A soldering sheet for dissimilar material welding and a method for manufacturing the same

Abstract

The application discloses a welding sheet for dissimilar material welding, which comprises a hollow welding sheet shell, a core layer flux and an outer layer flux, the core layer flux is uniformly dispersed in the hollow of the welding sheet shell, and the outer layer flux is loaded on the surface of the welding sheet; raw materials of the core layer flux include, by weight, 10-12 parts of potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal, 2-4 parts of cesium fluoroaluminate and 2-4 parts of nano-nickel modified graphene oxide; raw materials of the outer layer flux include, by weight, 10-12 parts of potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal, 2-4 parts of cesium fluoroaluminate, 2-4 parts of nano-nickel modified graphene oxide, 0.1-0.2 parts of fluorocarbon surfactant and 3-4 parts of polyvinyl alcohol; and the application further discloses a preparation method of the welding sheet. The application can be used for welding of aluminum alloy and alloy steel, improves welding effect, and improves mechanical properties and corrosion resistance of a welding seam.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brazing, in particular to a welding sheet for dissimilar material welding and a preparation method thereof. BACKGROUND

[0002] The composite structure of aluminum alloy and steel has comprehensive advantages such as light weight, high strength, corrosion resistance, etc., and is one of the important ways to realize lightweight, energy saving and emission reduction, and increase efficiency. It is widely used in the fields of aerospace, automobile manufacturing and shipbuilding, etc.

[0003] However, the solubility between aluminum and iron is low, the crystal structure and thermal physical properties are greatly different, and the reaction to generate brittle intermetallic compounds is easy to occur. In addition, aluminum alloy is easy to oxidize and difficult to remove film, so the mechanical properties and corrosion resistance of the weld after aluminum / steel dissimilar metal welding are insufficient.

[0004] Moreover, due to the difference in the properties of the base material and its surface oxides, the wetting and spreading performance of the same filler metal on different base materials is different, often leading to a single filler metal that cannot simultaneously weld dissimilar materials. Therefore, in the actual brazing process, the base material surface needs to be brushed with flux to help brazing.

[0005] However, this process often brings several problems: (1) The amount of flux brushing cannot be accurately controlled. If the amount of flux brushing is too much, the residual flux will be more, and if the amount of brushing is too little, the welding effect will be affected. (2) It is difficult to brush flux on the special-shaped structure and cannot be well welded. SUMMARY

[0006] Based on the technical problems existing in the background technology, the present application provides a welding sheet for dissimilar material welding and a preparation method thereof. The present application can be used for welding of aluminum alloy and alloy steel, improving the welding effect, and improving the mechanical properties and corrosion resistance of the weld.

[0007] The present application provides a welding sheet for dissimilar material welding, comprising: a hollow welding sheet shell, a core layer flux, and an outer layer flux, the core layer flux being uniformly dispersed in the hollow of the welding sheet shell, and the outer layer flux being loaded on the surface of the welding sheet.

[0008] The raw materials of the core layer flux include, by weight: eutectic crystal of potassium tetrafluoroaluminate + potassium hexafluoroaluminate 10-12 parts, cesium fluoroaluminate 2-4 parts, and nano-nickel modified graphene oxide 2-4 parts.

[0009] The raw materials of the outer layer flux include, by weight: eutectic crystal of potassium tetrafluoroaluminate + potassium hexafluoroaluminate 10-12 parts, cesium fluoroaluminate 2-4 parts, nano-nickel modified graphene oxide 2-4 parts, fluorocarbon surfactant 0.1-0.2 parts, and polyvinyl alcohol 3-4 parts.

[0010] The application can avoid the problem of the flux raw material falling off and the flux dosage being difficult to control by setting the flux on the inner core and the outside of the soldering piece, thereby maintaining stable welding effect; compared with the eutectic crystal of potassium tetrafluoroaluminate and potassium hexafluoroaluminate, a small amount of polyvinyl alcohol is selected to improve the adhesion of the flux on the surface of the soldering piece, avoid the flux from falling off, and maintain stable welding effect.

