KR20220026401A - Aluminum alloy for flux-free brazing and brazing method using the same - Google Patents

Abstract

The present invention relates to an aluminum alloy for brazing capable of enabling a flux-free brazing process, and a brazing method using the same. The aluminum alloy for brazing, based on an Al-Si alloy, includes: 4.00-15.00 wt% of silicon (Si); 0.005-1.00 wt% of magnesium (Mg); 0.005-1.00 wt% of yttrium (Y); 0.005-1.00 wt% of lanthanum (La) or cerium (Ce) or a composition thereof, 0-0.045 wt% of strontium (Sr); 0-1.00 wt% of copper (Cu); 0-2.50 wt% of zinc (Zn); 0-1.50 wt% of manganese (Mn); 0.-0.80 wt% of iron (Fe); and the remaining of aluminum (Al) and inevitable impurities.

Description

Aluminum alloy for flux-free brazing and brazing method using the same

The present invention relates to an aluminum alloy for brazing capable of a flux-free brazing process and a brazing method using the same. The aluminum alloy is based on an Al-Si alloy.

1 is an exemplary view of a brazing method according to the prior art.

Brazing is a technique for joining the same or different types of metal materials using a filler metal 3 having a lower melting point than the base material 1 and 2 metal to be joined. ) can be joined without melting, so it is possible to minimize the deterioration of the properties of the base material, and it can be applied to parts with complex shapes and structures, and is widely used industrially as a joining process suitable for mass production. In particular, aluminum alloy is widely used as a bonding material for parts in the fields of heat exchangers and air conditioners.

In general, Al4xxx-based alloys are mainly used as filler metals for aluminum-based brazing, and these alloys have good fluidity in the molten state until the alloy is embrittled, and solidify as the melting point decreases as the Si content increases up to 15%. This is because cracks do not occur easily. Among them, Al-Si-based alloys such as 4043, 4045, and 4047 are used as alloys for brazing using flux, and Al-Si-Mg-based types such as 4004 and 4005 have a welding crack suppression effect, so it is an Al-Cu alloy that is sensitive to cracking. Mainly used for welding.

The oxide film formed on the surface of aluminum is dense and strong and has excellent corrosion resistance. On the other hand, since this film adversely affects the wettability of brazing, brazing is generally difficult compared to other metals, so a flux capable of destroying the oxide film is required. However, when using a flux, hydrochloric acid, nitric acid, sulfuric acid, etc. are required, so a waste liquid treatment process is required after the bonding process, and there is a problem in that a large amount of Cl-based corrosion and environmental polluting gases are discharged during the pre/post treatment and cleaning process and bonding.

Therefore, there is a continuous need for an aluminum alloy that can be brazed without using a flux.

[Document 1] Republic of Korea Patent Publication No. 10-1184173 (registered on Apr. 1, 2016) [Document 2] Korean Patent Publication No. 10-0058055 (published on June 3, 2013) [Document 3] Korean Patent Publication No. 10-0177797 (published on June 20, 2016) [Document 4] Korean Patent Publication No. 10-7010419 (published on August 18, 2011) [Document 5] European Patent Publication EP1360207B1 (Registered on May 25, 2011) [Document 6] Korean Patent Publication No. 10-0773218 (Registered on October 29, 2007)

Brazing is a technique of joining metal materials of the same or different types by using a welding material having a lower melting point than the base metal to be joined.

Among them, aluminum is widely credited as a basic bonding material in the fields of automobiles and heat exchangers due to its light weight, corrosion resistance and excellent heat transfer properties. However, aluminum is easily oxidized in air, and the aluminum oxide film interferes with the bonding properties and coatability of brazing. In order to remove such an oxide film, brazing is performed by adding flux to the brazing filler, but problems such as removal of flux residues and odors during the process occur. In order to solve this problem, a method of brazing in a vacuum state without using a flux has been developed, but the vacuum equipment is very complicated and the maintenance cost is expensive, and magnesium (Mg), which adversely affects the brazing filler to remove the oxide film, is used. There are limits to what you can use.

Korean Patent Registration No. 10-1184173 discloses a document that attempts to conduct brazing under a flux-free condition in a nitrogen atmosphere by adding yttrium (Y), but the amount of silicon added is extremely small, so there is a limit to brazing properties.

Korean Patent Laid-Open Patent Publication No. 10-0058055 discloses a document that attempts to proceed with brazing under flux-free conditions, but there is a limitation in that the amount of magnesium added is high and the brazing is limited to cotton.

