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Diffusion bonding of aluminum and aluminum alloys
| Details |
Inventors: Cooper, Graham A.; Bottomley, Ian E.;
Assignee: British Aerospace PLC (London, GB)
Primary Examiner: Heinrich; Samuel M.
Assistant Examiner:
Attorney, Agent or Firm: Kerkam, Stowell, Kondracki & Clarke
A process is described of forming a diffusion bonded article from components made of aluminum or an alloy thereof that forms a protective coating of an oxide that inhibits such bonding. The process comprises removing the oxide layer and immediately forming the components into a stack, placing the stack in the chamber of an electron beam welding device, evacuating the chamber and electron beam welding the edge regions of the stack; the welded stack can then be diffusion bonded at leisure without the oxide re-forming. The diffusion bonded article can be superplastically formed to a finished or semi-finished shape. |
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DETAILED DESCRIPTION We claim: 1.
A process of forming a structure from metallic components made of aluminum or an aluminum alloy that is liable to form a surface coating of oxide, which process comprises the steps of: substantially removing the oxide surface coating from the aluminum or aluminum alloy components; applying a stopping-off material to selected regions of the components, which stopping-off material prevents diffusion bonding in said selected regions during the diffusion bonding step; assembling the components together to form a stack; placing the stack in a chamber of an electron beam welding apparatus; evacuating the chamber; welding edge regions of the components together by electron beam welding; removing the welded stack from the chamber; subjecting the stack to a diffusion bonding step in which the components are bonded together except in said selected regions; and subjecting the thus bonded stack to superplastic forming to form the said structure by heating the stack to a temperature at which the components become superplastic, and subjecting the stack to deformation to produce the structure.
2.
A process as claimed in claim 1, wherein the components are in sheet-form.
3.
A process as claimed in claim 1, wherein the step of removing the oxide surface comprises subjecting the component(s) to an acid etch or to treatment with a de-oxidising solution, grit blasting the components and then treating the component(s) chemically to remove remaining oxide.
4.
A process as claimed in claim 1, wherein the diffusion bonding step is performed in a heated press.
5.
A process as claimed in claim 4, wherein the diffusion bonding step is performed by hot isostatic pressing.
6.
A process as claimed in claim 1, wherein in the diffusion bonding step the stack is compressed by means of a membrane across which a differential pressure is maintained.
7.
A process as claimed in claim 1, wherein the diffusion bonding is performed with the simultaneous working of the components.
8.
A process as claimed in claim 1, wherein the diffusion bonding is performed without the simultaneous working of the components
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Generators or Motors 
