Liquid-Film-Assisted Ceramic-Metal Bonding

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The objective of this study is to identify, examine and understand new mechanisms by which ceramic constituents can be joined into complex multicomponent assemblies using multilayer metallic interlayers as bonding agents. The approach utilizes liquid-film- assisted joining (LFAJ), which exploits structural and chemical changes occurring over microscopic to macroscopic length scales to achieve bonding at temperatures low enough to minimize the microstructural and property degradation of temperature-sensitive components, thereby enabling the formation of material combinations inaccessible by conventional methods. The proposed work focuses on joining a model ceramic-metal combination, Al2O3-Nb, using Ni/Nb/Ni trilayers. During joining a thin liquid film of Nb-saturated Ni will allow rapid Nb transport, and should facilitate direct Al2O3-Nb bonding. Optimizing LFAJ will require microdesign of the trilayer structure and chemistry, and tailoring of the joining surfaces. This project will assess the feasibility of this approach, and contributes to an ability to understand and ultimately control the formation of strong and durable bonds between ceramic components, facilitating the development of assemblies with arbitrarily complex shape.The work will establish fundamental microstructure-processing- property relationships in a more complex model system than prior studies, providing a template to guide successful extension of LFAJ to other systems. It will expose new avenues for joining bulk ceramics to bulk metals, and train graduate and undergraduate students in the increasingly important science of joining that is vital to materials integration in a wide range of transportation, medical, electronic and energy industries. Publications and presentations at meetings will disseminate the results to the broader materials community.