Slow sintering in garnet-containing Y and Gd zirconate–aluminate mixtures for thermal barrier coatings |
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Authors: | Yueh-Cheng Yu Eeshani P Godbole Josselyne Berrios Nethmi Hewage David L Poerschke |
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Affiliation: | Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA |
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Abstract: | 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. |
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Keywords: | aluminates rare-earth oxides sintering thermal barrier coatings zirconates |
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