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Long‐Term Behavior and Application Limits of Plasma‐Sprayed Zirconia Thermal Barrier Coatings
Author(s) -
Langjahr Petra A.,
Oberacker Rainer,
Hoffmann Michael J.
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00833.x
Subject(s) - thermal barrier coating , materials science , monoclinic crystal system , tetragonal crystal system , microstructure , temperature cycling , phase (matter) , cubic zirconia , scanning electron microscope , sintering , composite material , analytical chemistry (journal) , crystallography , thermal , crystal structure , thermodynamics , ceramic , chemistry , physics , organic chemistry , chromatography
Investigations of changes in phase composition, mechanical properties, and microstructure of ZrO 2 ‐based plasma‐sprayed thermal barrier coatings (TBCs) with 8 mol% CeO 2 , 19.5 mol% CeO 2 /1.5 mol% Y 2 O 3 , 35 mol% CeO 2 , and 4.5 mol% Y 2 O 3 after long‐term heat treatments at typical operation temperatures (1000°–1400°C) are presented. Experimental studies include X‐ray diffractometry, mechanical testing, and scanning electron microscopy. Thermal cycling experiments also have been performed. TBCs with 8 mol% CeO 2 contain mainly the tetragonal equilibrium phase and, therefore, show rapid failure because of the high amount of tetragonal → monoclinic phase transformation, even after relatively short heat treatments (1250°C/1 h). In the case of the other systems that consist mainly of the tetragonal or cubic nonequilibrium phases, TBCs with 19.5 mol% CeO 2 /1.5 mol% Y 2 O 3 or 35 mol% CeO 2 reveal a smaller amount of monoclinic phase after long‐term heat treatments (1250°C/1000 h) compared with TBCs containing 4.5 mol% Y 2 O 3 . TBCs containing 35 mol% CeO 2 show a higher degree of sintering than the TBCs with 19.5 mol% CeO 2 /1.5 mol% Y 2 O 3 and, therefore, a greater increase of the elastic modulus. Among the systems investigated, TBCs containing 4.5 mol% Y 2 O 3 exhibit the highest resistance to failure in thermal‐cycling experiments.