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3782 |
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Lanthanum zirconates coatings deposited by plasma spray |
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Mario Tului* / Centro Sviluppo Materiali S.p.A., Italy Rosanna Pileggi / Centro Sviluppo Materiali S.p.A., Italy Francesco Marra/ Sapienza University of Rome, Italy Giovanni Pulci/ Sapienza University of Rome, Italy Teodoro Valente/ Sapienza University of Rome, Italy |
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In the recent years lanthanum zirconate La2Zr2O7 (LZ) and lanthanum cerium zirconate La2 (Zr0.7 Ce0.3)2O7, (LZC) were investigated for their potential applications as high temperature TBC (Thermal Barrier Coatings), because traditional and currently used materials have reached the limits of their temperature capabilities. As the selection of TBC is restricted by some basic requirements, composite LZC with mixed fluoritic-pyrochloric structure was proposed as candidate material due to its low thermal conductivity and phase stability up to the operation temperature. In this work La2Zr2O7 and La2 (Zr0.7 Ce0.3)2O7 single layer coatings were deposited by Atmospheric Plasma Spray (APS) starting from commercial oxides, after agglomeration by Spray Drying. The effect of optimized thermal treatments (TT) on agglomerated powders were evaluated in terms of deposition efficiency and compared with results on coatings obtained from not treated powders. The coatings were characterized by XRD and SEM-EDS, showing that no decomposition took place during thermal spraying of the TT powders. Mechanical testing was carried out at room and at high temperature on the produced coatings, in order to create a data base of the mechanical properties to be used in the design of innovative TBC, constituted by different ceramic materials, including lanthanum zirconates. |