the use of toxic metals in manufacturing and service will make the continued use of metals such as lead, cadmium and hexavalent chromium increasingly problematic for the aerospace industry and the basic understanding and development of aerospace-relevant replacement technologies must begin now. Pb containing materials are used extensively in Pb-based solders for electrical connections on printed circuit boards and printed wiring boards. Commercial Pb-free products are available for non-aerospace sectors but the limits to their use in the much harsher aerospace environment are unknown. The objectives of this project are firstly to investigate the reliability of Pb-free solders under electrical/thermal regimes relevant to the harsh aerospace environment; and secondly to develop basic understanding and numerical analyses describing the electrical reliability of toxic metal replacement materials. Nanoindentation at room and elevated temperature is being used to measure the spatial distribution of mechanical properties within lead free joints themselves, using joints typical of aerospace electronics, avionics and other configurations. The mechanical behaviour (constitutive laws) are then captured in finite element analyses of the evolution of thermal stresses in the joint region, and how these change and relax with time. Electron microscopy is being used extensively to relate mechanical data to the microstructure in various conditions of the joints: as manufactured (in-house), after isothermal ageing at elevated temperature, and after thermal cycling in a pre-programmed aerospace standard thermal cycling rig. (Funded by EPSRC and an aerospace consortium)
Advanced materials for plasma facing components (PFCs) in fusion devices
N. Bridge, G. Thomas, Professor P.S. Grant
This project concerns the use of vacuum plasma spraying to produce thick tungsten (W) coatings on reduced activation steels for first wall applications in fusion reactors. In particular, novel strategies to retain very thick W coatings during thermal cycling are being studied, such as the use of repeating millimetre scale “sculptures” over the substrate to enhance adhesion and control coating segmentation. (Supported by TWI and UKAEA)
Bulk nanostructured Al based alloys
A. Kelly, C. Banjongprasert, Dr. J. Mi, N. Rounthwaite, Dr. M. Galano, Professor F. Audebert*, Professor G.D.W. Smith, Professor P.S. Grant
Development and processing of Al based nanocomposites alloys for high strength applications in bulk shape by several processing techniques, in particular spray forming. Alloys including Al-Fe-Cr-Ti are being produced in billet form and their microstructures and properties compared with those produced by rapid solidification and mechanical alloying. Characterisation includes electron microscopy and X-ray diffractometry using synchrotron radiation at Diamond. Downstream processing includes forging and extrusion, with mechanical properties studied as a function of temperature. Scaled-up billet sizes are being used for specific component trials. (Funded by EPSRC and industrial consortium, *University of Buenos Aires, Argentina)
Nanostructures for energy applications
X. Zhao, B. Mendoza, 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.
10 public active projects
Research Publications
Spray deposition of steam treated and functionalized single and multi-walled carbon nanotube films for supercapacitors, X. Zhao, W. Wang, B.T. Chu, B. Ballesteros, W. Wang, C. Johnston, J.M. Sykes and P.S. Grant, Nanotechnology, 20 (2009), 065605, doi:10.1088/0957-4484/20/6/065605.
Spray deposited fluoropolymer/multi-walled carbon nanotube composite films with high dielectric permittivity at low percolation threshold, X. Zhao, A.A. Koos, B.T.T. Chu, C. Johnston, N. Grobert, P.S. Grant, Carbon, 47 (2009), 561-569. doi:10.1016/j.carbon.2008.10.042.
Spray deposition of polymer nanocomposite films for dielectric applications X. Zhao, C. Hinchliffe, C. Johnston, P.J. Dobson and P.S. Grant, Mat. Sci. Eng. B, 151 (2008), 140–145. doi:10.1016/j.mseb.2008.05.024.
Modelling the shape and thermal dynamics during the spray forming of Ni superalloy rings. Part 1: droplet deposition, splashing and re-deposition J. Mi and P.S. Grant, Acta Mat., 56 (2008), 1588-1596, doi:10.1016/j.actamat.2007.12.021.
