Development of Advanced Thermal Barrier Coatings for Severe Environments

1995 ◽  
Author(s):  
Warren A. Nelson ◽  
Robert M. Orenstein ◽  
Paul S. DiMascio ◽  
Curtis A. Johnson
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Field Experience ◽  
Practical Knowledge ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Design Engineers ◽  
Component Design

Air plasma sprayed yttria-stabilized zirconia thermal barrier coatings (TBCs) have been successfully used to extend life of superalloy components in utility gas turbines. GE Power Generation has over ten years of field experience with TBCs on combustor hardware, and over 20,000 hours of field experience with TBCs on turbine nozzles. Despite this promising experience, the full advantage of TBCs can be achieved only when the reliability of the coating approaches that of the superalloy component substrate. Recent work at GE has emphasized characterization of mechanical properties and physical attributes of TBCs to understand better the causes of delamination crack growth and coating spallation. In addition, unique tests to examine the TBC response under conditions simulating severe gas turbine service environments have been developed. Through evaluation of the results from comparative TBC ranking tests, pre-production application experience and field test results, gas turbine design engineers and materials process engineers are rapidly gaining the practical knowledge needed to integrate the TBC into the component design.

scholarly journals Impact of Cooling with Thermal Barrier Coatings on Flow Passage in a Gas Turbine

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 85
Author(s):  
Yuanzhe Zhang ◽  
Pei Liu ◽  
Zheng Li
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Power Sources ◽  
Barrier Coatings ◽  
Flow Passage ◽  
Blade Cooling ◽  
The Impact

Inlet temperature is vital to the thermal efficiency of gas turbines, which is becoming increasingly important in the context of structural changes in power supplies with more intermittent renewable power sources. Blade cooling is a key method for gas turbines to maintain high inlet temperatures whilst also meeting material temperature limits. However, the implementation of blade cooling within a gas turbine—for instance, thermal barrier coatings (TBCs)—might also change its heat transfer characteristics and lead to challenges in calculating its internal temperature and thermal efficiency. Existing studies have mainly focused on the materials and mechanisms of TBCs and the impact of TBCs on turbine blades. However, these analyses are insufficient for measuring the overall impact of TBCs on turbines. In this study, the impact of TBC thickness on the performance of gas turbines is analyzed. An improved mathematical model for turbine flow passage is proposed, considering the impact of cooling with TBCs. This model has the function of analyzing the impact of TBCs on turbine geometry. By changing the TBCs’ thickness from 0.0005 m to 0.0013 m, its effects on turbine flow passage are quantitatively analyzed using the proposed model. The variation rules of the cooling air ratio, turbine inlet mass flow rate, and turbine flow passage structure within the range of 0.0005 m to 0.0013 m of TBC thicknesses are given.

Development of Advanced TBC for 1650 °C Class Gas Turbine

2021 ◽  
Author(s):  
Yoshifumi Okajima ◽  
Taiji Torigoe ◽  
Masahiko Mega ◽  
Masamitsu Kuwabara ◽  
Naotoshi Okaya
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Operating Temperature ◽  
Critical Role ◽  
Thermal Barrier ◽  
Barrier Coatings

Abstract Increasing operating temperature plays a critical role in improving the thermal efficiency of gas turbines. This paper assesses the capability of advanced thermal barrier coatings being developed for use in 1700 °C class gas turbines. Parts sprayed with these coatings were evaluated and found to have excellent durability and long-term reliability.

scholarly journals Effects of Alloy Composition on the Performance of Yttria Stabilized Zirconia–Thermal Barrier Coatings

1999 ◽  
Author(s):  
Josh Kimmel ◽  
Zaher Mutasim ◽  
William Brentnall
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Base Alloy ◽  
Critical Factor ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Component ◽  
Industrial Gas Turbines ◽  
Materials Used

