WO2022137626A1

WO2022137626A1 - Brazing sheet for heat exchanger, joint structure for brazing sheet for heat exchanger, and heat exchanger

Info

Publication number: WO2022137626A1
Application number: PCT/JP2021/028269
Authority: WO
Inventors: 孝仁中島; 泰行李; 浩崇北川
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2020-12-25
Filing date: 2021-07-30
Publication date: 2022-06-30
Also published as: CN116323062A; JP2022102282A

Abstract

This brazing sheet (10A) comprises a core material (11), a brazing material layers (12, 13), and an intermediate sacrificial layer (14). The brazing material layers (12, 13) are positioned on the outer side relative to each of the two surfaces of the core material (11). The intermediate sacrificial layer (14) is laminated on at least one of the surfaces of the core material (11). The brazing material and a sacrificial positive electrode material both do not contain copper (Cu). The core material (11) contains copper (Cu) in the range of 0.3-1.2 mass%. The intermediate sacrificial layer (14) has a thickness of 50 μm or less.

Description

Joining structure of brazing sheet for heat exchanger and brazing sheet for heat exchanger, and heat exchanger

The present disclosure relates to a brazing sheet used for a member constituting a heat exchanger, a joining structure for joining the brazing sheets to each other, and a heat exchanger having the joining structure.

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

When manufacturing a heat exchanger, joining with brazing material is generally used to attach fins to the pipe. If both the pipe and the fin are made of aluminum, 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 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 layer (sacrificial layer) made of a sacrificial anode material is clad on the other surface is used.

As an example of the brazing sheet in which the sacrificial layer is clad, for example, the one disclosed in Patent Document 1 is known. Patent Document 1 discloses an aluminum alloy brazing sheet used for a heat exchanger for an automobile, particularly a passage component of a fluid (cooling water, a refrigerant, etc.). In this brazing sheet, the components of the core material and the sacrificial anode material are adjusted in order to achieve good brazing property and excellent strength and corrosion resistance after brazing.

Specifically, in this brazing sheet, the content of silicon, iron (Fe) and manganese (Mn) in the sacrificial anode material is regulated to 0.15% by mass or less. The reason for such regulation is to suppress the formation of Al—Mn—Si or Al—Fe—Mn—Si compounds and suppress the decrease in strength after brazing. Further, in this brazing sheet, the silicon content of the core material is restricted to 0.15% by mass or less, and copper is added to the core material in the range of 0.40 to 1.2% by weight. The reason for adding copper is to improve the strength of the core material, increase the potential difference between the core material and the sacrificial anode layer, etc., and improve the anticorrosion effect due to the sacrificial anode action.

Further, as another example of the brazing sheet in which the sacrificial layer is clad, for example, the one disclosed in Patent Document 2 is known. Patent Document 2 also discloses an aluminum alloy brazing sheet used for heat exchangers for automobiles, particularly fluid passage constituents. This brazing sheet has a sacrificial anticorrosive effect on both sides and has a brazing function on one side thereof, and in this brazing sheet, in order to prevent preferential corrosion of the joint, not only the core material and the sacrificial anode material but also the sacrificial anode material. The composition of the brazing material is also adjusted.

In this brazing sheet, zinc (Zn) is added not only to the sacrificial anode material but also to the brazing material, and copper is further added to the brazing material in the range of 0.1 to 0.6 mass%. Copper is also added to the core material in the range of 0.05 to 1.2 mass%. The purpose of adding copper to each material is different, for the brazing material, to make the potential of the brazing material noble, and for the core material, to improve the strength of the core material.

Japanese Unexamined Patent Publication No. 2010-163674 Japanese Unexamined Patent Publication No. 2013-155404

The brazing sheet disclosed in Patent Document 1 aims to improve the strength by adding copper to the core material and the anticorrosion effect by the sacrificial anode action. However, in this brazing sheet, the silicon content of both the sacrificial anode material and the core material is limited to 0.15% by mass or less, and the core material also contains various metal elements other than copper. It is specified in detail. Therefore, the range of material choices that can be used as the core material and the sacrificial anode material is reduced. Moreover, this brazing sheet limits the silicon content of the sacrificial anode material to a very small amount. Therefore, it is considered that this sacrificial layer does not function as a general brazing material.

In the brazing sheet disclosed in Patent Document 2, by adding copper together with zinc to the brazing material, not only zinc is concentrated at the brazed joint but also copper is concentrated in the same manner. Therefore, this brazing sheet is intended to prevent the potential of the joint portion from being excessively lowered by zinc due to the concentration (containing) of this copper. However, when copper and zinc are used in combination, as a result of diligent studies by the present inventors, it has been clarified that the preferential corrosive action of the sacrificial layer is reduced and the corrosion resistance is lowered.

For example, depending on the type of heat exchanger, a structure is included in which when the brazing sheets are joined to each other, the angle formed by the respective joining surfaces becomes an acute angle. For convenience, such a structure is referred to as an "acute-angled joining structure", and a surface adjacent to the joining surface of the brazing sheet and not joined is referred to as a "non-joining adjacent surface". Fillets are formed between adjacent surfaces. This fillet is defined herein as a solidified wax or sacrificial anode material that has flowed out of the joint surface during joining.

In the brazing sheet disclosed in Patent Document 2, copper segregates on the surface of the fillet after brazing. The segregated copper functions as a cathode in the corrosion reaction, but the sacrificial layer around the segregated copper on the fillet surface becomes noble. As a result, the potential difference between the sacrificial layer and the core material becomes smaller, so that the function of the sacrificial layer (priority corrosion action) is reduced. Depending on the situation, there is a risk of early penetration due to intergranular corrosion of the core material.

The present disclosure effectively suppresses or prevents preferential corrosion of the fillet even when the fillet generated adjacent to the joint between the brazing sheets contains copper and zinc, and has good corrosion resistance of the heat exchanger. The purpose is to make it.

The brazing sheet according to the present disclosure is used in a heat exchanger and includes a core material, a brazing material layer, and an intermediate sacrificial layer. The core material is made of aluminum alloy. The brazing filler metal layer is made of an aluminum alloy brazing filler metal containing silicon (Si). The intermediate sacrificial layer is made of a sacrificial anode material of an aluminum alloy containing zinc (Zn) in the range of 0.5 to 6.0% by mass. The brazing filler metal layer is located outside when viewed from both sides of the core wood, and an intermediate sacrificial layer is laminated on at least one surface of the core wood. Neither the brazing material nor the sacrificial anode material contains copper (Cu), and the core material contains copper (Cu) in the range of 0.3 to 1.2% by mass, which is an intermediate sacrifice. The thickness of the layer is 50 μm or less.

Further, the joining structure of the brazing sheet according to the present disclosure is configured by using the brazing sheet according to the present disclosure. The brazing sheet according to the present disclosure has a joint surface that constitutes a joint portion by being joined to each other, and a non-joint adjacent surface adjacent to the joint surface. When the joint surfaces are joined together, a fillet is formed between the non-joint adjacent surfaces and adjacent to the joint surface, which flows out from the joint surface and solidifies the brazing material.

Further, the heat exchanger according to the present disclosure has a structure having a joining structure of the brazing sheet according to the present disclosure.

The present disclosure effectively suppresses or prevents preferential corrosion of the fillet even when the fillet generated adjacent to the joint between the brazing sheets contains copper and zinc by the above configuration, and is a heat exchanger. Corrosion resistance can be made good.

It is a schematic sectional drawing which shows the schematic structure of the brazing sheet which concerns on the typical embodiment of this disclosure. It is a schematic cross-sectional view which shows the schematic structure of the joint structure of the brazing sheet which concerns on embodiment. It is a schematic sectional drawing which shows the structure of another brazing sheet which concerns on embodiment. It is a schematic sectional drawing which shows the structure of another brazing sheet which concerns on embodiment. It is a schematic sectional drawing which shows the structure of another brazing sheet which concerns on embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a header of a plate fin laminated heat exchanger configured by using the brazing sheet shown in FIG. 1A. FIG. 3 is an enlarged schematic partial cross-sectional view of the joining structure of the brazing sheet included in the header shown in FIG. 3A. FIG. 3 is a schematic partial cross-sectional view showing an example of a parallel flow capacitor (PFC) configured by using the brazing sheet shown in FIG. 1A. FIG. 4 is a schematic partial cross-sectional view showing an enlarged joint structure of the brazing sheet of the PFC shown in FIG. 4A. FIG. 3 is a schematic cross-sectional view showing an example of a header of a plate fin laminated heat exchanger (laminated heat exchanger for an Air To Water heat pump) configured by using the brazing sheet shown in FIG. 2B. FIG. 5 is an enlarged schematic partial cross-sectional view of the joining structure of the brazing sheet included in the header shown in FIG. 5A. It is a figure which shows the schematic structure and the corrosion resistance test result of the brazing sheet which concerns on Example, comparative example or reference example in this disclosure. It is a graph which shows the concentration of copper in the joint part of the brazing sheet which concerns on Example 1, Comparative Example 1, and Reference Example shown in FIG. It is a figure which schematically explains the position of the joint part which is the horizontal axis of the graph shown in FIG. 7A.

According to such a configuration, in the brazing sheet according to the present disclosure, an intermediate sacrificial layer made of a sacrificial anode material is arranged between at least one brazing filler metal layer and the core material, and the brazing filler metal layer and the intermediate sacrificial layer are formed. Copper is not contained, and copper is contained only in the core material within a predetermined range. As a result, when the brazing material layers of the brazing sheet according to the present disclosure are joined to each other, copper is diffused from the core material through the intermediate sacrificial layer to the brazing material layer constituting the joint portion of the brazing sheet, and the copper is joined. Copper in the core material also diffuses into the fillet formed adjacent to the portion. Therefore, in the brazing sheet according to the present disclosure, copper is likely to segregate at the fillet at the end.

Here, at the time of joining at high temperature, the brazing material becomes liquid phase, but the intermediate sacrificial layer does not become liquid phase. Therefore, copper is likely to segregate in the fillet, but zinc is present in a suitable concentration around the fillet due to the intermediate sacrificial layer. As a result, a state in which zinc is appropriately present around the fillet in which copper segregates is realized, so that the brazing sheet according to the present disclosure can realize a good sacrificial anode action in the fillet. In addition, the brazing sheet according to the present disclosure can realize a good sacrificial anode action without copper hindering the appropriate leveling of the potential by zinc.