Modelling the shape and thermal dynamics during the spray forming of Ni superalloy rings. Part 2: heat flow and solidification, J. Mi and P.S. Grant, Acta Mat., 56 (2008), 1597-1608, doi:10.1016/j.actamat.2007.12.022.
An electrochemical study of repassivation of aluminium alloys with SEM examination of the pit interiors using resin replicas, K.L. Moore, J.M. Sykes and P.S. Grant, Corros. Sci., 50 (2008), 3233-3240. doi:10.1016/j.corsci.2008.08.027.
Pitting corrosion of spray formed Al–Li–Mg alloys, K.L. Moore, J.M. Sykes, S.C. Hogg and P.S. Grant, Corros. Sci., 50 (2008), 3221-3226. doi:10.1016/j.corsci.2008.08.012
The use of interfacial 3D geometry to control stress distributions in W coatings for fusion armour applications, G. Thomas, R. Vincent, G. Matthews, B. Dance and P.S. Grant, Mat. Sci. Eng. A, 477 (2008), 35–42. doi:10.1016/j.msea.2007.05.120
Multiphysics modelling of the spray forming process, J. Mi, U. Fritsching, O. Belkessam, I. Garmendia, A. Landaberea and P.S. Grant, Mat. Sci. Eng. A, 477 (2008), 2–8. doi:10.1016/j.msea.2007.08.083
Solidification in spray forming, P.S. Grant, Mat. Trans. A, 38A (2007), 1520—1529. doi:10.1007/s11661-006-9015-3
Processing, microstructure and property aspects of a spray cast Al-Mg-Li-Zr alloy, S.C. Hogg, I.G. Palmer, L.G. Thomas and P.S. Grant, Acta Mat., 55 (2007), 1885–1894. doi:10.1016/j.actamat.2006.10.057
Optimal robot path for minimizing thermal variations in a spray deposition process, P.D.A. Jones, S.R. Duncan, T. Rayment and P.S. Grant, IEEE Trans. Control Systems Techn., 15 (2007), 1-11. doi:10.1109/TCST.2006.883196
Evolution of percolation properties in nanocomposite films during particle clustering, T.K.H. Starke, C. Johnston and P.S. Grant, Scripta Mat., 56 (2007), 425-428. doi:10.1016/j.scriptamat.2006.10.034.
Microstructure evolution of vacuum plasma sprayed CoNiCrAlY coatings after heat treatment and isothermal oxidation, P. Poza and P.S. Grant, Surf. Coatings Techn., 201 (2006), 2887-2896. doi:10.1016/j.surfcoat.2006.06.001
Scientific, technological and economic aspects of rapid tooling by electric arc spray forming, A. Roche, S.R. Duncan and P.S. Grant, J. Thermal Spray Tech., 15 (2006), 796-801. doi:10.1361/105996306X1468794
The effect of particle distribution inhomogeneities on the dielectric properties of polymer/ceramic films, T.K.H. Starke, C. Johnston, S. Hill, P.D. Dobson and P.S. Grant, J. Phys. D: Appl. Phys., 39 (2006), 1305-1311.
Microstructural characterisation of spray formed Si-30Al for thermal management applications, S. Hogg, A. Lambourne, A. Ogilvy and P.S. Grant, Scripta Mat., 55 (2006), 111-114.
Oxidation during the electric arc spray forming of steel, A.P. Newbery and P.S. Grant, J. Mat. Processing Techn., 178 (2006), 259-269.
An investigation of novel spraycast Al-Mg-Li-Zr-(Sc) alloys, S.C. Hogg, I.G. Palmer and P.S. Grant, Mat. Sci. Forum, 519-521 (2006), 1629-1633.
Applied periodic l-infinity control: presenting prototype designs for a real spray form tooling process, V.A. Tsachouridis, P.D.A. Jones, S.R. Duncan and P.S. Grant, Control Eng. Practice, 14 (2006), 1477-1493.
Modelling the heat flow in spray formed steel shells for tooling applications, T. Rayment and P.S. Grant, Met. Mat. Trans. B, 37B (2006), 1037-1047.