Korean Patent Laid-Open Patent No. 10-0177797 discloses a document that attempts to proceed with brazing under flux-free conditions, but the object of the patent relates to flux-free brazing capable of brazing at low temperatures, and the present invention is significantly different from the present invention in that the brazing process is carried out under vacuum conditions. There is a difference.

Korean Patent Laid-Open Patent No. 10-7010419 discloses a document that attempts to proceed with brazing under a flux-free condition, but a rolling or thermal spraying process is required to manufacture the brazing sheet, and grain boundary separation due to the low solubility of bismuth (Bi) in aluminum There is a risk of occurrence, and this has a limitation in that it is disadvantageous for long-term storage of the brazing sheet.

European Patent EPEP1360207B1 discloses a document in which a protective aluminum alloy having a higher solidus line than the liquidus of the brazing filler alloy is further joined to remove the oxide film formed on the surface of the brazing filler when brazing is carried out under flux-free conditions. It is manufactured through a hot rolling process between the welding material - the brazing material - the protective material to join the aluminum alloy, and there is a limitation in that the thickness control of each layer is disadvantageous.

Korean Patent Laid-Open Patent No. 10-0773218 discloses a document in which a nickel (Ni) layer is plated on the surface of a brazing filler to remove an oxide film formed on the surface of the brazing filler when brazing is performed under a flux-free condition. There is a disadvantage in that a post-processing process such as wastewater treatment is forced to proceed with nickel (Ni) metal plating.

An object of the present invention is to solve the problems of the prior art as described above, and since it is possible to omit the flux required for brazing of conventional heat exchangers or automobile parts, an additional process such as waste liquid treatment is not required, and environmental pollution An object of the present invention is to provide an aluminum alloy composition for flux-free brazing that can prevent gas emission, and increase joint reliability due to corrosion resistance and adhesion.

In addition, another object of the present invention, in contrast to the conventional method, after coating the brazing alloy on the heat exchanger tube by spraying (spraying) is combined with the fins to proceed with the brazing process.

In addition, another object of the present invention is to coat an aluminum or nickel layer through an economical and reasonable method through a thermal spraying process rather than rolling or electroplating, which has been previously reported to suppress the formation of an oxide film of the brazing filler layer, in contrast to the conventional method. will do

A typical heat exchanger brazing method is to join a plate-shaped fin clad acting as a brazing material to a plate-shaped fin core acting as a structural material, and brazing the fins and tubes. The present invention is to provide a method of omitting the filler attached to the pin as a process differentiated from the conventional process, and attaching the filler directly to the tube.

In order to solve the above problems, the aluminum alloy for flux-free brazing according to an embodiment of the present invention is based on an Al-Si alloy as an aluminum alloy for brazing, and includes: 4.00 to 15.00 wt% of silicon (Si); 0.005 to 1.00 wt % of magnesium (Mg); 0.005 to 1.00 wt % of yttrium (Y); 0.005 to 1.00 wt % of lanthanum (La) or cerium (Ce), or a combination thereof; 0 to 0.045 wt% of strontium (Sr); 0 to 1.00 wt% of copper (Cu); 0 to 2.50 wt% of zinc (Zn); 0 to 1.50 wt% of manganese (Mn); 0 to 0.80 wt% of iron (Fe); And the rest is characterized in that it is composed of aluminum (Al) and unavoidable impurities.

In an embodiment of the present invention, the aluminum alloy is characterized in that the content ratio of the magnesium to the yttrium is 1:1 to 1:2.

In an embodiment of the present invention, the aluminum alloy is Ti, Bi, B, Zr, Cr, V, Ni, In, Sn, Ge, Pb, Bi, Ca, Na, P, B, Ag, Pd, Sb, Sc , Nb, Co, Mo, characterized in that it further comprises at least one selected from the group consisting of Be.

And in order to solve the above problems, a brazing method using an aluminum alloy for flux-free brazing according to an embodiment of the present invention includes an alloy processing step of processing the aluminum alloy into a wire or powder form; A thermal spraying step of forming a filler by applying the aluminum alloy in the form of a wire or powder to the surface of the first base material by a thermal spraying process; and disposing a second base material on the surface of the filler, and heating the filler to melt it.

In an embodiment of the present invention, the brazing method may be performed without flux or with flux.

In an embodiment of the present invention, the heating step is characterized in that it is carried out in an inert atmosphere.

