Preceramic Precursor Routes to Tailorable, Low-Activation, Silicon-Carbide-Based Joints

72957S03-I Energy from thermonuclear fusion systems offers a long range option for decreasing U.S. dependence on foreign energy sources, enhancing national security, and mitigating climate change. Of the current options available for first-wall materials, composites made from silicon carbide fibers, incorporated in a matrix of silicon carbide (SiCf/SiCm), are a leading candidate. In order to utilize these composite materials, however, a reliable method of joining components to form large structures is required. This project will develop methods for joining SiCf/SiCm with tailorable, low-activation materials that can be applied in the field. In Phase I, experiments will be performed to understand the effects of active and inert fillers on the microstructure and strength of material and joints derived from the pyrolysis of preceramic precursors. Issues of mechanical properties, microstructural stability, and practical joining methods will be assessed. In Phase II, joint microstructures and processing methods will be optimized for improved joint strength and microstructural stability. Commercial Applications and Other Benefits as described by awardee: The primary commercial application is for joining silicon-carbide-based ceramics. Aside from assembling first-wall components for fusion energy systems, the joining methods would be attractive to manufacturers of other products containing SiCf/SiCm components. Such products include microelectronic processing equipment, space-based communication and observation equipment, high-temperature chemical process equipment, and turbine engine components.