Thermal barrier coatings (TBCs) provide an alloy surface temperature reduction when applied to turbine component surfaces. Thermal barrier coatings can be used as a tool for the designer to augment the power and/or enhance the efficiency of gas turbine engines. TBCs have been used successfully in the aerospace industry for many years, with only limited use for industrial gas turbine applications. Industrial gas turbines operate for substantially longer cycles and time between overhauls, and thus endurance becomes a critical factor. There are many factors that affect the life of a TBC including the composition and microstructure of the base alloy and bond coating. Alloys such as Mar-M 247, CMSX-4 and CMSX-10 are materials used for high temperature turbine environments, and usually require protective and/or thermal barrier coatings for increased performance. Elements such as hafnium, rhenium, and yttrium have shown considerable improvements in the strength of these alloys. However these elements may result in varying effects on the coatability and environmental performance of these alloys. This paper discusses the effects of these elements on the performance of thermal barrier coatings.

Effects of Alloy Composition on the Performance of Yttria Stabilized Zirconia—Thermal Barrier Coatings

2000 ◽  
Vol 122 (3) ◽  
pp. 393-400 ◽  
Author(s):  
Josh Kimmel ◽  
Zaher Mutasim ◽  
William Brentnall
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Base Alloy ◽  
Critical Factor ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Component ◽  
Industrial Gas Turbines ◽  
Materials Used

Thermal barrier coatings (TBCs) provide an alloy surface temperature reduction when applied to turbine component surfaces. Thermal barrier coatings can be used as a tool for the designer to augment the power and/or enhance the efficiency of gas turbine engines. TBCs have been used successfully in the aerospace industry for many years, with only limited use for industrial gas turbine applications. Industrial gas turbines operate for substantially longer cycles and time between overhauls, and thus endurance becomes a critical factor. There are many factors that affect the life of a TBC including the composition and microstructure of the base alloy and bond coating. Alloys such as Mar-M 247, CMSX-4, and CMSX-10 are materials used for high temperature turbine environments, and usually require protective and/or thermal barrier coatings for increased performance. Elements such as hafnium, rhenium, and yttrium have shown considerable improvements in the strength of these alloys. However, these elements may result in varying effects on the coatability and environmental performance of these alloys. This paper discusses the effects of these elements on the performance of thermal barrier coatings. [S0742-4795(00)02603-X]

scholarly journals The Effect of Coating Composition and Geometry on Thermal Barrier Coatings Lifetime

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Bruce A. Pint ◽  
Michael J. Lance ◽  
J. Allen Haynes
Keyword(s):  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Average Lifetime ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Bond Coatings ◽  
Bond Coating ◽  
Negative Effect ◽  
Plasma Sprayed

Several factors are being investigated that affect the performance of thermal barrier coatings (TBC) for use in land-based gas turbines where coatings are mainly thermally sprayed. This study examined high velocity oxygen fuel (HVOF), air plasma-sprayed (APS), and vacuum plasma-sprayed (VPS) MCrAlYHfSi bond coatings with APS YSZ top coatings at 900–1100 °C. For superalloy 247 substrates and VPS coatings tested in 1 h cycles at 1100 °C, removing 0.6 wt %Si had no effect on average lifetime in 1 h cycles at 1100 °C, but adding 0.3%Ti had a negative effect. Rod specimens were coated with APS, HVOF, and HVOF with an outer APS layer bond coating and tested in 100 h cycles in air + 10%H2O at 1100 °C. With an HVOF bond coating, initial results indicate that 12.5 mm diameter rod specimens have much shorter 100 h cycle lifetimes than disk specimens. Much longer lifetimes were obtained when the bond coating had an inner HVOF layer and outer APS layer.

Modelling Failures of Thermal Barrier Coatings

2007 ◽  
Vol 333 ◽  
pp. 155-166 ◽  
Author(s):  
Anette M. Karlsson
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Metal Substrate ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Design Engineers ◽  
Material Physics ◽  
Temperature Exposure ◽  
And Diffusion

Thermal barrier coatings are commonly used in high temperature parts of gas turbines, to protect the underlying metal substrate from deterioration during high temperature exposure. Unfortunately, the coatings fail prematurely, preventing the design engineers to fully utilize their implementation. Due to the complexity of the coatings, there are many challenges involved with developing failure hypotheses for the failures. This paper reviews some aspects of the current stateof- the-art on modeling failures of thermal barrier coatings, focusing on mechanics based models (such as finite element simulations) where the material physics is incorporated (such as oxidation and diffusion).