[0011] In the flux, the eutectic crystal of potassium tetrafluoroaluminate and potassium hexafluoroaluminate and cesium fluoroaluminate cooperate with each other to remove the surface oxide film of the base material, reduce the surface tension, and improve the wettability of the filler metal; and in cooperation with the nano nickel modified graphene oxide, the graphene has good thermal conductivity, the surface energy of the nano nickel is low, and the two can further promote the spreading and wetting of the filler metal droplet on the surface of the base material.

[0012] In addition, in the nano nickel modified graphene oxide, the nano nickel can form a solid solution with Fe on one hand, and on the other hand, the nano nickel has small particle size and good diffusivity, can form a phase with Al, hinders the combination of Fe and Al, and inhibits the growth of interfacial compounds; and the graphene oxide can be mixed in the weld to play a pinning effect, inhibit grain growth, and refine grains, so that the weld structure is refined and uniform; the mutual cooperation of the above-mentioned effects improves the mechanical properties and corrosion resistance of the weld.

[0013] Preferably, in the preparation process of the nano nickel modified graphene oxide, a mixed aqueous solution of graphene oxide and nickel acetate is spray dried, and then heated in an inert gas atmosphere to obtain the nano nickel modified graphene oxide.

[0014] The application selects a mixed solution of graphene oxide and nickel acetate for spray drying and heating treatment, so that the nano nickel is uniformly distributed on the surface of the graphene oxide ball, thereby avoiding the problem of easy agglomeration of the nano nickel, and the graphene oxide itself has good dispersibility and the nano nickel on its surface can make the nano nickel modified graphene oxide have good dispersibility with other substances in the flux; agglomeration of the nano nickel and the graphene oxide is avoided.

[0015] The inert gas can be nitrogen, argon or the like.

[0016] Preferably, in the preparation process of the nano nickel modified graphene oxide, the weight ratio of graphene oxide to nickel acetate in the mixed aqueous solution is 0.04-0.06:1.

[0017] Preferably, in the preparation process of the nano nickel modified graphene oxide, the concentration of nickel acetate in the mixed aqueous solution of graphene oxide and nickel acetate is 8-10g / L.

[0018] Preferably, in the preparation process of the nano nickel modified graphene oxide, the heating temperature is 500-550℃, and the heating time is 4-5h.

[0019] Preferably, in the preparation process of the nano-nickel modified graphene oxide, the inlet temperature of the spray drying is 170-190 DEG C, and the outlet temperature is 110-120 DEG C.

[0020] Preferably, the dissimilar materials refer to two materials of aluminum alloy and alloy steel.

[0021] Preferably, the aluminum alloy is 6061 aluminum alloy, 3003 aluminum alloy.

[0022] Preferably, the alloy steel is Q235 steel, 304 steel.

[0023] Preferably, the raw material of the hollow solder shell comprises: Al 86-86.5%, Si 11.5-12%, Ni 1.5-2.5% by weight.

[0024] The ratio of each raw material in the hollow solder can be adjusted to further improve the mechanical properties of the weld, and the content of Ni element is controlled to cooperate with the nano-nickel modified graphene oxide, further forming a solid solution and refining the grain, thereby further improving the mechanical properties and corrosion resistance of the weld.

[0025] Preferably, the core layer flux accounts for 1-2wt% of the weight of the solder.

[0026] Preferably, the outer layer flux accounts for 1-2wt% of the weight of the solder.

[0027] The application also provides a preparation method of the solder for welding dissimilar materials, comprising the following steps: mixing and melting the raw material of the hollow solder shell, and then pressure casting to obtain a hollow solder shell; mixing the raw material of the core layer flux, and then adding it into the hollow of the solder shell, and stamping to obtain an intermediate solder; mixing the raw material of the outer layer flux and water, coating on the surface of the intermediate solder, and drying to obtain the solder for welding dissimilar materials.

[0028] The method can accurately control the amount of flux, and can be used for welding of special-shaped structures.

[0029] Advantages:

[0030] 1. The application selects a mixed solution of graphene oxide and nickel acetate for spray drying, and is heated to make the nano-nickel uniformly distributed on the surface of the graphene oxide ball, so that the nano-nickel modified graphene oxide has good dispersibility with other substances in the flux, and agglomeration is avoided.