Projects Available
Nanostructured thin film supercapacitors for next generation energy storage
P S Grant
A supercapacitor is a compact electrochemical capacitor that can store and discharge electrical energy rapidly. They overcome the limitations of batteries at high powers. Current supercapacitors can be found in consumer electronics, power smoothing, regenerative braking and emergency power applications – and their use is forecast to grow dramatically. A supercapacitor is a deceptively simple device – two electrodes are separated by an electrolyte and charge is stored at the interface of each electrode.
The use of single and multi wall carbon nanotubes (CNTs) in supercapacitor electrodes has been studied for their potential to enhance specific area and/or mesoporosity for ion diffusion. However, the potential for the beneficial addition of relatively small proportions (< 20%) of CNTs in asymmetric electrode arrangements (different anode and cathode) has recently been demonstrated in Oxford and appears particularly attractive for the reduction of resistive losses and improvement in electrode integrity, without the need for parasitic binders. This project will extend these studies, and will include the synthesis of nano-wires, tubes, rods, etc, their stable suspension, and the fabrication of meso-porous thin films with a particular emphasis on the scaleability and reproducibility of any developed approaches. Both single material meso-porous films and hybrid or composite structures comprising mixtures of materials, for example to optimise energy storage and mechanical stability, will be studied in terms of their processability, microstructure and energy and power performance.
A candidate with experience and interest in both materials science and chemistry would be ideal for this project. This project forms part of EPSRC’s Supergen – Energy Storage Consortium http://www.energystorage.org.uk/.
Further information on the project itself can be sought by e-mailing patrick.grant@materials.ox.ac.uk direct. General enquiries on how to apply can be made by e-mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies and further information can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/index.html.
This advertisement will be updated shortly with further information about eligibility, stipend and fees.
Also see homepages:Patrick Grant
Materials for fission and fusion power
S G Roberts, A J Wilkinson, E A Marquis, G D W Smith, P S Grant
Do you want to help to solve the future energy crisis? Are you interested in doing novel and exciting experimental work? Would you like opportunities for international collaborations and travel? Then read on….
Fusion reactors potentially offer a complete solution to the problem of future energy supply, and are environmentally friendly: they emit no greenhouse gases, and so would not contribute to global warming. The recent success of the JET project at Culham in the south of Oxfordshire, which proved that plasma could be heated and controlled to produce fusion, has demonstrated the feasibility of the concept. The next step is to construct a prototype reactor (ITER) which is now the focus of a major international project. This will be followed by a prototype commercial reactor (DEMO). So far relatively little demand has been made on the properties of the materials used for JET and other prototype reactors, since they had only to contain an operating plasma for very short times. For actual fusion power plants, materials issues will be crucial to success.
In the closer future, advanced fission reactors will be needed to meet some at least of the world energy demand, as fossil stocks dwindle and as their use become less environmentally acceptable. Materials degradation by radiation damage is a serious issue in current-generation reactors, and the new “generation IV” reactors currently being proposed will place even heavier demands on materials.
The materials needed will operate at temperatures of 600ºC or more, will need to withstand stresses up to 300MPa, and will accumulate over their lifetime radiation damage from fast neutrons amounting to ~100 displacements per atom. In fusion reactors, an additional problem will arise due to the high levels of helium and hydrogen produced in transmutation reactions. It is essential that any material used maintains adequate strength and toughness, while suffering minimal dimensional change through swelling and creep. These are very demanding requirements, which cannot be met by conventional structural materials. It will be necessary to develop and evaluate new materials.
Ion irradiation is currently the only non-activating method of mimicking the fast neutron damage produced in nuclear fission and fusion reactors (with or without co-implantation with He or H, to mimic the effects of fusion by-products). Implanted layers are ~2-3 microns deep or less. We have developed micromechanical test methods, using ion beam machining to make specimens only a few microns in size, for determination of the elastic, plastic and fracture properties of candidate materials. This is linked with parallel electron microscopy and atom-probe microscopy studies of the development and nature of the radiation damage, and of the interactions between radiation damage and mobile dislocations which give rise to hardening and embrittlement. The experimental work is closely linked to the development and verification of computer models of radiation defects and their interactions.