Health Monitoring and Life Prediction of Thermal Barrier Coatings Using a Laser-Based Method

2005 ◽  
Author(s):  
Robert J. Visher ◽  
Luis Gast ◽  
William A. Ellingson ◽  
Albert Feuerstein
Keyword(s):  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Gas Turbines ◽  
Physical Vapor Deposition ◽  
Laser System ◽  
Experimental Results ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Thermal Cycles ◽  
Barrier Coatings

Thermal barrier coatings (TBCs) are a critical component in low-emission gas turbines. A reliable method is required to monitor the condition of the TBC and predict coating failure. The condition of the interface between the metallic bond coat and TBC has been shown to be a potential indicator of spallation. The TBC is optically translucent; therefore, the bond coat/TBC interface can be probed using laser light with a wavelength of 0.632 microns or higher. A laser system in an optical backscatter configuration has been used to investigate several yttria-stabilized zirconia (YSZ) TBCs applied with either electron-beam physical vapor deposition (EB-PVD) or air plasma spraying (APS). The TBCs were thermally cycled for one hour increments until failure and investigated by the laser backscatter method after set numbers of thermal cycles. Correlations have been established between laser backscatter data and the number of thermal cycles, suggesting that the laser backscatter method can be used to predict failure. A theoretical model has been used to compare interface topography scatter to experimental results. This paper will discuss the laser backscatter technique and the experimental results and will compare the experimental data and theoretical scatter.

MICROCRACKS CHARACTERIZATION FOR THERMAL BARRIER COATINGS AT HIGH TEMPERATURE

2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350035 ◽  
Author(s):  
J. J. HUA ◽  
W. WU ◽  
C. C. LIN ◽  
Y. ZENG ◽  
H. WANG ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Heating System ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Service Temperature ◽  
Air Plasma ◽  
Barrier Coatings

Thermal barrier coatings (TBCs), used in gas turbine blades, are exposed to oxidation and thermal fatigue conditions. The characterization of TBCs was often performed in laboratory experiments, therefore, its detail failure mechanism is not quite obvious. For better understanding of the phenomenon, it is recommended to observe it under the condition simulating the real service conditions of gas turbines. In the present work, ZrO 2 coatings were prepared by air plasma spraying (APS). Scanning electron microscope (SEM), equipped with a heating system, was used to study the in situ microstructure change of TBCs at service temperature at which the aircraft is operated. The bond coat (BC) layer's thickening process and thermally grown oxide (TGO) generation along with the cracks growth are revealed. Moreover, the influence of the service temperature and holding time on the failure mechanism of TBCs is discussed. The crack healing produced during the coating re-melting reaction is observed, and it is the key factor to increase the thermal conductivity of the coating.

The Effects of Environmental Contaminants on Industrial Gas Turbine Thermal Barrier Coatings

1996 ◽  
Author(s):  
H. E. Eaton ◽  
N. S. Bornstein ◽  
J. T. DeMasi-Marcin
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Chemical Properties ◽  
Turbine Engines ◽  
Thermal Barrier ◽  
Gas Turbine Engines ◽  
Silicon Iron ◽  
Barrier Coatings ◽  
Industrial Gas Turbine

Thermal barrier coatings, (TBCs) play a crucial role in the performance of advanced aircraft gas turbine engines that power the commercial and military fleets. The same technology is currently being applied to the industrial gas turbines. However the task is more challenging. The environment of the industrial gas turbine is far more demanding. Studies are in progress delineating the relationships between time, temperature and the sinterability of candidate ceramics for use in industrial gas turbine engines. Typical sintering aids include the oxides and alkali salts of silicon, iron, magnesium and calcium. Other experiments focus on the role of the alkali compounds as they affect the mechanical and chemical properties of candidate materials.

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