As a result, it is possible to avoid the possibility that the corrosion priority action of the sacrificial anode material existing in the vicinity is reduced due to the segregation of copper as in the conventional case. Therefore, the brazing sheet according to the present disclosure can effectively suppress or prevent the possibility that corrosion progresses from the fillet to the joint portion and causes a decrease in the joint strength of the joint portion. Thereby, the brazing sheet according to the present disclosure can further improve the corrosion resistance at the joint portion of the heat exchanger.

The brazing sheet according to the present disclosure has a structure in which a brazing material layer is laminated on one surface of a core material, and a brazing material layer is laminated on an intermediate sacrificial layer laminated on the other surface of the core material. You may.

Further, the brazing sheet according to the present disclosure may have a structure in which intermediate sacrificial layers are laminated on both surfaces of the core material, and brazing material layers are laminated on these intermediate sacrificial layers.

Further, the brazing sheet according to the present disclosure may further include a flux-containing layer or a magnesium-containing layer, and the flux-containing layer or the magnesium-containing layer may be configured to be located outside when viewed from the intermediate sacrificial layer. The flux-containing layer is made of a flux material for brazing. The magnesium-containing layer is configured as a layer independent of the brazing filler metal layer, and at least magnesium (Mg) is added to the brazing filler metal.

Further, in the brazing sheet according to the present disclosure, the flux-containing layer or the magnesium-containing layer may be configured to be adjacent to the brazing filler metal layer.

Further, in the brazing sheet according to the present disclosure, the core material may be a structure in which copper is added within the above range to any of 3000 series, 5000 series, or 6000 series aluminum alloys. good. The intermediate sacrificial layer may have a structure in which zinc is added within the above range to a 1000 series or 3000 series aluminum alloy.

Further, in the brazing sheet according to the present disclosure, the brazing filler metal layer may be configured to be a 4000 series aluminum alloy.

Further, the joining structure of the brazing sheet according to the present disclosure is configured by using the brazing sheet according to the present disclosure. The brazing sheet according to the present disclosure has a joint surface that constitutes a joint portion by being joined to each other, and a non-joint adjacent surface adjacent to the joint surface. Then, when the joint surfaces are joined together, a fillet that flows out from the joint surface and solidifies the brazing material is formed at a portion between the respective non-joint adjacent surfaces and adjacent to the joint surface. be.

In the joining structure of the brazing sheet according to the present disclosure, the angle formed by the respective non-joining adjacent surfaces may be an acute angle.

Further, the heat exchanger according to the present disclosure may be a plate fin laminated heat exchanger or a parallel flow capacitor (PFC).

(Embodiment)
Hereinafter, a typical embodiment, which is an example of the present disclosure, will be described with reference to the drawings. In the following, the same or corresponding elements are designated by the same reference numerals throughout all the figures, and the overlapping description thereof will be omitted.

[Blazing sheet]
First, the configuration of the brazing sheet 10A according to the embodiment of the present disclosure and the configuration of the joining structure 20 of the brazing sheet 10A according to the embodiment of the present disclosure will be described with reference to FIGS. 1A and 1B. FIG. 1A is a schematic cross-sectional view showing a schematic configuration of the brazing sheet 10A according to the embodiment. FIG. 1B is a schematic cross-sectional view showing a schematic configuration of the joining structure 20 of the brazing sheet 10A according to the embodiment.

The brazing sheet 10A according to the embodiment of the present disclosure is a brazing sheet used for a heat exchanger and is made of an aluminum alloy. Specifically, for example, as shown in FIG. 1A, the brazing sheet 10A includes a core material 11, a brazing material layer 12, a brazing material layer 13, and an intermediate sacrificial layer 14. In FIG. 1A, the brazing

filler metal layers

12 and 13 are formed so as to be located on the outer sides of both sides of the brazing sheet 10A, and the brazing filler metal layer 12 is located on the lower surface (first surface) of FIG. 1A. The brazing filler metal layer 13 is located on the upper surface (second surface) of FIG. 1A. That is, the brazing

filler metal layers

12 and 13 are located on the outer side when viewed from both sides of the core wood 11.

In FIG. 1A, the brazing filler metal layer 12 is coated (claded) on one surface (first surface) of the core material 11. An intermediate sacrificial layer 14 is laminated on the other surface (second surface) of the core material 11, and the brazing filler metal layer 13 is coated on the outside of the intermediate sacrificial layer 14. Therefore, the intermediate sacrificial layer 14 is positioned so as to intervene between the core material 11 and the brazing material layer 13. That is, the brazing filler metal layer 13 is laminated on the intermediate sacrificial layer 14 laminated on the other surface (second surface) of the core material 11. The core material 11, the brazing material constituting the brazing

filler metal layers

12 and 13, and the sacrificial anode material constituting the intermediate sacrificial layer 14 are all aluminum alloys.

In the brazing sheet 10A, the intermediate sacrificial layer 14 and the brazing material layer 13 are laminated on the side of the core material 11 that becomes the joint surface 11a. By joining the joining surfaces 11a to each other, a joining portion 21 in which the brazing sheets 10A are joined to each other is formed. The structure in which the brazing sheets 10A are joined to each other on the joining surface 11a is the joining structure 20 of the brazing sheet 10A according to the embodiment of the present disclosure. The brazing sheet 10A has a non-joining adjacent surface 11b adjacent to the joining surface 11a. When the brazing sheets 10A are joined together to form the joining structure 20, the angle θ1 formed by the respective non-joining adjacent surfaces 11b is an acute angle. That is, the joining structure 20 is configured by using the brazing sheet 10A, and the joining surface 11a constituting the joining portion 21 by joining the brazing sheets 10A to each other and the non-joining adjacent surface 11b adjacent to the joining surface 11a. Has.

Specifically, for example, as shown in FIG. 1B, the joining structure 20 of the brazing sheet 10A according to the embodiment of the present disclosure is configured by joining the joining surfaces 11a of the brazing sheet 10A to each other. Further, in the joining structure 20 of the brazing sheet 10A according to the embodiment of the present disclosure, the angle θ1 formed between the non-joining adjacent surfaces 11b adjacent to the joining surface 11a is not particularly limited, but a sharp angle, that is, 90 is a preferable example. Less than ° (θ1 <90 °) can be mentioned. The angle θ1 formed by each non-joint adjacent surface 11b constituting the joint structure 20 is referred to as “adjacent surface formation angle θ1” for convenience of explanation, and is shown by a dotted line in FIG. 1B.

The preferable range of the adjacent surface forming angle θ1 is not particularly limited as long as it is an acute angle, that is, less than a right angle (less than 90 °) as described above. The adjacent surface formation angle θ1 may be, for example, in the range of 40 ° to 80 ° depending on various conditions such as the type of heat exchanger and the structure of the heat exchanger in which the brazing sheet 10A is used (40 ° ≦ θ1 ≦). 80 °), and may be in the range of 50 ° to 70 ° (50 ° ≦ θ1 ≦ 70 °). Alternatively, the adjacent surface formation angle θ1 may be, for example, only the lower limit of 15 ° or more (15 ° ≦ θ1) or 20 ° or more (20 ° ≦ θ1).

In the joining structure 20, when the brazing sheets 10A are joined together to form the joining portion 21, a fillet 22 is formed between the non-joining adjacent surfaces 11b as shown in FIG. 1B. The heat exchanger includes a member or structure on which such a fillet 22 is formed, and in such a member or structure, the non-joined adjacent surfaces 11b often form an acute angle. .. In the present embodiment, the fillet 22 is defined as a solidified wax material flowing out from the joint surface 11a at the time of joining. That is, in the joining structure 20, when the joining surfaces 11a are joined to each other, the brazing material flows out from the joining surface 11a and solidifies at a portion between the respective non-joining adjacent surfaces 11b and adjacent to the joining surface 11a. The fillet 22 is formed.

The heat exchanger using the brazing sheet 10A according to the embodiment of the present disclosure effectively suppresses or avoids the preferential corrosion of the fillet 22. If the adjacent surface formation angle θ1 becomes too large, for example, when it approaches 180 °, that is, horizontal, the fillet 22 is structurally difficult to form. Further, if the adjacent surface forming angle θ1 is too small, the fillet 22 is difficult to be formed because the non-joined adjacent surfaces 11b approach parallel to each other, although it depends on the structure of the heat exchanger and the like. Therefore, as a preferable example of the adjacent surface forming angle θ1, an angle within the range of the above-mentioned upper limit value and the lower limit value, or an angle equal to or larger than the lower limit value can be mentioned.

In the brazing sheet 10A, a non-joining adjacent surface 11b is set adjacent to the joining surface 11a. As described above, the non-joined adjacent surfaces 11b have an acute angle (adjacent surface forming angle θ1) formed with each other when the brazing sheets 10A are joined to each other. Therefore, for example, as shown in FIG. 1B, the non-joining adjacent surface 11b may be inclined with respect to the joining surface 11a.

In the example shown in FIG. 1B, the non-joining adjacent surface 11b is inclined so as to form an angle θ2 with respect to the joining surface 11a. Therefore, if the joint surfaces 11a are joined to form the joint portion 21, the non-joint adjacent surfaces 11b adjacent to the respective joint surfaces 11a form an acute-angled adjacent surface formation angle θ1. The inclination angle θ2 of the non-joint adjacent surface 11b with respect to the joint surface 11a is referred to as “adjacent surface inclination angle θ2” for convenience of explanation, and is shown by a dotted line in FIG. 1B together with an extension line of the joint surface 11a.

The specific angle of the adjacent surface inclination angle θ2 is not particularly limited. However, for example, as shown in FIG. 1B, if the shapes of the brazing sheets 10A joined to each other are line-symmetrical with respect to the joining surface 11a, the adjacent surface forming angle θ1 is the adjacent surface inclination angle θ2. It is doubled (θ1 = θ2 × 2). Therefore, if the adjacent surface forming angle θ1 is an acute angle, the adjacent surface inclination angle θ2 may be less than 45 °. However, the shape of the brazing sheet 10A does not have to be line-symmetrical, and depending on various conditions such as the type of heat exchanger and the structure of the heat exchanger, the brazing sheets 10A having various shapes are joined together at the joint surface 11a. It will be. Further, the adjacent surface forming angle θ1 does not necessarily have to be an acute angle. Therefore, the adjacent surface inclination angle θ2 is not limited to less than 45 °.

For example, there may be a joining structure 20 in which the brazing sheet 10A having a different shape is joined to the joining surface 11a of the substantially flat brazing sheet 10A in an inclined state. In this case, the non-joining adjacent surfaces 11b of the substantially flat brazing sheet 10A are not inclined with respect to the joining surface 11a, and are set as different regions on the brazing filler metal layer 13. Therefore, the adjacent surface inclination angle θ2 may be 0 ° (θ2 = 0 °). That is, the non-junction adjacent surface 11b may be a region of a continuous flat surface that is not inclined with respect to the junction surface 11a (see the junction structure of a parallel flow capacitor described later).

