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Evolution of microstructural and mechanical properties of lanthanum zirconate thermal barrier coatings at high temperature

TitleEvolution of microstructural and mechanical properties of lanthanum zirconate thermal barrier coatings at high temperature
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2015
AuthorsDi Girolamo, G., Marra F., Schioppa M., Blasi C., Pulci G., and Valente T.
JournalSurface and Coatings Technology
Volume268
Pagination298-302
ISSN02578972
KeywordsBending tests, Ceramic thermal barrier coatings, Coatings, Curvature measurement, Elastic moduli, Inelastic deformation, Lamellar microstructure, Lanthanum, Lanthanum zirconate, Mechanical properties, Microstructure, Plasma jets, Plasma spraying, Porous microstructure, Silicon carbide, Sintering, Specific heat, Sprayed coatings, Stress relaxation, Stresses, Thermal aging, Thermal barrier coatings, Thermal expansion, Thermal expansion coefficients, Young's Modulus
Abstract

Ceramic thermal barrier coatings (TBCs) are advanced systems for more efficient turbine engines. In this work, thick lanthanum zirconate TBCs were fabricated by Air Plasma Spraying (APS). The coatings showed a lamellar microstructure containing splat boundaries, pores and microcracks. After thermal exposure at 1200 and 1350. °C the partial sintering of the porous microstructure occurred.High-temperature evolution of the mechanical properties was investigated by arranging specific bending tests up to 1500. °C using SiC testing assembly which allowed to calculate the strain by means of curvature measurement. The mechanical properties improved with increasing the testing temperature, due to the inelastic deformation and stress relaxation which counteracted the sintering effects. The elastic modulus increased after thermal aging, but decreased for the aged coatings tested at higher temperature. The thermal expansion coefficient of as-sprayed coatings slightly increased after thermal aging, while a reduction of specific heat capacity was noticed. © 2014 Elsevier B.V.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84926258035&doi=10.1016%2fj.surfcoat.2014.07.067&partnerID=40&md5=636064ee2c5c0759906bd43b9b550e1c
DOI10.1016/j.surfcoat.2014.07.067
Citation KeyDiGirolamo2015298