[0031] 2. The application sets flux in the inner core and the outer part of the soldering sheet, which can avoid the problem of easy falling of flux raw materials and difficult control of flux dosage; a small amount of polyvinyl alcohol is selected to cooperate with potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal, which improves the adhesion of flux on the surface of the soldering sheet, avoids the falling of flux, and thus maintains stable welding effect.

[0032] 3. The mutual cooperation of potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal and cesium fluoroaluminate can remove the surface oxide film of the base material, reduce the surface tension, and improve the wettability of the filler metal; and the cooperation with nano nickel modified graphene oxide can further promote the spreading and wetting of the filler metal droplet on the surface of the base material.

[0033] 4. In the nano nickel modified graphene oxide, on the one hand, nano nickel can form a solid solution with Fe, and on the other hand, nano nickel has small particle size and good diffusivity, which can form a phase with Al, hinder the combination of Fe and Al, and inhibit the growth of interfacial compounds; and the graphene oxide can be mixed in the weld to play a pinning effect, inhibit grain growth, and refine grains, so that the weld structure is refined and uniform; the mutual cooperation of the above-mentioned effects can improve the mechanical properties and corrosion resistance of the weld. And cooperating with a suitable soldering sheet formula, the mechanical properties and corrosion resistance of the weld can be further improved. DETAILED DESCRIPTION

[0034] The technical solutions of the application will be described in detail below through specific examples.

[0035] Example 1

[0036] A soldering sheet for welding dissimilar materials, comprising: a hollow soldering sheet shell, a core layer flux, and an outer layer flux, the core layer flux being uniformly dispersed in the hollow of the soldering sheet shell, and the outer layer flux being loaded on the surface of the soldering sheet;

[0037] The raw materials of the hollow soldering sheet shell include, by weight percentage: Al 86%, Si 11.5%, and Ni 2.5%;

[0038] The raw materials of the core layer flux include, by weight parts: potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal 10 parts, cesium fluoroaluminate 2 parts, and nano nickel modified graphene oxide 2 parts;

[0039] The raw materials of the outer layer flux include, by weight parts: potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal 10 parts, cesium fluoroaluminate 2 parts, nano nickel modified graphene oxide 2 parts, fluorocarbon surfactant 0.1 part, and polyvinyl alcohol 3 parts;

[0040] In the preparation process of the nano-nickel modified graphene oxide, the graphene oxide aqueous dispersion liquid is uniformly mixed with the nickel acetate aqueous solution, so that the concentration of the nickel acetate in the mixed solution is 8 g / L, the weight ratio of the graphene oxide to the nickel acetate is 0.04:1, then the inlet temperature is adjusted to 190℃, the outlet temperature is adjusted to 110℃, spray drying is performed, the obtained particles are collected, heated to 550℃ in a nitrogen atmosphere, and kept for 4h to obtain the nano-nickel modified graphene oxide.

[0041] The preparation method of the welding sheet for dissimilar material welding includes the following steps: uniformly mixing raw materials of the hollow welding sheet shell, melting, and then pressure casting to obtain the hollow welding sheet shell; uniformly mixing raw materials of the core layer flux, and then adding the hollow welding sheet shell, and stamping to obtain the intermediate welding sheet; uniformly mixing raw materials of the outer layer flux and water, coating on the surface of the intermediate welding sheet, and drying to obtain the welding sheet for dissimilar material welding, the core layer flux accounts for 1wt% of the weight of the welding sheet, and the outer layer flux accounts for 2wt% of the weight of the welding sheet.

[0042] Example 2

[0043] A welding sheet for dissimilar material welding includes a hollow welding sheet shell, a core layer flux, and an outer layer flux, the core layer flux is uniformly dispersed in the hollow of the welding sheet shell, and the outer layer flux is loaded on the surface of the welding sheet.

