Corrosion resistance of nonstoichiometric gadolinium zirconate coatings against CaO-MgO-Al2O3-SiO2 silicate

Gadolinium zirconate is a promising next-generation thermal barrier coating material and its CaO-MgO-Al2O3SiO2 (CMAS) resistance needs to be further increased. In this study, three gadolinium zirconate coatings with different Gd/Zr ratios are successfully prepared via atmospheric plasma spray using amorphous feedstock. Their mechanical properties and corrosion resistance are investigated. The Young?s moduli and hardness of as-sprayed coatings are comparable with the gadolinium zirconate coatings reported in previous literature. Furthermore, the higher Gd content promotes the formation of the Gd-apatite and the depletion rate of CMAS corrosion. As a result, the infiltration depth of Gd2.3Zr1.7O6.85 coating after 24 h annealing decreases up to 35 % compared with those of Gd2.0Zr2.0O7.0 and Gd1.8Zr2.2O7.1, exhibiting an enhanced long-term corrosion resistance. This work develops a viable fabrication method to produce non-stoichiometric gadolinium zirconate coatings with tailorable CMAS corrosion resistance and is expected to promote the future design of thermal barrier coatings with long service life.

Automated summary

The study successfully prepared three different Gd/Zr ratio gadolinium zirconate coatings, with the higher Gd content promoting the formation of Gd-apatite and reducing the infiltration depth of the coatings after annealing, resulting in enhanced long-term corrosion resistance against CMAS.