JP2021063264A - Brazing sheet for heat exchanger and heat exchanger for air conditioner - Google Patents

Abstract

To provide a brazing sheet used in a heat exchanger for an air conditioner, enabling corrosion resistance and pressure resistance to be favorably compatible with each other and including a sacrificial anode material layer.SOLUTION: A brazing sheet 10 is used in a heat exchanger of an air conditioner and includes an aluminum (Al) alloy core material 11, an Al alloy brazing material layer 12 coated with one surface of the core material and containing Si, and an Al alloy sacrificial anode material layer 13 coated with the other surface of the core material and containing Zn and Si. The thickness of the sacrificial anode material layer 13 is within a range of 15-25 μm. When the temperature T of the brazing sheet 10 at the time of joining is within the range of 580-660°C, the content XSi of Si in the sacrificial anode material is equal to or smaller than a value derived from the formula (1):T=660-8×exp(0.3XSi) and also is equal to or larger than a value derived from the formula (2):T=580+55×exp(-0.5(XSi-1.7)).SELECTED DRAWING: Figure 1

Description

The present invention relates to a brazing sheet used for a member constituting a heat exchanger and a heat exchanger for an air conditioner configured by using the brazing sheet.

A general heat exchanger usually includes a pipe and fins, and has a configuration in which a plurality of fins are attached to the outer circumference of the pipe. As the material of the tube, copper (Cu) or an alloy thereof (referred to as "copper material" for convenience) has been used, but in recent years, aluminum (Al) or an alloy thereof (aluminum material) has also been used. As a fin material, an aluminum material is generally used.

In the manufacture of heat exchangers, brazing filler metal joints are generally used to attach fins to pipes. If both the pipe and the fin are made of an aluminum material, for example, a brazing sheet in which a brazing material layer is clad (coated) on at least one surface of a core material made of an aluminum alloy is used. Considering the corrosion resistance of the pipe and fins, a brazing sheet in which a brazing material is clad on one surface of the core material and a sacrificial anode material layer is clad on the other surface is used.

As the brazing material, an aluminum-silicon (Si) -based alloy used for brazing an aluminum alloy is generally used, and as a sacrificial anode material, aluminum is generally used in order to make its potential low. An alloy in which zinc (Zn) is added is used. As a typical sacrificial anode material, a brazing material of a general aluminum-silicon alloy with zinc added can be mentioned. As a result, the sacrificial anode material also functions as a brazing material.

By the way, since heat exchangers for automobiles may come into contact with exhaust gas, higher corrosion resistance is required as compared with heat exchangers used for air conditioners for buildings and the like. For example, Patent Document 1 discloses an aluminum alloy brazing sheet that can be used as a fluid passage component of an automobile heat exchanger. In this brazing sheet, the sacrificial anode material contains Si: 2.5 to 7.0 mass%, Zn: 1.0 to 5.5 mass%, Fe 0.05 to 1.0 mass%, and the balance Al and unavoidable impurities. It is an aluminum alloy made of, and the clad thickness of the sacrificial anode material is 25 to 80 μm.

On the other hand, Patent Document 2 discloses an aluminum alloy brazing fin material for a heat exchanger used, for example, in an air conditioner (room air conditioner, air conditioner) or a heat exchanger for a refrigerator. In this brazing fin material, the sacrificial anode material contains Zn: 7 to 15% by mass, and the balance is composed of an aluminum alloy composed of Al and unavoidable impurities, which is preferable as the clad thickness of the sacrificial anode material. Is 7 μm or more, more preferably 7 to 40 μm. Further, the sacrificial anode material has a composition which may contain 8.0% by mass or less of Si from the viewpoint of suppressing excessive coarsening of crystal grains and improving corrosion resistance.

International Publication No. 2011/034102 Japanese Unexamined Patent Publication No. 2017-155308

Here, as a result of diligent studies by the present inventors, it has become clear that the brazing sheet in the heat exchanger for an air conditioner needs to have a higher joint strength than the brazing sheet for an automobile. This is because, in general, the upper limit of the allowable refrigerant pressure (allowable internal pressure) of the heat exchanger for an air conditioner is relatively higher than that of the heat exchanger for an automobile. When the sacrificial anode material also serves as a brazing material, of course, the sacrificial anode material is also required to have high bonding strength.

The brazing sheet disclosed in Patent Document 1 is for automobiles and must contain iron (Fe). On the other hand, in the brazing fin material disclosed in Patent Document 2, it is not assumed that the sacrificial anode material also serves as a brazing material, and the inclusion of Si is intended to contribute to the sacrificial anode action.

