Nano-phase Exothermic Brazing Processes and Joint Design for CMC Attachment

MRi is proposing an innovative, nano-phase exothermic braze technology that will provide an innovative and cost effective way to join and attach ceramic composites to themselves and to metals for fabricating aircraft CMC components. The initial application of this technology will be aimed at JSF jet engine components, more specifically “T-attachment ribs” on SiC:SiNC flaps that might be used in the JSF vectoring nozzle. The proposed joining technology will utilize nano-phase exothermic particulate performs made from specially milled reactive precursor compounds. The nano-phase composite preforms will, upon ignition, react and generate over 3,000ºC locally, enough to fuse an react adjoining CMC or CMC:metal surfaces. The precursor materials will be selected to result in refractory composite joint materials capable of operating up to 4,000°F. MRi has teamed with Materials Research and Design for their CMC design and analysis capability and with Exotherm Corporation for their exothermic materials expertise. MR&D will analyze and design joints compatible with the proposed exothermic brazing technology. Phase I investigations would focus on design, analyzing and developing nano-phase braze mixtures and braze processes for making SiC:SiNC “T-section” joints. Various exothermic material systems will be investigated a selection of the more optimum joining performs will be made and demonstrated on small T-section SiC:SiNC small scale flat coupons followed by metallographic evaluations and thermal exposure tests.BENEFITS: The proposed nano-phase technology has applications for joining a and CMC materials for use in wide range of aircraft applications such as combustor liners, ducts, deflectors and engine nozzles. CMC rocket engine nozzles and ducts thermal protection (TPS) systems for aero or space structure would be more easily and cost effectively produced if such a cost effective joining technology were developed. Other DoD applications include large ceramic gun barrel liners and composite ceramic armor. The ability to directly join ceramic-ceramic and ceramic-metal structures would make applications for power turbines, industrial thermal processing equipment, ceramic tooling, x-ray targets, and high temperature molds possible.