In the joint structure 20 of the brazing sheet 10A, corrosion may proceed in the directions indicated by the block arrows C1 and C2 in FIG. 1B. The direction of the block arrow C1 is the corrosion direction traveling from the non-joining adjacent surface 11b (and the non-joining surface not adjacent to the joining surface 11a (the surface opposite to the joining surface 11a, etc.)) toward the core material 11. Further, the direction of the block arrow C2 is the corrosion direction that progresses along the direction of the joint surface 11a at the joint portion 21 including the fillet 22. In the following, the block arrow C1 will be referred to as a corrosion direction C1, and the block arrow C2 will be referred to as a corrosion direction C2.

Of these, the corrosion that progresses in the corrosion direction C1 is suppressed (avoided or prevented) by the sacrificial anode action of the intermediate sacrificial layer 14 located inside (on the core 11 side) when viewed from the brazing filler metal layer 13 constituting the joint surface 11a. To. On the other hand, the corrosion that progresses in the corrosion direction C2 may progress because the potential of the joint portion 21 including the fillet 22 is excessively lowered due to the concentration of zinc in the fillet 22. The brazing sheet 10A effectively corrodes in the corrosion direction C2 by containing copper in the core material 11 within a predetermined range and substantially not containing copper in the brazing material layers 12, 13 and the intermediate sacrificial layer 14. Can be suppressed (avoided or prevented).

The brazing sheet 10A may be configured to include the core material 11, the brazing material layers 12, 13 and the intermediate sacrificial layer 14, and the intermediate sacrificial layer 14 and the brazing material layer 13 are located on the joint surface 11a side of the core material 11. That is, the brazing sheet according to the present disclosure is not limited to the four-layer structure as in the brazing sheet 10A shown in FIG. 1A.

Here, the configurations of the brazing sheets 10B to 10D according to the embodiment of the present disclosure will be described with reference to FIGS. 2A to 2C. 2A to 2C are schematic cross-sectional views showing the configurations of the brazing sheets 10B to 10D according to the embodiment.

The brazing sheet according to the present disclosure may have a laminated structure of five or more layers, for example, the brazing sheets 10B to 10D shown in FIGS. 2A to 2C.

For example, in the brazing sheet 10B shown in FIG. 2A, the brazing material layer 12a is laminated on one surface (first surface) of the core material 11, and the intermediate sacrificial layer 14 is laminated on the other surface (second surface) of the core material 11. The brazing filler metal layer 13 is located on the outside (second surface side) of the intermediate sacrificial layer 14. In this respect, the brazing sheet 10B is similar to the brazing sheet 10A shown in FIG. 1A, but is different from the brazing sheet 10A in that it is further provided with the flux-containing layer 15.

More specifically, in the brazing sheet 10B, the intermediate sacrificial layer 14, the flux-containing layer 15, and the brazing material layer 13 are laminated (coated) on the second surface side of the core material 11. Further, a brazing material layer 12a, a flux-containing layer 15, and a brazing material layer 12b are laminated (coated) on the first surface side of the core material 11. Therefore, the brazing sheet 10B shown in FIG. 2A has a seven-layer laminated structure.

As will be described later, the flux-containing layer 15 may be a layer containing a known brazing flux material, and may be laminated so as to be adjacent to the brazing material layers 12 and 13. In the brazing sheet 10B shown in FIG. 2A, the second surface side has a laminated structure of two layers of the brazing material layer 13 and the flux-containing layer 15 from the outside, and the first surface side has the brazing material layer 12b from the outside. It has a three-layer structure consisting of a flux-containing layer 15 and a brazing filler metal layer 12a. However, the laminated structure of the brazing

filler metal layers

12 and 13 including the flux-containing layer 15 is not limited to this. The laminated structure of the brazing

filler metal layers

12 and 13 including the flux-containing layer 15 may have, for example, a three-layer structure on the second surface side of the brazing sheet 10B or a two-layer structure on the first surface side. Further, the laminated structure of the brazing

filler metal layer

12 and 13 including the flux-containing layer 15 may be, for example, a two-layer or three-layer structure in both the first surface and the second surface, and the brazing

filler metal layer

12, 13 may be formed. And the laminated structure of the flux-containing layer 15 may be four or more layers.

Alternatively, the brazing sheet 10C shown in FIG. 2B is similar to the brazing sheet 10A shown in FIG. 1A in that it does not include the flux-containing layer 15, but includes the core material 11, the brazing material layers 12, 13 and the intermediate sacrificial layer 14. However, the brazing sheet 10C is different from the brazing sheet 10A in that the intermediate sacrificial layer 14 is laminated not only on the second surface side of the core material 11 but also on the first surface side.

More specifically, in the brazing sheet 10C, the intermediate sacrificial layer 14 and the brazing material layer 13 are laminated (covered) on the second surface side of the core material 11, and are also intermediate on the first surface side of the core material 11. The sacrificial layer 14 and the brazing filler metal layer 12 are laminated (coated). That is, in the brazing sheet 10C, the intermediate sacrificial layers 14 are laminated on both surfaces of the core material 11, and the brazing

filler metal layers

12 and 13 are laminated on the intermediate sacrificial layers 14. Therefore, the brazing sheet 10C shown in FIG. 2B has a five-layer laminated structure.

In other words, in the brazing sheet 10A shown in FIG. 1A, since the intermediate sacrificial layer 14 is laminated on the second surface side of the core material 11, it can be said that the second surface is the joint surface 11a. On the other hand, in the brazing sheet 10C shown in FIG. 2B, since the intermediate sacrificial layer 14 is laminated on both sides of the core material 11, it can be said that both the first surface and the second surface are the joint surfaces 11a.

Alternatively, in the brazing sheet 10D shown in FIG. 2C, the brazing material layer 12 is laminated on one surface (first surface) of the core material 11, and the intermediate sacrificial layer 14 is laminated on the other surface (second surface) of the core material 11. , The brazing filler metal layer 13 is laminated on the outside (second surface side) of the intermediate sacrificial layer 14. In this respect, the brazing sheet 10D is similar to the brazing sheet 10A shown in FIG. 1A, but is different from the brazing sheet 10A in that the magnesium-containing layer 16 is further laminated on the outside of the brazing

filler metal layers

12 and 13.

As will be described later, the magnesium-containing layer 16 is a "brazing material layer" in which at least magnesium (Mg) is added to the brazing material (preferably, bismuth (Bi) or the like is added in addition to Mg). By providing such a magnesium-containing layer 16, it is possible to bond the brazing sheets 10D to each other without using flux (so-called flux-free or fluxless). That is, the brazing sheet 10D is configured as a layer independent of the brazing

filler metal layers

12 and 13, and includes a magnesium-containing layer 16 in which at least magnesium (Mg) is added to the brazing filler metal.

Although not shown, the laminated structures of the brazing sheets 10A to 10D shown in FIGS. 1A or 2A to 2C can be appropriately combined, and the stacking order can be changed. For example, the flux-containing layer 15 or the magnesium-containing layer 16 may be located on the first surface or the second surface of the brazing sheet 10C having a five-layer structure shown in FIG. 2B. Alternatively, the brazing sheet 10B shown in FIG. 2A is located inside the brazing material layer 13 or the brazing material layer 12b in which the flux-containing layer 15 is the outermost layer, but the flux-containing layer 15 is located outside. May be good.

Therefore, as shown in the brazing sheets 10A to 10D according to the embodiment of the present disclosure, the brazing

filler metal layers

12 and 13 do not necessarily have to be the outermost layer (outermost surface layer), and the brazing

filler metal layers

12 and 13 are It suffices if it is located on the outside when viewed from both sides of the core material 11. Further, as shown in the brazing sheets 10A to 10D, the intermediate sacrificial layer 14 may be laminated on at least one of both surfaces of the core material 11. Further, as shown in the brazing sheets 10A to 10D, the intermediate sacrificial layer 14 and the brazing filler metal layer 13 (or the brazing filler metal layer 12) may be in direct contact with each other, and another layer such as the flux-containing layer 15 may be in direct contact between them. May intervene.

Further, the flux-containing layer 15 or the magnesium-containing layer 16 may be located outside the intermediate sacrificial layer 14. As a typical example, as shown in FIG. 2A or FIG. 2C, the flux-containing layer 15 or the magnesium-containing layer 16 may be located adjacent to the brazing

filler metal layers

12 and 13, but the flux-containing layer 12 is not necessarily located. , 13 does not have to be in direct contact.

The joining structure 20 of the brazing sheet 10A configured by using the brazing sheet 10A is an example of the joining structure of the brazing sheet according to the present disclosure. The joining structure 20 of the brazing sheets 10B to 10D configured by using the brazing sheets 10B to 10D, which is mentioned as another example of the brazing sheet of the present disclosure, is also an example of the joining structure of the brazing sheet according to the present disclosure.

[Blazing sheet material]
Next, the material of the brazing sheet 10A will be described.

In the present embodiment, the brazing sheet 10A is made of an aluminum alloy as described above, and the core material 11, the brazing material, and the sacrificial anode material are all aluminum alloys. Specifically, the core material 11 may be a known aluminum alloy that can realize the required physical properties according to various conditions such as the type or structure of the heat exchanger, but in the present embodiment, copper (Cu) is used. ) Is added (contained) in the range of 0.3 to 1.2% by mass.

Examples of the aluminum alloy used as the core material 11 include the following as typical examples in the field of heat exchangers. That is, 3000 series (aluminum-manganese (Al-Mn) alloy), 5000 series (aluminum-magnesium (Al-Mg) alloy), or 6000 series (aluminum-magnesium-silicon (Al-Mg-Si) alloy). ) Etc. can be mentioned. However, the core material 11 is not limited to these aluminum alloys. In the present embodiment, the core material 11 may be obtained by adding Cu to these aluminum alloys or other aluminum alloys by a known method so as to be within the above range.

If the aluminum alloy before adding Cu is used as the "base material" for convenience, Cu may be contained in advance as an unavoidable impurity in the base material. Even if Cu is contained as an unavoidable impurity, its concentration may be, for example, 0.2% by mass or less. However, an aluminum alloy containing Cu at a concentration exceeding 1.2% by mass in advance, such as a 2000 series alloy, cannot be used as a base material for the core material 11.

