Advances in Coating Design for High-Performance Gas Turbines

MRS Bulletin ◽  
2003 ◽  
Vol 28 (9) ◽  
pp. 659-670 ◽  
Author(s):  
J. R. Nicholls
Keyword(s):  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
High Performance ◽  
Surface Engineering ◽  
Thermal Protection ◽  
Low Cost ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Aluminide Coatings ◽  
Coating Design

AbstractSurface engineering is now a key materials technology in the design of future advanced gas-turbine engines. This article focuses on coating systems for hot-gas-path components, which can vary from low-cost aluminide diffusion coatings to the more exotic, and therefore expensive, thermal-barrier coatings. Available coating systems and their relative benefits are reviewed in terms of performance against manufacturing complexity and cost. Future trends in the design of environmental- and thermal-protection coatings are discussed, including the addition of multiple reactive elements, modified aluminide coatings, diffusion-barrier concepts, the design of “smart” corrosion-resistant coatings, and the development of structurally modified, low-thermal-conductivity thermal-barrier coatings.

Investigation of Thermo-Mechanical Properties of Slurry Based Thermal Barrier Coatings under Repeated Thermal Shock

2009 ◽  
Vol 417-418 ◽  
pp. 197-200 ◽  
Author(s):  
Phuc Nguyen ◽  
Andrei G. Kotousov ◽  
Sook Ying Ho ◽  
Stuart Wildy
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Nuclear Power ◽  
Thermal Stresses ◽  
Low Cost ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Thermal Barrier ◽  
Barrier Coatings

Thermal Barrier Coatings have existed for over 40 years, and with in the last 15 years their use in industrial applications has dramatically increased. Thermal Barrier Coatings (TBCs) are currently used in gas turbines, diesel engines, throughout aerospace and nuclear power industries. The purpose of TBC is to reduce temperature and thermal stresses, and, as a result, increase the reliability and life of load-bearing components subjected to high temperature or temperature flux. However, TBCs often fail under thermal cyclic loading with reliability still being the major issue impeding their wide-spread applications. The focus of this work is on experimental investigations of zirconia/nickel graded TBC system, subject to thermal shock loading. The graded TBC systems were fabricated utilising a recently developed slurry spray manufacturing technique. This is a robust technique, and is able to cover large and curved surfaces at low cost, and provides many advantages in comparison with its alternatives. This paper describes the developed technique and presents selected results of thermo-mechanical and fracture testing of the TBCs including graded coatings fabricated using this new technique.

Self Diagnostic EB-PVD Thermal Barrier Coatings

2010 ◽  
Vol 72 ◽  
pp. 65-74 ◽  
Author(s):  
John R. Nicholls ◽  
Richard G. Wellman ◽  
Remy Steenbakker ◽  
Jörg Feist
Keyword(s):  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Performance Monitoring ◽  
Thermal Protection ◽  
Interface Temperature ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Design And Manufacture ◽  
Tbc Systems

Thermal barrier coatings (TBCs) are an enabling materials technology to improve the efficiency and durability of gas turbines and thus through such efficiency improvements offer reduce fuel usage and an associated reduction in CO2 emission. This commercial drive is pushing both aero- and industrial turbines to be lifetime dependent on TBC performance – the TBC must be “prime reliant”. However, the prediction of the durability of the TBC system has proved difficult, with lifetimes varying from sample to sample and component to component. One factor controlling this is the inability to measure accurately the bondcoat/ceramic interface temperature when buried under a TBC. In operating engines this is further exacerbated by the fact that such TBC systems operate in strong temperature gradients due to the need to cool aerofoil components. This research examines the design and manufacture of self diagnostic thermal barrier coatings capable of accurately measuring the interface temperature under the TBC, whilst providing the requisite thermal protection. Data on the temperature sensing capability of various rare earth doped EB-PVD thermal barrier coatings will be reported. It will be shown that systems exist capable of measuring temperatures in excess of 1300oC. Details of the measurement method, the compositions and the thermal stability of such systems will be discussed in this paper. The ability to produce a sensing TBC capable of measuring interface temperature, surface temperature and heat flux will further be discussed permitting the design of thermal barrier protected components capable of in-situ performance monitoring.

