CN113909734B

CN113909734B - High-conductivity flux-cored brazing sheet

Info

Publication number: CN113909734B
Application number: CN202111333591.0A
Authority: CN
Inventors: 孙韶; 司秉林
Original assignee: Yantai Jingchuanglihe Technology Co ltd
Current assignee: Yantai Jingchuanglihe Technology Co ltd
Priority date: 2021-11-11
Filing date: 2021-11-11
Publication date: 2024-12-17
Anticipated expiration: 2041-11-11
Also published as: CN113909734A

Abstract

The invention discloses a high-conductivity flux-cored soldering lug, which belongs to the field of soldering, in particular to the field of aluminum alloy soldering, and comprises metal and solder, wherein the melting point of the solder is lower than that of the metal, the metal is connected with the solder in a winding way or metal particles made of the metal are filled in the solder, the solder is pressed into a sheet shape, and a certain amount of high-melting-point metal material is arranged in the sheet-shaped solder alloy to penetrate through two sides of the sheet-shaped solder to form a stable conductive channel. The channel materials do not melt during the welding process, and after welding they remain in the weld joint without affecting the joint strength. Therefore, the conductivity of the whole welding process is ensured, the conditions of spark and splash explosion of welding materials in high current are avoided, and the welding quality is ensured.

Description

High-conductivity flux-cored brazing sheet

Technical Field

The invention belongs to the field of brazing, in particular to the field of aluminum alloy brazing, and particularly relates to a high-conductivity flux-cored brazing sheet.

Background

The aluminum motor is one development direction of the current motor industry, and the aluminum material is used for replacing copper material as a coil material of a large-sized motor, so that the aluminum motor has the advantages of low cost, weight reduction and convenience in construction. The coil is composed of a large number of aluminum wires with rectangular cross sections. After the aluminum wires are installed one after the other in the assembly stage, they are connected to each other end to end. The joint of the wires needs to ensure conductivity and strength by welding.

The currently mainly used method is fusion welding (argon arc welding). This way, the welding strength and the conductivity can be ensured.

However, the efficiency of argon arc welding is relatively low, and each joint takes several minutes. In a motor with up to a thousand joints, argon arc welding clearly limits the production efficiency considerably.

A further serious disadvantage is that in order to save space, the aluminum wires are arranged very closely, the joints of the wires are very close, the welding gun for argon arc welding is difficult to extend into the assembly space through the joints of other wires to weld the welded junctions inside, and in order to solve the problem, the designer must adjust the design scheme and sacrifice the motor performance to ensure welding.

A further significant disadvantage is that the argon arc welding is very high in temperature, the local arc temperature reaches tens of thousands of degrees celsius, and after welding one or two joints in succession, the wire temperature is very high, which can easily damage the adjacent insulating cladding material. To solve this problem, the process design must wait for the temperature of the joint to drop after the welding is completed and then perform the coating of the local insulation material. This severely affects the coating quality and the production efficiency.

In the production of conventional copper motors, a resistance heating brazing process is commonly employed by practitioners. The copper coil joint is clamped by a clamp made of conductive graphite, and copper-phosphorus brazing alloy is preset between the joints. After being electrified, the graphite chuck is heated by huge current, then the copper material is heated, and then the copper-phosphorus brazing alloy is heated. And after the melting point of the alloy is reached, the brazing alloy is connected with the copper material through the financial liquid under the action of the phosphorus element in the copper-phosphorus brazing alloy, and a good joint is formed after cooling, so that brazing is completed. Compared with argon arc welding, the process has the advantages of convenient construction, high efficiency and low temperature.

However, this process is difficult to achieve in the production of aluminum electrical machines. This is because there is no braze alloy like copper phosphorus alloy that can "self-braze" in the alternative materials for aluminum brazing. The soldering of aluminum materials must be additionally added with flux, however, flux powder is insulating, and if the flux is coated on the surface of aluminum solder alloy according to a general scheme, a current path cannot be formed when the joint is heated, and thus the graphite chuck cannot be heated, and the soldering cannot be completed.

There is therefore a need for an aluminum alloy brazing material that is both electrically conductive and provides sufficient brazing aid.

