CN101407003B - Flux formulation suitable for medium temperature brazing of magnesium-containing aluminum alloys - Google Patents

Abstract

The invention relates to a formula for the braze welding of magnesium containing aluminum alloy, in particular to an intermediate temperature brazing flux formula which is applied to the braze welding of the magnesium containing aluminum alloy and of which the brazing temperature range is between 530 and 570 DEG C, and belongs to the welding technical field. Compared with the conventional chloride formula, the formula produces after-welding brazing flux residue which has the characteristics of no moisture absorption and no corrosivity; the formula better utilizes the characteristics of the phase diagram of a multicomponent compound, reduces the active temperature range of the brazing flux so as to be applied to the aluminum alloy with high strength level and low melting point, thereby widening the application range, lowering cost and improving the efficiency.

Description

Flux formulation suitable for medium temperature brazing of magnesium-containing aluminum alloys

technical field

The invention relates to a formula suitable for brazing magnesium-containing aluminum alloys, in particular to a medium-temperature brazing flux formula suitable for brazing magnesium-containing aluminum alloys with a brazing temperature range of 530-570°C, which belongs to the field of welding technology .

Background technique

Magnesium-containing aluminum alloys are easy to form interstitial oxide films of alumina and magnesia, which have high chemical stability and are difficult to remove, which seriously hinders the wetting and spreading of solder. The role of the brazing flux is to melt before the brazing filler metal during heating and brazing, remove the oxide film on the surface of the aluminum alloy, and form a layer of liquid film attached to the surface of the base metal to promote the melting and spreading of the brazing filler metal on the aluminum alloy surface. achieve the purpose of protection. The traditional chloride aluminum brazing flux is very effective in removing film, but its residue after welding has strong corrosiveness due to moisture absorption, and strict cleaning must be carried out after brazing. The melting temperature of traditional fluoride flux is 560°C, and the brazing temperature is above 590°C, which belongs to high-temperature brazing. Chinese invention patents 86101487 and 200610161295.6 respectively describe a method of brazing magnesium-containing aluminum alloys, but the former formula contains silicon strontium lanthanum, and it is used in a hydrogen atmosphere. On the one hand, it is a safety hazard, and on the other hand, the cost is too high; the latter formula Using pure aluminum or 3A21 aluminum alloy solder not only has a narrow application range, but also takes too long to weld, resulting in changes in the properties of the welded workpiece material, and the brazing temperature of these two methods is above 595°C.

Contents of the invention

Aiming at the above deficiencies, the present invention provides a non-corrosion flux formula suitable for brazing magnesium-containing aluminum alloys at medium temperature (brazing 540-560° C.).

The present invention is achieved through the following technical solutions: the formula is: 450 grams of aluminum trifluoride, 350 grams of potassium fluoride, 2 grams of beryllium difluoride, 1 gram of lithium fluoride, and 100 grams of cesium fluoride.

The formula is: 350 grams of aluminum trifluoride, 450 grams of potassium fluoride, 1 gram of beryllium difluoride, 2 grams of lithium fluoride, and 50 grams of cesium fluoride.

The formula is: 400 grams of aluminum trifluoride, 400 grams of potassium fluoride, 1 gram of beryllium difluoride, 1.5 grams of lithium fluoride, and 80 grams of cesium fluoride.

The brazing flux is to add aluminum trifluoride, potassium fluoride, beryllium difluoride, lithium fluoride, and cesium fluoride in an appropriate amount of water in turn under rapid stirring until completely mixed evenly, and the mixture is kept at 150°C for 2 hours Prepared by removing water. The brazing flux is analytically pure powder. The water is distilled water or deionized water, the melting point of the brazing flux is 480-520°C, the brazing temperature is 530-570°C, and the brazing protective atmosphere is nitrogen.

The invention adopts the fluoride formula, and compared with the traditional chloride formula, the flux residue after welding has the characteristics of non-hygroscopicity and non-corrosion; the invention makes good use of the characteristics of the multi-component phase diagram and reduces the activation temperature of the flux range, making it suitable for aluminum alloys with higher strength levels and lower melting points, expanding the scope of application, reducing costs and improving efficiency.

