scholarly journals Ceramic Thermal Barrier Coatings for Turbine Engine Components

1982 ◽  
Author(s):  
D. S. Duvall ◽  
D. L. Ruckle
Keyword(s):  
Thermal Barrier Coatings ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Thermal Environments ◽  
Strain Tolerance ◽  
Endurance Testing ◽  
Plasma Sprayed ◽  
Cooling Air

The durability of plasma sprayed ceramic thermal barrier coatings subjected to cyclic thermal environments has been improved substantially by improving the strain tolerance of the ceramic structure and also by controlling the substrate temperature during the application of the coating. Improved strain tolerance was achieved by using ceramic structures with increased porosity, microcracking or segmentation. Plasma spraying on a controlled-temperature substrate also has been shown to improve durability by reducing harmful residual stresses. The most promising of the strain tolerant ceramic coatings have survived up to 6000 cycles of engine endurance testing with no coating or vane platform damage. In side-by-side engine tests, thermal barrier coatings have shown that they greatly reduce platform distress compared to conventionally coated vanes in addition to permitting reductions in cooling air and attendant increases in engine efficiency.

The Evolution of Thermal Barrier Coatings in Gas Turbine Engine Applications

1994 ◽  
Vol 116 (1) ◽  
pp. 250-257 ◽  
Author(s):  
S. M. Meier ◽  
D. K. Gupta
Keyword(s):  
Thermal Barrier Coatings ◽  
Turbine Blades ◽  
Engine Performance ◽  
Design System ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Component Design ◽  
Integral Element ◽  
Plasma Sprayed

Thermal barrier coatings (TBCs) have been used for almost three decades to extend the life of combustors and augmentors and, more recently, stationary turbine components. Plasma-sprayed yttria-stabilized zirconia TBC currently is bill-of-material on many commercial jet engine parts. A more durable electron beam-physical vapor deposited (EB-PVD) ceramic coating recently has been developed for more demanding rotating as well as stationary turbine components. This ceramic EB-PVD is bill-of-material on turbine blades and vanes in current high thrust engine models and is being considered for newer developmental engines as well. To take maximum advantage of potential TBC benefits, the thermal effect of the TBC ceramic layer must become an integral element of the hot section component design system. To do this with acceptable reliability requires a suitable analytical life prediction model calibrated to engine experience. The latest efforts in thermal barrier coatings are directed toward correlating such models to measured engine performance.

scholarly journals Thermal Shock and Oxidation Stability Tests to Grade Plasma Sprayed Functionally Gradient Thermal Barrier Coatings

2019 ◽  
Vol 1 (1) ◽  
pp. 1-11
Author(s):  
Pasupuleti Kirti Teja ◽  
Parvati Ramaswamy ◽  
Narayana Murthy S.V.S.
Keyword(s):  
Thermal Barrier Coatings ◽  
Inconel 718 ◽  
Oxidation Stability ◽  
Ceramic Coatings ◽  
Functionally Graded ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Plasma Sprayed

Functionally graded layers in thermal barrier coatings reduce the stress gradient between the overlaid ceramic coatings and the underlying metallic component. Introduced to alleviate early onset of spallation of the coating due to thermal expansion mismatch, this facilitates improvement in the life of the component. Conventional thermal barrier coatings typically comprise of duplex layers of plasma sprayed 8% yttria stabilized zirconia (ceramic) coatings on bond coated (NiCrAlY) components/substrates (Inconel 718 for example). This work highlights the superiority of plasma sprayed coatings synthesized from blends of the intermetallic bond coat and ceramic plasma spray powders on Inconel 718 substrates in three-layer configuration over the duplex layered configuration. Assessed through (a) thermal shock cyclic tests (at 1200oC and 1400oC) in laboratory scale basic burner rig test facility and (b) oxidation stability test in high temperature furnace (at 800oC and 1000oC) the functionally graded coatings of certain configurations exhibited more than double the life of the conventional 8% yttria stabilized zirconia duplex (double layer) coatings. Micro- and crystal structure analysis support the findings and results are detailed and discussed.

The Evolution of Thermal Barrier Coatings in Gas Turbine Engine Applications

1992 ◽  
Author(s):  
Susan Manning Meier ◽  
Dinesh K. Gupta
Keyword(s):  
Thermal Barrier Coatings ◽  
Turbine Blades ◽  
Engine Performance ◽  
Design System ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Component Design ◽  
Integral Element ◽  
Plasma Sprayed