The applicant of the present invention has conceived during the development process of the manner in which flux-cored sheet aluminum alloy filler metal is produced. The solder alloy is made into a flat tube shape, the flux powder is filled in the flat tube, or the thinner flux-cored wire is coiled into a clip-like or S-shaped flat ring. These two solder forms are theoretically possible to solve. However, in the actual use process, the problem of sparking and explosion occurs, and the spark-explosion type explosion-proof device cannot be used at all.

The problem of spark explosion is that the flow state of the melted brazing filler metal is unstable in a small space of a joint due to the fluctuation influence of factors such as people, machines, materials, methods, rings and the like in specific construction, and the brazing flux clamped in the tubular brazing filler metal cannot flow out in time, so that oxides on the metal surface cannot be dissolved in time. This causes local poor conduction during the gradual softening and flow of the solder, excessive local current due to too small contact area, and rapid vaporization by joule heat. Local arcing is then initiated due to the extremely short electrical gap. Such an arc can impact burning of local materials, especially if the brazing aid is instantaneously overheated, and can decompose and gasify. This causes discoloration of the surface of the base material, even excessive burning and melting, the light person cannot continue to complete brazing, and the heavy person causes scrapping of the base material.

There is thus a strong need for a sheet-like aluminum alloy brazing material that is capable of conducting electricity stably, does not spark, and is capable of providing sufficient flux.

Disclosure of Invention

The invention aims at the aspect of aluminum alloy brazing and provides a sheet-shaped aluminum alloy brazing material which can conduct electricity stably, does not spark and can provide enough soldering flux.

In order to solve the above problems, the design scheme of the adopted material is to provide a plurality of high-melting-point metal materials which are placed in the sheet-shaped brazing alloy to penetrate through two sides of the sheet-shaped brazing alloy, so that stable conductive channels with certain areas are formed. The channel materials do not melt during the welding process, and the channel materials remain in the welding interface after welding without affecting the joint strength. Therefore, the condition of too small conductive contact area is impossible, and the welding quality and the conductivity can be well ensured.

Concretely, when the low-melting-point brazing filler metal is zinc-aluminum alloy, the brazing auxiliary agent is FB502S brazing auxiliary agent powder in JB/T6045-2017 brazing flux standard. The high-melting point metal is zinc alloy or aluminum alloy with liquidus line higher than that of the low-melting point brazing filler metal by more than 20 ℃.

The zinc-aluminum alloy used as the low-melting-point brazing filler metal is preferably 78-98% of Zn and 2-22% of Al. For example, zn98% Al2% alloy, zn95% Al5% alloy, zn85% Al15%, and Zn78% Al22% alloy.

The aluminum alloy to be used as the high-melting point metal to be mixed with the zinc-aluminum alloy is preferably BAl Si, BAl Si, BAl Si and BAl88Si in GB/T13815-2008 aluminum-based brazing filler metal.

When the low-melting-point brazing filler metal is aluminum-silicon alloy, the brazing auxiliary agent selects FB501S brazing auxiliary agent powder in JB/T6045-2017 brazing flux standard. The high-melting-point metal is an aluminum alloy with a liquidus line higher than that of the low-melting-point brazing filler metal by more than 20 ℃.

The above aluminum-silicon alloy as the low melting point brazing filler metal is preferably BAl Si, BAl Si, and BAl Si in GB/T13815-2008 aluminum-based brazing filler metal.

The aluminum alloy used as the high-melting-point metal and aluminum-silicon alloy is preferably SAl 1070 in GB/T10858-2008 aluminum and aluminum alloy welding wire.

In addition, the scheme also discloses a preparation method of the high-conductivity flux-cored brazing sheet.

The manufacturing method comprises the steps of arranging a hollow pipeline in the low-melting-point alloy, and then canning a brazing auxiliary agent in the pipeline to obtain the seamless flux-cored wire, wherein the brazing auxiliary agent content is 5% -20% (the brazing auxiliary agent accounts for the total weight of the seamless flux-cored wire). The seamless flux-cored wire is intertwined with a high-melting point wire. This wound body is then calendered into a sheet by means of a calender.

