Bonded brazing

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

Porous P/M products can be sinter bonded to soHd metals. They can also be welded, brazed, or soldered. Filling the voids with flux or molten metal has to be avoided. P/M porous products can be machined, but blocking of the porous passages has to be avoided. Press fitting and epoxy bonding are commonly used. 

Brazing filler metal is carried on a plastic-bonded tape. ... 

Bonded. Tubes on which fins are bonded to the outside surface by hot-dip galvanizing, brazing, or welding. 

Fig 19 11 Joining methods for ceramics (a) glaze bonding, (b) diffusion bonding, (c) metallisation plus brazing. In addition, ceramics can be clamped, and can be joined with adhesives. 

An interesting example of judicious choice of braze filler is to be found in the selection of silver alloys for the brazing of stainless steels to be subsequently used in a tap-water environment . Although the brazed joint may appear to be quite satisfactory, after a relatively short exposure period failure of the joint occurs by a mechanism which appears to be due to the break-down of the bond between the filler and the base metal. Dezincifica-tion is a prominent feature of the phenomenon and zinc-free braze alloys based on the Ag-Cu system with the addition of nickel and tin have been found to inhibit this form of attack. A similar result is obtained by electroplating 0-007 mm of nickel over the joint area prior to brazing with a more conventional Ag-Cu-Zn-Cd alloy. 

Brazing is the process of joining metals by flowing a thin, capillary thickness layer of nonferrous filler metal into the space between them. Bonding results from the intimate contact produced by the dissolution of a small amount of base metal in the molten filler metal, without fusion of the base metal. The term brazing is used where the temperature exceeds 425°C (800°F). 

Transition joints are used to join dissimilar metals where flanged, screwed, or threaded connections are not practical. They are used when fusion welding of two dissimilar metals forms interfaces that are deficient in mechanical strength and the ability to keep the system leak-tight. Transition joints consist of a bimetallic composite, a stainless steel, and a particular kind of aluminum bonded together by some proprietary process. Some of the types in use throughout the cryogenic industry are friction- or inertia-welded bond, roll-bonded joint, explosion-bonded joint, and braze-bonded joint. 

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