Diffusion bonding involves the joining of parent materials, below their melting point, by heating and applying force in a clean vacuum environment.
Interlayer diffusion bonding involves the joining of parent materials, below their melting point, by using a metallic interlayer which deforms under heat and pressure in a clean vacuum environment. STG has developed this method, with an aluminium interlayer, to produce low-distortion viewports due to the relatively low processing temperatures involved (~500C).
Process benefits of interlayer diffusion bonding include:
- Consistency – The furnace environment and process are automated.
- Low distortion – The low process temperature minimises the effect of differential expansion in dissimilar joints producing joints of very low stress.
- Versatility – Al interlayers can produce diffusion bonded joints with much lower requirements on surface finish and flatness compared to parent-parent diffusion bonding.
- Rework – Aluminium bonds can be dissolved to recover and re-bond valuable component materials such as diamond and sapphire (often used in specialist viewports)
Successful bonding design depends upon:
- Joint geometry, surface finish
- Choice of parent material and interlayer
- Planning for furnace tooling
Please contact the experienced staff at STG at the earliest stage of design to get the best end results.
STG develop novel diffusion bonded solutions for fusion challenges, but also supply components to semiconductor, quantum, and metrology customers.
Diffusion-bonded components made by STG have operated successfully for decades as a safety-critical boundary in the JET fusion reactor and are now being qualified for the same use in the larger ITER fusion reactor. STG have a wealth of experience in qualifying novel processes for use in stringent regulatory regimes.
