Slow sintering in garnet‐containing Y and Gd zirconate–aluminate mixtures for thermal barrier coatings

Mixtures of rare‐earth zirconates and aluminates containing Y or Y + Gd that form a two‐phase garnet–fluorite mixture exhibit much slower sintering than pure fluorite at 1400°C. An equivalent Y‐free, Gd‐containing composition that forms a perovskite aluminate instead of garnet showed faster densific...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2023-08, Vol.106 (8), p.4519-4525
Main Authors: Yu, Yueh‐Cheng, Godbole, Eeshani P., Berrios, Josselyne, Hewage, Nethmi, Poerschke, David L.
Format: Article
Language:English
Subjects:
Aluminates
Coatings
Densification
Fluorite
Gadolinium
Garnets
Mixtures
Perovskites
Porosity
rare‐earth oxides
sintering
Sintering (powder metallurgy)
Thermal barrier coatings
Zirconates
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Summary:Mixtures of rare‐earth zirconates and aluminates containing Y or Y + Gd that form a two‐phase garnet–fluorite mixture exhibit much slower sintering than pure fluorite at 1400°C. An equivalent Y‐free, Gd‐containing composition that forms a perovskite aluminate instead of garnet showed faster densification after the metastable garnet decomposes. At 1500°C, the Y‐free sample also showed the fastest initial sintering rate, whereas there was more divergence in the sintering rate for the samples containing Y + Gd. The zirconate–aluminate with equimolar Y + Gd shows the slowest densification at 1500°C and retains ∼25% porosity after 250 h. The results highlight possibilities for designing compliant thermal barrier coatings that can retain significant porosity at 1400°C or higher.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.19121