Aerospace applications in which high heat fluxes are reached necessitate the use of unique materials to withstand these harsh environments. The need for environmental barrier coatings (EBCs) are of particular importance in limiting the oxidation of aerospace components and the volatility of the SiO2 scale commonly found in silicon-based ceramic coatings. Rare earth mono- and disilicates have been identified as promising EBCs due to their ease of application via various plasma spray processes. However, a robust examination of the insulating thermal properties of these systems has yet to be performed. To better understand the thermal processes and anisotropy associated with these disilicates, we examine the commonly used polymorph of yttrium disilicate, γ-Y2Si2O7. Using a combination of time- and frequency-domain thermoreflectance, we compare the extracted thermal conductivity maps to associated electron backscatter diffraction micrographs. The thermal conductivity maps exhibit strong anisotropy in the monoclinic structure, in good agreement with other anisotropic features of the system. The results are significant in that they are the first experimental measurements of the anisotropic thermal conductivity in a thermal barrier coating, and should provide a basis for plasma-based applications in which the potential for texturing is strong.
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E