Further, in Patent Document 2, it is said that the sacrificial anode action cannot be exhibited unless the Zn content of the sacrificial anode material is 7.0% by mass or more, but according to the study by the present inventors, the Zn content is 7. It can be less than 0% by mass. On the other hand, when the sacrificial anode material also serves as a brazing material, it is possible to increase the bonding strength by increasing the Si content, but if the Si content is too large, the fluidity becomes too high. It was also clarified that the corrosion resistance of the brazing sheet was significantly reduced.

The present invention has been made to solve such a problem, and includes a sacrificial anode material layer which is used in a heat exchanger for an air conditioner and can achieve both corrosion resistance and pressure resistance satisfactorily. The purpose is to provide a brazing sheet.

The brazing sheet according to the present invention is a brazing sheet used for a heat exchanger of an air conditioner in order to solve the above-mentioned problems, and is coated on one surface of an aluminum alloy core material and the core material. A brazing material layer made of an aluminum alloy brazing material containing silicon (Si) and a sacrificial anode material made of an aluminum alloy sacrificial anode material coated on the other surface of the core material and containing zinc (Zn) and silicon (Si). When the thickness of the sacrificial anode material layer is in the range of 15 to 25 μm and the temperature T at the time of joining the brazing sheets is in the range of 580 to 660 ° C., the sacrifice is provided. _{The silicon content X Si} in the anode material is calculated by the following equation (1).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
It is a configuration that is greater than or equal to the value derived from.

Alternatively, the brazing sheet according to the present invention is a brazing sheet used for a heat exchanger of an air conditioner in order to solve the above-mentioned problems, and covers both the surface of the aluminum alloy core material and the surface of the core material. A sacrificial anode material layer made of a sacrificial anode material of an aluminum alloy containing zinc (Zn) and silicon (Si), and the thickness of the sacrificial anode material layer is in the range of 15 to 25 μm. When the temperature T at the time of joining the brazing sheet is in the range of 580 to 660 ° C., the silicon content X _Si in the sacrificial anode material is calculated by the following equation (1).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
The configuration may be greater than or equal to the value derived from.

According to the above configuration, in the brazing sheet used in the heat exchanger for an air conditioner, the sacrificial anode material layer contains zinc and silicon within the above range. Thereby, in the sacrificial anode material which also serves as a brazing material, not only the zinc content but also the silicon content can be optimized. Therefore, even if the thickness of the sacrificial anode material layer is within the above range, it is possible to achieve both corrosion resistance and pressure resistance in the bonding structure of the brazing sheet.

The present invention also includes a heat exchanger for an air conditioner, which is configured by using the brazing sheet having the above configuration.

According to the present invention, it is possible to provide a brazing sheet provided with a sacrificial anode material layer, which is used in a heat exchanger for an air conditioner and can have both corrosion resistance and pressure resistance satisfactorily. It works.

(A) is a schematic cross-sectional view showing a schematic structure of a brazing sheet according to a typical embodiment of the present invention, and (B) is a joining of a brazing sheet according to a typical embodiment of the present invention. It is a schematic cross-sectional view which shows the schematic structure of the structure. It is a schematic cross-sectional view which shows an example of the header of the plate fin laminated type heat exchanger constructed by using the brazing sheet shown in FIG. It is a schematic cross-sectional view which shows an example of the header of the plate fin laminated type heat exchanger constructed by using the brazing sheet which provided the sacrificial anode material layer on both sides. (A) to (D) are the figure which shows the corrosion resistance test result of the joint structure of the brazing sheet which concerns on Example or Comparative Example. It is a figure which shows the corrosion resistance test result of the joint structure of the brazing sheet which concerns on other examples.

The brazing sheet according to the present disclosure is used for a heat exchanger of an air conditioner, and is made of an aluminum alloy core material and an aluminum alloy coated on one surface of the core material and containing silicon (Si). The sacrifice includes a brazing material layer made of a brazing material and a sacrificial anode material layer made of a sacrificial anode material of an aluminum alloy coated on the other surface of the core material and containing zinc (Zn) and silicon (Si). When the thickness of the anode material layer is in the range of 15 to 25 μm and the temperature T at the time of joining the brazing sheet is in the range of 580 to 660 ° C., the silicon content X _{Si in the sacrificial anode material.} Is the following equation (1)
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
It is a configuration that is greater than or equal to the value derived from.

Further, the brazing sheet according to the present disclosure is a brazing sheet used for a heat exchanger of an air conditioner, and is coated on both surfaces of an aluminum alloy core material and the core material, and zinc (Zn) and silicon (Zn) and silicon ( A sacrificial anode material layer made of a sacrificial anode material of an aluminum alloy containing Si) is provided, the thickness of the sacrificial anode material layer is in the range of 15 to 25 μm, and the temperature T at the time of joining the brazing sheet is high. When the temperature is in the range of 580 to 660 ° C., the silicon content X _Si in the sacrificial anode material is determined by the following equation (1).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
The configuration may be greater than or equal to the value derived from.