The present invention can provide a brazing filler having a low-temperature melting point in the range of 500 to 560 ℃ as a direct replacement for Al-Si-based brazing alloy, so that it has improved functions in wettability, mechanical strength, and resistance to external factors than in the conventional brazing alloy composition It improves brazing properties by representing

In addition, the brazing composition of the present invention increases the oxidation resistance of the brazing alloy due to the addition of yttrium (Y), so that when brazing is performed in a non-vacuum state, the adhesion is excellent even without flux, and due to the increase in workability, it is used as a brazing wire. It facilitates the manufacturing process.

In addition, the brazing composition of the present invention improves corrosion resistance by reducing local corrosion due to the addition of lanthanum (La) and cerium (Ce), and improves workability during brazing by increasing the strength and ductility of the brazing alloy, and improves wettability to improve the brazing properties.

In addition, the brazing alloy of the present invention can omit the cladding of the fins because the fins and the fins are brazed after being coated through thermal spray coating on the tubes of the heat exchanger, and brazing without flux is facilitated.

Finally, according to the present invention, by coating an aluminum alloy or nickel having a high melting point on the brazing filler layer through a thermal spraying process, it is possible to suppress the generation of an oxide film in the brazing filler layer.

1 is an exemplary view of a brazing method according to the prior art.
2 is an exemplary view of a brazing method according to the present invention.

Hereinafter, an aluminum alloy for flux-free brazing according to the present invention and a brazing method using the same will be described.

Since the embodiments described in this specification are only the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, there may be various equivalents and modifications that can be substituted for them at the time of the present application. should understand On the other hand, the content indication in the present invention is a ratio with respect to the total weight of the aluminum alloy. All content indications in the description and claims of the present invention are also the same.

In the case of composition development of metal alloys, it is a well-known fact that, even if the composition of alloy elements changes by 0.005%, significant changes occur in physical properties due to the specificity of the alloy technology field.

Since there are as many types of alloying elements as there are types of metals on the periodic table, numerous combinations can occur in the development of alloy compositions. Therefore, even minute changes in the type and composition of alloy elements can significantly improve the properties of the new alloy, so minute changes in composition and composition are very important in the field of alloy composition development.

The aluminum alloy for flux-free brazing according to an embodiment of the present invention is based on an Al-Si alloy system, comprising: silicon (Si) in an amount of 4.00 to 15.00 wt%; 0.005 to 1.00 wt % of magnesium (Mg); 0.005 to 1.00 wt % of yttrium (Y); 0.005 to 1.00 wt % of lanthanum (La) or cerium (Ce), or a combination thereof; 0 to 0.045 wt% of strontium (Sr); 0 to 1.00 wt% of copper (Cu); 0 to 2.50 wt% of zinc (Zn); 0 to 1.50 wt% of manganese (Mn); 0 to 0.80 wt% of iron (Fe); and the remainder is composed of aluminum (Al) and unavoidable impurities.

Effect of addition of aluminum alloying elements.

The main alloying elements in the aluminum brazing alloy are silicon (Si), magnesium (Mg), copper (Cu), zinc (Zn), iron (Fe), yttrium (Y), lanthanum (La) and cerium (Ce). The effect on the characteristics of is as follows.

Silicon (Si).

Silicon (Si) is a major component that increases the fluidity and lowers the melting point during the aluminum brazing process. When an appropriate amount is added, the melting point is lowered, minimizing the effect of the aluminum material being brazed to allow brazing, and increasing fluidity ensures no gaps in the joint. Filled. If it is added too little, the melting point increases and the fluidity deteriorates during the brazing process. Likewise, if it is added too much, the fluidity deteriorates.

A preferred range in the present invention is 4.0 to 15.0 wt%, and a more preferred range is 6.0 to 14.0 wt%.

Magnesium (Mg).

Magnesium (Mg) improves mechanical strength by the solid solution effect. Corrosion resistance to seawater is improved, and weldability and surface finish properties are also improved. In the case of an appropriate content, it acts as a wetting agent during brazing. If the content is more than an appropriate amount, the fluidity deteriorates and the bond with oxygen is strong, so care must be taken to introduce oxides.

A preferred range in the present invention is in the range of 0.005 to 1.00 wt%.

Copper (Cu).

It is known that when copper (Cu) is more than an appropriate content, there is a tendency to form precipitates at grain boundaries, which increases sensitivity to intergranular corrosion and local corrosion, resulting in a side effect of lowering strength. It is known to improve the resistance to stress corrosion cracking in the case of a small addition of 1.00 wt% or less.

