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Current Major Research Projects:

1. Laser Additive Manufacturing of Very-High Temperature Niobium Silicide-Based Alloys

Niobium silicide-based alloys, in the application of gas turbine blades, promise significant efficiency improvements compared to current Ni-based alloys. The higher temperature capability would allow the engine to run at a higher temperature than that of current alloys, increasing engine efficiency. Nb-Si based alloys possess a lower density, due to the presence of ceramic phases such as Nb5Si3 and/or Nb3Si. This would reduce the weight of the rotating blades. However, improvements in certain properties, such as ductility, room temperature toughness and oxidation resistance are needed. The alloy must also be cost effective to manufacture if niobium silicide systems are to reach their full potential. This study focuses on the manufacturability aspect of the powder feeding laser additive manufacturing (LAM) process to engineering Nb-Si based alloy samples. Inlaser additive manufacturing (LAM) process, CAD models of the components are constructed and sliced layer by layer for laser multilayer cladding, which directly forms the component shapes. LAM has the advantage of forming near-net shapes without the use of expensive cores and moulds for the reactive Nb-Si melt. Fine microstructure and even chemical composition distribution with reduced macro-segregation are obtained. With the use of power feeding system, new Nb-Si based alloys are LAMed with varying Ti, Si, Cr, Al, Hf, V concentrations.

2. Materials and Processing Techniques for Aero-engine Turbine Components

This area of research has been carried out with collaborators from Rolls-Royce, Universities of Cambridge and Birmingham. It aims to bring knowledge-inspired decision making to production routes of aero-engine turbine blades. As an example, by detailed examination of modelling results, I originated a patent for producing new single crystals with finer microstructures - a technique is being taken forward by industry. The new processing route results in not only saving manufacturing costs but also leading to new materials with higher performance. Current research projects in this area include: 1. development of novel 2-dimentional grain selectors for selecting single crystal during casting, 2. characterising and eliminating or reducing surface defects in single-crystal turbine blades, 3. development of materials thermophysical properties database of Ni-base alloys for advanced processing.

3. Welding Techniques for Deep-sea/Sub-sea Oil and Gas Transportation Systems

The demand for deep-sea oil and gas supply is increasing due to the higher demand on energy and security of energy supply. The pipelines for transporting oil and gas are constructed by joining high strength steel linepipes that are produced through the UOE process involving seam welding (UOE linepipes are produced by forming and seam welding steel plates. UOE stands for the main forming operations involved: U-ing, O-ing and Expanding. Seam welding is performed after O-ing and before pipe Expanding.). Therefore how to achieve a defect-free seam weld with favourable microstructure and properties in UOE linepipe production is of vital importance to the pipelines especially to be laid at deep and ultra-deep waters. The current project is designed with a view to addressing these issues in terms of microstructure evolution and defect formation and avoidance during linepipe seam welding from the first principles, and meanwhile delivering a computer based system for practical applications.

4. Interaction at Solid/Liquid Interfaces from Actomic Scale to Micro-scale using Synchrontron X-ray and a combined calorimetry and X-ray Radiography

The aim of this proposal is to develop a novel combined Calorimetry-X-Ray Radiography (X-Cal) system to characterise phase transformations In Situ via thermodynamic and morphological measurement at meso- and micro- length scales. It is expected that the first such combined technique will be able to provide critical information and promote a better fundamental understanding of phase transformations and their influence upon the nature of the processing-structure-property relationship. The obtained quantitative information will be of great useful to British Industry in modelling and optimising existing processes in the metals and materials sectors. Synchrotron X-ray experiments at Diamond (diamond.ac.uk) will be carried out for the atomic scale characterisation and micro-scale experiments will be carried at Leicester using a Micro-focus X-ray and a laboratory made equipment to measure solid-liquid interfacial energies. The cutting edge research will provide a deep insight into the atomictic scale interface interaction which are important for the present and future technologies such as fluidity, nucleation, crystallization, as well as chemical reactions for microfluidic devices or semiconductor nanowires. The application of the research outcome will guide the construction of deep-sea gas and oil transportation systems to meet the increasing demand on energy and security of energy supply.

5. Modelling of Solidification

By using dynamic adaptive meshing (DAM) algorithm, DAM allows great increases in computational efficiency, making possible simulations of microstructures that are accurately resolved down to tens of nanometers at the solid-liquid interface. Therefore DAM can simulate large-scale solidification microstructures in parameter regimes previously inaccessible through conventional fixed-grid techniques, enabling a complete description of solidification.

Past Major Research Projects

FP7 Collaborative Project on Modelling of Interface Evolution in Advanced Welding (MIntweld)

Prof. Dong led a consortium for an European Framework (FP7) project on the Modelling of Interface Evolution in Advanced Welding (MintWeld). This 4-year multi-million euro research project started in September 2009 and ended in November 2014. The project developed an accurate, predictive, and cost-effective modelling tool that could find widespread application in the relevant European metals industry for penetrating novel markets of high economic and strategic importance, an essential task to ensure that Europe maintains its competitiveness. The consortium includes well known academic partners (University of Leicester UK -Coordinator, University College Dublin Ireland, University of Oxford UK, NTNU Norway, Royal Institute of Technology Sweden, Delft University of Technology Netherlands, and the Ecole Polytechnique Fédérale de Lausanne Switzerland) and partners representing the major European steel industries (CORUS UK, The Welding Institute UK, Institute of Welding Poland, and FRENZAK Sp. Poland).  Mintweld project website: www.le.ac.uk/mintweld .

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