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Problems
Electron beam physical vapour deposition, plasma spraying techniques, pulsed ion and electron beam surface modification technologies have been used in aviation industry for engineering of thermal barrier and oxidation resistant coatings. High R&D cost is the only drawback of these efficient and environment friendly methods of material treatment. In order to reduce time-to-market and R&D costs it is therefore essential to complement a conventional trial and error approach to selecting operational parameters by using mathematical modelling and scientific computing… Read more
The operational challenges of only one surface engineering technique, namely the intense current electron beam treatment, are proposed for consideration at the Study Group. The following three problems have been selected for investigation.
Problem 1. Repair/overhaul of the protective coatings of gas turbine blades
Thermal barrier and corrosion resistant coatings degrade with time and require replacement. The removal of the used coatings is followed by the deposition of new ones. It has been proposed that old coatings can be removed by electron beam ablation.
Problem 2. Cracking in turbine blades with cooling holes
The incorporation of extensive numbers of film-cooling holes into hollow gas turbine blades maximises the heat pick-up of the cooling air, allowing the turbine entry temperature increase with associated improvements in gas turbine engine efficiency. However, holes can act as stress concentrators and preferred cites for crack initiation during electron beam surface treatment.
Problem 3. Redistribution of alloying elements by the intensive current electron beam irradiation
It has been observed that the intensive current electron beam treatment leads to noticeable improvement of corrosion resistance due to the redistribution of alloying elements in the surface layers of irradiated materials. A clearer insight needs to be gained in order to harness the potential of this phenomenon.