According to the above configuration, in the brazing sheet used in the heat exchanger for an air conditioner, the sacrificial anode material layer contains zinc and silicon within the above range. Thereby, in the sacrificial anode material which also serves as a brazing material, not only the zinc content but also the silicon content can be optimized. Therefore, even if the thickness of the sacrificial anode material layer is within the above range, it is possible to achieve both corrosion resistance and pressure resistance in the bonding structure of the brazing sheet.

In the brazing sheet having the above configuration, the brazing sheet has a joint portion that constitutes a joint portion by being joined to each other and an inclined portion adjacent to the joint portion, and the inclined portion of the inclined portion with respect to the joint portion. The inclination angle may be 40 ° or less.

Further, in the brazing sheet having the above configuration, the core material is an aluminum alloy of 3000 series, 5000 series, or 6000 series, and the sacrificial anode material is a 4000 series aluminum alloy, and the above. It may be configured to contain zinc and silicon within the range.

Further, in the brazing sheet having the above structure, the brazing material may be a 4000 series aluminum alloy.

The heat exchanger for the air conditioner according to the present disclosure may be configured by using the brazing sheet having the above configuration.

Further, the heat exchanger for the air conditioner having the above configuration may have a configuration in which plate fins are laminated.

Hereinafter, typical embodiments of the present invention will be described with reference to the drawings. In the following, the same or corresponding elements will be designated by the same reference numerals throughout all the figures, and duplicate description thereof will be omitted.

The brazing sheet according to the present disclosure is made of an aluminum alloy used for a heat exchanger. Specifically, for example, as shown in FIG. 1A, the brazing sheet 10 according to the present disclosure includes a core material 11, a brazing material layer 12, and a sacrificial anode material layer 13. The brazing material layer 12 is coated (clad) on one surface of the core material 11, and the sacrificial anode material layer 13 is coated on the other surface of the core material 11, that is, the surface opposite to the surface on which the brazing material layer 12 is coated. Has been done. The core material 11, the brazing material forming the brazing material layer 12, and the sacrificial anode material forming the sacrificial anode material layer 13 are all aluminum alloys.

Alternatively, although not shown, the brazing sheet 10 according to the present disclosure may include a core material 11 and a sacrificial anode material layer 13, and may not include a brazing material layer 12. In such a brazing sheet 10, a sacrificial anode material layer 13 is formed on both surfaces of the core material 11.

The brazing sheet 10 according to the present disclosure has a joint portion at least on the side of the sacrificial anode material layer 13, and the joint portion is formed by joining the joint surfaces of the joint portions to each other. The structure in which the brazing sheets 10 are joined to each other at the joining site is the joining structure of the brazing sheets 10 according to the present disclosure. The specific shape of the brazing sheet 10 according to the present disclosure is not particularly limited, but a typical example may be a configuration having an inclined portion adjacent to the joint portion and inclined with respect to the joint portion.

Specifically, for example, as shown in FIG. 1B, the joining structure 20 of the brazing sheet 10 according to the present disclosure is configured by joining the joining portions 10a of the brazing sheet 10 to each other. The inclined portion 10b is adjacent to the joint portion 10a, and the inclination angle θ1 of the inclined portion 10b with respect to the joint portion 10a is not particularly limited, but the angle θ2 formed between the inclined portions 10b in the joint structure 20 is an acute angle, that is, 90 °. Since it may be less than (θ2 <90 °), the inclination angle θ1 may be less than 45 °, which is 1/2 of that. Further, as shown in FIG. 1B, fillets 22 are formed between the inclined portions 10b. In the present embodiment, the fillet 22 is defined as a solidified wax material or sacrificial anode material that has flowed out from the joint portion 10a at the time of joining.

The angle θ2 formed by each inclined portion 10b constituting the joint structure 20 is referred to as an “inclined portion forming angle” for convenience of explanation. Further, in FIG. 1B, the inclination angle θ1 and the inclination portion formation angle θ2 are shown by dotted lines, but the reference of these angles is the thickness of the brazing sheet 10 as shown by the dotted line in the figure. (A line having an intermediate thickness (depth) from both one surface and the other surface). However, the reference of these angles θ1 and θ2 is not limited to the intermediate line of the thickness, and may be another known reference (for example, an angle with respect to the surface on the joint side).

The inclination angle θ1 may be less than 45 ° as described above, but the upper limit thereof is preferably less than 40 °, more preferably less than 35 °. Depending on the structure of the heat exchanger for the air conditioner, if the inclination angle θ1 exceeds 40 °, the brazing sheet 10 may be partially thinned or the core material 11 may be partially eroded during press working. There is a risk of doing so.

