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

Guijosa-García, Cynthia Y.; Rivera-Gil, Marco Antonio; Ramana, C. V.; Naraparaju, Ravisankar; Schulz, Uwe; Muñoz-Saldaña, J.

doi:10.1007/s11837-022-05302-3

Cited by 5 publications

(3 citation statements)

References 39 publications

(94 reference statements)

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“…Apatite and Fluorite: The formation of apatite (Ca 2 Gd 8 (SiO 4 ) 6 O 2 ) as an initial reaction product due to its high reaction kinetics was observed for various rare-earth zirconates with a large variety of CMAS and VA compositions and has been described intensively in the literature [7,39,41,[44][45][46]. In this study, it formed with all three deposits, both at an initial state (10 min) and at long annealing times (up to 50 h).…”

Section: Influence Of the Chemical Composition Of The Cmas On The Rea...mentioning

confidence: 99%

Microstructure Refinement of EB-PVD Gadolinium Zirconate Thermal Barrier Coatings to Improve Their CMAS Resistance

et al. 2023

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Rare-earth zirconates are proven to be very effective in restricting the CMAS attack against thermal barrier coatings (TBCs) by forming quick crystalline reaction products that seal the porosity against infiltration. The microstructural effects on the efficacy of Electron Beam-Physical Vapor Deposition gadolinium zirconate (EB-PVD GZO) against CMAS attack are explored in this study. Four distinct GZO microstructures were manufactured and the response of two selected GZO variants to different CMAS and volcanic ash melts was studied for annealing times between 10 min and 50 h at 1250 °C. A significant variation in the microstructural characteristics was achieved by altering substrate temperature and rotation speed. A refined microstructure with smaller intercolumnar gaps and long feather arms lowered the CMAS infiltration by 56%–72%. Garnet phase, which formed as a continuous layer on top of apatite and fluorite, is identified as a beneficial reaction product that improves the CMAS resistance.

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Section: Influence Of the Chemical Composition Of The Cmas On The Rea...mentioning

confidence: 99%

Microstructure Refinement of EB-PVD Gadolinium Zirconate Thermal Barrier Coatings to Improve Their CMAS Resistance

et al. 2023

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“…Zirconia stabilized with 7% weight of yttria (7YSZ) is the most widely used materials for this purpose. However, 7YSZ possesses a low resistance to Si-based particle infiltration at high operating temperatures [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…Lanthanum gadolinium zirconate (LGZO50), with pyrochlore phase, exhibits excellent features as a thermal barrier material and possesses a high resistance to siliceous particles infiltration at operating temperatures, around 1250 ºC [2,4], due to the formation of a thin apatite (Ap) layer that stops melt infiltration [3,5]. Additionally, monoclinic zirconia (m-ZrO2), with globular morphology, has also been reported as a reaction product [2]. For these excellent resistance against Si-based melts, rare earth zirconate such as LZO has captured the attention of the scientific community.…”

Section: Introductionmentioning

confidence: 99%

Phase identification on infiltrated thermal barrier materials by 2D Raman spectroscopy

Bedoya Trujillo,

Herrera Rodríguez,

Perez-Bedoya

et al. 2023

Enhanced Spectroscopies and Nanoimaging 2023

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Thermochemical degradation of thermal barrier coatings generated by the infiltration of siliceous debris at high temperatures is considered a serious threat by aircraft industry due to phase destabilization of the thermal barrier material induces changes on its properties. Most materials-based strategies to mitigate the infiltration aim to promote the reactive crystallization of phases such as apatite. In this work, 2D Raman spectroscopy was carried out over the cross sections of lanthanum-gadolinium zirconate ceramic samples infiltrated by Colima and Popocatepetl volcanic ashes at 1250 °C for 10 h to identify the phases reprecipitated after infiltration. Raman mappings showed the characteristic peaks and the distribution of reprecipitated phases such as rare-earth apatite, monoclic and tetragonal zirconia. Additionally, rare-earth zirconate ceramics were identified by the characteristic F2g band of the pyrochlore structure. At the reaction layer, two zones were observed. Zirconia phases reprecipitating right at the upper zone while rare-earth apatite reprecipitating at the lower zone. For apatite, the peak corresponding to stretching vibrations of Si-O tetrahedra shows shifting to higher wavenumber values as gadolinium content increases in the rare-earth zirconate infiltrated. The 2D Raman spectroscopy was very effective to observe the distribution of the reprecipitated phases in addition to correlate the influence of gadolinium in the formed apatite. A correlation between infiltration depth and bands were confirmed.

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High temperature infiltration behavior and reaction characteristics of Colima volcanic ashes on gadolinium zirconate coatings deposited by atmospheric plasma spraying

Bedoya-Trujillo,

Gutiérrez-Pérez,

Pérez

et al. 2024

emergent mater.

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Volcanic ashes are considered a serious threat to the aircraft industry. At high temperatures, they inflict severe thermochemical damage to the typical 7 wt.% yttria-stabilized zirconia thermal barrier coatings that protect the aircraft turbine. There is a need to evaluate alternative materials with excellent resistance to infiltration of molten siliceous particles, such as gadolinium zirconate. In this work, free-standing thermal barrier coatings of gadolinium zirconate were manufactured by atmospheric plasma spraying, varying deposit parameters to obtain different relative densities to evaluate the infiltration of molten Colima volcanic ashes for 1 h and 10 h at 1250 °C. The infiltration depth and the reaction products resulting from each interaction, were studied by different characterization techniques. In general, the coatings show high resistance to the infiltration of the volcanic ashes, reaching infiltration depths between 50 µm and 80 µm after 10 h of infiltration time. In this sense, gadolinium zirconate coatings are excellent candidates against the infiltration of Colima volcanic ashes compared to the typical yttria-stabilized zirconia-based thermal barrier coatings.

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

Cited by 5 publications

References 39 publications

Microstructure Refinement of EB-PVD Gadolinium Zirconate Thermal Barrier Coatings to Improve Their CMAS Resistance

Microstructure Refinement of EB-PVD Gadolinium Zirconate Thermal Barrier Coatings to Improve Their CMAS Resistance

Phase identification on infiltrated thermal barrier materials by 2D Raman spectroscopy

High temperature infiltration behavior and reaction characteristics of Colima volcanic ashes on gadolinium zirconate coatings deposited by atmospheric plasma spraying

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