A preferred range in the present invention is 1.00 wt% or less.

Zinc (Zn).

Zinc (Zn) coexists with magnesium (Mg) to improve mechanical properties through age hardening and to improve resistance to stress corrosion cracking. In addition, when an appropriate amount is added, the melting point is lowered and corrosion resistance is increased. If more than an appropriate amount is added, cracks or pores occur during the brazing process because it evaporates quickly due to high vapor pressure.

A preferred range in the present invention is 2.50 wt% or less.

Strontium (Sr).

Strontium (Sr), as a modifier, improves the flowability by changing the shape of the alloy structure, particularly the AlSi structure, from a needle to a fine spherical shape. A content of 0.045wt% or less is the most suitable ratio, and when it exceeds this, the nucleation of Si element is suppressed to suppress the effect of addition, so be careful because there is a disadvantage in that the mechanical strength is lowered.

The effect appears from the addition of 80ppm, and if it is over 450ppm, it may cause the formation of air bubbles during welding, so be careful.

A preferred range in the present invention is 0.045 wt% or less.

Yttrium (Y).

Yttrium increases its strength by increasing the recrystallization temperature by Al ₂ Y ₃ generated inside the aluminum alloy. In addition, the solid solution strengthening effect appears by the Mg ₂ Y ₃ precipitation phase in combination with Mg. In addition, by suppressing the oxide layer at the junction, when brazing is performed in a non-vacuum state, adhesion is excellent even without flux. If more than an appropriate amount is added, there is a problem that the production cost increases due to the high unit price of yttrium, so the range of 0.005 to 1.00 wt% is preferable.

Lanthanum (La) and Cerium (Ce).

Lanthanum (La) and cerium (Ce) act to reduce local corrosion. In addition, corrosion resistance is strengthened by reducing components such as iron (Fe) and nickel (Ni), which are corrosion-resistant elements present in the molten metal during brazing alloy manufacturing.

In addition, by changing the microstructure of the oxide film, the ductility of the oxide film is increased to prevent separation of the film, and an inward wedge shape is formed in the oxide film to increase the adhesion between the substrate and the oxide film. In addition, the formation of pores is suppressed by the vacancy collapse effect, and the chemical bond between the oxide film and the matrix is improved. That is, by suppressing the formation of pores that may be formed between the oxide film and the matrix, a space between the oxide film and the matrix is prevented, and by forming a wedge-shaped oxide film with the matrix, the adhesion of the oxide film is increased.

In addition, since the rare earth metal has an effect of increasing the corrosion potential, it is possible to minimize the addition of copper (Cu) or to replace copper (Cu). Therefore, when the copper (Cu) content is increased to increase the corrosion potential, there is an effect of minimizing these side effects, and thus the corrosion resistance is improved.

In addition, by increasing the strength and ductility of the brazing alloy, the brazing property is improved, and the wettability is improved to improve the brazing properties.

In the present invention, the preferred content range of lanthanum (La) or cerium (Ce), or a combination thereof is 0.005 to 1.00 wt%.

other elements.

In all the above cases, the aluminum alloy is an alloying element widely used in the aluminum industry (Ti, Bi, B, Zr, Cr, V, Ni, In, Sn, Ge, Pb, Bi, Ca, Na, P, B, Ag, Pd, Sb, Sc, Nb, Co, Mo, or Be) and unavoidable impurities may be further included.

To summarize the features of the present invention, the fluidity is increased by adding silicon (Si) to the aluminum alloy for brazing, the oxide layer is suppressed at the junction by the addition of yttrium (Y), and the addition of lanthanum (La) or cerium (Ce) The brazing property is improved by adding magnesium (Mg) as a wetting agent while increasing the brazing property and corrosion resistance. In addition, the addition of strontium (Sr) can prevent embrittlement of the junction by refining the crystal grains. The addition of these alloying elements must be simultaneously added, and the added amount must be optimized at the same time to achieve the object of the present invention. This point is a distinction of the present invention, and the brazing property is greatly improved compared to the prior art.

In addition, in order to prevent deterioration of brazing properties due to the formation of an aluminum oxide film of the brazing filler, a high-melting-point aluminum alloy or nickel (Ni) through a thermal spraying process may be coated on the filler to further improve the brazing properties.

Hereinafter, a brazing method using the aluminum alloy will be described with reference to FIG. 2 .

