Diffusion bonding

Overview

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. We have developed this method, with an aluminium interlayer, to produce low-distortion viewports due to the relatively low processing temperatures involved (~500C).

Benefits

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)

Bonding design

Successful bonding design depends upon:

• joint geometry, surface finish
• choice of parent material and interlayer
• planning for furnace tooling

We develop novel diffusion bonded solutions for fusion challenges, but also supply components to semiconductor, quantum, and metrology customers.

Our team has made diffusion-bonded components which operated successfully for decades as a safety-critical boundary in the JET fusion machine. They are now being qualified for the same use in the larger ITER fusion machine. We have a wealth of experience in qualifying novel processes for use in stringent regulatory regimes.

For best results contact us at the earliest stage of design.

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