ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
SiC fiber reinforced SiC matrix (SiC/SiC) composites are one of the most promisingmaterials for high temperature structural applications such as power generation and propulsionsystems. SiC/SiC composites are, however, susceptible to accelerated attacks in water vaporenvironments 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 forEBCs. Topcoat materials must be stable in the high-water-vapor pressurized environments at hightemperatures. Also, it is important that the thermal expansion coefficient of topcoat materials issimilar to that of the SiC/SiC composites.In this study, first, zirconium oxides, lutetium silicates and yttrium silicates were selected astopcoat candidate materials. They were exposed in a water-containing atmosphere at a temperature of1673 K for 100 h under a total pressure 0.96 MPa. Mass changes, structure of crystals andmicrostructures were investigated after the exposure experiments in order to evaluate the thermalstability of these materials. After their estimation, lutetium silicates were considered to be promisingfor topcoat materials.Then, lutetium silicates were coated as the topcoat of an EBC system on SiC/SiC composites, andtheir fracture toughness and microstructures were investigated after exposure to an oxidizingatmosphere. The evaluation results of the topcoat materials are reported in this paper
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/51/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.317-318.549.pdf
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