Advanced Environmental Barrier Coatings for SiC/SiC Composites

2005 ◽  
Author(s):  
Tania Bhatia ◽  
Harry Eaton ◽  
Ellen Sun ◽  
Thomas Lawton ◽  
Venkat Vedula
Keyword(s):  
Silicon Carbide ◽  
Field Tests ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Carbide Matrix ◽  
Higher Temperature ◽  
Engine Testing ◽  
Sic Composites ◽  
Combustor Liner

Environmental barrier coatings (EBCs) are being developed for silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composites to protect against accelerated oxidation and subsequent silica volatilization in high temperature, high-pressure steam environments encountered in gas turbine engines. Engine testing of three-layer barium strontium aluminosilicate (BSAS) has demonstrated a life of over 15,000 hours in a combustor liner application at a nominal temperature of 2200°F (1204°C). The engine field tests have shown that useful engine life is limited by BSAS recession and potential eutectic reactions between BSAS and silica. BSAS based coatings have also been shown to survive severe thermal gradient burner rig tests with 2700°F (1482°C) surface temperature and a 300°F (167°C) gradient through the coating. Promising EBC candidates for longer life and/or higher temperature applications include strontium aluminosilicate (SAS) based coatings.

Development and Evaluation of Environmental Barrier Coatings for Si-Based Ceramics

2004 ◽  
Author(s):  
Tania Bhatia ◽  
Venkat Vedula ◽  
Harry Eaton ◽  
Ellen Sun ◽  
John Holowczak ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Field Tests ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
And Performance ◽  
Combustor Liner

Environmental barrier coatings (EBCs) are being developed for silicon carbide (SiC) based composites and monolithic silicon nitride (Si3N4) to protect against the accelerated oxidation and subsequent silica volatilization in high temperature, high-pressure steam environments encountered in gas turbine engines. While EBCs for silicon carbide (EBCSiC) have been demonstrated in combustor liner applications, efforts are ongoing in the development of EBC systems for silicon nitride (EBCSiN). The challenges of adapting EBCSiC to monolithic Si3N4 are discussed in this paper. Progress in the area of EBCSiN including development and performance during field tests and tests simulating engine conditions are reviewed.

scholarly journals Thermal and Mechanical Evaluation of Environmental Barrier Coatings for SiCf-SiC Composites

2017 ◽  
Vol 30 (2) ◽  
pp. 84-93 ◽  
Author(s):  
Yeon-Hwa Chae ◽  
Heung Soo Moon ◽  
Seyoung Kim ◽  
Sang Kuk Woo ◽  
Ji-Yeon Park ◽  
...  
Keyword(s):  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Sic Composites

Development and Evaluation of Environmental Barrier Coatings for Silicon Nitride

2002 ◽  
Author(s):  
Ellen Y. Sun ◽  
Harry E. Eaton ◽  
John E. Holowczak ◽  
Gary D. Linsey
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Ceramic Matrix Composites ◽  
Turbine Engines ◽  
Matrix Composites ◽  
Gas Turbine Engines ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Temperature Capability

Environmental barrier coatings (EBCs) are required for applications of silicon nitride (Si3N4) and silicon carbide (SiC) based materials in gas turbine engines because of the accelerated oxidation of Si3N4 and SiC and subsequent volatilization of silica in the high temperature high-pressure steam environment. EBC systems for silicon carbide fiber reinforced silicon carbide ceramic matrix composites (SiC/SiC CMC’s) were first developed and have been demonstrated via long-term engine tests. Recently, studies have been carried out at United Technologies Research Center (UTRC) to understand the temperature capability of the current celsian-based EBC systems and its suitability for silicon nitride ceramics concerning thermal expansion mismatch between the EBC coating and silicon nitride substrates. This paper will present recent progress in improving the temperature capability of the celsian –based EBC systems and discuss their effectiveness for silicon nitride.

scholarly journals Correlation of Process Conditions, Porosity Levels and Crystallinity in Atmospherically Plasma Sprayed Yb2Si2O7 Environmental Barrier Coatings

2021 ◽  
Vol 5 (8) ◽  
pp. 198
Author(s):  
Robert Vaßen ◽  
Emine Bakan ◽  
Doris Sebold ◽  
Yoo Jung Sohn
Keyword(s):  
Gas Turbines ◽  
Single Layer ◽  
Hot Water ◽  
Process Conditions ◽  
Standard Material ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Sic Composites ◽  
Plasma Sprayed

Environmental barrier coatings are necessary to protect fibre reinforced ceramics from high recession rates in fast and hot water vapor-containing gases as they typically are found in the hot gas sections of gas turbines. A standard material to protect SiC/SiC composites is atmospherically plasma sprayed (APS) Yb2Si2O7. For this material, it is difficult to obtain at reasonable substrate temperatures both low porosity and high crystallinity levels during APS. In this paper results of coatings prepared by a so-called high velocity APS process and also more conventional processes are presented. All coatings have been prepared by a single layer deposition method which avoids inter passage porosity bands. Furthermore, the samples were heat-treated in air at 1300 °C for 100 h and the influence of the topcoat density on the growth of the silica scale on the used silicon bond coat was studied.

Evaluating Environmental Barrier Coatings on Ceramic Matrix Composites After Engine and Laboratory Exposures

2002 ◽  
Author(s):  
Karren L. More ◽  
Peter L. Tortorelli ◽  
Larry R. Walker ◽  
Josh B. Kimmel ◽  
Narendernath Miriyala ◽  
...  
Keyword(s):  
Ceramic Matrix Composite ◽  
Field Tests ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Test Site ◽  
Engine Test ◽  
Test Analysis ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier

SiC/SiC continuous fiber-reinforced ceramic matrix composite (CFCC) combustor liners having protective environmental barrier coatings (EBCs) applied to the liner working surfaces have been field-tested in a Solar Turbines’ Centaur 50S SoLoNOx engine at the Chevron, Bakersfield, CA engine test site. This latest engine test ran for a total of 13,937h. The EBCs significantly increased the lifetime of the in-service liners compared with uncoated CFCC liners used in previous field-tests. The engine test was concluded when a routine borescope inspection revealed the formation of a small hole in the inner liner. Extensive microstructural evaluation of both the inner and outer liners was conducted after removal from the engine. Post-test analysis indicated that numerous degradation mechanisms contributed to the EBC and CFCC damage observed on the liners, including EBC volatilization, sub-surface CFCC oxidation and recession, and processing defects which resulted in localized EBC spallation and accelerated CFCC oxidation. The characterization results obtained from these field-tested liners have been compared with the analyses of similarly-processed CFCC/EBCs that were laboratory-tested in a high-pressure, high temperature exposure facility (the ORNL “Keiser Rig”) for >6000h.

Sign in / Sign up

Export Citation Format

Share Document