Microstructural investigations of plasma-sprayed yttria partially stabilized zirconia TBC (in relation to thermomechanical resistance and high-temperature oxidation mechanisms)

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Journal of Engineering for Gas Turbines and Power; (United States)

DOI:https://doi.org/10.1115/1.2906802· OSTI ID:7237175

Alperine, S; Lelait, L ^[1]

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1. O.N.E.R.A., Chatillon (France). Materials Science Dept.

This study deals with microstructural investigations of plasma-sprayed yttria partially stabilized zirconia thermal barrier coatings, performed by classical and analytical transmission electron microscopy. The aim of the study was to determine eventual relationships between coating microstructure and toughness. The ceramic/metal interface, which plays an important role during TBC thermomechanical solicitation, has also been studied. In the 6--8 wt. percent Y[sub 2]O[sub 3] range, the metastable tetragonal t[prime] phase is observed, showing special faulted microstructural features, such as grain twinning and antiphase boundary planes. Moreover, after high-temperature annealing in air, a very fine and stable precipitation of the equilibrium cubic phase appears. It is believed that these microstructural elements could act as crack deviation sites and enhance the coatings' intrinsic toughness. Microstructural investigations of the alumina scales grown during high-temperature annealing reveal yttrium segregation at oxide grain boundaries as well as significant quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain boundary oxygen diffusion mechanism. The presence of zirconium inside the alumina grains suggests that Al[sub 2]O[sub 3] also partially forms by chemical reduction of ZrO[sub 2] by Al.

• OSTI ID: 7237175
• Journal Information: Journal of Engineering for Gas Turbines and Power; (United States), Vol. 116:1; ISSN 0742-4795
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
36 MATERIALS SCIENCE
GAS TURBINES
HEAT RESISTANT MATERIALS
MICROSTRUCTURE
YTTRIUM OXIDES
ZIRCONIUM OXIDES
SPRAYED COATINGS
CHALCOGENIDES
COATINGS
EQUIPMENT
MACHINERY
MATERIALS
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TURBINES
TURBOMACHINERY
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
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360201 - Ceramics
Cermets
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