USER CASE STUDY: Paul Withey (Rolls Royce PLC)
“In order to remain competitive in the aerospace engine market, investment into both cutting-edge research and new engineering talent is needed. The Innovative metals processing CDT provides Rolls Royce with the opportunity to streamline investment for maximum return. This research is a promising project with the potential for a large increase in gas turbine engine efficiency. The Centre also provides training for its students with taught modules and practical work, creating knowledgeable and innovative engineers that Rolls Royce and other high added value manufacturing industries in the UK need.” – Prof Paul Withey, PhD, CEng, FIMMM, FICME, Rolls-Royce Engineering Associate Fellow in Casting Technology
Nickel-based superalloys, currently used in turbine blades of gas turbine engines, have reached a plateau in temperature capability. Increasing the operating temperature of jet engines increases their efficiency. A new material is needed that can withstand the increased temperatures required. Rolls Royce PLC is sponsoring research students at IMPaCT to investigate one such material that shows promise in being able to replace nickel-based superalloys – niobium silicides. They possess a high liquidus temperature of (1880°C) and a low density of (7g cm-3 compared to 9g cm-3 for nickel-based superalloys). There are however material properties that need improvement if these materials are to succeed. Room temperature ductility is low, medium to high temperature oxidation resistance is poor and the material is difficult to cast due to high temperature reactions with mould materials such as alumina and silica. Improvement in these areas will be the focus of this collaborative project between IMPaCT and Rolls Royce PLC, which involves seven PhD students in total.
IMPaCT student Adam Allen has travelled to a project collaborator, Northwestern Polytechnical University in China, to fabricate niobium silicide-based alloys using laser additive manufacture (pictured). This relatively new technique eliminates the requirement for a mould, hence eliminating this processing issue. EPSRC equipment funding with matched funding from Leicester has invested in an induction furnace capable of directional solidification at the very high temperatures required. This technique is similar to the current technique for casting nickel-based superalloys. A variety of experimental techniques are being used to characterise these alloys, from x-ray diffraction (XRD) to transmission electron microscopy (TEM). IMPaCT student Ruiyao Zhang has conducted neutron diffraction experiments at the Diamond Light Source facility in Harwell as part of his first year summer project.