In the brazing sheet 10A according to the present embodiment, if the Cu content (concentration) in the core material 11 is less than 0.3% by mass, Cu is sufficiently concentrated from the core material 11 to the fillet 22 as described later. May not spread. Further, when the Cu content in the core material 11 exceeds 1.2% by mass, the intergranular corrosion sensitivity of the core material 11 becomes high and the progress of corrosion is effective, although it depends on the strength of the sacrificial anode action of the sacrificial anode material. It may become uncontrollable.

The Cu content in the core material 11 may be in the range of 0.3 to 1.2% by mass, but a preferable example may be in the range of 0.3 to 0.7% by mass. That is, the upper limit of the Cu content may be 1.2% by mass or less, but may be 0.7% by mass or less depending on various conditions. When the Cu content is 0.7% by mass or less, the possibility that the intergranular corrosion sensitivity of the core material 11 becomes high can be effectively suppressed even when the sacrificial anode action of the sacrificial anode material is relatively weak. Can be done.

In the present embodiment, 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 (concentration) 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 of Si in the brazing filler metal may be in the range of 2.5 to 13% by mass, and may be in the range of 3.5 to 12% by mass. 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 10A itself.

The Al—Si alloy as the brazing material may contain an element other than Si as long as it does not affect the function as the brazing material. Further, the Al—Si alloy as the brazing filler metal may contain various elements as unavoidable impurities. However, Cu is not substantially contained in the Al—Si alloy as the brazing material. Substantially free of Cu means that Cu is not contained at a concentration exceeding the unavoidable impurities. The upper limit of the concentration allowed as an unavoidable impurity varies depending on various conditions, but generally, less than 0.1% by mass in the entire Al—Si alloy can be mentioned.

The aluminum alloy used as the sacrificial anode material contains zinc (Zn) in the range of 0.5 to 6.0% by mass in order to exert the sacrificial anode action. That is, an Al—Zn-based alloy can be mentioned as a typical example of the intermediate sacrificial layer 14. If the Zn content (concentration) in the sacrificial anode material is less than 0.5% by mass, a good sacrificial anode action cannot be exhibited. On the other hand, if the Zn content exceeds 6.0% by mass, the sacrificial anodic action proceeds too early and the intermediate sacrificial layer 14 disappears from the brazing sheet 10A, which may reduce the corrosion resistance of the brazing sheet 10A. be.

The Al—Zn-based alloy as the sacrificial anode material may contain an element other than Zn as long as it does not affect the sacrificial anode action. Further, the Al—Zn-based alloy as the sacrificial anode material may contain various elements as unavoidable impurities. However, even in the Al—Zn-based alloy as the sacrificial anode material, Cu is substantially not contained. The fact that Cu is not substantially contained means that Cu is not contained at a concentration exceeding the unavoidable impurities, as in the case of the Al—Si alloy as a brazing material, and generally, the entire Al—Zn alloy is contained. The concentration may be less than 0.1% by mass. Alternatively, the upper limit of the concentration of unavoidable impurities may be based on the alloy composition specified in a known standard such as JIS.

The type of aluminum alloy specifically used as the brazing material is not particularly limited, but a 4000 series (aluminum-silicon (Al-Si) series alloy) can be typically used. The type of aluminum alloy used as the sacrificial anode material is not particularly limited, but 1000 series (industrial pure aluminum) or 3000 series (aluminum-manganese (Al-Mn) series alloy) can be typically used. can. As the sacrificial anode material, a material to which Zn is added by a known method so that the content is in the range of 0.5 to 6.0% by mass with respect to the 1000 series or 3000 series aluminum alloy may be used. ..

As the flux material for brazing, a flux material known in the field of brazing of aluminum or an alloy thereof (a material for removing an oxide film of an aluminum-based material) can be preferably used. Examples of the main component of the flux material include fluorides of metal elements of Group 1 or Group 2 of the periodic table such as CsF, CaF ₂ , NaF, LiF, and KF, but are not particularly limited. The flux-containing layer 15 may be configured as a layer containing such a brazing flux material, and in the present embodiment, a layer in which aluminum or an alloy powder thereof and a brazing flux material are mixed is mentioned. be able to.

Further, a known method can be preferably used for forming the flux-containing layer 15 containing such a brazing flux material, and the method is not particularly limited. Typical examples are Reference 1: TRILLIUM (R) ACTIVE BRAZING, Granges AB, <https://www.granges.com/globalassets/09.-kampanjer/01.-trillium/05. -learn-more / granges_trillium_brochure_180124.pdf>, (Searched on November 5, 2020) can be mentioned.

As for the magnesium-containing layer 16 which is a flux-free or fluxless brazing material, a material known in the field of brazing of aluminum or an alloy thereof can be preferably used. Specifically, for example, the brazing material containing 0.1 to 6% by mass of magnesium described in Reference 2: Patent No. 3701847 (Japanese Unexamined Patent Publication No. 2002-18570), or magnesium 0.1. Examples thereof include brazing materials containing up to 6% by mass and 0.01 to 1% by mass of bismuth.

The content of Reference 1 that describes a typical configuration example of the flux material for brazing and the flux-containing layer 15 is a part of the description of the present specification by reference in the present specification. Further, the contents of Reference 2 which describes a typical configuration example of the flux-free magnesium-containing brazing filler metal and the magnesium-containing layer 16 are referred to herein as a part of the description thereof.

[Diffusion of copper due to joining of brazing sheets]
Next, the diffusion of Cu and Zn in the fillet 22 formed by joining the brazing sheets 10A to 10D according to the embodiment will be described.

In the present embodiment, a plurality of brazing sheets 10A to 10D are superposed on the joint surfaces 11a, and the brazing material and the sacrificial anode material are melted and brazed at a high temperature (for example, 580 ° C. or higher). A plurality of brazing sheets 10A to 10D are joined to each other. For example, as shown in FIG. 1B, in the joint structure 20 of the brazing sheet 10A, the brazing filler metal layer 13 constituting the joint surface 11a is located at a portion adjacent to the joint surface 11a (joint portion 21) between the non-joint adjacent surfaces 11b. The sacrificial anode material flowing out of the material solidifies to form a fillet 22.

When the brazing sheets 10A (or brazing sheets 10B to 10D) are joined to each other, Zn is diffused from the intermediate sacrificial layer 14 located under the brazing filler metal layer 13 constituting the joining surface 11a to the brazing filler metal layer 13. Further, Cu diffuses from the core material 11 to the brazing material layer 13 via the intermediate sacrificial layer 14. Therefore, the fillet 22 contains Zn derived from the intermediate sacrificial layer 14 and Cu derived from the core material 11.

The Cu concentration in the fillet 22 (joint portion 21) is higher than that of the core material 11 and the brazing material layer 13 (and the intermediate sacrificial layer 14), so that Cu is substantially localized in the fillet 22. Shows a high concentration distribution. From the results of Examples and Comparative Examples described later, when the Cu concentration in the core material 11 is within a predetermined range and the brazing material layer 13 and the intermediate sacrificial layer 14 do not substantially contain Cu, the following is true. Shows behavior. That is, when joining at a high temperature, the Cu of the core material 11 diffuses into the liquid phase portions of the joining portion 21 and the fillet 22.

Since the liquid phase portion can contain a larger amount of Cu than the solid phase portion, when the liquid phase portion solidifies, Cu is likely to segregate at the fillet 22 at the end, which is the final solidification site. As a result, the fillet 22 has a higher potential than the surroundings, and penetration of the joint portion 21 due to preferential corrosion can be prevented. Here, the brazing sheet 10A includes an intermediate sacrificial layer 14, and the intermediate sacrificial layer 14 does not become liquid phase at the time of joining at a high temperature. Therefore, Zn can be present at a suitable concentration around the fillet 22. This makes it possible to withstand corrosion around the fillet 22 even better.

In the bonding structure 20 of the brazing sheet 10A according to the present embodiment, the Cu concentration and the Zn concentration in the fillet 22 are not particularly limited, but the Cu concentration may be 2.0% by mass or less, and the Zn concentration is less than the Cu concentration. All you need is. When the Cu concentration in the fillet 22 exceeds 2.0% by mass, aging precipitation of the intermediate compound phase containing Cu occurs in a short period of time as compared with the life of the heat exchanger. Since such a precipitate functions as a cathode in a corrosion reaction, the corrosion current density in the fillet 22 increases, and the corrosion resistance around the fillet 22 may be significantly deteriorated.

As a result of experimental verification by the present inventors, a proportional relationship can be seen between the Cu concentration (initial Cu concentration) of the core material 11 and the Cu concentration of the bonding portion 21 (fillet 22) in the bonding structure 20. .. Therefore, if the Cu concentration of the core material 11 is 1.2% by mass or less, the Cu concentration of the fillet 22 is considered to be 2.0% by mass or less. On the other hand, the Cu concentration of the core material 11 may be 0.3% by mass or more, but at this time, it is considered that the Cu concentration of the fillet 22 in the bonded structure 20 is 0.5% by mass or more. Therefore, the lower limit of the Cu concentration of the fillet 22 in the bonded structure 20 may be the Zn concentration or more, but preferably 0.5% by mass or more.

As described above, even in the conventional brazing sheet disclosed in Patent Document 2, the core material contains Cu in the range of 0.05 to 1.2 mass%, but in this brazing sheet, wax is used. The material also contains Cu in the range of 0.1 to 0.6 mass%. When the brazing material contains Cu in this way, the periphery of the fillet or the layer of the sacrificial anode material becomes noble and the potential difference from the core material becomes smaller, so that the sacrificial anticorrosion performance (priority corrosion action) deteriorates. Further, since the conventional brazing sheet disclosed in Patent Document 2 does not have an intermediate sacrificial layer, it cannot be expected that Zn is present at a suitable concentration due to the intermediate sacrificial layer around Cu segregated in the fillet.

In the present embodiment, when the brazing sheet 10A has, for example, a bent portion (see FIG. 1B or the like), the dislocation density increases in the portion, so that the diffusion of Cu is promoted more than the surroundings (diffusion). The coefficient increases). In the present embodiment, since the brazing sheets 10A to 10D have the intermediate sacrificial layer 14, Cu diffuses from the core material 11 to the liquid phase portion through the intermediate sacrificial layer 14 which is a solid phase at the time of joining at a high temperature. If the brazing sheets 10A to 10D have a processed portion such as a bending process, it is considered that the diffusion amount of Cu in the processed portion is significantly affected as compared with the case where the core material 11 and the liquid phase portion are in direct contact with each other (described later). Comparison between Example 1 and Reference Example).

