In order to improve jet engine efficiency and performance, manufacturers have been trying overthe last five decades to increase the working temperature of gas turbines. This was achieved byimproving materials performance and component design. The latter technological breakthrough is known as Thermal Barrier Coating (TBC), which consists of applying a ceramic insulating layer on theinternally cooled parts of the turbine. This technology is now applied in military and civil aircraftengines, and allows temperature improvement up to 150°C. However, understanding degradationmechanisms and improvement in manufacturing still remain important activities in turbinedevelopment.This PhD thesis was founded by a turbine manufacturer, Snecma, with the aim of developing anew type of high temperature coating. The ceramic topcoat of TBC’s is currently deposited on typical binary platinum aluminide diffusion coating or NiCoCrAlY overlay, called bondcoat, which stands at thecomponent/ceramic interface. In this work, a new kind of intermetallic was studied, a ternary compound of the Ni-Al-Pt system, called α.phase, and a manufacturing route to deposit it as an overlaycoating was developed.The main result of this thesis is the achievement of a reliable, reproducible, and controlledmanufacturing process of α-phase coatings. This process is based on sputtering multlilayers of puremetals, followed by the annealing of the layered coating. Produced coatings are thinner than commercial systems as they are richer in platinum (typically 5 m instead of 70 m), hence the so-called name of "low mass bondcoat".Such high temperature intermetallic coatings were characterised during this project (by XRD,SEM, EDS, FIB and TEM), as well as their isothermal and thermal cycled oxidation behaviour at hightemperature. These systems were topped with a commercial ceramic layer in order to assess theirpotential as bondcoats for a full TBC system. Lifetimes are relatively promising, and failure modes,which will be described and discussed, are very specific compared to state of the art coatings. Thisspecificity is proven to be due to the non conventional deposition route rather than to the new compound used as a bondcoat.
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