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50 items found (0 items not approved), displaying 11 to 20.[First/Prev] 1, 2, 3, 4, 5 [Next/Last]

Instruments / Technical Area	Publication Details	Published
Electrical Engineering Mechanical Engineering	Design and FEA of an innovative rotating SiC filter for high-energy X-ray beam Walter Tizzano , Thomas Connolley , Steve Davies , Michael Drakopoulos , George Howell MEDSI 2018 DOI: 10.18429/JACoW-MEDSI2018-THOAMA04 Open Access Show Abstract ▼ Abstract: I12 is a high-energy imaging, diffraction and scattering beamline at Diamond. Its source is a superconducting wiggler with a power of approximately 9kW at 500 mA after the fixed front-end aperture; two permanent filters aim at reducing the power in photons below the operating range of the beamline of 50-150 keV, which accounts for about two-thirds of the total*. This paper focuses on the design and simulation process of the secondary permanent filter, a 4mm thick SiC disk. The first version of the filter was vulnerable to cracking due to thermally induced stress, so a new filter based on an innovative concept was proposed: a water-cooled shaft rotates, via a ceramic interface, the SiC disk; the disk operates up to 900 degrees C, and a copper absorber surrounding the filter dissipates the heat through radiation. We utilised analysis data following failure of an initial prototype to successfully model the heat flow using FEA. This model informed different iterations of the re-design of the assembly, addressing the issues identified. The operational temperature of the final product matches within a few degrees C the one predicted by the simulation.	Dec 2018
I12-JEEP: Joint Engineering, Environmental and Processing	Revealing internal flow behaviour in arc welding and additive manufacturing of metals Lee Aucott , Hongbiao Dong , Wajira Mirihanage , Robert Atwood , Anton Kidess , Shian Gao , Shuwen Wen , John Marsden , Shuo Feng , Mingming Tong , Thomas Connolley , Michael Drakopoulos , Chris R. Kleijn , Ian M. Richardson , David J. Browne , Ragnvald H. Mathiesen , Helen Atkinson Nature Communications 9 DOI: 10.1038/s41467-018-07900-9 Diamond Proposal Number(s): [8218, 7855] Open Access Show Abstract ▼ Abstract: Internal flow behaviour during melt-pool-based metal manufacturing remains unclear and hinders progression to process optimisation. In this contribution, we present direct timeresolved imaging of melt pool flow dynamics from a high-energy synchrotron radiation experiment. We track internal flow streams during arc welding of steel and measure instantaneous flow velocities ranging from 0.1ms−1 to 0.5ms−1. When the temperaturedependent surface tension coefficient is negative, bulk turbulence is the main flow mechanism and the critical velocity for surface turbulence is below the limits identified in previous theoretical studies. When the alloy exhibits a positive temperature-dependent surface tension coefficient, surface turbulence occurs and derisory oxides can be entrapped within the subsequent solid as result of higher flow velocities. The widely used arc welding and the emerging arc additive manufacturing routes can be optimised by controlling internal melt flow through adjusting surface active elements.	Dec 2018
I12-JEEP: Joint Engineering, Environmental and Processing	Superior techniques for eliminating ring artifacts in X-ray micro-tomography Nghia T. Vo , Robert. C. Atwood , Michael Drakopoulos Optics Express 26 DOI: 10.1364/OE.26.028396 Open Access Show Abstract ▼ Abstract: Synchrotron-based X-ray micro-tomography systems often suffer severe ring artifacts in reconstructed images. In sinograms the artifacts appear as straight lines or stripe artifacts. These artifacts are caused by the irregular response of a detecting system giving rise to a variety of observed types of stripes: full stripes, partial stripes, fluctuating stripes, and unresponsive stripes. The use of pre-processing techniques such as distortion correction or phase retrieval blurs and enlarges these stripes. It is impossible for a single approach to remove all types of stripe artifacts. Here, we propose three techniques for tackling all of them. The proposed techniques are easy to implement; do not generate extra stripe artifacts and void-center artifacts; and give superior quality on challenging data sets and in comparison with other techniques. Implementations in Python and a challenging data set are available for download.	Oct 2018
