Oxide Composite Materials for Thermal Barrier Coating: Synthesis and Characterization
25th Advanced Aerospace Materials and Processes (AeroMat) Conference and Exposition
16-19 Jun 2014
|| Statopoulos Vassilis
, Sadykov Vladislav Aleksandrovich
, Pavlova Svetlana Nikolaevna
, Kuznetsova Tatiana Georgievna
, Bespalko Yulia Nikolaevna
, Fedorova Yuliya E.
, Larina Tatyana Viktorovna
, Khabibulin Dzhalil Faridovich
, Krieger Tamara Andreevna
, Ishchenko Arcady Vladimirovich
, Salanov Aleksei Nikolaevich
, Stoyanovskii Vladimir Olegovich
, Ivanov Vyacheslav Pavlovich
, Gulyaev Roman Vladimirovich
Boreskov Institute of Catalysis SB RAS
Technological Educational Institute of Sterea Ellada
Refractory oxide nanocomposites with a low thermal conductivity, improved thermal shock resistance and better creep behaviour are promising as advanced thermal barrier coatings. In this work, nanocomposites comprised of La2Zr2O7 (pyrochlore structure) and LaAlO3 (perovskite structure) were prepared and studied both as bulk materials and thin layers supported on top-coat YSZ layer on Ni superalloy substrate. Complex oxides were prepared via several methods including Pechini route, soft mechanochemistry, starch templating, microwave heating of salts mixture with carbon and hydroxides coprecipitation by ammonia followed by hydrothermal aging. Nanocomposites were prepared by ultrasonic treatment of the mixture of oxides or hydroxide precursors in isopropanol with addition of surfactants, and their thin layers on YSZ/NiCr superalloy substrate were supported by slip casting of these suspensions. Genesis of bulk composites and coatings texture, composition and real/defect structure after annealing under air up to 1200 oC were studied by combination of diffraction methods (high resolution SEM and TEM with EDX, XRD) and spectroscopic methods (27Al and 139La MAS NMR, FTIRS of lattice modes, UV-Vis, Raman, XPS, SIMS, laser-excited luminescence spectra). For separate oxides, well-crystalline samples are obtained after sintering at 1100 oC, though surface layers are disordered due to their enrichment by smaller Zr and Al cations. In nanocomposites substantial disordering of coordination spheres of cations and residual mesoporosity remain even after sintering at 1300 oC, while redistribution of cations between phases is small. Thin nanocomposite layers on YSZ/NiCr sintered up to 1300 oC demonstrate a good matching with YSZ along with smaller particle sizes of pyrochlore and perovskite phases and their higher disordering as compared with bulk nanocomposite. Good thermal shock resistance (heating up to 1100 oC) was demonstrated for this multilayer design of thermal barrier coating.
Support by THEBARCODE project (№310750-FP7) is gratefully acknowledged.