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 + 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 forms perovskite aluminate instead garnet showed faster densification after the metastable decomposes. At 1500°C, Y-free sample also fastest initial rate, whereas there was more divergence in rate for samples Gd. The zirconate–aluminate with equimolar shows slowest 1500°C retains ∼25% porosity 250 h. results highlight possibilities designing compliant thermal barrier coatings can retain significant 1400°C higher.