In addition, Cu remains in the core material 11 at a portion other than the joint portion 21. When the core material 11 contains Cu within a predetermined range, the core material 11 is noble, so that the potential difference from the intermediate sacrificial layer 14 can be increased. Thereby, the sacrificial anode action by the intermediate sacrificial layer 14 can be better exhibited. Further, by adding Cu to the core material 11, the strength of the core material 11 can be improved. Therefore, the inclusion of Cu in the core material 11 is advantageous in reducing the thickness of the brazing sheet 10A and improving the withstand voltage of the heat exchanger.

As a method of suppressing or avoiding preferential corrosion of the joint without containing Cu, the joint is shielded from the surroundings by painting or partially removing the brazing filler metal layer and the intermediate sacrificial layer. Can be considered. However, such a method requires an additional step of painting or partial removal of each layer, which increases the manufacturing cost, complicates or complicates the entire manufacturing process, and peels off the coating film in the case of painting. And problems such as scattering occur. On the other hand, in the present embodiment, since the Cu concentration of the fillet 22 can be optimized only by adding Cu to the core material 11 and joining the core material 11, no additional step is required and easy production is possible.

Here, the specific thickness of the brazing sheets 10A to 10D according to the present embodiment is not particularly limited, and the thickness of each layer constituting the brazing sheets 10A to 10D is also not particularly limited. However, from the viewpoint of satisfactorily suppressing or preventing the preferential corrosion of the fillet 22, it is preferable to set the upper limit of the thickness of the intermediate sacrificial layer 14.

In the brazing sheets 10A to 10D according to the present embodiment, the core material 11 contains Cu in the range of 0.3 to 1.2% by mass, and the brazing material and the sacrificial anode material contain Cu. , The intermediate sacrificial layer 14 is provided. As a result, as is clear from the results of Examples (Comparative Examples 1, 2, Examples 1, 2 and Reference Examples) described later, the brazing sheets 10A to 10D according to the present embodiment have preferential corrosion of the fillet 22. Can be satisfactorily suppressed or prevented (Examples 1 and 2 described later).

Here, even a brazing sheet that does not necessarily have the intermediate sacrificial layer 14 may be able to suppress or prevent preferential corrosion of the fillet 22. For example, in the brazing sheet 10E of the reference example described later, the brazing material layer 13 also serves as a sacrificial anode material, so that the preferential corrosion of the fillet 22 can be suppressed or prevented in the joint structure of the brazing sheet 10E (reference example described later). ). However, by having the intermediate sacrificial layer 14 that does not become liquid phase at the time of joining, when Cu segregates to a high concentration in the fillet 22, Zn can be present in a suitable concentration around the intermediate sacrificial layer 14. As a result, the brazing sheets 10A to 10D according to the present embodiment provided with the intermediate sacrificial layer 14 can satisfactorily suppress or prevent the preferential corrosion of the fillet 22.

Since the brazing sheets 10A to 10D are provided with the intermediate sacrificial layer 14, the brazing material layer 13 (or the brazing material layer 12), which is the surface layer of the brazing sheets 10A to 10D, suppresses the volatilization of Zn of the intermediate sacrificial layer 14 in the furnace. Further, although the brazing filler metal layer 13 (and the brazing filler metal layer 12) flows in the furnace, the intermediate sacrificial layer 14 itself located inside the brazing filler metal layer 13 does not flow. Therefore, the intermediate sacrificial layer 14 can stably function as a sacrificial anode material.

However, if the thickness of the intermediate sacrificial layer 14 is too large (too thick), it becomes difficult for Cu diffused from the core material 11 to reach the brazing filler metal layer 13 (or the brazing filler metal layer 12). In this case, it becomes difficult for Cu to diffuse into the liquid phase portion of the joint portion 21 and the fillet 22, and it becomes difficult to realize the preferential corrosion prevention action of the fillet 22 (Comparative Example 1 described later). On the other hand, if the thickness of the intermediate sacrificial layer 14 is too small (too thin), the function as the sacrificial anode material may not be sufficiently realized.

Further, if the Cu concentration in the core material 11 is too low (too thin), Cu cannot be satisfactorily diffused to the brazing material layer 13 via the intermediate sacrificial layer 14, and there is a possibility that priority corrosion prevention of the fillet 22 cannot be realized (). Comparative example 2) described later. On the other hand, if the Cu concentration in the core material 11 is too high (too high), the presence of Cu ions may reduce the corrosion resistance.

Therefore, in the brazing sheets 10A to 10D according to the present embodiment, the Cu concentration in the core material 11 is set within the range of 0.3 to 1.2% by mass as described above, and the thickness of the intermediate sacrificial layer 14 is increased. The upper limit is 50 μm or less. As a result, the brazing sheets 10A to 10D according to the present embodiment can effectively suppress or prevent the possibility that corrosion progresses from the fillet 22 to the joint portion 21 and the joint strength of the joint portion 21 is lowered. can.

It is assumed that the upper limit of the thickness of the intermediate sacrificial layer 14 is set based on a mathematical model. Specifically, for example, the diffusion of Cu from the core material 11 to the brazing material layer 13 is calculated by the solute concentration formula based on Fick's second law, and the thickness of the intermediate sacrificial layer 14 is set based on the calculation result. Can be considered. However, as a result of diligent studies by the present inventors, it has become clear that it is difficult to calculate the thickness of the intermediate sacrificial layer 14 with a simple mathematical model.

When the brazing sheets 10A to 10D are joined, the brazing filler metal layer 13 melts and liquefies. Cu diffused from the core material 11 has a substantially constant concentration in the brazing filler metal of the liquid phase, but solidifies when the brazing filler metal solidifies. Cu is likely to segregate on the surface of the phase brazing material (fillet 22 or the like). In such situations, predictions based on simple mathematical models are difficult. Therefore, in the present embodiment, the diffusion coefficient D in the solute concentration formula based on Fick's second law is adjusted based on the specific laminated structure and joining conditions of the brazing sheets 10A to 10D to adjust the diffusion coefficient D of the intermediate sacrificial layer 14. The upper limit of the thickness is set. Further, in the present embodiment, when Cu is diffused into the brazing filler metal layer 13, the upper limit of the thickness of the intermediate sacrificial layer 14 is set by paying attention to the Cu concentration at the boundary between the intermediate sacrificial layer 14 and the brazing filler metal layer 13. It is set. Then, in the present embodiment, the Cu concentration at this boundary is used in the solute concentration formula, and the simulation is carried out based on the experimental results described later, so that the upper limit of the thickness of the intermediate sacrificial layer 14 is set to 50 μm. Has been done.

The lower limit of the thickness of the intermediate sacrificial layer 14 is not particularly limited, and may be thick enough to function as a sacrificial anode material between the brazing material layer 13 and the core material 11. As a lower limit value at which the sacrificial anode material using Zn can exhibit good corrosion resistance, for example, 0.05 μm can be mentioned. However, depending on the specific laminated structure of the brazing sheets 10A to 10D or the joining conditions of the brazing sheets 10A to 10D, the lower limit value at which the sacrificial anode material using Zn can exhibit good corrosion resistance is 0.05 μm or less. May be good.

In the brazing sheets 10A to 10D according to the present embodiment, the clad ratio of the brazing material and the sacrificial anode material is not particularly limited, and can be mentioned within a general range. As a general clad ratio, for example, it may be in the range of 2 to 30% by mass, and may be in the range of 3 to 20% by mass. Further, the thicknesses of the brazing sheets 10A to 10D and the thicknesses of the core material 11 and the brazing material layers 12 and 13 (excluding the thickness of the intermediate sacrificial layer 14) are not particularly limited. These thicknesses can be appropriately set according to the configuration of the brazing sheet 10A, the type or part of the heat exchanger to be manufactured, and the like.

Further, the method for evaluating the potential of the joint portion 21 including the fillet 22, the brazing filler metal layer 13, the intermediate sacrificial layer 14, etc. is not particularly limited, and a known method can be preferably used. A typical method is to connect a sample for potential measurement, a counter electrode, and a reference electrode to a potentiostat / galvanostat and immerse the sample in an electrolytic solution to measure the potential difference between the sample and the reference electrode. The sample for potential measurement is, for example, a brazing sheet 10A, a core material 11, a brazing material layer 13, an intermediate sacrificial layer 14, a fillet 22 or a joint portion 21, or an alloy having a composition simulating these. The reference electrode is, for example, a silver / silver chloride (Ag / AgCl) electrode. The electrolytic solution is, for example, a 5% by weight sodium chloride (NaCl) solution.

The manufacturing method of the brazing sheet 10A according to the present embodiment is not particularly limited, and a known manufacturing method can be preferably used. Specifically, for example, an aluminum alloy containing Cu in the range of 0.3 to 1.2% by mass is formed into a plate shape by a known method to obtain a core material 11. A sacrificial anode material of an aluminum alloy containing Zn is clad on one surface of the core material 11 by a known method to form an intermediate sacrificial layer 14. Then, the brazing material of the aluminum alloy containing Si is clad on the upper surface of the intermediate sacrificial layer 14 by a known method, and the brazing material of the aluminum alloy is clad on the other surface of the core material 11 by a known method. Then, the brazing filler metal layer 13 and the brazing filler metal layer 12 may be formed. In the present embodiment, the conditions for manufacturing the brazing sheet 10A can be appropriately set according to the configuration of the brazing sheet 10A, the type or part of the heat exchanger to be manufactured, and the like.

[Blazing sheet joint structure and heat exchanger]
Next, the heat exchanger according to the embodiment of the present disclosure, which has the bonding structure 20 of the brazing sheets 10A to 10D, will be described with reference to FIGS. 3A to 5B.

FIG. 3A is a schematic cross-sectional view showing an example of a header of a plate fin laminated heat exchanger configured by using the brazing sheet 10A, and FIG. 3B is a bonding structure of the brazing sheet 10A included in the header shown in FIG. 3A. 20 is an enlarged schematic partial cross-sectional view of 20. Further, FIG. 4A is a schematic partial cross-sectional view showing an example of a parallel flow capacitor (PFC) 40 configured by using the brazing sheet 10A. FIG. 4B is an enlarged schematic partial cross-sectional view of the joining structure 20 of the brazing sheet 10A included in the PFC 40 shown in FIG. 4A. Further, FIG. 5A is a schematic cross-sectional view showing an example of a header of a plate fin laminated heat exchanger (laminated heat exchanger for an Air To Water heat pump) configured by using the brazing sheet 10C. FIG. 5B is an enlarged schematic partial cross-sectional view of the joining structure 20 of the brazing sheet 10C included in the header shown in FIG. 5A.