B16-Test Beamline I12-JEEP: Joint Engineering, Environmental and Processing Optics	X-ray phase-contrast imaging with engineered porous materials over 50 keV Hongchang Wang , Biao Cai , Matthew James Pankhurst , Tunhe Zhou , Yogesh Kashyap , Robert Atwood , Nolwenn Le Gall , Peter Lee , Michael Drakopoulos , Kawal Sawhney Journal Of Synchrotron Radiation 25 DOI: 10.1107/S1600577518005623 Diamond Proposal Number(s): [14033] Open Access Show Abstract ▼ Abstract: X-ray phase-contrast imaging can substantially enhance image contrast for weakly absorbing samples. The fabrication of dedicated optics remains a major barrier, especially in high-energy regions (i.e. over 50 keV). Here, the authors perform X-ray phase-contrast imaging by using engineered porous materials as random absorption masks, which provides an alternative solution to extend X-ray phase-contrast imaging into previously challenging higher energy regions. The authors have measured various samples to demonstrate the feasibility of the proposed engineering materials. This technique could potentially be useful for studying samples across a wide range of applications and disciplines.	Jul 2018
I12-JEEP: Joint Engineering, Environmental and Processing	Designing steel to resist hydrogen embrittlement Part 2 – precipitate characterisation S. W. Ooi , T. I. Ramjaun , C. Hulme-smith , R. Morana , M. Drakopoulos , H. K. D. H. Bhadeshia Materials Science And Technology 192, 1 - 12 DOI: 10.1080/02670836.2018.1496536 Diamond Proposal Number(s): [9880] Open Access Show Abstract ▼ Abstract: A novel, low-alloy steel has been designed for use in the oil and gas industry. Its high strength and hydrogen trapping potential are derived from a martensitic microstructure containing a dispersion of fine vanadium–molybdenum alloy carbides that evolve during tempering. In this second paper, the effect of quench rate from austenitisation and tempering conditions are investigated with respect to the microstructure. The alloy loses its tempering resistance following slow-cooling from austenitisation as a result of MC precipitation, leading to vanadium depletion and significant MC coarsening. This is predicted using computer simulation and confirmed by high energy X-ray diffraction, combined with electron microscopy.	Jul 2018
I12-JEEP: Joint Engineering, Environmental and Processing	Identifying the Cause of Rupture of Li-Ion Batteries during Thermal Runaway Donal P. Finegan , Eric Darcy , Matthew Keyser , Bernhard Tjaden , Thomas M. M. Heenan , Rhodri Jervis , Josh J. Bailey , Nghia T. Vo , Oxana V. Magdysyuk , Michael Drakopoulos , Marco Di Michiel , Alexander Rack , Gareth Hinds , Dan J. L. Brett , Paul Shearing Advanced Science 5 DOI: 10.1002/advs.201700369 Diamond Proposal Number(s): [13884] Open Access Show Abstract ▼ Abstract: As the energy density of lithium-ion cells and batteries increases, controlling the outcomes of thermal runaway becomes more challenging. If the high rate of gas generation during thermal runaway is not adequately vented, commercial cell designs can rupture and explode, presenting serious safety concerns. Here, ultra-high-speed synchrotron X-ray imaging is used at >20 000 frames per second to characterize the venting processes of six different 18650 cell designs undergoing thermal runaway. For the first time, the mechanisms that lead to the most catastrophic type of cell failure, rupture, and explosion are identified and elucidated in detail. The practical application of the technique is highlighted by evaluating a novel 18650 cell design with a second vent at the base, which is shown to avoid the critical stages that lead to rupture. The insights yielded in this study shed new light on battery failure and are expected to guide the development of safer commercial cell designs.	Oct 2017
I12-JEEP: Joint Engineering, Environmental and Processing I16-Materials and Magnetism I22-Small angle scattering & Diffraction	Processing two-dimensional X-ray diffraction and small-angle scattering data in DAWN 2 J. Filik , A. W. Ashton , P. C. Y. Chang , P. A. Chater , S. J. Day , M. Drakopoulos , M. W. Gerring , M. L. Hart , O. V. Magdysyuk , S. Michalik , A. Smith , C. C. Tang , N. J. Terrill , M. T. Wharmby , H. Wilhelm Journal Of Applied Crystallography 50 DOI: 10.1107/S1600576717004708 Diamond Proposal Number(s): [12735, 10311] Show Abstract ▼ Abstract: software package for the calibration and processing of powder X-ray diffraction and small-angle X-ray scattering data is presented. It provides a multitude of data processing and visualization tools as well as a command-line scripting interface for on-the-fly processing and the incorporation of complex data treatment tasks. Customizable processing chains permit the execution of many data processing steps to convert a single image or a batch of raw two-dimensional data into meaningful data and one-dimensional diffractograms. The processed data files contain the full data provenance of each process applied to the data. The calibration routines can run automatically even for high energies and also for large detector tilt angles. Some of the functionalities are highlighted by specific use cases.	Jun 2017
