Residual stress analysis of plasma sprayed thermal barrier coatings

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:82862

Scardi, P; Lutterotti, L; Orsini, P G ^[1]; Bertamini, L ^[2]

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1. Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali
2. Centro Sviluppo Materiali, Trento (Italy)

The residual stress field produced by the spray process has a marked influence on the thermomechanical behavior of Thermal Barrier Coatings (TBCs) used for automotive and aeronautical applications. Samples coated with Yttria-Partially-Stabilized Zirconia (YPSZ) and sprayed under different cooling conditions, were analyzed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The microstructure was studied using the conventional Bragg-Brentano geometry with the purpose of determining the phase composition, stabilizer content, crystallite size and microstrain distribution. The data were processed by a numerical procedure that permits the simultaneous modeling of the entire XRD pattern. The parallel beam geometry was employed to investigate the macrostress field on the surface of the TBC, using the sin{sup 2}{psi} method. The microstructure resulting from the spraying does not allow for the presence of a high residual macrostress. Although the thermal history of the composite substrate-coating leads to the development of a high thermal strain, the resulting stress is released by a complex cracking and sliding of the lamellar structure. It was evidenced how critical operating conditions are. By changing the cooling system layout, the surface residual stress of the ceramic coating was strongly affected and very different phase composition were obtained, together with a different microstructure.

• OSTI ID: 82862
• Report Number(s): CONF-940113--; ISBN 0-7918-1190-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
EXPERIMENTAL DATA
HEAT ENGINES
MICROSTRUCTURE
PROTECTIVE COATINGS
RESIDUAL STRESSES
SPRAYED COATINGS
X-RAY DIFFRACTION
YTTRIUM OXIDES
ZIRCONIUM OXIDES