Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure

first_pagesettingsOrder Article Reprints Open AccessArticle Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure by Giulia Di Iorio,Laura Paglia *ORCID,Giulia PedrizzettiORCID,Virgilio GenovaORCID,Francesco MarraORCID,Cecilia BartuliORCID andGiovanni PulciORCID INSTM Reference Laboratory for Materials and Surface Engineering, Sapienza University of Rome, Eudossiana 18, 00184 Rome, Italy * Author to whom correspondence should be addressed. Coatings 2023, 13(9), 1602; https://doi.org/10.3390/coatings13091602 Original submission received: 10 August 2023 / Revised: 31 August 2023 / Accepted: 11 September 2023 / Published: 13 September 2023 Downloadkeyboard_arrow_down Browse Figures Review Reports Versions Notes Abstract SiC/SiC ceramic matrix composites (SiCf/SiC CMCs) are regarded as the new materials for the hot-section components of aircraft gas turbine engines, since they have one-third of the density of metallic superalloys, a higher temperature capability, good mechanical strength, and excellent thermal shock resistance. However, high-temperature water-vapor-rich combustion gases can induce severe surface recession phenomena in SiC/SiC leading to component failure. For this reason, it is necessary to design protective coatings, i.e., environmental barrier coatings (EBCs), able to protect the SiC/SiC surface in combustion environments. In the present work, ytterbium monosilicate (Yb2SiO5), stable when exposed to water vapor at high temperatures, and ytterbium disilicate (Yb2Si2O7), characterized by a thermal expansion coefficient closer to that of the substrate, were selected for a multilayer EBC system. EBCs were processed using the atmospheric plasma spray (APS) technique. A set of deposition parameters were tested, varying the power of the torch, and the composition and microstructure of the deposited coatings were studied in terms of porosity, crack density, and post-deposition phase retention by performing SEM, EDS, and XRD analysis. The results allow for the definition of the influence of deposition parameters on the final properties of multilayer EBC coatings.