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 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.

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.

scholarly journals Ceramic Thermal Barrier Coatings for Gas Turbine Engines

1982 ◽  
Author(s):  
R. J. Bratton ◽  
S. K. Lau ◽  
C. A. Andersson ◽  
S. Y. Lee
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Critical Role ◽  
Thick Layer ◽  
Ceramic Coatings ◽  
Turbine Engines ◽  
Thermal Barrier ◽  
Gas Turbine Engines ◽  
Barrier Coatings ◽  
Combustion Gases

Ceramic thermal barrier coatings are currently under active development in the U.S. for both aircraft and industrial/Utility gas turbine operation. These coating systems generally consist of an oxidation-corrosion resistant metal bond coat of the MCrAlY type and either a single thick layer ceramic overcoat or a graded ceramic/MCrAlY overcoat. This paper summarizes studies conducted on the high-temperature corrosion resistance of ZrO2 · Y2O3, ZrO2 · MgO and Ca2SiO4 plasma sprayed coatings that are candidates for use as thermal barrier coatings in gas turbine engines. Coatings were evaluated in both atmospheric burner rig and pressurized passage tests using GT No. 2 fuel and that doped with corrosive impurities such as sodium, sulfur and vanadium. The test results showed that the coatings perform very well in the clean fuel pressurized passage tests as well as burner rig tests. With impure fuels, it was found that chemical reactions between the ceramic coatings and combustion gases/condensates played the critical role in coating degradation. This work was conducted for NASA and EPRI under contract NAS3-21377. Advanced coating development studies have also been conducted for NASA and DOE under contract DEN3-110.

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 Long-Term Failure Mechanisms of Thermal Barrier Coatings in Heavy-Duty Gas Turbines

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1022
Author(s):  
Feng Xie ◽  
Dingjun Li ◽  
Weixu Zhang
Keyword(s):  
Thermal Barrier Coatings ◽  
Mixed Oxide ◽  
Gas Turbines ◽  
Mechanical Performance ◽  
Failure Mechanisms ◽  
Thermal Barrier ◽  
Heavy Duty ◽  
Thermal Cycles ◽  
Barrier Coatings

Thermal barrier coatings serve as thermal insulation and antioxidants on the surfaces of hot components. Different from the frequent thermal cycles of aero-engines, a heavy-duty gas turbine experiences few thermal cycles and continuously operates with high-temperature gas over 8000 h. Correspondingly, their failure mechanisms are different. The long-term failure mechanisms of the thermal barrier coatings in heavy-duty gas turbines are much more important. In this work, two long-term failure mechanisms are reviewed, i.e., oxidation and diffusion. It is illustrated that the growth of a uniform mixed oxide layer and element diffusion in thermal barrier coatings are responsible for the changes in mechanical performance and failures. Moreover, the oxidation of bond coat and the interdiffusion of alloy elements can affect the distribution of elements in thermal barrier coatings and then change the phase component. In addition, according to the results, it is suggested that suppressing the growth rate of uniform mixed oxide and oxygen diffusion can further prolong the service life of thermal barrier coatings.

scholarly journals A Comparative Study on the Synthesis and Properties of Yttria Stabilized Zirconia (YSZ) and Lanthana Doped YSZ Plasma Sprayed Thermal Barrier Coatings

2013 ◽  
Author(s):  
S. T. Aruna ◽  
N. Balaji ◽  
B. Arul Paligan
Keyword(s):  
Thermal Conductivity ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Operating Temperature ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Spray Parameters ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Plasma Sprayed

Ceramic thermal barrier coatings (TBCs) have been used for decades to extend the life of combustors and high temperature turbine stationary and rotating components to increase the operating temperature and in turn the performance of gas turbines or diesel engines can be increased. At present, thermal barrier coatings (TBCs) of Y2O3 partially stabilized ZrO2 (YSZ) films are widely used. In recent years ceramic compositions useful in thermal barrier coatings having reduced thermal conductivity are being explored to further increasing the operating temperature of gas turbines and improve the engine efficiency. In the present study, a comparison of the properties of state-of-the art 8wt% yttria stabilized zirconia (YSZ) and lanthana doped YSZ plasma sprayed coatings is presented. Plasma sprayable powders were prepared in the laboratory by a single step precipitation method and characterized. Both the powders had good flowability. These powders were plasma sprayed at identical critical plasma spray parameters. The coatings were characterized for phase, microstructure and thermal conductivity. Both the powders and coatings exhibited tetragonal form of zirconia and no traces of lanthana were observed. Both the coatings exhibited similar porosity levels. Microstructure of the coatings revealed porous coating with good adhesion of the bondcoat with the topcoat. Plasma sprayed 8wt% YSZ and lanthana doped YSZ exhibited thermal conductivity values of 0.88 and 0.67 W m−1 K−1 respectively which is lower than that reported in literature. This study shows that lanthana doping in YSZ helps in lowering the thermal conductivity and hence this coating may be a potential candidate for TBC application.