2 is an exemplary view of a brazing method according to the present invention.

Brazing method using the aluminum alloy according to an embodiment of the present invention, an alloy processing step of processing the aluminum alloy in the form of a wire or powder; A thermal spraying step of forming a filler by applying the aluminum alloy in the form of a wire or powder to the surface of the first base material by a metal spraying process; and disposing a second base material on the surface of the filler, and heating the filler to melt it.

In the alloy processing step, an ingot of an aluminum alloy having the above composition ratio is manufactured, then cast in a billet form, and then extruded and drawn to a wire or powder form having a diameter suitable for arc spray coating.

Thereafter, in the thermal spraying step, the filler 30 for brazing is formed by applying the processed aluminum alloy wire or powder to the surface of the first base material 10 through a thermal spraying process.

Thereafter, in the heating step, the second base material 20 is disposed on the surface of the filler 30 , and the filler 30 is heated and melted in an inert atmosphere. This step can be carried out in an inert atmosphere using, for example, nitrogen.

Thereafter, as the molten filler 30 is cooled, bonding of the first base material 10 and the second base material 20 is completed.

Meanwhile, between the thermal spraying step and the heating step, a second thermal spraying step of additionally forming a nickel (Ni) or high-melting-point aluminum alloy layer on the surface of the first base material 10 by using a wire or powder-type metal in a thermal spraying process. can be further performed. Accordingly, by coating the filler 30 with an aluminum alloy or nickel having a high melting point, it is possible to suppress the generation of an oxide film on the filler 30 .

In addition, the first base material 10 and the second base material 20 may correspond to, for example, a tube and a fin of a heat exchanger, respectively. In addition, various aluminum or alloy products that require a bonding process by a brazing method are applicable. can do.

In the brazing method according to the embodiment of the present invention, the aluminum alloy is processed in the form of a wire or powder and used in the thermal spraying process, but the aluminum alloy according to the embodiment of the present invention is processed in the form of a plate and used by bonding to the first base material. may be

(Example)

The brazing alloy according to the present invention was prepared by using an electric crucible furnace at the temperature of the molten alloy in a temperature range of 670 to 850° C. as an ingot. This ingot was cast again in the form of a billet, and then passed through extrusion and drawing processes, and finally processed into a wire with a thickness of 1.6Φ. The manufactured wire was thermally sprayed on the heat exchanger tube through thermal spray coating, and the brazing was performed through a general brazing process under a nitrogen atmosphere. The brazing composition of Comparative Examples and Examples of the present invention is shown in Table 1.

division Furtherance ( wt% ) Si Mg Y La or Ce Sr Al comparative example Al 4043 4.5-6.0 <0.05 - - - REM Al 4045 9.0-11 <0.05 - - - REM Al 4047 11-14 <0.15 - - - REM Example One 5.5 0.05 - - - REM 2 9.5 0.05 - - - REM 3 12.0 0.05 - - - REM 4 12.0 - - - - REM 5 12.0 0.25 - - - REM 6 12.0 0.75 - - - REM 7 12.0 0.75 0.5 - - REM 8 12.0 0.75 - 0.30 - REM 9 12.0 0.75 - - 0.030 REM 10 12.0 0.75 0.5 0.30 0.030 REM

※ The above composition is a target value, and the manufacturing error of the composition according to the actual brazing alloy manufacturing is within the normal error range.

After preparing an aluminum alloy ingot with the components shown in Table 1, a brazing wire was processed. After that, the heat exchanger tube was coated through a thermal spraying process and then brazed with the fins under nitrogen conditions. The brazing wettability / spreadability and corrosion resistance of the brazed aluminum alloy prepared in this way were measured and shown in Table 2.

In the evaluation of wettability, the wetting angle was evaluated and then the penetration depth by capillary force of the molten brazing agent was evaluated through a joint gap filling test. The wetting angle test induced the melting of the brazing agent by placing the pin in the tube onto which the brazing agent was sprayed and then maintaining it at 570° C. for 5 minutes under a nitrogen atmosphere. After that, the brazed section was cut to analyze the wetting angle between the tube and the fin. Wetting angle was evaluated in 3 parts per specimen, and it was expressed as an average value. In the joint gap filling test, the change in penetration depth was analyzed after a pin was placed on a tube with a brazing agent sprayed, and then melted after reaching 570°C in a nitrogen atmosphere for 5 minutes. The salt spray test to evaluate the corrosion resistance was evaluated according to ASTM standard ASTM B117, 100H, and the results were expressed in mm/year.

