Reaction Products from High Temperature Treatments of (LaxGd1−x)2Zr2O7 System and Volcanic Ash Powder Mixtures.

Autor: Guijosa-Garcia, Cynthia Y., Rivera-Gil, Marco Antonio, Ramana, C. V., Naraparaju, Ravisankar, Schulz, Uwe, Muñoz-Saldaña, Juan
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Zdroj: JOM: The Journal of The Minerals, Metals & Materials Society (TMS); Jul2022, Vol. 74 Issue 7, p2791-2808, 18p
Abstrakt: Rare-earth zirconate (REZ) pyrochlores, specifically (La,Gd)2Zr2O7, are promising alternatives to substitute 7YSZ in thermal barrier coatings (TBC) due to their increased phase stability and resistance to calcium-magnesium-aluminosilicate (CMAS)-based damage at high temperatures. This work analyses the reaction products of isothermal treatments at 1250°C of (LaxGd1−x)2Zr2O7 powder mixtures in reaction with natural volcanic ashes (VAs) with different chemical compositions (Popocatepetl, Colima, and Eyjafjallajökull). The chemical composition in the (LaxGd1−x)2Zr2O7 system showed a strong influence on the formation of reprecipitation products (Zr,Gd,La oxides), reactive crystallization products (La-Gd apatites, lanthanum silicates, zirconolite, and garnets), and intrinsic crystallization products (hematite-like structures). The formation of garnets, which enhances the mitigation effect against molten VAs/Si deposit damage, was observed more promptly on (La0.5Gd0.5)2Zr2O7 promoted by high contents of Fe, Ca, Ti, and Mg on VAs. Thus, the (La0.5Gd0.5)2Zr2O7 system stands as a possible candidate to overcome today's threats for the integrity of current TBCs. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index