A New Class of Creep Resistant Oxide/Oxide Ceramic Matrix Composites

Despite progress in the development of SiC/SiC ceramic matrix composites (CMCs), their application in industrial turbines and microturbines for distributed energy (DE) systems has been limited. The poor oxidation resistance of non-oxide ceramics requires the use of envrionmental barrier coatings (EBCs), which lead to issues with the life expectancy of the coatings. Oxide/oxide CMCs are potential replacements, but their use is limited by poor creep resistance at high temperatures, particularly above 1200 C. This project will use yttrium aluminum garnet (YAG) as a material system to advance the state-of-the-art in oxide/oxide-fiber-reinforced CMCs. Innovations in the composition and microstructure of the matrix, and in the processing of the matrix material will lead to high temperature mechanical properties not hitherto achieved. Phase I will demonstrate that the composition and microstructure of the matrix will have superior high temperature strength compared to oxide materials. To this end, test samples will be fabricated and creep studies will be performed. A further objective is to demonstrate that the proposed novel processing approach will lead to a sufficiently high density matrix without degrading the fiber. In Phase II oxide/oxide CMC prototype parts will be fabricated. Commercial Applications and other Benefits as described by the awardee: The new composites should allow turbines to run at higher temperatures, increasing operating efficiency and simultaneously reducing hydrocarbon and carbon dioxide emissions. The need for higher efficiency is particularly relevant due to the high cost of natural gas. According to one estimate, continued development of CMCs over the next several years can lead to savings of almost $1 billion.