SBIR-STTR Award

Phase i aims to demonstrate the feasibility of fabricating preforms for ceramic composite shapes of interest to fossil energy by using proprietary three-dimensional braiding technology. High performance ceramic composites, operating in extreme conditions of temperature and corrosive environment, require preform architectures that can provide toughness, strength, and a capacity to eliminate failure from incipient crack formation in the ceramic matrix. This requires a three-dimensional fiber architecture, providing strength and stiffness in all directions and an intertwined network of fibers capable of confronting-and deflecting-any cracks that may form in the host matrix during operation. This crack containment results in damage containment and continued operation of the ceramic composite component. Lifetime and reliability should be greatly extended. Three-dimensional braids operate successfully in polymeric composites. They provide reinforcement and enhance mechanical properties in three dimensions, extend life-time and reliability, and provide damage tolerance of a high degree. Although the failure mechanisms appear different for ceramic composites, the existence of these braided preforms is expected to have comparable effects on ceramic composites. Phase i selects refractory fibers and will attempt to make preforms from them, using three-dimensional braiding technology, in shapes of interest to fossil energy. Various fiber architectures will be made to determine the flexibility of the refractory fibers to operate in the range of fabrication capability of the braiding technology.

Phase II will expand on the success of Phase I to demonstrate the feasibility of fabricating threedimensional braided preforms for shapes of interest to the energy community, using refractory fibers represented by Nicalon. The program will expand the scope of application to include, besides chemical vapor infiltration, such other candidate matrix forming systems as polymeric precursor and sol-gel casting. Processing studies will produce test pieces suitable for characterizing the properties of the candidate ceramic composite systems (using three-dimensional braided preforms). The studies will thus form a technical base for further development of more promising composite systems, fabrication of preforms for complex shapes of interest to users of ceramic composites, subsequent infiltration with the "prime matrix processing" technology, and testing and evaluating the demonstration complex ceramic composite shape. Extensive industry/ government liaison and market research will be conducted to both inform the ceramics community of development and assess the potential market for these new products. If the market research yields favorable results, it will guarantee continuation of this developing technology to pursue manufacturing and marketing of these high performance ceramic composite shapes.Anticipated Results/Potential Commercial Applications as described by the awardee:A successful preform for ceramic composites means significant elevation of the performance level of these materials, permitting wide application in areas where their thermal stability and chemical inertness have already made them attractive. Potential markets include power generation,both stationary (as in power supplies for communities) and mobile (gas turbine engines); high temperature candle filters in power stations; heat exchanger elements; automotive motor applications; and jet engines.