Thermal barrier coatings (TBCs) have been used for almost three decades to extend the life of combustors and augmentors and, more recently, stationary turbine components. Plasma sprayed yttria stabilized zirconia TBC currently is bill-of-material on many commercial jet engine parts. A more durable electron beam-physical vapor deposited (EB-PVD) ceramic coating recently has been developed for more demanding rotating as well as stationary turbine components. This ceramic EB-PVD is bill-of-material on turbine blades and vanes in current high thrust engine models and is being considered for newer developmental engines as well. To take maximum advantage of potential TBC benefits, the thermal effect of the TBC ceramic layer must become an integral element of the hot section component design system. To do this with acceptable reliability requires a suitable analytical life prediction model calibrated to engine experience. The latest efforts in thermal barrier coatings are directed toward correlating such models to measured engine performance.

scholarly journals Revisiting the Birth of 7YSZ Thermal Barrier Coatings: Stephan Stecura †

Coatings ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 255 ◽  
Author(s):  
James Smialek ◽  
Robert Miller
Keyword(s):  
Thermal Barrier Coatings ◽  
Yttria Stabilized Zirconia ◽  
Turbine Engines ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Power Turbine ◽  
Plasma Sprayed ◽  
The Impact

Thermal barrier coatings are widely used in all turbine engines, typically using a 7 wt.% Y2O3–ZrO2 formulation. Extensive research and development over many decades have refined the processing and structure of these coatings for increased durability and reliability. New compositions demonstrate some unique advantages and are gaining in application. However, the “7YSZ” (7 wt.% yttria stabilized zirconia) formulation predominates and is still in widespread use. This special composition has been universally found to produce nanoscale precipitates of metastable t’ tetragonal phase, giving rise to a unique toughening mechanism via ferro-elastic switching under stress. This note recalls the original study that identified superior properties of 6–8 wt.% yttria stabilized zirconia (YSZ) plasma sprayed thermal barrier coatings, published in 1978. The impact of this discovery, arguably, continues in some form to this day. At one point, 7YSZ thermal barrier coatings were used in every new aircraft and ground power turbine engine produced worldwide. 7YSZ is a tribute to its inventor, Dr. Stephan Stecura, NASA retiree.

scholarly journals Microstructural Characterization of Thermal Barrier Coatings Glazed by a High Power Laser

2016 ◽  
Vol 723 ◽  
pp. 247-251 ◽  
Author(s):  
Hong Zhou ◽  
Fei Li ◽  
Jun Wang ◽  
Bao De Sun
Keyword(s):  
Surface Roughness ◽  
Thermal Barrier Coatings ◽  
High Power ◽  
Microstructural Characterization ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
High Power Laser ◽  
Power Laser ◽  
Barrier Coatings ◽  
Plasma Sprayed

Thermal barrier coatings have been widely used in in both energy and propulsion systems. Plasma-sprayed thermal barrier coatings have relatively high interconnected porosity and lamina structure, which bring out a low bond strength, and lead to a short thermal cycling life. Lasers can be used for modification of materials surface. In this paper, plasma-sprayed thermal barrier coatings were laser-glazed by a high power laser in order to modify the structures. The microstructure of laser-glazed TBCs is investigated. The change on surface roughness has been examined. The result indicates that a smooth and dense glazed surface with craters and a network of microcracks is obtained after laser-glazing. The laser-glazed region consists of a columnar microstructure. There are segmentation microcracks in the laser-glazed coatings, which don’t run through the coatings along thickness. Surface roughness has been reduced significantly for the laser treated ceramic coatings.

Properties of ZrO2-7wt%Y2O3 Thermal Barrier Coatings in Relation to Plasma Spraying Conditions

1997 ◽  
Author(s):  
C. Funke ◽  
B. Siebert ◽  
D. Stöver ◽  
R. Vaßen
Keyword(s):  
Elastic Modulus ◽  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Free Edge ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Normal Stresses ◽  
Barrier Coatings ◽  
Plasma Sprayed

Abstract Superalloy samples were coated with thermal barrier coatings (TBC). This TBC-system consisted of two layers. The first layer was a vacuum-plasma sprayed, corrosion resistant layer (MCrAlY) which also acted as a bond coat. The ceramic top layer was atmospheric-plasma sprayed Y2O3-stabilized ZrO2. In order to produce different microstructures, the plasma-spraying parameters for the production of the ceramic coatings were varied. The different ceramic coatings were characterized in terms of porosity and mean elastic modulus. The porosity distribution was also investigated due to its influence on the measured elastic modulus. To record the changes of the plasma sprayed Zirconia due to sintering, the mean elastic modulus of selected coatings was measured as a function of annealing time. One series of TBC-coated specimens was cyclically oxidized at a maximum temperature of 1100°C. After 500 h of thermal cycling, creep within the MCrAlY-bond coat led to a coating failure at both the internal beveled edge and free edge around the specimen. A finite element analysis study of the cyclic oxidation experiment was performed to gain insight into the stress redistributions within the bond coat as a function of time. During the initial temperature increase, critical tensile normal stresses developed above the MCrAlY-Zirconia interface at the free edge. However, these normal stresses became compressive for all following cooling cycles. On the other hand, large tensile normal stresses developed above the MCrAlY-Zirconia interface at the beveled edge during all the cooling cycles. Therefore, high normal stresses responsible for debonding were present within the ceramic coating during all cooling cycles with the most critical stresses occurring at the free edge during the first cooling cycle and near the beveled edge for all the following cooling cycles.

