Diffusion Bonding – Hot Uniaxial Pressing

Diffusion welding refers to a family of processes based on diffusion mechanisms of various kinds to achieve a strong bond between two solid metal parts. Diffusion welding does not involve a liquid phase. Diffusion mechanisms combine with viscoplastic deformation at the material contact zone. To achieve this, during a diffusion welding cycle, a certain contact pressure and temperature must be applied simultaneously. Other parameters, such as the surface condition of the parts or the atmosphere, also influence diffusion welding quality.

There are several technologies available for diffusion welding. Uniaxial hot pressing is the technology presented in this article.

The fields of application for this assembly process are vast. Prototypes have been produced in fields such as heat exchangers and injection molds; in these examples, the aim is to achieve complex, fine internal geometries that are inaccessible or difficult to access by other mechanical processes on large assemblies (the press can support a surface area of 900 x 1,000 mm). The study and design philosophy is central to the project, and enables us to demonstrate the technology's potential.

Other benefits of the technology are then presented: weight reduction through the use of special materials, and the advantages of vacuum. The advantages and disadvantages of the technology are summarized. Diffusion welding technology is still quite costly, and an alternative to purchasing a machine is to outsource this service.

A glossary of terms is provided at the end of the article.