CMCs will replace the Ni-based super-alloys as the structural material of gas turbines on the hot zones, whereas EBCs will protect CMCs against environment and high temperature. These turbine parts today are made of high temperature Ni-based metallic super-alloys and protected against high temperature and environment by a ZrO 2-7-8wt.%Y 2O 3 (YSZ) thermal barrier coating (TBC). In the future, it is expected that nozzles, blades and afterburners will also be manufactured from CMCs. These components include the combustion chambers and shrouds. Those are key society requirements in the 21 st century.ĮBCs and CMCs are now slowly being introduced as parts of the components located in hot zones (sections) of aerospace gas turbines. The driving force behind this technology is found on the non-stoppable demand for more efficient and environmentally friendly propulsion and energy generation systems (Spitsberg and Steibel (Ref 1) and Padture (Ref 2)). The content of this paper shall be understood by anyone with basic knowledge in materials processing and surface engineering.įrom a materials engineering point-of-view, the combined application of environmental barrier coatings (EBCs) and ceramic matrix composites (CMCs) will be the greatest disruptive technology for enabling the manufacturing of ceramic-based gas turbines. Finally, highlights on how EBCs/CMCs are tested at high temperature will be provided. It will explain the non-stop driving force for increasing combustion temperatures show the basic concepts of CMCs, the paramount need of EBCs, and the complexity of creating EBC architectures via air plasma spray (APS). The objective of this tutorial paper is to present the reader how these feats are achieved by the concomitant combination of imaginative engineering. In addition, according to “conventional wisdom”, some of these engineering feats are in fact opposing each other (e.g., higher operation temperatures versus lower emissions). Although these achievements are true, they are generally not well-explained to the reader on how together they come to be. Among these achievements, it is typically highlighted (i) turbine weight reduction, (ii) reduced fuel consumption, (iii) higher operation temperatures, (iv) superior thrust-to-weight ratio and (v) lower emission of toxic gases to the atmosphere. There are many sets of information in the literature (e.g., papers, books and websites) about the great achievements that are expected for aerospace gas turbine engines by the employment of ceramic matrix composites (CMCs) and thermally sprayed environmental barrier coatings (EBCs) in their hot zones (e.g., combustion chambers, vanes, shrouds, blades and afterburners).
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