A new large research project in this area, an EPSRC programme grant centred at Oxford University, has just started. It involves UK and European partners (especially Liverpool University, CCFE Culham laboratory, the Commissariat à l'Énergie Atomique (CEA), and Rolls Royce). It aims at providing a thorough understanding of the mechanical properties and irradiation response of materials with potential for fusion and advanced fission reactor applications, including low-activation ferritic-martensitic steels, oxide-dispersion strengthened steels, model Fe-Cr alloys and tungsten alloys.
Studentships are available, starting October 2010, in the following areas:
Radiation hardening and embrittlement
1. Effects of radiation on structure and strength in iron-based alloys
2. Effects of radiation on structure and strength in tungsten alloys.
Grain boundary embrittlement
3. Grain boundary strength in model Fe-Cr binaries.
4. Grain boundary strength in pure and “commercially pure” tungsten.
Oxide Dispersion Strengthened alloys
5. Microstructural development in model ODS alloys
6. High-temperature mechanical properties and deformation mechanics of ODS alloys
This advertisement will be updated shortly with further information about eligibility, stipend and fees.
Also see homepages:Patrick Grant Emmanuelle Marquis Steve Roberts George Smith Angus Wilkinson
Spray forming of hierachical metal-metal composites
P S Grant
Spray forming is a high technology casting process for producing large scale advanced alloys with unmatched quality and performance. This project will explore spray forming for the processing of “designer” alloys by co-spraying a second (or more) liquid or metal phase into the primary sprayed alloy so that co-deposition and mixing occur to produce unusual and potentially highly useful structures and properties. This project will make use of the leading spray forming facilities at Oxford to manufacture and study hierachical metal-metal composites in which microstructural features at the nano, micro and meso scale are attempted to be controlled separately by co-spraying of different materials, from the simplest mixture of two pure metals that are then heavily deformed to produce nanofibrils, through to the co-injection of nanoscale powders and mixing of different liquid sprays to produce in-situ reactions and otherwise difficult to process compositions and phases. The microstructure and mechanical properties will be studied for the most promising combinations, together with the effect of downstream processing operations.
Also see homepages:Patrick Grant
Control of microstructure by grain multiplication
P. Grant
This project concerns the control of nucleation and subsequent microstructural evolution during solidification by intrinsic grain multiplication using external physical means such as acoustic/shock waves and pulsed magnetic fields. Fragments from broken dendrites are well-known to multiply the number of final grains in a casting, and so provide grain refinement and attendant improvements in quality and performance. The central idea of this project is to enhance dramatically this effect by disrupting continuously the thermal conditions in the melt and at growing solid/liquid interface, without any melt contamination. While various external field approaches have been developed, there remains some uncertainty in the mechanism of dendrite fragmentation, and this project will study both the underlying physics of grain multiplication as well as a new approach for its enhancement.
Also see homepages:Patrick Grant
Novel processing of nanostructured films for energy storage
P S Grant
This project will study a new and scaleable spray deposition technology developed at Oxford that can produce thin films (0.5micron up to 10’s of microns) from aqueous and non-aqueous suspensions of nanomaterials over areas of (currently) up to 750cm2. In particular, the processing of 1D nanostructures (rods and wires) of transition metal oxides into large area meso-porous films for supercapacitors and battery/photovoltaic hybrids will be studied. As well as the synthesis of nanostructures and their suspension, the project will focus on the manufacture of the films themselves with a particular emphasis on the scaleability and reproducibility of any developed approaches. Both single material meso-porous films formed from rods, wires and tubes, and hybrid or composite structures comprising mixtures of materials, for example to optimise energy storage and mechanical stability, will be studied in terms of their processability, microstructure and energy and power performance in real supercapacitor configurations.
Also see homepages:Patrick Grant
Also see a full listing of New projects available within the Department of Materials.
