There is an identified need to braze together components in a wider range of aluminium alloys than is currently possible. This arises from the low melting points of these alloys, relative to those of existing brazes, and restrictions imposed by the alternative joining methods.
An example of the latter is mechanical fastening, where allowable geometries of components are limited and there are heavy penalties in terms of machining and assembly costs, Moreover, assurance on integrity and reliability can be difficult to establish. The aim of the project is to address this requirement by identifying and developing aluminium alloy brazes that melt below 500 C.
Most high strength aluminium engineering alloys cannot be joined by brazing because they either degrade or melt at the temperature at which commercially available aluminium brazes are used.
A brazing process suitable for joining aluminium engineering alloys has been developed employing 2 novel low melting point brazes. The brazes are available as ductile foil preforms. The process is fluxless so that no postjoining cleaning treatments are necessary. The aluminium components and the brazing foil require a simple chemical treatment prior to their use. The brazing process involves heating to a temperature of 510 to 550 C, maintained for a period of 5 to 45 min, in either vacuum or a furnace chamber that is purged continuously with nitrogen gas. Alternatively the brazes can be used in air with a suitable flux. High strength joints with adequate resistance to corrosion can be made. Some promising new applications for aluminium brazing technology have been developed, based on this new process.
That such brazes are to be found in aluminium alloy systems containing silicon and germanium plus other elements. Joining processes based on selected compositions will be developed for use in industrial manufacturing.
The ultimate goal of the project is to braze a range of representative components for airframe, aerospace and automotive applications that are difficult or impossible to braze at
A successful outcome is likely to enable major improvements to be made to the design and performance of components and improve the cost-effectiveness of their manufacture.
In consequence, this would raise the competitive edge of European manufacturing industry.
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