Novel Oxide Ceramic Matrix Composites for Gas Turbine Applications

The use of Ceramic Matrix Composites (CMCs) as hot-section components in gas turbines and engines could significantly increase the operating temperature, resulting in enhanced energy efficiency and reduced emission of harmful gases. CMCs offer high temperature capability compared to superalloys and improved reliability compared to monolithic ceramics. However, current non-oxide CMCs, such as SiC-based Continuous Fiber Ceramic Composites (CFCC) or oxide CMCs based on polycrystalline alumina fibers, show significant corrosion under hydrothermal oxidation conditions or have a temperature limit of 1100oC, respectively. As a consequence, an environmental barrier coating (EBC) or a thermal protection system (TPS) must be applied to current CMCs (both non-oxide or oxide) used in turbine applications. These protective systems provide only limited reliability, and they increase processing costs. This problem will be addressed by developing an oxide-ceramic-composite system by combining high temperature (~1400oC) oxide fibers with a hydrothermally and thermally stable matrix and interphase. This novel CMC will work continuously under gas turbine operating conditions greater than1200oC without relying on the protection provided by EBC or TPS. In Phase I, several matrix and interphase compositions will be identified and their hydrothermal stability will be evaluated. Composites will be fabricated by combining the high temperature fibers and hydrothermally stable matrix with a porous interphase between them. Mechanical properties of the novel composite will be measured, before and after long time exposure at high temperature hydrothermal oxidation conditions, in order to demonstrate the feasibility for gas turbine applications. Commercial Applications and other Benefits as described by the awardee: A novel CMC material, which can be used under gas turbine operating conditions greater than 1200oC and without relying on EBC or TPS protection, should result in a useful and marketable product. It should impact the power generation and aero-engine industries, improving their energy efficiency dramatically. This material also should find application in other industries due to its durability and light weight. In addition, the new material would benefit environmental protection since it would reduce the emission of harmful exhaust gases from turbines and engines