The Department of Energy has been funding the development of the generation of energy through controlled nuclear fusion. Future commercial fusion reactors can only be constructed when materials that are strong and tough at high temperatures are developed. These materials should not become excessively radioactive under the condition of intense neutron irradiation that will exist in these reactors. Silicon-carbide-fiber-reinforced silicon carbide is a candidate composite material for this demanding application. As future reactors will be large, individual panels and components of these composites will have to be assembled and joined into complex structures. In this project, innovative methods for the joining of silicon carbide to these composite parts will be evaluated and demonstrated. Two joining approaches will be evaluated: First, a "pre-ceramic" polymer will be used as the "glue" to hold the parts together. Upon heating this novel polymer will itself transform into silicon carbide, thus yielding a strong joint at high temperatures. Second, chemical reactions involving molten metals will be used to obtain strong bonding between different components. In this second case, the resultant "adhesive" will also be silicon carbide. Phase I of this project will establish the engineering viability of both approaches. The mechanical strength of the joints will be measured at ambient and high temperatures. In Phase II, the methods for joining silicon carbide fusion reactor components will be further developed. Extensive analysis and reliability testing will be performed.Commercial Applications and other Benefits as described by the awardee:Numerous commercial industrial applications exist for fiber-reinforced composites that must be joined to themselves or other materials, including stationary high-temperature gas turbine engines, internal combustion engines, heat recovery systems, burners and combustors, waste incineration systems, separation and filtration equipment, refractories, and chemical process equipment.