The brazing sheet 10A according to the present embodiment can be particularly preferably used for manufacturing a heat exchanger as described above. As described above, the bonding structure 20 formed when the brazing sheet 10A according to the present embodiment is applied to the heat exchanger is a structure as exemplified in FIG. 1B. As an example of the heat exchanger having the bonding structure 20 of the brazing sheet 10A according to the present embodiment, more specifically, a plate fin laminated heat exchanger having a structure as shown in FIGS. 3A and 3B can be mentioned. Be done. Further, as another example, a parallel flow capacitor (PFC) having a structure as shown in FIGS. 4A and 4B, or a laminated heat exchanger for an AirToWater heat pump having a structure as shown in FIGS. 5A and 5B. And so on.

First, the application to the plate fin laminated heat exchanger will be explained. 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 cause these first fluids. It exchanges heat with the fluid and the second fluid. The plate fin included in this plate fin laminated 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 communicating with each first fluid flow path in this flow path region. It comprises a header area having a flow path.

In the plate fin laminated heat exchanger, end plates having substantially the same shape as the plate fin in a plan view are provided on both sides of the plate fin laminated body in the laminating direction. Then, these pair of end plates and a plurality of plate fins interposed between them are joined and integrated by brazing in a laminated state. FIG. 3A shows the schematic structure of the header portion of the plate fin laminated body 30 of this plate fin laminated heat exchanger as a partial cross section, and a plurality of plate fins 32 with respect to the end plate 31 located at the uppermost part in the drawing. Are laminated.

The end plate 31 and the plate fin 32 are each provided with an opening, 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. 3A, 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 figure, 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 so as to intersect the space formed between the plate fins 32 in 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.

FIG. 3B is a partially enlarged view of the plate fin laminate 30 shown in FIG. 3A, and schematically shows an example of the joining structure 20 of the brazing sheet 10A according to the present embodiment. In the example shown in FIGS. 3A and 3B, the plate fin 32 is the brazing sheet 10A (see FIG. 1A) according to the present embodiment. Further, the joint structure 20 according to the present embodiment corresponds to the joint portion 21 located on the header opening 33 side. That is, the joining structure 20 according to the present embodiment has a joining surface 11a constituting a joining portion 21 located on the header opening 33 side and a non-joining adjacent surface 11b, and when the joining surfaces 11a are joined to each other. In addition, it is a structure in which the fillet 22 is formed. In FIG. 3B, for the plate fin 32 which is the brazing sheet 10A, the brazing material layer 13 on the joint surface 11a side (second surface side) is highlighted by hatching, and the fillet 22 is also highlighted by hatching. There is.

At the joint portion 21 on the header opening 33 side, the joint surfaces 11a of the plate fins 32 are joined to each other, and a fillet 22 is formed between the non-joint adjacent surfaces 11b adjacent to the joint surface 11a. In the present embodiment, the core material 11 of the plate fin 32 contains Cu in the range of 0.3 to 1.2% by mass, and the brazing material layers 12 and 13 and the intermediate sacrificial layer 14 of the plate fin 32 are both Cu. Is not substantially contained. Therefore, the fillet 22 contains Cu having a concentration exceeding 2.0% by mass or less of the core material 11, the brazing material layers 12, 13 and the intermediate sacrificial layer 14. As a result, the preferential corrosion of the joint portion 21 is satisfactorily suppressed (avoided or prevented), so that the brazing sheet 10A has the joint structure 20 of the brazing sheet 10A, and the plate fin laminated type heat exchange according to the embodiment of the present disclosure. The corrosion resistance of the vessel can be improved.

Specific configuration examples of such a plate fin laminated heat exchanger are, for example, JP-A-2017-180856, JP-A-2018-066531, JP-A-2018-066532, 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, and the like. The contents of these publications are incorporated herein by reference.

In the joint structure 20 shown in FIG. 3B, the plate fin 32, which is the brazing sheet 10A, has a structure having a two-step bent portion. That is, the non-joining adjacent surface 11b is inclined so as to form an acute-angled adjacent surface inclination angle θ2 with respect to the joint surface 11a on the right side in the drawing, and further, on the left side of the non-joining adjacent surface 11b, the joint surface 11a is formed. There is a non-joining surface parallel to it. However, the specific shape of the brazing sheet 10A is not limited to the shape having such a two-step bent portion, and the brazing sheet 10A may have a flat shape having no bent portion. Further, the brazing sheet 10A may have a shape having a one-step bent portion as schematically shown in FIG. 1B, a shape having three or more steps of bent portions, a curved portion and the like. It may be a shape having another three-dimensional structure. The specific shape of the brazing sheet 10A is appropriately set depending on various conditions such as the type and structure of the heat exchanger.

Further, the specific configuration of the plate fin 32 shown in FIGS. 3A and 3B is not limited to the brazing sheet 10A shown in FIG. 1A, and may be any brazing sheet within the scope of the present disclosure. For example, the plate fin 32 may be any of the brazing sheets 10B to 10D shown in FIGS. 2A to 2C, or is a brazing sheet obtained by appropriately combining or changing the laminated structure of these brazing sheets 10A to 10D. You may.

Next, the application to the parallel flow capacitor (PFC) will be described. A parallel flow condenser (PFC) is a heat exchanger widely used for car air conditioners (air conditioners for automobiles). Multiple flat tubes are arranged between a pair of header tubes, and heat is dissipated between these flat tubes. Corrugated fins are arranged. These header tubes, flat tubes, corrugated fins, etc. are joined by brazing. FIG. 4A shows the schematic structure of the connecting portion between the header tube 41 and the flat tube 42 in the PFC 40 as a partial cross section. Corrugated fins 43 are provided between the flat tubes 42, and these are also joined by brazing. However, the joining structure 20 according to the present embodiment is flat with the header tube 41 as shown in an enlarged view in FIG. 4B. It corresponds to the connecting portion with the pipe 42. That is, the joining structure 20 according to the present embodiment has a joining surface 11a constituting the joining portion 21 and a non-joining adjacent surface 11b, and a fillet 22 is formed when the joining surfaces 11a are joined to each other. It is a structure.

In the example shown in FIG. 4B, the header pipe 41 and the flat pipe 42 are both the brazing sheet 10A, and for the header pipe 41 and the flat pipe 42, the brazing material layer 13 on the joint surface 11a side (second surface side) is hatched. It is highlighted in. The fillet 22 is also highlighted by hatching. Since the brazing filler metal layer 13 of the flat pipe 42 is flat, the joining surface 11a of the flat pipe 42 and the non-joining adjacent surface 11b are set as different regions on a continuous single surface (the surface or the second surface of the brazing filler metal layer 13). Will be done. Therefore, the flat tube 42 has a flat shape such that the brazing sheet 10A does not have a bent portion.

The header pipe 41 has an opening for penetrating and inserting the flat pipe 42, and the joint surface 11a and the non-joint adjacent surface 11b are provided in this opening. In FIG. 4B, the joint surface 11a of the header tube 41 is shown as a surface parallel to the joint surface 11a (outer surface) of the flat tube 42, but is not limited to this, and is parallel to the outer surface of the flat tube 42. It may be a surface that does not become. The opening of the header tube 41 has a shape having a one-step bent portion as the brazing sheet 10A.

In the joining structure 20 shown in FIG. 4B, a fillet 22 is formed between the non-joining adjacent surface 11b adjacent to the joining surface 11a of the header pipe 41 and the non-joining adjacent surface 11b adjacent to the joining surface 11a of the flat pipe 42. Has been done. In the present embodiment, the core material 11 of the header tube 41 and the flat tube 42 contains Cu in the range of 0.3 to 1.2% by mass, and the brazing material layers 12 and 13 of the header tube 41 and the flat tube 42 and None of the intermediate sacrificial layers 14 substantially contains Cu. Therefore, the fillet 22 contains Cu having a concentration exceeding 2.0% by mass or less of the core material 11, the brazing material layers 12, 13 and the intermediate sacrificial layer 14. As a result, the preferential corrosion of the joint portion 21 is satisfactorily suppressed (avoided or prevented), so that the brazing sheet 10A improves the corrosion resistance life of the PFC 40 according to the embodiment of the present disclosure, which has the joining structure 20 of the brazing sheet 10A. can do.

Further, the specific configuration of the header tube 41 and the flat tube 42 shown in FIGS. 4A and 4B is not limited to the brazing sheet 10A shown in FIG. 1A, and may be any brazing sheet within the scope of the present disclosure. For example, the header tube 41 or the flat tube 42 may be any of the brazing sheets 10B to 10D shown in FIGS. 2A to 2C, and the laminated structure of these brazing sheets 10A to 10D may be appropriately combined or changed. It may be a brazing sheet.

The method for manufacturing the bonded structure 20 of the brazing sheets 10A to 10D is not particularly limited, and a known brazing method or the like can be preferably used. For example, a method of applying a known flux to the joint surface 11a of the brazing sheets 10A to 10D and then heating at a temperature of, for example, about 600 ° C. in a nitrogen atmosphere furnace can be mentioned. In particular, in the bonding structure 20 according to the present embodiment, the Cu content in the fillet 22 (and the bonding portion 21) is not substantially affected by the detailed bonding conditions.

Next, the application to the plate fin laminated heat exchanger (laminated heat exchanger for AirToWater heat pump) will be described. As shown in FIG. 5A, the plate fin laminate 34 constituting the laminated heat exchanger for the Air To Water heat pump has a basic configuration of the plate fins of a general plate fin laminated heat exchanger shown in FIG. 3A. It is the same as the laminated body 30. However, as shown in FIG. 5B, the plate fins 35 constituting the plate fin laminate 34 are different from the plate fins 32 constituting the plate fin laminate 30 in that both sides thereof can be joint surfaces 11a. different. Therefore, in FIGS. 5A and 5B, as an example, the plate fin 35 has the brazing sheet 10C shown in FIG. 2B (intermediate sacrificial layers 14 are laminated on both sides of the core material 11, and the brazing material layers 12 and 13 are located on the outer sides thereof, respectively. Configuration) can be mentioned. Therefore, in FIGS. 5A and 5B, 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.

