scholarly journals Predicting EBC Temperature Limits for Industrial Gas Turbines

2021 ◽  
Author(s):  
Bruce A. Pint ◽  
Padraig Stack ◽  
Kenneth A. Kane
Keyword(s):  
Gas Turbines ◽  
Ceramic Matrix Composites ◽  
Failure Criteria ◽  
Matrix Composites ◽  
Bond Coating ◽  
Scale Thickness ◽  
Silica Scale ◽  
Industrial Gas Turbines ◽  
Initial Work ◽  
Maximum Temperatures

Abstract Higher turbine inlet temperatures may require the use of ceramic matrix composites (CMC) such as SiC/SIC, which require environmental barrier coatings (EBCs) to protect them against the detrimental effect of water vapor. The goal of this project is to determine the maximum bond coating temperature for EBCs for land-based turbines, where the minimum coating lifetime is 25,000 h. If the temperature exceeds the 1414°C melting point of the Si bond coating, then coatings without a bond coating also need to be evaluated. Thus, current Yb2Si2O7 EBCs with a Si bond coating and next-generation EBCs without a Si bond coating are being evaluated in laboratory testing using 1-h cycles in air+90%H2O. For this initial work, coatings were deposited on CVD SiC coupons. Reaction kinetics at 1250°, 1300° and 1350°C have been evaluated by measuring the thickness of the thermally grown silica scale after 100–500 h exposures. For comparison, scale growth rates for uncoated SiC and Si specimens in dry and wet environments were included as minimum and maximum values, respectively. Based on a critical scale thickness failure criteria, estimated maximum temperatures were calculated for both EBC systems using this initial data.

scholarly journals Melt Infiltrated Ceramic Matrix Composites for Shrouds and Combustor Liners of Advanced Industrial Gas Turbines

2011 ◽  
Author(s):  
Gregory Corman ◽  
Krishan Luthra ◽  
Jill Jonkowski ◽  
Joseph Mavec ◽  
Paul Bakke ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Industrial Gas Turbines

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.

scholarly journals Nondestructive Characterization of Ceramic Composites Used as Combustor Liners in Advanced Gas Turbines

1995 ◽  
Author(s):  
W. A. Ellingson ◽  
S. A. Rothermel ◽  
J. F. Simpson
Keyword(s):  
Gas Turbines ◽  
Thermal Characteristics ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Full Field ◽  
X Ray ◽  
X Ray Imaging ◽  
Combustor Liner ◽  
Nondestructive Characterization

Nondestructive characterization (NDC) methods which can provide full field information about components prior to and during use are critical to the reliable application of continuous fiber ceramic matrix composites in high firing temperature (>1350°C) gas turbines. For combustor liner applications, although nonmechanical load bearing components, thermal characteristics as well as mechanical integrity is vitally important. NDC methods being developed to provide necessary information include x-ray computed tomography (mainly for through-wall density and delamination detection), infrared-based thermal diffusivity imaging, and single-wall through-transmission x-ray imaging (mainly for fiber content and alignment detection). Correlation of the data obtained from NDC methods with subscale combustor liner tests have shown positive results at thermal cycling temperatures from 700°C to 1177°C.

Failure Criteria Development for Dynamic High-Cycle Fatigue of Ceramic Matrix Composites

2000 ◽  
Vol 37 (2) ◽  
pp. 319-324 ◽  
Author(s):  
Howard F. Wolfe ◽  
Michael P. Camden ◽  
Larry W. Byrd ◽  
Donald B. Paul ◽  
Larry W. Simmons ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Failure Criteria ◽  
Matrix Composites ◽  
Cycle Fatigue

Nondestructive Characterization of Ceramic Composites Used as Combustor Liners in Advanced Gas Turbines

1996 ◽  
Vol 118 (3) ◽  
pp. 486-490
Author(s):  
W. A. Ellingson ◽  
S. A. Rothermel ◽  
J. F. Simpson
Keyword(s):  
Gas Turbines ◽  
Thermal Characteristics ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Full Field ◽  
X Ray ◽  
X Ray Imaging ◽  
X Ray Computed ◽  
Nondestructive Characterization

Nondestructive characterization (NDC) methods, which can provide full-field information about components prior to and during use, are critical to the reliable application of continuous fiber ceramic matrix composites in high-firing-temperature (>1350°C) gas turbines. [For combustor liners, although they are nonmechanical load-bearing components, both thermal characteristics and mechanical integrity are vitally important.] NDC methods being developed to provide necessary information include x-ray computed tomography (mainly for through-wall density and delamination detection), infrared-based thermal diffusivity imaging, and single-wall through-transmission x-ray imaging (mainly for fiber content and alignment detection). Correlation of the data obtained from NDC methods with subscale combustor liner tests have shown positive results at thermal cycling temperatures from 700°C to 1177°C.

Effect of Microporosity on Damage Initiation in Ceramic Matrix Composites

2019 ◽  
Author(s):  
Suhasini Gururaja ◽  
Abhilash Nagaraja
Keyword(s):  
Gas Turbines ◽  
Ceramic Matrix Composites ◽  
Local Stress ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Damage Initiation ◽  
The Matrix ◽  
Homogenization Approach ◽  
Matrix Porosity ◽  
Monolithic Ceramics

Abstract Ceramic matrix composites (CMC) are a subclass of composite materials consisting of reinforced ceramics. They retain the advantages of ceramics such as lower density and better refractory properties but exhibit better damage tolerance compared to monolithic ceramics. This combination of properties make CMCs an ideal candidate for use in high temperature sections of gas turbines. However, modeling the damage mechanisms in CMCs is complex due to the heterogeneous microstructure and the presence of processing induced defects such as matrix porosity. The effect of matrix pore location and orientation on damage initiation in CMCs is of interest in the present work. CMCs fabricated by various fabrication processes exhibit matrix pores at different length scales. Microporosities exist within fiber bundles in CMCs have a significant effect on microscale damage initiation and forms the focus of the current study. In a previous work by the authors, a two step numerical homogenization approach has been developed to model statistical distribution of matrix pores and to obtain the effective mechanical properties of CMCs in the presence of matrix porosity. A variation of that approach has been adopted to model matrix pores and investigate the severity of pores with respect to their location and orientation. CMC microstructure at the microscale has been modeled as a repeating unit cell (RUC) consisting of fiber, interphase and matrix. Ellipsoidal pores are modeled in the matrix with pore distance from the interphase-matrix interface and pore orientation with respect to the loading direction as parameters. Periodic boundary conditions (PBCs) are specified on the RUC by means of constraint equations. The effect of the pore on the local stress fields and its contribution to matrix damage is studied.

Development of failure criteria for dynamic high cycle fatigue of ceramic matrix composites

1998 ◽  
Author(s):  
Howard Wolfe ◽  
Larry Byrd ◽  
M. Camden ◽  
L. Simmons ◽  
Donald Paul ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Failure Criteria ◽  
Matrix Composites ◽  
Cycle Fatigue
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