Preferably, the material is selected to be a seamless flux-cored wire made of one high-melting-point metal wire and one to three low-melting-point metals which are intertwined. Preferably, a high melting point wire is intertwined with a seamless flux-cored wire made of a low melting point metal.

Preferably, the winding mode is that the seamless flux-cored wire made of low-melting point metal is tightly wound on one high-melting point metal wire in the center.

Preferably, the diameter of the middle high-melting-point metal wire is larger than that of the seamless flux-cored wire made of the low-melting-point metal and smaller than twice that of the seamless flux-cored wire made of the low-melting-point metal.

Taking brazing filler metal and metal, preparing the metal into metal particles, placing the metal particles in the brazing filler metal, and calendaring the metal particles into sheets through a calendaring machine.

Compared with the prior art, the high-conductivity flux-cored soldering sheet can conduct electricity stably, does not spark, and can provide enough soldering flux.

Drawings

Fig. 1 is a schematic view of the structure of one to ten embodiments of the highly conductive flux cored brazing sheet of the present invention.

FIG. 2 is a schematic structural view of an eleventh embodiment of the highly conductive flux cored soldering sheet of the invention

Fig. 3 is a golden phase diagram of a welding interface according to the first embodiment.

Fig. 4 is an enlarged metallographic view of the first embodiment.

Fig. 5 is a golden phase diagram of the first embodiment.

Fig. 6 shows a golden phase diagram of embodiment eleven corresponding to embodiment one.

Detailed Description

The following detailed description of the invention is presented in conjunction with the accompanying drawings and is provided to aid in understanding the invention and is not to be construed as a limitation.

Embodiment one:

in FIG. 1, a high conductivity flux cored brazing sheet comprises a metal and a brazing filler metal, wherein the melting point of the brazing filler metal is lower than that of the metal, and the brazing filler metal is wound and connected with the metal and pressed into a sheet shape.

The high-melting-point metal is aluminum alloy, and the aluminum alloy is BAl Si in GB/T13815-2008 aluminum-based brazing filler metal.

The low-melting-point brazing filler metal is zinc-aluminum alloy, wherein Zn accounts for 98% and Al accounts for 2%.

The soldering flux in the flux-cored brazing filler metal is FB502S brazing auxiliary agent powder in JB/T6045-2017 brazing flux standard.

As shown in FIG. 3, the A region is the welded base material, and is industrial pure aluminum. The B area is the Zn98Al alloy of the metal component in the flux-cored solder, and the C area is BAl Si metal. It can be seen that the filling effect of the entire braze interface is outstanding, and that the transition layers are also very diffuse.

As shown in FIG. 4, the transition diffusion layer between the Zn98Al2 alloy and BAal Si alloy can be more clearly observed by further observing the metallographic change.

As shown in FIG. 5, a better brazing effect was also obtained in a wider area of Al95 Si.

Embodiment two:

The low-melting-point brazing filler metal is zinc-aluminum alloy, wherein Zn accounts for 95% and Al accounts for 5%.

Embodiment III:

The low-melting-point brazing filler metal is zinc-aluminum alloy, wherein Zn accounts for 85% and Al accounts for 15%.

Embodiment four:

The low-melting-point brazing filler metal is zinc-aluminum alloy, wherein Zn accounts for 78% and Al accounts for 22%.

Fifth embodiment:

The high-melting-point metal is aluminum alloy, and the aluminum alloy is SAl 1070 in GB/T10858-2008 aluminium and aluminum alloy welding wire.

The low-melting-point brazing filler metal is a silicon-aluminum alloy, and the silicon-aluminum alloy is BAl Si in GB/T13815-2008 aluminum-based brazing filler metal.

The soldering flux in the flux-cored brazing filler metal is FB501S brazing auxiliary agent powder in JB/T6045-2017 brazing flux standard.

Example six:

Embodiment seven:

In addition, the invention also discloses a preparation method of the high-conductivity flux-cored brazing sheet, and the specific examples are as follows:

example eight:

As shown in fig. 1, a low melting point brazing filler metal is provided in a hollow pipe, and then a brazing aid is canned in the pipe to prepare a seamless flux-cored wire, wherein the brazing aid accounts for 5% of the total weight of the seamless flux-cored wire. The seamless flux-cored wire is intertwined with a high-melting point wire. This wound body is then calendered into a sheet by means of a calender.

