Computational design of CMAS-resistant multiphase thermal and environmental barrier coatings for CMCs

Although ceramic matrix composites (CMCs) have been a material of interest for gas turbine components with operating temperatures 100-150 deg;C higher than typical superalloy materials, the temperature capability of CMCs is still limited by the lack of environmental durability of coatings. One of the main degradation mechanisms at high temperature (gt;1200 deg;C) is due to calcia-magnesia-alumina-silicate (CMAS) deposit. Under this SBIR program, QuesTek Innovations LLC will utilize its expertise in Integrated Computational Materials Engineering (ICME) and Materials by Designreg; approach to design multilayer thermal-environmental barrier coatings (T-EBCs) with improved environmental durability for enhanced performance of advanced CMC engine components. While EBC such as ytterbium disilicate is promising for protection against volatilization of thermally grown oxide, it is ineffective as a long-term protection against CMAS attack. Phase I will focus on development of a multiphase TBC with desired properties such as high reactivity with CMAS, high fracture toughness, low thermal conductivity and small coefficient of thermal expansion. This multiphase TBC acts as sacrificial layer by promoting reactive crystallization to mitigate CMAS infiltration and protect underlying materials from CMAS attack. QuesTek will leverage computational thermodynamic models and databases to predict CMAS-coating interactions and develop a CMAS-resistant multilayer T-EBC capable of extended performance at temperatures at or above 1482deg;C by the end of Phase II. The proposed integrated computational and experimental approach will accelerate material and architecture design to balance multiple competing performance requirements by reducing the need for time-consuming experiments.