Detailed ways

The brazing flux formula components suitable for medium temperature brazing of magnesium-containing aluminum alloys according to the present invention and the weight percentages of each component are: aluminum trifluoride: 35-45%, potassium fluoride: 35-45%, difluoride Beryllium: 1-2%, Lithium Fluoride: 1-2%, Cesium Fluoride: 5-10%.

The brazing flux is prepared by adding aluminum trifluoride, potassium fluoride, beryllium difluoride, lithium fluoride, and cesium fluoride in an appropriate amount of water in turn under rapid stirring until completely mixed, and the mixture is kept at 150°C for 2 hours to remove water. income.

Described flux is analytical pure powder, and described water is distilled water or deionized water,

The melting point of the flux is 480-520° C., the brazing temperature is 530-570° C., and the brazing protective atmosphere is nitrogen.

The brazing flux formula of the present invention contains active ions such as beryllium and lithium, which can effectively remove the composite oxide film on the surface of the magnesium-containing aluminum alloy, and promote the wetting and spreading of the brazing material on the aluminum surface

This flux formula is suitable for medium-temperature brazing of 6063 and other magnesium-containing aluminum alloys.

1) Embodiment 1

First, take 200 grams of distilled water in a 1L tank, add 450 grams of aluminum trifluoride, 350 grams of potassium fluoride, 2 grams of beryllium difluoride, 1 gram of lithium fluoride, and 100 grams of cesium fluoride in sequence under rapid stirring. Until it is completely mixed and uniform, the mixture is kept at 150°C for 2 hours to remove water. The flux has a melting point of 490°C. Finally, it is coated on the surface of the base metal and brazed at 550°C under the protection of nitrogen atmosphere.

2) Embodiment 2

First, take 100 grams of deionized water in a 1L tank, add 350 grams of aluminum trifluoride, 450 grams of potassium fluoride, 1 gram of beryllium difluoride, 2 grams of lithium fluoride, and 50 grams of fluoride under rapid stirring. Cesium, until it is completely mixed, the mixture is kept at 150°C for 2 hours to remove water, the melting point of the flux is 508°C, and finally coated on the surface of the base metal, and brazed at 560°C under the protection of nitrogen atmosphere.

3) Embodiment 3

First, take 100 grams of distilled water in a 1L tank, add 400 grams of aluminum trifluoride, 400 grams of potassium fluoride, 1 gram of beryllium difluoride, 1.5 grams of lithium fluoride, and 80 grams of cesium fluoride in sequence under rapid stirring. Until it is completely mixed and uniform, the mixture is kept at 150°C for 2 hours to remove water. The flux has a melting point of 510°C, and is finally coated on the surface of the base metal, and brazed at 560°C under the protection of nitrogen atmosphere.

Claims (7)

1. The flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys is characterized in that: its formula is: 450 grams of aluminum trifluoride, 350 grams of potassium fluoride, 2 grams of beryllium difluoride, 1 gram of lithium fluoride, Cesium fluoride 100 grams. 2. Flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys, characterized in that: the formula is: 350 grams of aluminum trifluoride, 450 grams of potassium fluoride, 1 gram of beryllium difluoride, 2 grams of lithium fluoride, Cesium fluoride 50 grams. 3. Flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys, characterized in that: the formula is: 400 grams of aluminum trifluoride, 400 grams of potassium fluoride, 1 gram of beryllium difluoride, 1.5 grams of lithium fluoride, Cesium fluoride 80 grams. 4. The flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys according to any one of claims 1 to 3, characterized in that: the flux is added in an appropriate amount of water and trifluoro Aluminum chloride, potassium fluoride, beryllium difluoride, lithium fluoride, and cesium fluoride are mixed until completely uniform, and the mixture is kept at 150°C for 2 hours to remove water. 5. The flux formulation suitable for medium-temperature brazing of magnesium-containing aluminum alloys according to any one of claims 1 to 3, characterized in that the flux is analytically pure powder. 6. The flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys according to claim 4, wherein the water is distilled water or deionized water. 7. The flux formula suitable for medium-temperature brazing of magnesium-containing aluminum alloys according to any one of claims 1 to 3, characterized in that: the melting point of the flux is 480-520°C, and the brazing temperature is 530-500°C. 570°C, the brazing protective atmosphere is nitrogen. the