Development and Performance Evaluation of Thick Air Plasma Sprayed Thermal Barrier Coatings

2000 ◽  
Author(s):  
Z.Z. Mutasim ◽  
Y.L. Nava
Keyword(s):  
Thermal Barrier Coating ◽  
Thermal Barrier Coatings ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Barrier Coating ◽  
And Performance ◽  
Plasma Sprayed ◽  
Industrial Gas Turbine

Abstract Air plasma sprayed thermal barrier coatings have been widely used to reduce metal wall temperatures of industrial gas turbine combustor liners. Thermal barrier coatings provide thermal gradients, with the goal of reducing the liner wall temperature to acceptable levels as a result of their low thermal conductivity. A typical thermal barrier coating consists of a 0.1-0.2 mm MCrAlY bond coating and a 0.25-0.35 mm thick 8 wt.% yttria stabilized zirconia ceramic top coating. A method to increase thermal barrier coating effectiveness is the application of thicker ceramic coatings. Development and performance testing of 0.5-0.8 mm thick ceramic coatings are discussed in this paper. Cyclic oxidation tests that simulate industrial gas turbine environments were conducted. Thermal barrier coating degradation-mechanisms were determined from microstructural evaluation of thermally exposed samples.

scholarly journals Erosion Performance of Atmospheric Plasma Sprayed Thermal Barrier Coatings with Diverse Porosity Levels

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 86
Author(s):  
Satyapal Mahade ◽  
Abhilash Venkat ◽  
Nicholas Curry ◽  
Matthias Leitner ◽  
Shrikant Joshi
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Sem Analysis ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Plasma Sprayed ◽  
Engine Components ◽  
Micro Indentation

Thermal barrier coatings (TBCs) prolong the durability of gas turbine engine components and enable them to operate at high temperature. Several degradation mechanisms limit the durability of TBCs during their service. Since the atmospheric plasma spray (APS) processed 7–8 wt.% yttria stabilized zirconia (YSZ) TBCs widely utilized for gas turbine applications are susceptible to erosion damage, this work aims to evaluate the influence of their porosity levels on erosion behavior. Eight different APS TBCs were produced from 3 different spray powders with porosity ranging from 14% to 24%. The as-deposited TBCs were examined by SEM analysis. A licensed software was used to quantify the different microstructural features. Mechanical properties of the as-deposited TBCs were evaluated using micro-indentation technique. The as-deposited TBCs were subjected to erosion tests at different angles of erodent impact and their erosion performance was evaluated. Based on the results, microstructure-mechanical property-erosion performance was correlated. Findings from this work provide new insights into the microstructural features desired for improved erosion performance of APS deposited YSZ TBCs.

Characterization of thermal barrier coatings formed by electon-beam physical vapor deposition (EB-PVD)

1989 ◽  
Vol 47 ◽  
pp. 426-427
Author(s):  
Ozer Unal
Keyword(s):  
Thermal Barrier Coatings ◽  
Physical Vapor Deposition ◽  
Ceramic Coating ◽  
High Vacuum ◽  
Ceramic Coatings ◽  
High Energy ◽  
Thermal Barrier ◽  
Protective Oxide ◽  
Barrier Coatings ◽  
Energy Beam

Interest in ceramics as thermal barrier coatings for hot components of turbine engines has increased rapidly over the last decade. The primary reason for this is the significant reduction in heat load and increased chemical inertness against corrosive species with the ceramic coating materials. Among other candidates, partially-stabilized zirconia is the focus of attention mainly because ot its low thermal conductivity and high thermal expansion coefficient.The coatings were made by Garrett Turbine Engine Company. Ni-base super-alloy was used as the substrate and later a bond-coating with high Al activity was formed over it. The ceramic coatings, with a thickness of about 50 μm, were formed by EB-PVD in a high-vacuum chamber by heating the target material (ZrO2-20 w/0 Y2O3) above its evaporation temperaturef >3500 °C) with a high-energy beam and condensing the resulting vapor onto a rotating heated substrate. A heat treatment in an oxidizing environment was performed later on to form a protective oxide layer to improve the adhesion between the ceramic coating and substrate. Bulk samples were studied by utilizing a Scintag diffractometer and a JEOL JXA-840 SEM; examinations of cross-sectional thin-films of the interface region were performed in a Philips CM 30 TEM operating at 300 kV and for chemical analysis a KEVEX X-ray spectrometer (EDS) was used.

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