The material is selected from a high-melting-point metal wire and three seamless flux-cored wires made of low-melting-point metals which are intertwined.

The diameter of the middle high-melting point metal wire is twice that of the seamless flux-cored wire made of low-melting point metal.

Example nine:

As shown in fig. 1, a low melting point brazing filler metal is provided in a hollow pipe, and then a brazing aid is canned in the pipe to prepare a seamless flux-cored wire, wherein the brazing aid accounts for 20% of the total weight of the seamless flux-cored wire. The seamless flux-cored wire is intertwined with a high-melting point wire. This wound body is then calendered into a sheet by means of a calender.

A high-melting point metal wire is wound with a seamless flux-cored wire made of low-melting point metal.

The diameter of the high-melting-point metal wire with the diameter being the middle is slightly larger than that of the seamless flux-cored wire made of the low-melting-point metal.

Example ten:

As shown in fig. 1, a low melting point brazing filler metal was provided in a hollow pipe, and then a brazing aid was canned in the pipe to make a seamless flux-cored wire wherein the brazing aid was 15% of the total weight of the seamless flux-cored wire. The seamless flux-cored wire is intertwined with a high-melting point wire. This wound body is then calendered into a sheet by means of a calender.

The winding mode is that a seamless flux-cored wire made of low-melting-point metal is tightly wound on a high-melting-point metal wire in the center.

The diameter of the high-melting point metal wire with the diameter being 1.5 times of that of the seamless flux-cored wire made of the low-melting point metal.

Example eleven:

This embodiment corresponds quite differently to the first to the second embodiments, shown in fig. 2, in that the metal is wound around the solder instead of being filled with metal particles made of metal, and pressed into a sheet shape.

As shown in fig. 6, when an alternative embodiment is used, it can be observed that a distinct grain BAl Si is present in the joint (C). The number of particles actually observed was lower than what we added, while the presence of concentrated crystals that were significantly rich in silicon could also be observed in the gold phase diagram (D) probably because many particles were eroded by the zinc-aluminum alloy due to the problem of heating and the boundaries were not apparent.

Blank case one:

The flux-cored brazing bar made of Zn98Al alloy is held by a flame brazing mode, and the brazing seams are continuously filled in the heating process until the brazing seams are fully filled. After testing the tensile strength, the sections were dissected and examined for metallography. And selecting a sample which is completely filled and has no macroscopic obvious defect as a qualified sample.

Blank case two:

And (3) preparing the low-melting-point brazing filler metal into a sheet, and heating by adopting the resistance brazing heating process. When heating, the two aluminum wires are bundled with aluminum wires to be used as an external conductive channel, so that the phenomena of sparking and splashing are prevented. After testing the tensile strength, the sections were dissected and examined for metallography. And selecting a sample which is completely filled and has no macroscopic obvious defect as a qualified sample.

Strength test the sheet made from the case was a sheet 0.7mm thick, 11.5mm wide and 28mm long. Two 10mm thick 12.5mm wide aluminum wires were lapped, with a lap length of 28mm. By the heating method, a joint of 28mm x 12.5mm is formed.

The strength values (GB/T228.1-2010 Metal Material tensile experiment) were averaged three times.

The detection of metallographic effects mainly focuses on whether microscopic defects exist or not, the state of a diffusion layer and the composition of an interface. Microscopic defects are difficult to avoid in brazing, however, the defects are small and tiny, and the application reliability can be ensured by the discontinuity.

In order to be able to realize industrial applications, the materials must be capable of being produced in large quantities with a smooth, cost-acceptable implementation. In the technology, the processing technology problems encountered in the actual production process mainly comprise 1. The affinity between different metals has a great influence, and after the high-pressure bonding, the bonding surfaces between the different metals need to have certain bonding strength so as to ensure the integrity in the grinding process. 2. Because the technology is a sheet material obtained by grinding, the stress caused by different ductility of different materials in the grinding process is overlarge, so that the deformation of the materials occurs. 3. In the metal grinding process, different metals have fatigue and other changes, annealing treatment is needed, and the more the annealing times are, the more unstable the material is, and the higher the cost is. 4. The relationship between compressive and extensional stresses at different locations during the lapping process for the material in the wound form is asymmetric, which results in different lower limits for the lapping thickness of the material.