	Engineering Science at the I12 Beamline at Diamond Light Source Michael Drakopoulos Synchrotron Radiation News 30, 41 - 47 DOI: 10.1080/08940886.2017.1316131 Open Access Show Abstract ▼ Abstract: Synchrotron-based engineering science covers a large field of applications. However, they are all connected in two ways. First, the very synchrotron techniques employed to study the various applications all work in the same way in that they determine structural parameters on the atomic and microscopic scale. Secondly, the portfolio of applications discussed here describes the complete life cycle of an engineering material, starting with processing of the base material—often from the melt—then the characterization of material properties, followed by the forming and joining into components, then component characterization during service, material aging, damage and failure and, finally, recycling or decommissioning. The structural problems which occur during the different stages in the life cycle of a material are complex, due to the advanced material technology of today's devices. We have created alloys for special applications, compound materials with novel properties, sophisticated bulk and surface treatments, and new forming and joining techniques. We are also concerned with the effect of the material on the environment after it has ended its service.	May 2017
I12-JEEP: Joint Engineering, Environmental and Processing	Characterising thermal runaway within lithium-ion cells by inducing and monitoring internal short circuits Donal P. Finegan , Eric Darcy , Matthew Keyser , Bernhard Tjaden , Thomas M. M. Heenan , Rhodri Jervis , Josh J. Bailey , Romeo Malik , Nghia T. Vo , Oxana V. Magdysyuk , Robert Atwood , Michael Drakopoulos , Marco Dimichiel , Alexander Rack , Gareth Hinds , Dan J. L. Brett , Paul R. Shearing Energy Environ. Sci. 5 DOI: 10.1039/C7EE00385D Diamond Proposal Number(s): [13884] Show Abstract ▼ Abstract: Lithium-ion batteries are being used in increasingly demanding applications where safety and reliability are of utmost importance. Thermal runaway presents the greatest safety hazard, and needs to be fully understood in order to progress towards safer cell and battery designs. Here, we demonstrate the application of an internal short circuiting device for controlled, on-demand, initiation of thermal runaway. Through its use, the location and timing of thermal runaway initiation is pre-determined, allowing analysis of the nucleation and propagation of failure within 18[thin space (1/6-em)]650 cells through the use of high-speed X-ray imaging at 2000 frames per second. The cause of unfavourable occurrences such as sidewall rupture, cell bursting, and cell-to-cell propagation within modules is elucidated, and steps towards improved safety of 18[thin space (1/6-em)]650 cells and batteries are discussed.	Mar 2017
I12-JEEP: Joint Engineering, Environmental and Processing	In situ HEXRD study of a Ca61Al39 metallic glass Stefan Michalik , Juraj Ďurišin , Dušan Balga , Karel Saksl , Martin Ďurišin , Michael Drakopoulos Journal Of Alloys And Compounds 687, 188 - 196 DOI: 10.1016/j.jallcom.2016.06.094 Diamond Proposal Number(s): [12163] Open Access Show Abstract ▼ Abstract: High energy X-ray diffraction (HEXRD) was used to characterize the amorphous structure of the as-prepared binary Ca61Al39 (at.%) metallic glass and its evolution during thermal loading. The investigation was performed in both reciprocal and real space by means of the first diffuse peak (FDP) analysis and the reduced atomic pair distribution function (PDF) analysis, respectively. It was found that bond lengths of the atomic CaeCa and CaeAl pairs of the as-prepared structure were 3.70 Å and 3.24 Å, respectively. The coordination number of the first coordination shell was estimated to be 11.9. The analysis of the FDP behaviour during thermal treatment proposed the existence of the elaxation temperature Tr at 150 °C. Analysis of summations of all absolute differences between two consecutive intensity curves in the region of the FDP as a function of temperature revealed two crystallization temperatures at 280 °C and 305 °C. Products of a devitrification process were identified to be alike a triclinic Ca8Al13 and monoclinic Ca13Al14 phase.	Dec 2016

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