Diffusion Bonding/Welding is a process where the strength of the joint results from the movement of atoms across the interface and secondarily from plastic deformation of the faying surfaces.
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What temperature is necessary to achieve sufficient diffusion?
About half the melting temperature of the parent metal.
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Describe the process.
The joint is put under pressure and heated, normally in a furnace although induction or resistance heating can be used.
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How can the weld surfaces be protected?
It can be carried out in an inert atmosphere.
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What can be added to assist the diffusion between two metals, and what is it called when this is done?
A filler can be added between the faying surfaces and the process can be called diffusion braising.
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What does the strength of the joint achieved depend on?
Pressure, Temperature, Cleanliness of faying surfaces, Surface preparation and profile and Time.
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How is the strength of the diffusion bond determined?
It will have the strength of the weaker of the two parent metals.
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What is the process used extensively for?
Joining dissimilar metals and for joining reactive metals.
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What other process is diffusion bonding used with to form sheet metal structures?
Plastic forming.
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Name the four types of diffusion that can occur during diffusion bonding.
Interstitial Diffusion, Exchange Diffusion, Ring Diffusion, Vacancy Diffusion
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Describe why porosities are not harmful if left in the grain.
They are not seen to be harmful to the weld joints as they are localised and spherical shaped, so not damaging, if diffusion is continued they will be eliminated.
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When was the process developed?
It was developed in the 1970's, but dates back to when goldsmiths bonded gold over copper to create filled gold.
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Other cards in this set
Card 2
Front
What temperature is necessary to achieve sufficient diffusion?
Back
About half the melting temperature of the parent metal.
Card 3
Front
Describe the process.
Back
Card 4
Front
How can the weld surfaces be protected?
Back
Card 5
Front
What can be added to assist the diffusion between two metals, and what is it called when this is done?
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