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Phase Transformations of Plasma‐Sprayed Zirconia–Ceria Thermal Barrier Coatings
Author(s) -
Lee Eui Yeol,
Sohn Yongho,
Jha Santosh K.,
Holmes John W.,
Sisson Richard D.
Publication year - 2002
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.1151-2916.2002.tb00405.x
Subject(s) - materials science , thermal barrier coating , tetragonal crystal system , cubic zirconia , phase (matter) , scanning electron microscope , coating , monoclinic crystal system , analytical chemistry (journal) , composite material , chemical engineering , mineralogy , crystallography , crystal structure , chemistry , chromatography , ceramic , organic chemistry , engineering
Phase constituents and transformations of plasma‐sprayed thermal barrier coatings (TBCs) with CeO 2 ‐stabilized ZrO 2 (CSZ; 16–26 wt% CeO 2 ) have been investigated using X‐ray diffractometry (XRD), scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS). The as‐coated CSZ coatings with 16 and 18 wt% CeO 2 consisted only of the nonequilibrium tetragonal ( t ′) phase. A mixture of the t ′ and the nonequilibrium cubic ( c ′) phases was observed for the as‐coated CSZ coatings containing 20–26 wt% CeO 2 . During 65 min cyclic oxidation at 1135°C (45 min hold time) in air, the t ′ or the mixture of the t ′ and the c ′ phases decomposed to the equilibrium tetragonal ( t ) and the equilibrium cubic ( c ) phases. Some of the t phase transformed to the monoclinic ( m ) phase on cooling. More m phase was observed to develop in the CSZ coating containing 16 wt% CeO 2 than in the other coatings. More m phase was observed on the top surface than on the bottom surface of the CSZ coating. Spalling of the plasma‐sprayed CSZ coating during thermal cycling occurred after 230 cycles for the CSZ coating containing 16 wt% CeO 2 , whereas the lifetime of the CSZ coatings with 18–26 wt% CeO 2 ranged between 320 and 340 cycles.