When the inclination angle θ1 of the inclined portion 10b with respect to the joint portion 10a becomes relatively large, a large amount of processing is applied to the brazing sheet 10 during press processing. As a result, the lasing sheet 10 is partially thinned. When the brazing sheet 10 is partially thinned, stress concentration or insufficient pressure resistance occurs in the thinned portion, so that the portion may be damaged.

Further, when a large processing is applied to the brazing sheet 10, the diffusion coefficient of silicon from the brazing material layer 12 to the core material 11 becomes large at the portion where the processing is applied, which causes erosion (melting of the core material 11). The risk increases. When erosion occurs, zinc contained in the sacrificial anode material layer 13 existing around the molten core material 11 is involved, and a part of the core material 11 becomes a “sacrificial anode material”. As a result, there is a possibility that the brazing sheet 10 penetrates early from the site where the erosion occurs.

On the other hand, when the inclination angle θ1 is 40 ° or less, the possibility that a large processing is applied to the brazing sheet 10 is reduced. Therefore, it is possible to effectively suppress the possibility that the brazing sheet 10 is partially thinned or the core material 11 is partially eroded. Of course, depending on the structure of the heat exchanger for the air conditioner, even if the inclination angle θ1 exceeds 40 °, partial wall thinning of the brazing sheet 10 or partial erosion of the core material 11 occurs during press working. Is sometimes suppressed, so the upper limit of the inclination angle θ1 is not always 40 °.

On the other hand, the lower limit of the inclination angle θ1 is not particularly limited, and a suitable lower limit value may be set according to the structure of the heat exchanger for the air conditioner. For example, in the case of the plate fin laminated heat exchanger described later, it is better not to make the inclination angle θ1 too small from the viewpoint of securing the flow path of the adjacent air (second fluid) due to the structure. The lower limit of the inclination angle θ1 in the plate fin laminated heat exchanger is preferably 15 ° or more, and more preferably 20 ° or more.

The core material 11 included in the brazing sheet 10 according to the present disclosure may be a known aluminum alloy that can realize the physical properties required according to various conditions such as the type and structure of the heat exchanger. Examples of the aluminum alloy used as the core material 11 include, in the field of heat exchangers, typically 3000 series (aluminum-manganese (Al-Mn) based alloy) and 5000 series (aluminum-magnesium (Al-Mg)). (Aluminum-based alloy), 6000-based (aluminum-magnesium-silicon (Al-Mg-Si) -based alloy), and the like, but are not limited thereto.

Alternatively, the core material 11 may contain an element known to the aluminum alloy in a content (concentration) exceeding the unavoidable impurities. The upper limit of the concentration allowed as an unavoidable impurity varies depending on various conditions, but for example, less than 0.1% by mass in the entire aluminum alloy can be mentioned. Alternatively, the upper limit of the concentration of unavoidable impurities may conform to the alloy composition defined in a known standard such as JIS.

In the present disclosure, the aluminum alloy used as the brazing material may be an alloy containing silicon (silicon, Si), that is, an aluminum-silicon (Al-Si) based alloy. The content of Si in the brazing material is not particularly limited, and may be within a range suitable for use as a brazing material. Specifically, for example, the content (concentration) of Si in the brazing material can be in the range of 2.5 to 13% by mass, even if it is in the range of 3.5 to 12% by mass. Good. If the Si content is too low, the Al—Si alloy may not function sufficiently as a brazing material. On the other hand, if the Si content is too high, Si may diffuse into the core material 11 or the mating material and melt the brazing sheet 10 itself. Further, the Al—Si alloy as the brazing material may contain an element other than Si in a content exceeding the unavoidable impurities as long as the function as the brazing material is not affected.

The aluminum alloy used as the sacrificial anode material contains zinc (Zn) in the range of 2.5 to 6.0% by mass in order to exert a sacrificial anode action. Further, in the present disclosure, since the sacrificial anode material also serves as a brazing material as described above, Si is contained in the same manner as the brazing material. The Si content (Si concentration) in the sacrificial anode material can be in the range of 3.0 to 6.0% by mass. Therefore, the aluminum alloy used as the sacrificial anode material may be an aluminum-silicon-zinc (Al-Si-Zn) alloy.

In the Al—Si—Zn-based alloy as the sacrificial anode material, if the Zn content (concentration) is less than 2.5% by mass, a good sacrificial anode action cannot be exhibited. On the other hand, when the Zn content exceeds 6.0% by mass, the sacrificial anode action proceeds too early and the sacrificial anode material layer 13 disappears from the brazing sheet 10 at an early stage, so that the corrosion resistance of the brazing sheet 10 deteriorates. There is a risk of

Further, in the Al—Si—Zn-based alloy as the sacrificial anode material, if the Si content is less than 3.0% by mass, the amount of Si is too small and the sacrificial anode material does not sufficiently flow, and as a brazing material. There is a risk that good adhesive strength cannot be exhibited. On the other hand, if the Si content exceeds 6.0% by mass, the fluidity as the sacrificial anode material is improved, but the fluidity becomes too high and the corrosion resistance may decrease.