division wetting angle ( ^*?* ) capillary force (mm) Corrosion resistance (mm/year) comparative example Al 4043 28.451 23.525 1.351 Al 4045 27.201 24.525 1.351 Al 4047 26.401 25.075 1.337 Example One 28.600 23.400 1.351 2 27.600 24.400 1.351 3 26.975 25.025 1.351 4 27.000 25.000 1.358 5 26.875 25.125 1.324 6 26.625 25.375 1.256 7 25.625 25.875 1.256 8 25.625 25.875 1.001 9 26.535 25.420 1.256 10 24.535 26.420 1.001

According to Table 2, the comparative example and the example of the present invention show that the conditions are similar except for a few other metal components, but the case of the present invention is more suitable for brazing.

When comparing A4043 and 4045 among Comparative Examples, it can be seen that as silicon (Si) increases, fluidity increases, so that the wetting angle decreases and capillary force increases. When comparing Examples 1 to 3, it can be seen that the brazing property is increased due to the increase in fluidity as the silicon (Si) increases in the same manner as above. When comparing Examples 4 to 6, it can be seen that the brazing property is improved as magnesium (Mg) acting as a wetting agent increases. In addition, when comparing Examples 6 and 7, 8, 9, and 10, it can be seen that the brazing property is increased due to the addition of yttrium (Y), lanthanum (La)/cerium (Ce) and strontium (Sr), respectively. . Yttrium (Y) has an effect of improving adhesion without flux when brazing is performed in a non-vacuum state, and lanthanum (La) and cerium (Ce) have a vacancy collapse effect, thereby inhibiting the formation of pores. Improves brazing properties. Strontium (Sr) has the effect of increasing the flowability by transforming the Al-Si structure into a fine spherical shape from a needle. In addition, when comparing Examples 6 and 8, it can be seen that the corrosion resistance is excellent due to the addition of lanthanum (La) and cerium (Ce).

10: first base material
20: second base material
30: filler

Claims (8)

As an aluminum alloy for brazing, based on the Al-Si alloy system,
4.00 to 15.00 wt% of silicon (Si);
0.005 to 1.00 wt % of magnesium (Mg);
0.005 to 1.00 wt % of yttrium (Y);
0.005 to 1.00 wt % of lanthanum (La) or cerium (Ce), or a combination thereof;
0 to 0.045 wt% of strontium (Sr);
0 to 1.00 wt% of copper (Cu);
0 to 2.50 wt% of zinc (Zn);
0 to 1.50 wt% of manganese (Mn);
0 to 0.80 wt% of iron (Fe); and
The rest is an aluminum alloy for flux-free brazing, characterized in that it contains aluminum (Al) and unavoidable impurities.
According to claim 1,
The aluminum alloy is an aluminum alloy for flux-free brazing, characterized in that the content ratio of magnesium and yttrium is 1:1 to 1:2.
The method of claim 1,
The aluminum alloy is Ti, Bi, B, Zr, Cr, V, Ni, In, Sn, Ge, Pb, Bi, Ca, Na, P, B, Ag, Pd, Sb, Sc, Nb, Co, Mo, An aluminum alloy for flux-free brazing, characterized in that it further comprises at least one selected from Be.
As a brazing method using the aluminum alloy of claim 1,
an alloy processing step of processing the aluminum alloy into a wire or powder form;
A thermal spraying step of forming a filler by applying the aluminum alloy in the form of a wire or powder to the surface of the first base material by a thermal spraying process; and
A brazing method using an aluminum alloy for flux-free brazing, comprising: disposing a second base material on the surface of the filler, and heating the filler to melt it.
5. The method of claim 4,
The brazing method is a brazing method using an aluminum alloy for brazing without flux, characterized in that it is carried out without flux.
5. The method of claim 4,
The brazing method is a brazing method using an aluminum alloy for brazing without flux, characterized in that it can be carried out even in a state in which flux is included.
5. The method of claim 4,
The heating step is a brazing method using an aluminum alloy for flux-free brazing, characterized in that it is carried out in an inert atmosphere.
5. The method of claim 4,
Between the thermal spraying step and the heating step, a second thermal spraying step of additionally forming a nickel (Ni) or high-melting-point aluminum alloy layer on the surface of the first base material 10 using a wire or powder-type metal in a thermal spraying process. A brazing method using an aluminum alloy for flux-free brazing, characterized in that it further comprises.

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