Optical Nondestructive Condition Monitoring of Thermal Barrier Coatings

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
A. L. Heyes ◽  
J. P. Feist ◽  
X. Chen ◽  
Z. Mutasim ◽  
J. R. Nicholls
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coatings ◽  
Condition Monitoring ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Uv Light ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Calibration Data ◽  
Barrier Coatings

This paper describes recent developments of the thermal barrier sensor concept for nondestructive evaluation (NDE) of thermal barrier coatings (TBCs) and online condition monitoring in gas turbines. Increases in turbine inlet temperature in the pursuit of higher efficiency will make it necessary to improve or upgrade current thermal protection systems in gas turbines. As these become critical to safe operation, it will also be necessary to devise techniques for online condition monitoring and NDE. The authors have proposed thermal barrier sensor coatings (TBSCs) as a possible means of achieving NDE for TBCs. TBSCs are made by doping the ceramic material (currently yttria-stabilized zirconia (YSZ)) with a rare-earth activator to provide the coating with luminescence when excited with UV light. This paper describes the physics of the thermoluminescent response of such coatings and shows how this can be used to measure temperature. Calibration data are presented along with the results of comparative thermal cycle testing of TBSCs, produced using a production standard air plasma spray system. The latter show the durability of TBSCs to be similar to that of standard YSZ TBCs and indicate that the addition of the rare-earth dopant is not detrimental to the coating. Also discussed is the manufacture of functionally structured coatings with discreet doped layers. The temperature at the bond coat interface is important with respect to the life of the coating since it influences the growth rate of the thermally grown oxide layer, which in turn destabilizes the coating system as it becomes thicker. Experimental data are presented, indicating that dual-layered TBSCs can be used to detect luminescence from, and thereby the temperature within, subsurface layers covered by as much as 500 μm of standard TBC material. A theoretical analysis of the data has allowed some preliminary calculations of the transmission properties of the overcoat to be made, and these suggest that it might be possible to observe phosphorescence and measure temperature through an overcoat layer of up to approximately 1.56 mm thickness.

Optical Non-Destructive Condition Monitoring of TBC’s

2007 ◽  
Author(s):  
A. L. Heyes ◽  
J. P. Feist ◽  
X. Chen ◽  
Z. Mutasim ◽  
J. R. Nicholls
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coatings ◽  
Condition Monitoring ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Calibration Data ◽  
Barrier Coatings ◽  
Non Destructive

The paper describes recent developments of the thermal barrier sensor concept for non-destructive evaluation (NDE) of thermal barrier coatings and on-line condition monitoring in gas turbines. Increases in turbine inlet temperature in pursuit of higher efficiency will make it necessary improve or upgrade current thermal protection systems in gas turbines. As these become critical to safe operation it will also be necessary to devise techniques for online conditions monitoring and NDE. The authors have proposed thermal barrier sensor coatings (TBSC) as a possible means of achieving NDE for thermal barrier coatings. TBSC’s are made by doping the ceramic material (currently yttria stabilised zirconia) with a rare earth activator to provide the coating with luminescence when excited with UV light. The paper describes the physics of the thermo-luminescent response of such coatings and shows how this can be used to measure temperature. Calibration data is presented along with the results of comparative thermal cycle testing of TBSC’s, produced using a production standard APS system. The latter show the durability of TBSC’s to be similar to that of standard YSZ TBC’s and indicate that the addition of the rare-earth dopant is not detrimental to the coating. Also discussed is the manufacture of functionally structured coatings with discreet doped layers. The temperature at the bond coat interface is important with respect to the life of the coating since it influences the growth rate of the thermally grown oxide layer which in turn destabilises the coating system as it becomes thicker. Experimental data is presented indicating that duallayered TBSC’s can be used to detect luminescence from, and thereby the temperature within, sub surface layers covered by as much as 500μm of standard TBC material. A theoretical analysis of the data has allowed some preliminary calculations of the transmission properties of the overcoat to be made and these suggest that it might be possible to observe phosphorescence and measure temperature through an overcoat layer of up to approximately 1.56mm thickness.

scholarly journals Analytical and Experimental Study of Residual Stresses in Thermal Barrier Coatings Deposited on Gas Turbine Blades in Laboratory Dimensions by APS and HVOF Methods to Calculate the Optimal Thickness

2021 ◽  
Vol 3 (1) ◽  
pp. 63-67
Author(s):  
Esmaeil Poursaeidi ◽  
◽  
Farzam Montakhabi ◽  
Javad Rahimi ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Analytical Model ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Optimal Thickness ◽  
Barrier Coatings

The constant need to use gas turbines has led to the need to increase turbines' inlet temperature. When the temperature reaches a level higher than the material's tolerance, phenomena such as creep, changes in mechanical properties, oxidation, and corrosion occur at high speeds, which affects the life of the metal material. Nowadays, operation at high temperatures is made possible by proceedings such as cooling and thermal insulation by thermal barrier coatings (TBCs). The method of applying thermal barrier coatings on the turbine blade creates residual stresses. In this study, residual stresses in thermal barrier coatings applied by APS and HVOF methods are compared by Tsui–Clyne analytical model and XRD test. The analytical model results are in good agreement with the experimental results (between 2 and 8% error), and the HVOF spray method creates less residual stress than APS. In the end, an optimal thickness for the coating is calculated to minimize residual stress at the interface between the bond coat and top coat layers.

