Innovative Ceramic Matrix Composite (CMC) Joining and Attachment Technology

Physical Sciences Inc. (PSI) will work with our team members to develop significantly less costly methods of attaching ceramic matrix composite (CMC) components to metal structures in jet turbine engines for JSF and other military platforms. We will demonstrate the ability to braze CMCs to representative superalloys, using brazing processes that are modifications to those commercially available. The CMC/superalloy joint will withstand the high rate cyclic thermal and mechanical loading and long service life required of components in military jet turbine engines. It is the goal of the overall proposed SBIR program to develop and validate brazed CMC to superalloy joints for JSF engine component types. This technology will be transitioned to JSF and other engine manufacturers. In the Phase I program we will demonstrate the feasibility of our approach by designing, fabricating and validating that brazed joints • Exceed shear strengths of 2.5 KSI, • Exceed tensile strengths of 40 KSI, • Accommodate thermal expansion differences between the CMC (~3.5*10-6/oF), braze and superalloy (~8.8*10-6/oF each) to withstand at least 1000 repetitive thermal cycles between room temperature and 1750oF, and • Withstand more than 4000 fatigue cycles representative of in-service design loads of approximately 250 lbf per attachment point. BENEFITS: The development of a successful CMC/superalloy brazing process will simplify and reduce the cost of integrating CMC components into jet engine systems by allowing CMCs to be attached directly to metallic mounts. CMC components will allow higher temperature operation resulting in greater fuel economy, lighter weight and reduced noise. Specific benefits to JSF from successful development of the joining technology include up to 10% cost reduction in afterburner flaps and seals. Additional JSF cost savings will result from the thermal insulating value of CMCs that will reduce nozzle costs through replacement of superalloy nozzle components with titanium.