Bilateral project: Transient-Liquid-Phase Bonding of UHTCs Using Refractory-Metal-Based Interlayers for High-Efficiency Energy-Generation Applications

This project seeks to fill an emerging technological need by developing effective methods of joining high-performance ultrahigh temperature ceramics (UHTCs) using metal-based materials through a fundamental understanding and exploitation of phenomena occurring at the interfaces between joining media and the materials being joined. The collaboration leverages extensive experience in processing UHTCs at CNR-ISTEC, conducting fundamental studies on high-temperature liquid metal-UHTC interactions at Kyushu University (KU), and developing innovative methods of joining UHTCs (ISTEC, KU). The proposed research will extend TLP bonding methods to allow the rapid, reliable fabrication of robust joints involving UHTCs, and thus, to enable the full use of their unique properties in a wide range of applications. Enabling the introduction of UHTCs in both energy-generating and energy-consuming systems would allow operation at higher temperatures, increasing conversion efficiencies and potentially decreasing emissions. By establishing the relationship between the diffusivity-solubility product of the liquid former, the interlayer design, and the isothermal solidification time, the work will enhance understanding of TLP bonding and facilitate identification of viable interlayers for joining a wider range of UHTCs. TLP bonding allows engineers to take full advantage of UHTCs, while minimizing overall production costs, in contrast to currently available conventional bonding methods for ceramics. Establishing a reliable joining method will promote wider use of UHTCs, provide an avenue for quickly improving existing designs, and for developing new designs with significantly better performance. Such improvements will play a vital role in increasing efficiencies in clean energy-generation applications.