All four of the above problems must be solved in order to be an industrially viable solution. The examples in the above table are all possible industrial solutions that can be carried out smoothly and at acceptable cost within the processing window.

Blank cases A and B are described mainly for achieving an optimal result. When a metallographic examination gave a good weld result (good filling, no defects) this was considered to be the best result that this material could achieve on this lap joint. The blank case one is compared with the traditional process, and the blank case two is compared with the traditional material under the resistance heating process. By adding extra conductive channels externally the problem of sparking and splashing is avoided, and the strength obtained in this case is a standard result that can be considered for the material under the process.

It can be observed that the material obtained by the technology is not inferior to the traditional material in terms of strength data, and the added high-melting point metal has no adverse effect on the brazing result.

The principle introduction is that a plurality of high-melting-point metal materials are arranged in a sheet-shaped brazing alloy to penetrate through two sides of the sheet-shaped brazing alloy, so that stable conductive channels with certain areas are formed. The channel materials do not melt during the welding process, and the channel materials remain in the welding interface after welding without affecting the joint strength. Therefore, the condition of too small conductive contact area is impossible, and the welding quality and the conductivity can be well ensured.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A high-conductivity flux-cored brazing sheet, characterized in that it comprises a metal and a brazing filler metal, wherein the melting point of the brazing filler metal is lower than the melting point of the metal, the metal and the brazing filler metal are wound and connected, or the metal is made into metal particles and filled into the brazing filler metal and pressed into a sheet shape, a high-melting-point metal material is placed in the sheet-shaped brazing filler metal alloy and penetrates both sides of the sheet-shaped brazing filler metal to form a stable conductive channel with a certain area, and these channel materials do not melt during the welding process.

2. The high-conductivity flux-cored brazing sheet according to claim 1, wherein the metal is a zinc alloy or an aluminum alloy, and the brazing filler metal is a flux-cored brazing filler metal.

3. The high conductivity flux-cored brazing sheet according to claim 2, characterized in that: the metal with a high melting point is a zinc alloy or an aluminum alloy, and the aluminum alloy is BAl95Si, BAl92Si, BAl90Si and BAl88Si in GB/T 13815-2008.

4. The high conductivity flux-cored brazing sheet according to claim 3, characterized in that the low melting point brazing filler metal is a zinc-aluminum alloy, wherein Zn accounts for 78-98% and Al accounts for 2-22%.

5. The high conductivity flux-cored brazing sheet according to claim 4, characterized in that the flux in the flux-cored brazing material is FB502S brazing aid powder in the JB/T 6045-2017 standard.

6. The high conductivity flux-cored brazing sheet according to claim 2, wherein the high melting point metal is an aluminum alloy, and the aluminum alloy is SAl 1070 in GB/T 10858-2008.

7. The high conductivity flux-cored brazing sheet according to claim 6, wherein the low melting point brazing filler metal is an aluminum silicon alloy, and the aluminum silicon alloy is BAl88Si, BAl90Si, and BAl92Si in GB/T 13815-2008.

8. The high conductivity flux-cored brazing sheet according to claim 7, characterized in that the flux in the flux-cored brazing material is FB501S brazing aid powder in the JB/T 6045-2017 standard.

9. A method for preparing the high conductivity flux-cored brazing sheet according to claim 1, characterized in that the preparation steps are as follows:

S1: Take the brazing material and the metal, and entwine the brazing material and the metal with each other;

S2: The wound body is calendered into a sheet by a calender.

10. A method for preparing the high conductivity flux-cored brazing sheet according to claim 1, characterized in that the preparation steps are as follows:

S1: Take the brazing material and metal, make the metal into metal particles, and place them inside the brazing material;

S2: Calendered into sheets by a calender.