Ceramic-metal joining techniques

Successful applications of ceramic materials in many structures and components need some types of ceramic-metal joining. Two main factors derive the need for the development of joining techniques (1) the difficulty to fabricate large ceramic structures with complex shapes (2) the requirement of ceramic only in one part of a structure. For the practical applications, it will be necessary to join the ceramic to either another ceramic, or to a metal. The development of feasible joining techniques will facilitate the adaptation of advanced ceramics into complex and multifunctional structures. 

Superplasticity is a very promising property, not only because, like in metals, the superplastic formation opens a way for the manufacturing of complex ceramic pieces for industrial applications, but also because the combination of GBS and diffusional processes makes superplasticity an interesting tool for joining ceramic pieces in shorter times and lower temperatures than the diffusional joining technique. 

With suitable bonding techniques, the metal parts can be joined vacuum tight to the ceramic insulator in automated brazing procedures. 

Why a section on bonding techniques The main reason is that, at this moment the bonding of materials is a live topic in both materials science and research. We want to combine ceramics with identical or different ceramics, but also with metals and plastic. Moreover ceramicists are also interested in joining materials from an artistic point of view. Certain developments in technology require not only identical, but mostly different materials to be linked. When an object or component is too big or too complex to make it entirely of ceramics, part of it is made of metals and consequently the metals and the ceramics have to be joined. Since ceramics are quite often brittle, is may be desirable to make the ceramic part of the object as little as possible and to manufacture the remaning part of metal. This section will make clear that materials can be joined in many different ways, depending on the combination of materials and the circumstances under which they must be joined. 

Shrinking is a so-called mechanical bonding technique. Two hot objects are fitted together. When they cool the outer part attaches itself to the inner one. For this to be possible the outer part must have a bigger thermal expansion coefficient than the inner one. In this way ceramics and metals can be joined. 

A new technique is under development for depositing metal onto a ceramic substrate (e.g., ceramic membrane) at room temperature. This ion vapor deposition process combines ion implementation and electron beam deposition [Anonymous, 1988]. The ceramic substrate is irradiated with argon or nitrogen ions while the metal is vaporized by an electron beam and deposited onto the ceramic surface. The ion implementation directs the metal to the surface to be joined. 

Jadoon, A.K., Ralph, B., and Hornsby, P.R., Metal to ceramic joining via a metallic interlayer bonding technique, J. Mater. Proc. Techn. 152 (2004) 257-265. 

Brazing is joining a metal to a ceramic. The technique is well illustrated by considering metallization processes for AIN. There are several possible routes for forming the interfaces. 

An adhesive is a non-metallic material used to join two or more materials together. Adhesive bonding is the modern term for gluing, and the technique is used to join metals to themselves and also a wide variety of metallic and non-metallic materials including thermoplastic and thermosetting plastics, metal, glass, ceramics, rubber, concrete and brick. Many types of adhesive are available. 

By definition, a structural bond involves the formation of a load-bearing joint between high-strength materials, typically metal, wood, ceramic, and certain plastics. The first step in the selection of a joining method should be a comparison of the relative merits of the available techniques.In addition to structural adhesives, these include a number of mechanical fastening methods, such as screws, bolts, nails, staples, and rivets, as well as metal fusion processes. Many of these techniques are usually associated with the joining of metal structures. 

Many techniques are available for joining ceramics to other ceramics or to metals. The review of ceramic joining by Suganuma et al. and an earlier review by Rice provide a more detailed overview. 

Reaction joining by a metal melt infiltration technique is another effective way to join SiC. Tian et al. (Tian et al., 2011) nsed tape-cast TiB -C interlayers with different compositions and thickness to bond SiC ceramics via reactive Si infiltration at 1450 °C in vacnnm. This method resnlted in strong bonding of SiC bodies by... 

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