In particular, in the present disclosure, the brazing sheet 10 is used in a heat exchanger for an air conditioner. In this case, when the brazing sheet 10 is used in a bonding structure 20 constituting a flow path of a refrigerant (plate fin lamination described later). Mold heat exchangers, etc.), adhesive strength that can withstand the upper limit of the allowable pressure of the refrigerant is required. Since this allowable pressure varies depending on various conditions such as the type, application, and performance of the air conditioner, the adhesive strength required for the sacrificial anode material can be appropriately set according to the conditions.

Here, in the present disclosure, in consideration of the temperature (brazing temperature) at the time of joining the brazing sheets 10 to each other, the Si content is the adhesion capable of realizing sufficient pressure resistance in the joining structure 20 of the brazing sheets 10. The balance between strength and sufficient corrosion resistance is important. As a result of diligent studies by the present inventors on this point, when the temperature T at the time of joining the brazing sheet 10 is in the range of 580 to 660 ° C., a particularly preferable content of Si in the sacrificial anode material is as follows. It became clear that it can be defined by (1) and (2).

Specifically, in the sacrificial anode material, when the Zn content (concentration) is in the range of 2.0 to 6.0% by mass and the Si content (concentration) is X _Si , this Si The concentration may be equal to or less than the value derived from the following equation (1) and greater than or equal to the value derived from the following equation (2).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
Even in the Al—Si—Zn-based alloy as the sacrificial anode material, the content of elements other than Si and Zn exceeds the unavoidable impurities as long as the sacrificial anode action and the function as the brazing material are not affected. It may be contained.

The types of aluminum alloys specifically used as the brazing material and the sacrificial anode material are not particularly limited, but typically 4000 series (aluminum-silicon (Al-Si) based alloys) can be used for both. For the sacrificial anode material, a 4000 series aluminum alloy having a Si content within the above range is selected, or Si is added by a known method to adjust the content so as to fall within the above range. Zn may be added by a known method so that the content of Zn is also within the above range.

In the brazing sheet 10 according to the present disclosure, the clad ratio of the brazing material and the sacrificial anode material is not particularly limited, and may be mentioned within a general range. The general clad ratio may be, for example, in the range of 2 to 30% by mass, and may be in the range of 3 to 20% by mass.

Further, the thickness of the brazing sheet 10 according to the present disclosure and the thicknesses of the core material 11, the brazing material layer 12, and the sacrificial anode material layer 13 are not particularly limited, and the brazing sheet 10 may be configured or manufactured. It can be appropriately set according to the type or parts of the heat exchanger to be used. However, in the present disclosure, the thickness of the sacrificial anode material layer 13 is in the range of 15 to 25 μm.

Since the brazing sheet 10 according to the present disclosure is used in a heat exchanger for an air conditioner, the thickness of the sacrificial anode material layer 13 can be made thinner than that for an automobile. If the thickness of the sacrificial anode material layer 13 can be reduced, the amount of the sacrificial anode material used can be reduced, so that an increase in the manufacturing cost of the brazing sheet 10 can be suppressed.

In particular, in the present disclosure, as will be described later, a plate fin laminated type can be mentioned as a preferable example, but in the plate fin laminated type heat exchanger, a plurality of plate fins are laminated to form a laminated body, and the laminated body is formed. Hold the body with a jig and join (braze). Therefore, if the thickness of the sacrificial anode material layer 13 is too large, the dimensional change of the laminated body becomes large, which may affect the joint structure 20. If the sacrificial anode material layer 13 can be set to 25 μm or less, such an influence on the joint structure 20 can be effectively suppressed.

On the other hand, if the sacrificial anode material layer 13 is less than 15 μm, the absolute amount of the sacrificial anode material with respect to the brazing sheet 10 becomes too small. Therefore, the sacrificial anode material layer 13 may disappear from the brazing sheet 10 at an early stage, and the corrosion resistance of the brazing sheet 10 may decrease.

In the present disclosure, a plurality of brazing sheets 10 are superposed on each other at the joining portions 10a, and the brazing material and the sacrificial anode material are melted and brazed at a high temperature (580 ° C. or higher) to braze the brazing sheets 10 to each other. Be joined. In the joining structure 20 of the brazing sheet 10 manufactured in this manner, as shown in FIG. 1B, the joining portion 10a is located between the inclined portions 10b and adjacent to the joining portion 10a (joining portion 21). The sacrificial anode material flowing out from the sacrificial anode material layer 13 is solidified to form a fillet 22.