In the present embodiment, the core material 11 of the plate fin 35 contains Cu in the range of 0.3 to 1.2% by mass, and the brazing material layers 12 and 13 and the intermediate sacrificial layer 14 of the plate fin 35 are both Cu. Is not substantially contained. Therefore, the fillet 22 contains Cu having a concentration exceeding 2.0% by mass or less of the core material 11, the brazing material layers 12, 13 and the intermediate sacrificial layer 14. As a result, preferential corrosion of the joint portion 21 is satisfactorily suppressed (avoided or prevented). Therefore, the brazing sheet 10C improves the corrosion resistance life of the plate fin laminated heat exchanger (laminated heat exchanger for AirToWater heat pump) according to the embodiment of the present disclosure, which has the bonding structure 20 of the brazing sheet 10C. be able to. Since the configurations shown in FIGS. 5A and 5B are the same as the configurations shown in FIGS. 3A and 3B 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 sheets 10A to 10D according to the present embodiment are used in heat exchangers such as plate fin laminated heat exchangers and parallel flow capacitors (PFC) 40, and the core material 11 and the brazing material layer 12 are used. , 13 and an intermediate sacrifice layer 14. The core material 11 is made of an aluminum alloy. The brazing

filler metal layers

12 and 13 are made of an aluminum alloy brazing filler metal containing silicon (Si). The intermediate sacrificial layer 14 is made of a sacrificial anode material of an aluminum alloy containing zinc (Zn) in the range of 0.5 to 6.0% by mass. The brazing

filler metal layers

12 and 13 are located outside when viewed from both sides of the core metal 11, and the intermediate sacrificial layer 14 is laminated on at least one surface of the core metal 11. Neither the brazing material nor the sacrificial anode material contains copper (Cu), and the core material 11 contains copper (Cu) in the range of 0.3 to 1.2% by mass, which is intermediate. The thickness of the sacrificial layer 14 is 50 μm or less.

According to such a configuration, in the brazing sheets 10A to 10D according to the present embodiment, the intermediate sacrificial layer 14 made of the sacrificial anode material is arranged between at least one brazing material layer 13 and the core material 11. Further, in the brazing sheets 10A to 10D according to the present embodiment, the brazing material layers 12 and 13 and the intermediate sacrificial layer 14 do not contain copper, and only the core material 11 contains copper within a predetermined range. As a result, when the brazing materials 10A to 10D of the brazing sheets 10A to 10D according to the present embodiment are joined together (the brazing filler metal layers 13 to each other or the brazing filler metal layer 12 and the brazing filler metal layer 13), copper diffuses as follows. .. That is, copper is diffused from the core material 11 through the intermediate sacrificial layer 14 to the brazing

filler metal layers

12 and 13 constituting the joint portions 21 of the brazing sheets 10A to 10D, and is formed adjacent to the joint portions 21. The copper of the core material 11 also diffuses into the fillet 22. Therefore, in the brazing sheets 10A to 10D according to the present embodiment, copper is likely to segregate at the fillet 22 at the end.

Here, at the time of joining at a high temperature, the brazing material becomes liquid phase, but the intermediate sacrificial layer 14 does not become liquid phase. Therefore, copper is likely to segregate in the fillet 22, but zinc is present in a suitable concentration around the fillet 22 due to the intermediate sacrificial layer 14. As a result, a state in which zinc is appropriately present around the fillet 22 in which copper segregates is realized. Therefore, the brazing sheets 10A to 10D according to the present embodiment realize a good sacrificial anode action in the fillet 22. Can be done. In addition, the brazing sheets 10A to 10D according to the present embodiment can realize a good sacrificial anode action without copper hindering the appropriate leveling of the potential by zinc.

As a result, it is possible to avoid the possibility that the corrosion priority action of the sacrificial anode material existing in the vicinity is reduced due to the segregation of copper as in the conventional case. Therefore, the brazing sheets 10A to 10D according to the present embodiment can effectively suppress or prevent the possibility that corrosion progresses from the fillet 22 to the joint portion 21 and the joint strength of the joint portion 21 is lowered. Thereby, the brazing sheets 10A to 10D according to the present embodiment can further improve the corrosion resistance at the joint portion 21 of the heat exchanger.

The present disclosure will be described more specifically with reference to FIGS. 6 to 7B based on examples, which are specific examples of embodiments, comparative examples, and reference examples, but the present disclosure is limited thereto. It's not a thing. Those skilled in the art may make various changes, modifications, and modifications without departing from the scope of the present disclosure. In addition, various evaluation methods and the like in the following Examples, Comparative Examples or Reference Examples were carried out as shown below.

(Evaluation method, etc.)
FIG. 6 is a diagram showing a schematic configuration and corrosion resistance test results of the

brazing sheets

10A, 10E, and 10F according to Examples, Comparative Examples, or Reference Examples in the present disclosure. FIG. 7A is a graph showing the concentration of copper in the joint portion 21 of the

brazing sheets

10A, 10E, and 10F according to Example 1, Comparative Example 1, and Reference Example shown in FIG. FIG. 7B is a diagram schematically illustrating the position of the joint portion 21, which is the horizontal axis of the graph shown in FIG. 7A.

[Jointed surface and non-joined adjacent surface of brazing sheet]
In Examples, Comparative Examples, or Reference Examples, as shown in FIG. 6, the four-layered

brazing sheet

10A and 10F including the intermediate sacrificial layer 14 or the three-layered brazing sheet 10E not including the intermediate sacrificial layer 14 Was used. The thicknesses of these

brazing sheets

10A, 10E, and 10F are all 200 μm.

Further, the joining surface 11a and the non-joining adjacent surface 11b of the

brazing sheets

10A and 10F were designated as the side surface (second surface) of the brazing material layer 13 adjacent to the intermediate sacrificial layer 14. Further, the bonded surface 11a and the non-bonded adjacent surface 11b of the brazing sheet 10E are the surfaces on the side of the brazing filler metal layer 13 using the brazing filler metal which also serves as the sacrificial anode material.

The angle of the non-joining adjacent surface 11b with respect to the joining surface 11a (adjacent surface inclination angle θ2) is basically about 30 ° ± 5 ° (although there are some differences depending on the

brazing sheets

10A, 10E, 10F). (Within the range of 25 to 35 °). When the joining surfaces 11a are joined to each other, the angle formed by the non-joining adjacent surfaces 11b (adjacent surface forming angle θ1) is about 60 ° ± 10 ° (within the range of 50 to 70 °).

[Elemental concentration analysis of joints]
The Cu concentration in the joint portion 21 (joint structure of the

brazing sheets

10A or 10E, 10F) between the brazing sheets 10A (or the

brazing sheets

10E, 10F) was analyzed. For the analysis, the electron probe microanalyzer (EPMA) used the product name EMPA-1600 manufactured by Shimadzu Corporation. As shown in FIG. 7B, the Cu concentration of the joint portion 21 is toward the opposite end portion (position: 0.7 mm) of the fillet 22 along the direction of the joint surface 11a with respect to the fillet 22 (position: 0 mm). Was analyzed. The analysis conditions are an acceleration voltage of 15 kV, a beam diameter of 2 μm, a step interval of 2 μm, and an integration time of 1 second.

[Corrosion resistance test]
The corrosion resistance of the bonded structure of the

brazing sheets

10A, 10E and 10F was evaluated based on the SWAAT test (Sea Water Acidified Test) defined by ASTM G85-A3.

(Comparative Example 1)
As shown in the uppermost part of FIG. 6, the brazing sheet 10F according to Comparative Example 1 has a four-layer structure including a core material 11, brazing material layers 12, 13 and an intermediate sacrificial layer 14, similar to the brazing sheet 10A according to the embodiment. be.

The thickness of the core material 11 is 116 μm, and the aluminum alloy used for the core material 11 is A3003 (containing 3003-0.5% Cu and Mn) containing 0.5% by mass of copper (Cu). The thickness of the brazing

filler metal layers

12 and 13 is 12 μm, and the brazing filler metal used for the brazing

filler metal layers

12 and 13 is silicon (Si) 10% by mass and the balance aluminum alloy (Al-10% Si). .. The thickness of the intermediate sacrificial layer 14 is 60 μm, and in this respect, the brazing sheet 10F is different from the brazing sheet 10A in which the thickness of the intermediate sacrificial layer 14 is 50 μm or less. The sacrificial anode material used for the intermediate sacrificial layer 14 is an aluminum alloy (Al-1% Zn) containing 1% zinc (Zn).

The joining structure of the brazing sheet 10F according to Comparative Example 1 was manufactured by brazing two brazing sheets 10F according to Comparative Example 1 on the joining surfaces 11a of each other at 610 ° C. to form a joining portion 21. ..

The above-mentioned corrosion resistance test was carried out on the obtained bonded structure of the brazing sheet 10F according to Comparative Example 1 and the corrosion resistance was evaluated. The results are shown in the uppermost part of FIG. Further, with respect to the bonded structure, the Cu concentration of the bonded portion 21 was analyzed as described above. The result is shown in the solid line graph of FIG. 7A.

(Comparative Example 2)
As shown in the second stage of FIG. 6, the brazing sheet 10E according to Comparative Example 2 has a three-layer structure having no intermediate sacrificial layer 14 (including a core material 11 and brazing material layers 12 and 13).

The thickness of the core material 11 is 160 μm, and the aluminum alloy used for the core material 11 is A3003 (containing 3003-0.16% Cu, Mn) containing 0.16% by mass of copper (Cu). The thickness of the brazing

filler metal layers

12 and 13 is 20 μm. Of these, the brazing material used for the brazing material layer 12 covering the first surface is an aluminum alloy (Al-7.5% Si) of silicon (Si) 7.5% by mass and the balance aluminum. The brazing material used for the brazing filler metal layer 13 covering the second surface is an aluminum alloy (Al-4% Si-4% Zn) containing 4% by mass of silicon (Si), 4% by mass of zinc, and the balance of aluminum. .. Therefore, the brazing filler metal layer 13 also serves as a layer of the sacrificial anode material.

The joining structure of the brazing sheet 10E according to the comparative example 2 was manufactured in the same manner as in the comparative example 1 except that the brazing sheet 10E according to the comparative example 2 was used. A corrosion resistance test was carried out on the obtained bonded structure of the brazing sheet 10E according to Comparative Example 2 in the same manner as in Comparative Example 1. The results are shown in the second stage of FIG.

(Example 1)
As shown in the third stage of FIG. 6, the brazing sheet 10A according to the first embodiment has a four-layer structure including a core material 11, brazing material layers 12, 13 and an intermediate sacrificial layer 14 (see FIG. 1A).

