Liquid-Film-Assisted Ceramic-Metal Bonding

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Engineering ceramics are candidates for many structural, biological, and microelectronics applications. Direct fabrication of large, complex ceramic structures is difficult, and an approach that involves the assembly and joining of smaller components is often used. Joining is also often necessary when ceramic components are incorporated into metal-based structures to exploit their unique properties. The quality of the interfaces and joints produced during assembly impacts device performance. The difficulties associated with joining ceramics can limit or prevent their use. The proposed work will explore a novel approach to joining structural ceramics by means of foil interlayers based on high-melting-point metals. Joining ceramics to refractory metals has generally involved processes that require elevated temperature, long times, significant bonding pressure, and extremely careful preparation of the surfaces to be joined. Such characteristics make these combinations and these processes unattractive for mass production. The intellectual merit of the proposed work is focused on exploring the use of a multilayer interlayer combining a high-melting-point metal, Nb, and very thin coating layers of a lower-melting-point metal, Ni, to provide a joining process that can be implemented at reduced temperatures to rapidly produce robust, reliable refractory joints by means of a liquid-film-assisted, transient-liquid-phase bonding processing that does not require scrupulous surface preparation or high bonding pressures. The broader impact of such a manufacturing-friendly process includes the creation of many new opportunities to more easily and economically fabricate ceramic-based or ceramic-containing devices with new functionality. The basic science approach underlying the study will help facilitate the extension of the joining approach to other systems, while educating and training young researchers in this vital area.