In the present disclosure, from the viewpoint of evaluating the corrosion resistance of the brazing sheet 10, the potentials of the joint portion 21 (including the fillet 22), the sacrificial anode material layer 13 and the like may be evaluated (measured) by a known method. As a typical method for evaluating an electric potential, a potential measurement sample (for example, a brazing sheet 10 or a core material 11, a brazing material, a sacrificial anode material, a fillet 22 or a joint portion 21, or these) is used in a potential stat / galvanostat. (For example, an alloy having a composition simulating), a counter electrode, and a reference electrode (for example, a silver / silver chloride (Ag / AgCl) electrode) are connected and immersed in an electrolytic solution (for example, a 5 wt% sodium chloride (NaCl) solution). Then, a method of measuring the potential difference between the sample and the reference electrode can be mentioned.

The method for producing the brazing sheet 10 according to the present disclosure is not particularly limited, and a known production method can be preferably used. Specifically, for example, an aluminum alloy having a desired composition is formed into a plate shape by a known method to obtain a core material 11, and a brazing material of an aluminum alloy containing Si is used for one of the core materials 11 by a known method. Aluminum alloy clad with and containing Zn in the range of 2.0 to 6.0% by mass and Si in the range of 3.0 to 6.0% by mass with respect to the other surface of the core material 11. The sacrificial anode material may be clad by a known method. In the present disclosure, the conditions for manufacturing the brazing sheet 10 can be appropriately set according to the configuration of the brazing sheet 10 or the type or parts of the heat exchanger for the air conditioner to be manufactured.

As described above, the brazing sheet 10 according to the present disclosure can be particularly suitably used for manufacturing a heat exchanger for an air conditioner. As described above, the bonding structure 20 formed when the brazing sheet 10 according to the present disclosure is applied to the heat exchanger has a structure as illustrated in FIG. 1 (B), but more specifically, it has a structure as illustrated in FIG. 1 (B). A plate fin laminated heat exchanger having a structure as shown in FIG. 2 or a laminated heat exchanger for an Air To Water heat pump having a structure as shown in FIGS. 4A and 4B can be mentioned. it can.

Although not shown, the plate fin laminated heat exchanger is a plate fin laminated body having a flow path through which a refrigerant, which is a first fluid, flows, and air, which is a second fluid, is flowed between each plate fin laminated body to flow the first fluid. It exchanges heat between the fluid and the second fluid. The plate fin included in this heat exchanger has a flow path region having a plurality of first fluid flow paths through which the first fluid flows in parallel, and a header flow path communicating with each first fluid flow path in this flow path region. It has a header area and.

In the plate fin laminated heat exchanger, end plates having substantially the same shape as the plate fins in a plan view are provided on both sides of the plate fin laminated body in the laminating direction, and are interposed between these pair of end plates. The plurality of plate fins to be formed are joined and integrated by brazing in a laminated state. FIG. 2 shows a schematic structure of a header portion in the plate fin laminated body 30 as a partial cross section, and a plurality of plate fins 32 are laminated on an end plate 31 located at the uppermost part in the drawing.

An opening is provided in each of the end plate 31 and the plate fin 32, and the header opening 33 is formed by laminating these plates to form the plate fin laminated body 30. In the configuration shown in FIG. 2, the refrigerant, which is the first fluid, flows in from the outside of the header opening 33 in the direction indicated by the block arrow in the drawing, and further flows in between the plate fins 32. As described above, each plate fin 32 is provided with the first fluid flow path, so that the refrigerant flowing between the plate fins 32 flows through the first fluid flow path. Further, the air, which is the second fluid, flows in the space formed between the plate fins 32 so as to intersect the direction in which the refrigerant flows (the direction of the first fluid flow path). As a result, the air is cooled by the refrigerant.

Specific configuration examples of such a plate fin laminated heat exchanger include, for example, JP-A-2017-180856, JP-A-2018-066531, JP-A-2018-066532, and JP-A-2018-066533. It is described in Japanese Patent Application Laid-Open No. 2018-066534, Japanese Patent Application Laid-Open No. 2018-066535, Japanese Patent Application Laid-Open No. 2018-066536, etc. It shall be a part of the description of the specification.

