Low-magnesium multilayer aluminum alloy brazing expansion material and application thereof

Abstract

The invention discloses a low-magnesium multilayer aluminum alloy brazing expansion material and application thereof. The low-magnesium multilayer aluminum alloy brazing expansion material comprises a core layer, a brazing layer and a covering layer which are sequentially compounded. The covering layer is prepared from, by weight percent, 0%-14% of Si, smaller than or equal to 0.3% of Fe, smaller than or equal to 0.1% of Mg, 0%-0.3% of Bi and the balance aluminum. The brazing layer is prepared from, by weight percent, 2%-15% of Si, smaller than or equal to 0.3% of Fe, 0.02%-0.15% of Mg, 0.05%-0.3% of Bi, 0%-4% of Zn, 0.05%-0.3% of rare earth elements and the balance aluminum. The core layer is prepared from, by weight percent, one of 1xxx, 3xxx, 5xxx, 6xxx and 7xxx or 0.05%-0.2% of rare earth elements and the balance one of 3xxx, 5xxx, 6xxx and 7xxx. By means of the low-magnesium multilayer aluminum alloy brazing expansion material and the application thereof, the welding quality of a brazed welding head can be saturated, and the defects that brazing flux is not likely to clean, and products are corroded are overcome.

Description

technical field [0001] The invention relates to a flux-free multilayer aluminum alloy brazing material. Background technique [0002] Usually, under the protection of inert gas, there is no need to add brazing flux inside the complex structure of the material, and the brazing of the alloy is completed only by melting, spreading and dissolving the oxide film on the surface of the parts to be brazed. Oxygen content on the outside is not easy to completely remove and control. When no flux is added, the oxygen content is higher than that of the interior due to the large external space, and the flux-free material on the exterior surface is easy to oxidize, resulting in insufficient flux-free exterior welding. In order to solve Flux-free external soldering is not full. Only for products with uncomplicated external structures, apply a small amount of flux that is less polluting and easy to remove on the outside. This is the way to minimize hazards and costs. In this way, the exter...

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Problems solved by technology

However, at present, the flux-free materials developed by various manufacturers are not suitable for flux components, because the outer surface has a high magnesium content, and a large amount of magnesium volatilized by diffusion reacts with the flux to form complex magnesium-containing salts, spreading the surface of the brazing liquid, making The brazing fluid cannot contact the aluminum substrate of the parts to be welded, resulting in gaps in the brazing seam on the outer surface after welding, and the appearance of the product is also blackened

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