[0044] The raw materials of the hollow welding sheet shell include, by weight percentage, Al 86.3%, Si 11.7%, and Ni 2%;

[0045] The raw materials of the core layer flux include, by weight parts, potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic 11 parts, cesium fluoroaluminate 3 parts, and nano-nickel modified graphene oxide 3 parts;

[0046] The raw materials of the outer layer flux include, by weight parts, potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic 11 parts, cesium fluoroaluminate 3 parts, nano-nickel modified graphene oxide 3 parts, fluorocarbon surfactant 0.15 parts, and polyvinyl alcohol 3.5 parts;

[0047] In the preparation process of the nano-nickel modified graphene oxide, the graphene oxide aqueous dispersion liquid is uniformly mixed with the nickel acetate aqueous solution, so that the concentration of the nickel acetate in the mixed solution is 9 g / L, the weight ratio of the graphene oxide to the nickel acetate is 0.05:1, then the inlet temperature is adjusted to 180℃, the outlet temperature is adjusted to 115℃, spray drying is performed, the obtained particles are collected, heated to 550℃ in a nitrogen atmosphere, and kept for 4.5h to obtain the nano-nickel modified graphene oxide.

[0048] The preparation method of the welding sheet for dissimilar material welding comprises the following steps: mixing and smelting raw materials of a hollow welding sheet shell, then pressure casting to obtain the hollow welding sheet shell; mixing raw materials of a core layer flux, then adding into the hollow of the welding sheet shell, and stamping to obtain an intermediate welding sheet; mixing raw materials of an outer layer flux with water, coating on the surface of the intermediate welding sheet, and drying to obtain the welding sheet for dissimilar material welding, the core layer flux accounts for 2wt% of the weight of the welding sheet, and the outer layer flux accounts for 1wt% of the weight of the welding sheet.

[0049] Example 3

[0050] A welding sheet for dissimilar material welding comprises a hollow welding sheet shell, a core layer flux and an outer layer flux, the core layer flux is uniformly dispersed in the hollow of the welding sheet shell, and the outer layer flux is loaded on the surface of the welding sheet.

[0051] The raw materials of the hollow welding sheet shell comprise, in percentage by weight, Al 86.5%, Si 12% and Ni 1.5%

[0052] The raw materials of the core layer flux comprise, in parts by weight, potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal 12 parts, cesium fluoroaluminate 4 parts and nano nickel modified graphene oxide 4 parts.

[0053] The raw materials of the outer layer flux comprise, in parts by weight, potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic crystal 12 parts, cesium fluoroaluminate 4 parts, nano nickel modified graphene oxide 4 parts, fluorocarbon surfactant 0.2 parts and polyvinyl alcohol 4 parts.

[0054] In the preparation process of the nano nickel modified graphene oxide, the graphene oxide aqueous dispersion and the nickel acetate aqueous solution are uniformly mixed, so that the concentration of the nickel acetate in the mixed solution is 10g / L, the weight ratio of the graphene oxide to the nickel acetate is 0.06:1, then the inlet temperature is adjusted to 170℃, the outlet temperature is adjusted to 120℃, the spray drying is performed, the obtained particles are collected, heated to 500℃ in a nitrogen atmosphere, and kept for 5h to obtain the nano nickel modified graphene oxide.

[0055] The preparation method of the welding sheet for dissimilar material welding comprises the following steps: mixing and smelting raw materials of a hollow welding sheet shell, then pressure casting to obtain the hollow welding sheet shell; mixing raw materials of a core layer flux, then adding into the hollow of the welding sheet shell, and stamping to obtain an intermediate welding sheet; mixing raw materials of an outer layer flux with water, coating on the surface of the intermediate welding sheet, and drying to obtain the welding sheet for dissimilar material welding, the core layer flux accounts for 2wt% of the weight of the welding sheet, and the outer layer flux accounts for 1wt% of the weight of the welding sheet.

[0056] Comparative Example 1

[0057] The core layer flux and the outer layer flux do not contain nano nickel modified graphene oxide, and the others are the same as in Example 3.

[0058] Comparative Example 2

[0059] Comparative Example 3

[0060] Comparative Example 4

[0061] Comparative Example 5

[0062] Comparative Example 6

[0063] Comparative Example 7

[0064] Comparative Example 8

[0065] Comparative Example 9

[0066] Comparative Example 10

[0067] Comparative Example 11

[0068] The 6061 aluminum alloy and Q235 steel were welded by using the soldering sheet described in Examples 1-3 and Comparative Examples 1-11, and the welding process was the same; then the mechanical properties and corrosion resistance of the welded joint were investigated, and the results are shown in Table 1.

