Modelling Oxygen Permeability through Top Coat and Thermally Grown Oxide in dense Yb 2 Si 2 O 7 Environmental Barrier Coatings

2021 ◽  
Author(s):  
Sonia Singh ◽  
Michel Nganbe ◽  
Kuiying Chen
Keyword(s):  
Oxygen Permeability ◽  
Thermally Grown Oxide ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Thermally Grown

Oxygen Permeability and Its Role in Governing Life of YbDS Environmental Barrier Coatings

2021 ◽  
Author(s):  
Sonia Singh ◽  
Michel Nganbe ◽  
Kuiying Chen
Keyword(s):  
Growth Kinetics ◽  
Oxygen Permeability ◽  
Parabolic Rate Constant ◽  
Thermally Grown Oxide ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Permeability Constant ◽  
Order Of Magnitude ◽  
Defect Reactions

Abstract The growth kinetics of thermally grown oxide (TGO) silica in Yb-disilicate (YbDS) environmental barrier coatings (EBCs) significantly affects the durability of EBCs. The oxygen permeability can control the TGO growth kinetics and thus could play an essential role in determining EBCs life. Therefore; the oxygen permeability constant of YbDS and TGO is systematically evaluated and quantified in terms of thermodynamics using defect reactions and the parabolic rate constant (kp); respectively. Dry oxygen and wet oxygen conditions as well as different temperatures; partial pressures and top coat modifiers are investigated. The results offer evidence that the oxygen permeability constant for the YbDS top coat is an order of magnitude higher than for the TGO. As such; the TGO hinders the oxidant diffusion stronger; proving to be the diffusion rate controlling layer. Moreover; water vapor strongly increases the oxygen permeability with defect reactions playing a key role. It is suggested that the mass transfer through the top coat is primarily by outward ytterbium ion diffusion and inward oxygen ion movement; with the latter being dominant; particularly in wet environments. The effect of top coat modifiers on oxidant permeation is composition sensitive and seems to be related to their interaction with oxygen ions and their mobility.

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

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

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

2015 ◽  
Vol 11 (2) ◽  
pp. 238-272 ◽  
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.

Thermal properties and Calcium-Magnesium-Alumina-Silicate (CMAS) resistance of LuPO4 as environmental barrier coatings

2020 ◽  
Vol 40 (4) ◽  
pp. 1471-1477 ◽  
Author(s):  
Xunxun Hu ◽  
Fangfang Xu ◽  
Kunwei Li ◽  
Yizhou Zhang ◽  
Yue Xu ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Calcium Magnesium

The effect of morphology of thermally grown oxide on the stress field in a turbine blade with thermal barrier coatings

2015 ◽  
Vol 276 ◽  
pp. 160-167 ◽  
Author(s):  
W. Zhu ◽  
M. Cai ◽  
L. Yang ◽  
J.W. Guo ◽  
Y.C. Zhou ◽  
...  
Keyword(s):  
Stress Field ◽  
Turbine Blade ◽  
Thermal Barrier Coatings ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Thermally Grown

Failure mechanisms of thermal barrier coatings on MCrAlY-type bondcoats associated with the formation of the thermally grown oxide

2009 ◽  
Vol 44 (7) ◽  
pp. 1687-1703 ◽  
Author(s):  
Dmitry Naumenko ◽  
Vladimir Shemet ◽  
Lorenz Singheiser ◽  
Willem Josef Quadakkers
Keyword(s):  
Thermal Barrier Coatings ◽  
Failure Mechanisms ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Thermally Grown
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