Effects of Powder Morphology, Microstructure, and Residual Stresses on Thermal Barrier Coating Thermal Shock Performance

1996 ◽  
Author(s):  
J. Wigren ◽  
J.-F. de Vries ◽  
D. Greving
Keyword(s):  
Residual Stresses ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Spray Parameters ◽  
Powder Morphology ◽  
Barrier Coatings ◽  
Barrier Coating

Abstract Thermal barrier coatings are used in the aerospace industry for thermal insulation in hot sections of gas turbines. Improved coating reliability is a common goal among jet engine designers. In-service failures, such as coating cracking and spallation, result in decreased engine performance and costly maintenance time. A research program was conducted to evaluate residual stresses, microstructure, and thermal shock life of thermal barrier coatings produced from different powder types and spray parameters. Sixteen coatings were ranked according to their performance relative to the other coatings in each evaluation category. Comparisons of residual stresses, powder morphology, and microstructure to thermal shock life indicate a strong correlation to thermal barrier coating performance. Results from these evaluations will aid in the selection of an optimum thermal barrier coating system for turbine engine applications.

Bond coating issues in thermal barrier coatings for industrial gas turbines

2005 ◽  
Vol 219 (2) ◽  
pp. 101-107 ◽  
Author(s):  
I. G. Wright ◽  
B. A. Pint
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Metallic Surface ◽  
Thermal Barrier ◽  
Protective Oxide ◽  
Barrier Coatings ◽  
Bond Coating ◽  
Industrial Gas Turbines

Thermal barrier coatings are intended to work in conjunction with internal cooling schemes to reduce the metal temperature of critical hot gas path components in gas turbine engines. The thermal resistance is typically provided by a 100-250 μm thick layer of ceramic (most usually zirconia stabilized with an addition of 7–8 wt% of yttria), and this is deposited on to an approximately 50 μ thick, metallic bond coating that is intended to anchor the ceramic to the metallic surface, to provide some degree of mechanical compliance, and to act as a reservoir of protective scale-forming elements (Al) to protect the underlying superalloy from high-temperature corrosion. A feature of importance to the durability of thermal barrier coatings is the early establishment of a continuous, protective oxide layer (preferably α-alumina) at the bond coating—ceramic interface. Because zirconia is permeable to oxygen, this oxide layer continues to grow during service. Some superalloys are inherently resistant to high-temperature oxidation, so a separate bond coating may not be needed in those cases. Thermal barrier coatings have been in service in aeroengines for a number of years, and the use of this technology for increasing the durability and/or efficiency of industrial gas turbines is currently of significant interest. The data presented were taken from an investigation of routes to optimize bond coating performance, and the focus of the paper is on the influences of reactive elements and Pt on the oxidation behaviour of NiAl-based alloys determined in studies using cast versions of bond coating compositions.

Bending Fatigue of Thermal Barrier Coatings

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Robert Eriksson ◽  
Zhe Chen ◽  
Krishna Praveen Jonnalagadda
Keyword(s):  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Base Alloy ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Fatigue ◽  
Crack Configuration ◽  
Lower Load ◽  
Delamination Damage

Thermal barrier coatings (TBCs) are ceramic coatings used in gas turbines to lower the base metal temperature. During operation, the TBC may fail through, for example, fatigue. In this study, a TBC system deposited on a Ni-base alloy was tested in tensile bending fatigue. The TBC system was tested as-sprayed and oxidized, and two load levels were used. After interrupting the tests, at 10,000–50,000 cycles, the TBC tested at the lower load had extensive delamination damage, whereas the TBC tested at the higher load was relatively undamaged. At the higher load, the TBC formed vertical cracks which relieved the stresses in the TBC and retarded delamination damage. A finite element (FE) analysis was used to establish a likely vertical crack configuration (spacing and depth), and it could be confirmed that the corresponding stress drop in the TBC should prohibit delamination damage at the higher load.

Evaluation of degradation and damage of thermal barrier coatings for 1700℃-class gas turbines

2002 ◽  
Vol 2002.2 (0) ◽  
pp. 219-220
Author(s):  
Masato NAKAYAMA ◽  
Tooru HISAMATSU ◽  
Taiji TORIGOE ◽  
Tsuneji KAMEDA ◽  
Hideyuki ARIKAWA ◽  
...  
Keyword(s):  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Barrier Coatings
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