As shown in FIG. 3, the plate fin laminate 34 constituting the laminated heat exchanger for the Air To Water heat pump has a basic configuration of the plate fin laminate of the general plate fin laminated heat exchanger shown in FIG. Similar to body 30. However, the plate fins 35 (brazing sheet 10 according to the present disclosure) constituting the plate fin laminate 34 have a sacrificial anode layer 13 on both sides thereof. Therefore, as shown in FIG. 3, the fillet 22 is formed not only at the joint portion 21 located on the header opening 33 side (inside) but also at the joint portion 21 located on the opposite side (outside) of the header opening 33 side. Has been done. Since the configuration shown in FIG. 3 is the same as the configuration shown in FIG. 2 except for the formation positions of the plate fins 35 and the fillets 22, the description thereof will be omitted.

As described above, the brazing sheet according to the present disclosure is used for a heat exchanger of an air conditioner, and is coated on one surface of an aluminum alloy core material and the core material and contains silicon (Si). An aluminum alloy brazing material layer and a sacrificial anode material layer of an aluminum alloy coated on the other surface of the core material and containing zinc (Zn) and silicon (Si), or a core material. A sacrificial anode material layer is coated on both surfaces of the above.

Further, in the brazing sheet according to the present disclosure, when the thickness of the sacrificial anode material layer is in the range of 15 to 25 μm and the temperature T at the time of joining the brazing sheet is in the range of 580 to 660 ° C., the sacrificial anode is used. The silicon content X _Si in the material is less than or equal to the value derived from the above formula (1) and greater than or equal to the value derived from the above formula (2). Thereby, in the sacrificial anode material which also serves as a brazing material, not only the zinc content but also the silicon content can be optimized. Therefore, even if the thickness of the sacrificial anode material layer is within the above range, it is possible to achieve both corrosion resistance and pressure resistance in the bonding structure of the brazing sheet.

The present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited thereto. Those skilled in the art can make various modifications, modifications, and modifications without departing from the scope of the present invention. The corrosion resistance test in the following Examples and Comparative Examples was carried out as follows.

[Corrosion resistance test]
The corrosion resistance of the bonded structure of the brazing sheet was evaluated based on the SWAAT test (Sea Water Acidified Test) defined by ASTM G85-A3.

(Comparative Example 1)
As the brazing sheet according to Comparative Example 1, the core material is an aluminum alloy of 3003, the brazing material layer is an aluminum alloy of 4343, and the sacrificial anode material layer is silicon (Si) 2.5% by mass and zinc (Zn). An aluminum alloy (Al-2.5% Si-4.0% Zn) having a balance of 4.0% by mass and the balance of aluminum (Al) was used. Further, the inclination angle θ1 of the inclined portion included in the brazing sheet was about 30 °.

The brazing sheets were brazed at each other's joints to form a joint. The joint surface of the joint site was a sacrificial anode material layer. Since the brazing temperature was 610 ° C., the Si content (concentration) in the sacrificial anode material at this time was in the range of about 2.9 to 6.1% by mass from the above formulas (1) and (2). Be inside. Visual observation of the joints confirmed that the joints were inadequate.

In addition, the corrosion resistance of the joints between the brazing sheets was evaluated by the corrosion test described above. As a result, as shown in the cross-sectional photograph of FIG. 4A, the sacrificial anode action of the sacrificial anode material layer could be confirmed, but the corrosion of the core material could not be confirmed.

(Example 1)
As the brazing sheet according to Example 1, an aluminum alloy (Al-2.8% Si) in which the sacrificial anode material layer is silicon (Si) 2.8% by mass, zinc (Zn) 4.0% by mass, and the balance aluminum (Al). The brazing sheets were brazed to each other to form a joint in the same manner as in Comparative Example 1 except that the one having -4.0% Zn) was used. Since the brazing temperature was set to 620 ° C., the Si content (concentration) in the sacrificial anode material at this time was in the range of about 2.3 to 5.3% by mass from the above formulas (1) and (2). Be inside. When the joint was visually confirmed, good joint was confirmed.

In addition, the corrosion resistance of the joints between the brazing sheets was evaluated by the corrosion test described above. As a result, as shown in the cross-sectional photograph of FIG. 4B, the sacrificial anode action of the sacrificial anode material layer could be confirmed, but the corrosion of the core material could not be confirmed.

(Example 2)
As the brazing sheet according to Example 2, an aluminum alloy (Al-4.4% Si) in which the sacrificial anode material layer is silicon (Si) 4.4% by mass, zinc (Zn) 4.0% by mass, and the balance aluminum (Al). The brazing sheets were brazed to each other to form a joint in the same manner as in Comparative Example 1 except that the one having -4.0% Zn) was used. Since the brazing temperature was set to 620 ° C., the Si content (concentration) in the sacrificial anode material at this time was in the range of about 2.3 to 5.3% by mass from the above formulas (1) and (2). Be inside. When the joint was visually confirmed, good joint was confirmed.

