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

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.

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.

Mullite–gadolinium silicate environmental barrier coatings for melt infiltrated SiC/SiC composites

2011 ◽  
Vol 205 (12) ◽  
pp. 3578-3581 ◽  
Author(s):  
Sivakumar Ramasamy ◽  
Surendra N. Tewari ◽  
Kang N. Lee ◽  
Ramakrishna T. Bhatt ◽  
Dennis S. Fox
Keyword(s):  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Sic Composites

Quest and Evaluation of Topcoat Materials for Environmental Barrier Coatings of SiC/SiC Composites

2006 ◽  
Vol 317-318 ◽  
pp. 549-552 ◽  
Author(s):  
H. Nakayama ◽  
Kohei Morishita ◽  
Shojiro Ochiai ◽  
Takahiro Sekigawa ◽  
K. Aoyama ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Water ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Zirconium Oxides ◽  
Sic Fiber ◽  
Structural Applications ◽  
Sic Composites ◽  
Thermal Stability Of

SiC fiber reinforced SiC matrix (SiC/SiC) composites are one of the most promising materials for high temperature structural applications such as power generation and propulsion systems. SiC/SiC composites are, however, susceptible to accelerated attacks in water vapor environments through oxidation and volatilization reaction. For protection from such attacks, Environmental Barrier Coatings (EBCs) are indispensable. We have investigated some oxides and rare-earth silicates as topcoat candidate materials for EBCs. Topcoat materials must be stable in the high-water-vapor pressurized environments at high temperatures. Also, it is important that the thermal expansion coefficient of topcoat materials is similar to that of the SiC/SiC composites. In this study, first, zirconium oxides, lutetium silicates and yttrium silicates were selected as topcoat candidate materials. They were exposed in a water-containing atmosphere at a temperature of 1673 K for 100 h under a total pressure 0.96 MPa. Mass changes, structure of crystals and microstructures were investigated after the exposure experiments in order to evaluate the thermal stability of these materials. After their estimation, lutetium silicates were considered to be promising for topcoat materials. Then, lutetium silicates were coated as the topcoat of an EBC system on SiC/SiC composites, and their fracture toughness and microstructures were investigated after exposure to an oxidizing atmosphere. The evaluation results of the topcoat materials are reported in this paper.

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