Preparation and corrosion resistance of nonstoichiometric lanthanum zirconate coatings

• Published in: Journal of the European Ceramic Society 2020-07, Vol.40 (8), p.3122-3128
• Main Authors: Zhang, Chengguan, Zhao, Juanli, Yang, Lan, Zhou, Yanchun, Wang, Qinfan, Chen, Hongfei, Yang, Guang, Gao, Yanfeng, Liu, Bin
• Format: Article
• Language: English
• Subjects: Composition; Corrosion resistance; Lanthanum zirconate; Thermal barrier coating
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2020.02.045

Lanthanum zirconate is a promising thermal barrier coating material owing to its excellent thermophysical properties and La plays the key role in its corrosion resistance. Here, an amorphous precursor is used as raw feedstock material so as to synthesize lanthanum zirconate coatings with tailorable composition by atmospheric plasma spray (APS). Three lanthanum zirconate coatings of La1.7Zr2.3O7.15, La2.0Zr2.0O7.0 and La2.3Zr1.7O6.85 are fabricated. Furthermore, the corrosion resistance of the as-sprayed coatings against CaO-MgO-Al2O3-SiO2 at 1250℃ is investigated. The increased La content promotes the formation of a sealing layer of the crystalline Ca2La8(SiO4)6O2 apatite, which slows down the penetration of molten CaO-MgO-Al2O3-SiO2. Therefore, the infiltration rate of the La2.3Zr1.7O6.85 coating decreased up to 42.6 % compared with the other two coatings. This work develops a feasible preparation strategy to control the La composition for the improved corrosion resistance, which is expected to guide the future coating design and synthesis for the materials with big composition changes during the APS process.