The thickness of the core material 11 is 152 μm, and the aluminum alloy used for the core material 11 is the same copper-containing A3003 (3003-0.5% Cu, Mn-containing) as in Comparative Example 1. The thickness of the brazing filler metal layer 12 (first surface side) is 18 μm, the thickness of the brazing filler metal layer 13 (second surface side) is 5 μm, and the brazing filler metal used for the brazing

filler metal layers

12 and 13 is Comparative Example 1. It is the same silicon-containing aluminum alloy (Al-10% Si) as above. The thickness of the intermediate sacrificial layer 14 is 25 μm, and the sacrificial anode material used for the intermediate sacrificial layer 14 is an aluminum alloy (Al-4% Zn) containing 4% zinc (Zn).

The joining structure 20 of the brazing sheet 10A according to the first embodiment was manufactured in the same manner as in the comparative example 1 except that the brazing sheet 10A according to the first embodiment was used. Similar to Comparative Example 1, the bonded structure 20 of the brazing sheet 10A according to Example 1 was subjected to a corrosion resistance test and an analysis of the Cu concentration of the bonded portion 21. The results of the corrosion resistance test are shown in the third stage of FIG. 6, and the analysis results of the Cu concentration are shown by the broken line graph of FIG. 7A.

(Example 2)
As shown in the fourth stage of FIG. 6, the brazing sheet 10A according to the second embodiment has a four-layer structure including a core material 11, brazing material layers 12, 13 and an intermediate sacrificial layer 14 (see FIG. 1A).

It is the same as the brazing sheet 10A according to the first embodiment except that the thickness of the core material 11 is 160 μm and the thickness of the intermediate sacrificial layer 14 is 17 μm. That is, the materials of the core material 11, the brazing

filler metal layers

12, 13 and the intermediate sacrificial layer 14 are the same as those of the first embodiment, and the thicknesses of the brazing

filler metal layers

12, 13 are also the same as those of the first embodiment.

The joining structure 20 of the brazing sheet 10A according to the second embodiment was manufactured in the same manner as in the comparative example 1 except that the brazing sheet 10A according to the second embodiment was used. A corrosion resistance test was carried out on the obtained joint structure 20 of the brazing sheet 10A according to Example 2 in the same manner as in Comparative Example 1. The results are shown in the fourth column of FIG.

(Reference example)
As shown in the lowermost stage (fifth stage) of FIG. 6, the brazing sheet 10E according to the reference example has a three-layer structure without the intermediate sacrificial layer 14 (including the core material 11 and the brazing material layers 12 and 13).

In Comparative Example 2, except that the aluminum alloy used for the core material 11 is A3003 (3003-0.5% Cu, containing Mn) having the same copper concentration as that of Comparative Example 1, Example 1 or Example 2. It is the same as the said brazing sheet 10E. That is, the materials of the brazing

filler metal layers

12 and 13 are the same as those of Comparative Example 2, and the thicknesses of the core material 11 and the brazing

filler metal layers

12 and 13 are also the same as those of Comparative Example 2.

The joining structure of the brazing sheet 10E according to the reference example was manufactured in the same manner as in Comparative Example 1 except that the brazing sheet 10E according to the reference example was used. For the bonded structure of the brazing sheet 10E according to the obtained reference example, a corrosion resistance test and an analysis of the Cu concentration of the bonded portion 21 were carried out in the same manner as in Comparative Example 1. The results of the corrosion resistance test are shown at the bottom of FIG. 6, and the analysis results of the Cu concentration are shown by the dotted line graph of FIG. 7A.

(Comparison of Comparative Examples, Examples and Reference Examples)
As is clear from the results of the corrosion resistance test shown in FIG. 6, in Example 1 or Example 2, it can be seen that the fillet 22 does not corrode in the joint structure 20 of the brazing sheet 10A, and good corrosion resistance can be realized.

On the other hand, as in Comparative Example 2, in the brazing sheet 10E in which the intermediate sacrificial layer 14 does not exist and the Cu concentration of the core material 11 is low, preferential corrosion occurs in the joining structure of the brazing sheet 10E as shown by an arrow. Further, even if the intermediate sacrificial layer 14 is present as in Comparative Example 1, even if the thickness is too large (too thick), preferential corrosion occurs in the joint structure of the brazing sheet 10F as shown by an arrow. ing. As is clear from the comparison between Comparative Example 1 and Comparative Example 2, the degree of corrosion is larger in Comparative Example 1 in which the intermediate sacrificial layer 14 is too thick.

In the reference example, it can be seen that even in the case of the brazing sheet 10E having a three-layer structure without the intermediate sacrificial layer 14, the fillet 22 does not corrode in the joint structure of the brazing sheet 10E, and good corrosion resistance can be realized. As is clear from the comparison between the reference example and the comparative example 2, if the Cu concentration in the core material 11 is too low, it is considered that good corrosion resistance cannot be realized.

As shown in FIG. 7A, when the Cu concentrations of the joints 21 in Comparative Example 1, Example 1 and Reference Example are compared, in Reference Example or Example 1, the Cu concentration in the fillet 22 is high, and the joints other than the fillet 22 are high. At 21, the Cu concentration is low. On the other hand, in Comparative Example 1, although a high Cu concentration was locally confirmed between the positions of 0.1 to 0.2 mm, the Cu concentration was about 0.2% by mass as a whole, and the fillet 22 had a high Cu concentration. Cu is not concentrated (segregated).

Further, when comparing Example 1 and Reference Example, it can be seen that Cu is more likely to concentrate (segregate) on the fillet 22 in Example 1. In the reference example having no intermediate sacrificial layer 14, the Cu concentration is relatively high up to a position of about 0.3 mm, but in Example 1 having the intermediate sacrificial layer 14, most of the joints 21 other than the fillet 22 have Cu. The concentration is about 0.2% by mass.

As described above, in the brazing sheet 10A according to the first embodiment, only the core material 11 contains copper, the intermediate sacrificial layer 14 and the brazing material layers 12 and 13 do not contain copper, and the thickness of the intermediate sacrificial layer 14 is thick. Is made suitable. Therefore, when the brazing filler metal layers 13 of the brazing sheet 10A are joined together, the copper of the core material 11 diffuses into the fillet 22 formed adjacent to the joining portion 21, and the copper tends to segregate at the fillet 22 at the end portion. .. On the other hand, the intermediate sacrificial layer 14 causes zinc to be present in a suitable concentration around the fillet 22. As a result, in the brazing sheet 10A according to the first embodiment, a state in which zinc is appropriately present around the fillet 22 in which copper segregates is realized, so that a good sacrificial anode action in the fillet 22 can be realized. .. In addition, the brazing sheet 10A according to the first embodiment can realize a good sacrificial anode action without copper hindering an appropriate leveling of the potential by zinc. The same can be said for the brazing sheets 10A according to the second embodiment, and the same can be said for the brazing sheets 10A to 10D according to the embodiment.

Note that the present disclosure is not limited to the description of the above embodiment, and various changes can be made within the scope of the claims. Further, the technical scope of the present disclosure also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments and the plurality of modifications.

The present disclosure can be widely and suitably used not only in the field of brazing sheets for heat exchangers having an intermediate sacrificial layer, but also in the field of heat exchangers using the brazing sheets.

10A brazing sheet

10B brazing sheet

10C brazing sheet

10D brazing sheet

10E brazing sheet

10F brazing sheet 11 core material 11a joint surface 11b non-joint adjacent surface 12 brazing material layer (non-joint surface side)
12a Brazing material layer (non-joining surface side)
12b Brazing material layer (non-joining surface side)
13 Wax layer (joint surface side)
14 Intermediate sacrificial layer 15 Flux-containing layer 16 Magnesium-containing layer 20 Blazing sheet joint structure 21 Joint 22 Fillet 30 Plate fin laminate 31 End plate 32 Plate fin 33 Header opening 34 Plate fin laminate 35 Plate fin 40 Parallel flow condenser ( PFC)
41 Header pipe 42 Flat pipe 43 Corrosion fin C1 Corrosion direction C2 Corrosion direction θ1 Adjacent surface formation angle θ2 Adjacent surface inclination angle

Claims

A brazing sheet used in heat exchangers,
Aluminum alloy core material and
A brazing filler metal layer made of an aluminum alloy brazing filler metal containing silicon (Si),
An intermediate sacrificial layer made of a sacrificial anode material of an aluminum alloy containing zinc (Zn) in the range of 0.5 to 6.0% by mass is provided.
The brazing filler metal layer is located outside when viewed from both sides of the core wood, and the intermediate sacrificial layer is laminated on at least one surface of the core wood.
Neither the brazing material nor the sacrificial anode material contains copper (Cu).
The core material contains copper (Cu) in the range of 0.3 to 1.2% by mass.
The thickness of the intermediate sacrificial layer is 50 μm or less.
Blazing sheet.
The brazing filler metal layer is laminated on one surface of the core wood.
The brazing filler metal layer is laminated on the intermediate sacrificial layer laminated on the other surface of the core material.
The brazing sheet according to claim 1.
The intermediate sacrificial layer is laminated on both surfaces of the core material, and the brazing filler metal layer is laminated on each of the intermediate sacrificial layers.
The brazing sheet according to claim 1.
Further, a flux-containing layer made of a flux material for brazing or a magnesium-containing layer having a layer independent of the brazing material layer and having at least magnesium (Mg) added to the brazing material is provided.
The flux-containing layer or the magnesium-containing layer is located outside the intermediate sacrificial layer.
The brazing sheet according to claim 2 or 3.
The flux-containing layer or the magnesium-containing layer is adjacent to the brazing filler metal layer.
The brazing sheet according to claim 4.
The core material is made by adding copper within the above range to any of 3000 series, 5000 series, or 6000 series aluminum alloys.
The intermediate sacrificial layer is made by adding zinc within the above range to a 1000 series or 3000 series aluminum alloy.
The brazing sheet according to any one of claims 1 to 5.
The brazing filler metal layer is a 4000 series aluminum alloy.
The brazing sheet according to any one of claims 1 to 6.
It is configured by using the brazing sheet according to any one of claims 1 to 7.
The brazing sheet has a joint surface that constitutes a joint portion by being joined to each other, and a non-joint adjacent surface adjacent to the joint surface.
When the joint surfaces are joined together, a fillet that flows out of the joint surface and solidifies the brazing material is formed at a portion between the non-joint adjacent surfaces and adjacent to the joint surface. ,
Blazing sheet joint structure.
The angle formed by each of the non-joined adjacent surfaces is an acute angle.
The joining structure of the brazing sheet according to claim 8.
It has the joining structure of the brazing sheet according to claim 8 or 9.
Heat exchanger.
Plate fin laminated heat exchanger or parallel flow capacitor (PFC),
The heat exchanger according to claim 10.