[0069] The wetting test was carried out according to GB / T 11364-2008; and the tensile strength of the welded joint was tested by using a universal material testing machine.

[0070] Salt spray test: the welded sample was placed in a salt spray corrosion box, and a 50g / L NaCl solution was used to carry out salt spray corrosion in an environment of 35±2℃, and the salt crystals condensed on the surface of the sample were blown off regularly, and then taken out on the 10th day, washed and dried, and the tensile strength of the welded joint was tested by using a universal material testing machine.

[0071] Table 1 test results

[0072]

[0073]

[0074] As can be seen from Table 1, the soldering sheet described in the application has good wettability when welding aluminum alloy and alloy steel, and can improve the mechanical properties and corrosion resistance of the welded joint.

[0075] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A welding sheet for welding dissimilar materials, characterized in that, include: Hollow solder sheet shell, core flux, and outer flux. The core flux is evenly dispersed in the hollow of the solder sheet shell, and the outer flux is loaded on the surface of the solder sheet. The raw materials of the core layer flux include, by weight: 10-12 parts of potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic, 2-4 parts of cesium fluoroaluminate, and 2-4 parts of nano-nickel modified graphene oxide. The raw materials of the outer flux, by weight, include: 10-12 parts of potassium tetrafluoroaluminate + potassium hexafluoroaluminate eutectic, 2-4 parts of cesium fluoroaluminate, 2-4 parts of nano-nickel modified graphene oxide, 0.1-0.2 parts of fluorocarbon surfactant, and 3-4 parts of polyvinyl alcohol. In the preparation of nano-nickel modified graphene oxide, a mixed aqueous solution of graphene oxide and nickel acetate is taken, spray-dried, and then heated in an inert gas atmosphere to obtain nano-nickel modified graphene oxide. In the preparation of nano-nickel modified graphene oxide, the weight ratio of graphene oxide to nickel acetate is 0.04-0.06:

1. The raw materials for the hollow solder sheet shell, by weight percentage, include: Al 86-86.5%, Si 11.5-12%, and Ni 1.5-2.5%. The core flux accounts for 1-2 wt% of the weight of the solder pad; the outer flux accounts for 1-2 wt% of the weight of the solder pad.

2. The welding sheet for welding dissimilar materials according to claim 1, characterized in that, In the preparation of nano-nickel modified graphene oxide, the concentration of nickel acetate in the mixed aqueous solution of graphene oxide and nickel acetate is 8-10 g / L.

3. The welding sheet for welding dissimilar materials according to claim 1, characterized in that, In the preparation of nano-nickel modified graphene oxide, the heating temperature is 500-550℃ and the heating time is 4-5h.

4. The welding sheet for welding dissimilar materials according to claim 1, characterized in that, In the preparation of nano-nickel modified graphene oxide, the inlet temperature of the spray dryer is 170-190℃ and the outlet temperature is 110-120℃.

5. The welding sheet for welding dissimilar materials according to claim 1, characterized in that, Dissimilar materials refer to two materials: aluminum alloy and alloy steel.

6. The welding sheet for welding dissimilar materials according to claim 5, characterized in that, The aluminum alloys are 6061 aluminum alloy and 3003 aluminum alloy.

7. The welding sheet for welding dissimilar materials according to claim 5, characterized in that, Alloy steel includes Q235 steel and 304 steel.

8. A method for preparing a welding sheet for welding dissimilar materials as described in any one of claims 1-7, characterized in that, The process includes the following steps: taking the raw materials of the hollow welding sheet shell, mixing and melting them, and then die-casting them to obtain the hollow welding sheet shell; taking the raw materials of the core layer flux, mixing them, and then adding them into the hollow of the welding sheet shell, and stamping them to obtain the intermediate welding sheet; taking the raw materials of the outer layer flux and mixing them with water, coating them on the surface of the intermediate welding sheet, and drying them to obtain the welding sheet for welding dissimilar materials.

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