Environmental Barrier Coatings Having a YSZ Top Coat

Volume 4: Turbo Expo 2002, Parts A and B ◽

10.1115/gt2002-30626 ◽

2002 ◽

Cited By ~ 1

Author(s):

Kang N. Lee

Keyword(s):

Atmospheric Pressure ◽

Atmospheric Pressure Plasma ◽

Second Phase ◽

Stabilized Zirconia ◽

Barrier Coatings ◽

Environmental Barrier Coatings ◽

Environmental Barrier ◽

Cte Mismatch ◽

Low Modulus ◽

Mismatch Stress

Environmental barrier coatings (EBCs) with a Si bond coat, a yttria-stabilized zirconia (YSZ) top coat, and various intermediate coats were investigated. EBCs were processed by atmospheric pressure plasma spraying. The EBC durability was determined by thermal cycling tests in water vapor at 1300°C and 1400°C, and in air at 1400°C and 1500°C. EBCs with a mullite (3Al2O3·2SiO2)+BSAS (1-xBaO·xSrO·Al2O3·2SiO2) intermediate coat were more durable than EBCs with a mullite intermediate coat, while EBCs with a mullite/BSAS duplex intermediate coat resulted in inferior durability. The improvement with a mullite+BSAS intermediate coat was attributed to enhanced compliance of the intermediate coat due to the addition of a low modulus BSAS second phase. Mullite+BSAS/YSZ and BSAS/YSZ interfaces produced a low melting (<1400 °C) reaction product, which is expected to degrade the EBC performance by increasing the thermal conductivity. EBCs with a mullite+BSAS/graded mullite+YSZ intermediate coat showed the best durability among the EBCs investigated in this study. This improvement was attributed to diffused CTE mismatch stress and improved chemical stability due to the compositionally graded mullite+YSZ layer.

Download Full-text

Steam oxidation of ytterbium disilicate environmental barrier coatings with and without a silicon bond coat

Journal of the American Ceramic Society ◽

10.1111/jace.17650 ◽

2020 ◽

Author(s):

K.A. Kane ◽

E. Garcia ◽

R. Uwanyuze ◽

M. Lance ◽

K.A. Unocic ◽

...

Keyword(s):

Bond Coat ◽

Steam Oxidation ◽

Barrier Coatings ◽

Environmental Barrier Coatings ◽

Environmental Barrier

Download Full-text

Computational investigation of foreign object damage sustained by environmental barrier coatings (EBCs) and SiC/SiC ceramic-matrix composites (CMCs)

Multidiscipline Modeling in Materials and Structures ◽

10.1108/mmms-07-2014-0039 ◽

2015 ◽

Vol 11 (2) ◽

pp. 238-272 ◽

Cited By ~ 9

Author(s):

Mica Grujicic ◽

Jennifer Snipes ◽

Ramin Yavari ◽

S. Ramaswami ◽

Rohan Galgalikar

Keyword(s):

Gas Turbine ◽

Ceramic Matrix ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Foreign Object ◽

Barrier Coatings ◽

Content Type ◽

Environmental Barrier Coatings ◽

Foreign Object Damage ◽

Environmental Barrier

Purpose – The purpose of this paper is to prevent their recession caused through chemical reaction with high-temperature water vapor, SiC-fiber/SiC-matrix ceramic-matrix composite (CMC) components used in gas-turbine engines are commonly protected with so-called environmental barrier coatings (EBCs). EBCs typically consist of three layers: a top thermal and mechanical protection coat; an intermediate layer which provides environmental protection; and a bond coat which assures good EBC/CMC adhesion. The materials used in different layers and their thicknesses are selected in such a way that the coating performance is optimized for the gas-turbine component in question. Design/methodology/approach – Gas-turbine engines, while in service, often tend to ingest various foreign objects of different sizes. Such objects, entrained within the gas flow, can be accelerated to velocities as high as 600 m/s and, on impact, cause substantial damage to the EBC and SiC/SiC CMC substrate, compromising the component integrity and service life. The problem of foreign object damage (FOD) is addressed in the present work computationally using a series of transient non-linear dynamics finite-element analyses. Before such analyses could be conducted, a major effort had to be invested toward developing, parameterizing and validating the constitutive models for all attendant materials. Findings – The computed FOD results are compared with their experimental counterparts in order to validate the numerical methodology employed. Originality/value – To the authors’ knowledge, the present work is the first reported study dealing with the computational analysis of the FOD sustained by CMCs protected with EBCs.

Download Full-text