Introduction to fundamentals of diffusion bonding
Within the confines of this definition, the db process, in practice, is limited to either press or gas pressure or bonding approaches. Diffusion bonding is an attractive joining technique for many advanced materials particularly, when these are degraded by traditional fusion welding processes and when the need for environmental or thermal stability in thin-sheet structures precludes adhesive bonding.
Process of diffusion bonding:
- DIFFUSION BONDING is only one of many solid-state joining processes wherein joining is accomplished without the need for a liquid interface (brazing) or the creation of a cast product via melting and resolidification (welding).
- In its most narrow definition, which is used to differentiate it from other joining processes such as deformation bonding or transient liquid phase joining, diffusion bonding (DB) is a process that produces solid-state coalescence between two materials under the following conditions:
- joining occurs at a temperature below the melting point, tm, of the materials to be joined
- coalescence of contacting surfaces is produced with loads below those that would cause macroscopic deformation to the part
- a bonding aid can be used, such as an interface foil or coating, to either facilitate bonding or prevent the creation of brittle phases between dissimilar materials, but the material should not produce a low-temperature liquid eutectic upon reaction with the materials to be joined.
Thus, diffusion bonding facilitates the joining of materials to produce components with no abrupt discontinuity in the microstructure and with a minimum of deformation. Within the confines of this definition, the DB process, in practice, is limited to either press or gas pressure or bonding approaches
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