In addition, the corrosion resistance of the joints between the brazing sheets was evaluated by the corrosion test described above. As a result, as shown in the cross-sectional photograph of FIG. 4C, the sacrificial anode action of the sacrificial anode material layer could be confirmed, but the corrosion of the core material could not be confirmed.

(Comparative Example 2)
As a brazing sheet according to Comparative Example 2, an aluminum alloy (Al-4.4% Si) in which the sacrificial anode material layer is silicon (Si) 7.0% by mass, zinc (Zn) 4.0% by mass, and the balance aluminum (Al). The brazing sheets were brazed to each other to form a joint in the same manner as in Comparative Example 1 except that the one having -4.0% Zn) was used. Since the brazing temperature was 610 ° C., the Si content (concentration) in the sacrificial anode material at this time was in the range of about 2.9 to 6.1% by mass from the above formulas (1) and (2). Be inside. When the joint was visually confirmed, good joint was confirmed.

In addition, the corrosion resistance of the joints between the brazing sheets was evaluated by the corrosion test described above. As a result, as shown in the cross-sectional photograph of FIG. 4D, not only the sacrificial anode action of the sacrificial anode material layer but also the progress of intergranular corrosion in the core material was confirmed.

(Example 3)
As the brazing sheet according to Example 3, brazing in the same manner as in Comparative Example 1 except that a sacrificial anode material layer having the same composition as that in Example 1 was provided on both sides of the core material and no brazing material layer was used. The sheets were brazed together to form a joint. When the joint was visually confirmed, good joint was confirmed.

In addition, the corrosion resistance of the joints between the brazing sheets was evaluated by the corrosion test described above. As a result, as shown in the cross-sectional photograph of FIG. 5, the sacrificial anode action of the sacrificial anode material layer could be confirmed, but the corrosion of the core material could not be confirmed.

The present invention is not limited to the description of the above-described embodiment, and various modifications can be made within the scope of the claims, and the present invention is disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the above technical means are also included in the technical scope of the present invention.

The present invention can be widely and suitably used not only in the field of brazing sheets used in heat exchangers for air conditioners having a sacrificial anode material layer, but also in the field of heat exchangers for air conditioners using the brazing sheets. it can.

10: Brazing sheet 10a: Joining part 10b: Inclined part 11: Core material 12: Brazing material layer 13: Sacrificial anode material layer 20: Joining structure of brazing sheet 21: Joining part 22: Fillet 30: Plate fin laminate 31: End plate 32: Plate fin 33: Header opening 34: Plate fin laminate 35: Plate fin

Claims (7)

A brazing sheet used in heat exchangers of air conditioners.
Aluminum alloy core material and
A brazing material layer made of an aluminum alloy brazing material coated on one surface of the core material and containing silicon (Si),
A sacrificial anode material layer composed of a sacrificial anode material of an aluminum alloy coated on the other surface of the core material and containing zinc (Zn) and silicon (Si).
With
The thickness of the sacrificial anode material layer is in the range of 15 to 25 μm.
When the temperature T at the time of joining the brazing sheet is in the range of 580 to 660 ° C.
_{The silicon content X Si} in the sacrificial anode material is calculated by the following equation (1).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
Characterized by being greater than or equal to the value derived from
Blazing sheet. A brazing sheet used in heat exchangers of air conditioners.
Aluminum alloy core material and
A sacrificial anode material layer composed of a sacrificial anode material of an aluminum alloy covering both surfaces of the core material and containing zinc (Zn) and silicon (Si).
With
The thickness of the sacrificial anode material layer is in the range of 15 to 25 μm.
When the temperature T at the time of joining the brazing sheet is in the range of 580 to 660 ° C.
_{The silicon content X Si} in the sacrificial anode material is calculated by the following equation (1).
T = 660-8 × exp (0.3X _Si ) ・ ・ ・ (1)
It is less than or equal to the value derived from, and the following equation (2)
T = 580 + 55 × exp (-0.5 (X _Si -1.7)) ・ ・ ・ (2)
Characterized by being greater than or equal to the value derived from
Blazing sheet. The brazing sheet has a joint portion that constitutes a joint portion by being joined to each other.
It has an inclined portion adjacent to this joint portion, and has.
The brazing sheet according to claim 1 or 2, wherein the inclination angle of the inclined portion with respect to the joint portion is 40 ° or less. The core material is an aluminum alloy of any of 3000 series, 5000 series, or 6000 series.
The sacrificial anode material is a 4000 series aluminum alloy and contains zinc and silicon within the above range.
The brazing sheet according to claim 1 or 2. The brazing material is a 4000 series aluminum alloy.
The brazing sheet according to claim 1. A heat exchanger for an air conditioner, which is configured by using the brazing sheet according to any one of claims 1 to 5. It is characterized by being a plate fin laminated type.
The heat exchanger for an air conditioner according to claim 6.

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