scholarly journals Characterization of Fatigue Mechanisms of Thermal Barrier Coatings by a Novel Laser-Based Test

1998 ◽  
Author(s):  
Uwe Rettig ◽  
Ulrich Bast ◽  
Dinorah Steiner ◽  
Matthias Oechsner
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Fatigue Behavior ◽  
Temperature Gradients ◽  
Stress Fields ◽  
Thermal Barrier ◽  
Data Set ◽  
Barrier Coatings

The use of high performance ceramic thermal barrier coatings in stationary gas turbines requires fundamental knowledge of their fatigue behavior under high temperature gradients and thermal cycling. An experimental method based on rapid laser heating complemented with finite-element calculations was developed in order to identify the major damage mechanisms and to obtain a data set for reliability assessment of thermal barrier coatings for temperature and stress fields similar to gas turbine conditions. The observed failures are strongly related to the pretreatment procedures such as annealing under high temperature gradients and isothermal long-term oxidation. The vertical crack patterns observed close to the top surface of the Zirconia coating are generated at the moment of rapid cooling. These cracks are induced by high biaxial tensile stresses caused by the temperature gradient and the stress reversion after relaxation of compressive stresses at high temperatures. The long-term fatigue behavior is decisively determined by two processes: (i) The porous Zirconia loses its damage tolerant properties by densification. (ii) The growth of an oxide layer at the bond coat degrades adhesion and produces localized stress fields at the interface. Cyclic loads increase the length of existing in-plane cracks and delaminations rather than enlarging their number. Misfit of the crack flanks and wedge effects are the driving forces for continued crack propagation. These experimental results are discussed in terms of fracture mechanics.

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.

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.

Deposition of Fuel Impurities Within Thermal Barrier Coatings in Gas Turbine Hot Gas Paths

2021 ◽  
pp. 1-46
Author(s):  
Christian Hollaender ◽  
Werner Stamm ◽  
Oliver Lüsebrink ◽  
Harald Harders ◽  
Lorenz Singheiser
Keyword(s):  
Gas Turbine ◽  
Diffusion Model ◽  
Thermal Barrier Coatings ◽  
Thermodynamic Equilibrium ◽  
Vapor Deposition ◽  
Gas Turbines ◽  
Recent Literature ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Hot Gas

Abstract For the reliable operation of modern gas turbines, Thermal Barrier Coatings (TBCs) need to withstand a wide range of ambient conditions resulting from impurities in inlet air or fuels. When analyzing deposition of detrimental hot gas constituents, previous efforts largely focus on the investigation of solid and molten deposit interaction with TBCs. Recent literature and observations in gas turbines indicate that not only liquids can penetrate porous TBCs, but the deposition from gas phase inside of pores and cracks is also an aspect of TBC degradation. To investigate this vapor deposition process, a diffusion model has been coupled with a thermodynamic equilibrium solver. The diffusion model calculates vapor transport of trace elements through pores and gaps in the TBC, where the thermodynamic equilibrium solver calculates local thermodynamic equilibria to predict whether deposition takes place. In this work the model is applied to discuss deposition properties of calcium. In recent literature calcium has – in some cases – been reported to deposit inside of TBCs as pure anhydrite (CaSO4). An actual anhydrite finding in the TBC of a stationary gas turbine blade was reproduced applying the introduced model. The vapor deposition is shown to occur within and on top of the TBC, depending on a number of factors, such as: pressure, temperatures, calcium to silicon ratio and calcium to sulfur ratio. The successful alignment of conditions in real engines with model results will allow to address the increasing demand for more fuel- and operational flexibility of current and future gas turbines.

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