JP2017155308A - Aluminum alloy-made brazing fin material for heat exchanger and aluminum alloy-made heat exchanger using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy-made brazing fin material for heat exchanger by cladding a brazing material on one surface of a core material and a sacrificial anode material on another surface respectively, effectively improving corrosion resistance of a junction between a fin and a heat transfer pipe and excellent in corrosion resistance of the heat transfer pipe.SOLUTION: A core material is constituted by an aluminum alloy containing Mn:0.5 to 2.0 mass% and Zn:0.1 mass% or less and the balance Al with inevitable impurities, a brazing material is constituted by an aluminum alloy containing Si:6.5 to 12.5 mass%, Zn:0.1 mass% or less and Cu:0.001 to 0.5 mass% and the balance Al with inevitable impurities and a sacrificial anode material is constituted by an aluminum alloy containing Zn:7 to 15 mass% and the balance Al with inevitable impurities and then an aluminum alloy-made brazing fin material for heat exchanger is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aluminum alloy brazing fin material for a heat exchanger and an aluminum heat exchanger using the same, and in particular, a fin member obtained by molding an aluminum alloy brazing fin material, an aluminum heat transfer tube, and the like. Brazing sheet material made of aluminum alloy for forming fins in heat exchangers manufactured by brazing and joining, for example, heat exchangers for outdoor units of room air conditioners, heat exchangers for indoor units, evaporators for refrigerators, etc. Especially, it is related with the brazing fin material made from aluminum alloy excellent in corrosion resistance, and the aluminum heat exchanger excellent in corrosion resistance obtained using such a fin material.

  Conventionally, as a heat exchanger in an air conditioner or a refrigerator, a heat exchanger of a type configured by combining a large number of plate fins laminated at a predetermined interval and a heat transfer tube passing therethrough (hereinafter, Plate fin type heat exchangers) have been widely used. And since the plate fin is lightweight and has excellent thermal conductivity and workability, an aluminum plate is used, and the heat transfer tube has excellent thermal conductivity and processability. A copper tube is used. Further, in such a plate fin type heat exchanger, after laminating plate fins having a cylindrical through hole of a predetermined shape, a heat transfer tube is inserted into the cylindrical through hole, and then the diameter of the heat transfer tube By extending the outer surface of the heat transfer tube, the heat transfer tube and the fin are mechanically fixed and joined by bringing the outer peripheral surface of the heat transfer tube into contact with the inner surface of the through hole.

  By the way, due to the recent increase in the price of copper used for heat transfer tubes in plate fin type heat exchangers, there is a problem that the cost of plate fin type heat exchangers when using copper tubes increases. Changing the material of the heat tube from copper to aluminum is being studied. Moreover, the merit that recyclability improves will be acquired by using an aluminum alloy as this heat-transfer tube material.

  And in such a plate fin type heat exchanger using aluminum as the heat transfer tube material, as a method of joining the plate fin and the heat transfer tube, the heat transfer tube is expanded as in the case of using the copper tube. In addition to the method of bringing plate fins into close contact with each other, a method of using brazing fin materials and assembling the fin members obtained therefrom to an aluminum heat transfer tube and brazing them together is known.

  Moreover, as a brazing fin material which gives a heat exchanger by brazing joining with the above-mentioned aluminum heat transfer tube, it is made of an Al-Si aluminum alloy brazing material on both sides or one side of an Al-Mn aluminum alloy core material. A brazing fin material clad with a material is used. And in such Al-Mn type aluminum alloy core material and Al-Si type aluminum alloy brazing material, Zn is 0.5-5% as an alloy component in order to prevent corrosion of heat transfer tubes by sacrificial anodic action of fins. The brazing fin material added so much is generally used (Patent Document 1: Japanese Patent Application Laid-Open No. 2014-084521 (WO 2014/066535 A1)).

  Furthermore, as a brazing fin material for a plate fin type heat exchanger, since the joining surface is only one surface of the fin material, Al-Mn used as a heat transfer tube material for aluminum heat exchangers for automobiles such as radiators and heater cores. A sacrificial anode material made of an Al-Zn aluminum alloy is clad on one surface of the aluminum alloy core material, and an Al-Si aluminum alloy brazing material is coated on the core material surface opposite to the clad side of the sacrificial anode material. It has been clarified that a brazing sheet with clad is used as a fin material (Patent Document 2: Japanese Patent Laid-Open No. 11-241133, Patent Document 3: Japanese Patent Laid-Open No. 2004-217882, Patent Document 4: Japanese Patent Laid-Open No. 2010). -18872 gazette, patent document 5: Unexamined-Japanese-Patent No. 2014-177694).

JP 2014-084521 A (WO 2014/066535 A1) Japanese Patent Laid-Open No. 11-241133 JP 2004-217982 A JP 2010-18872 A JP 2014-177694 A

  However, in the heat exchanger obtained by brazing and joining the heat transfer tube using the brazing sheet made of an aluminum alloy in which the brazing material is clad on one side of the core material described in Patent Document 1, In order to protect the heat transfer tube by the sacrificial anticorrosive action of the material, since a predetermined amount of Zn is added to the core material constituting the fin material, the Zn is concentrated in the joint after brazing, and therefore the joint Due to this preferential corrosion, there will be a problem that the fins peel off early.

  Moreover, the brazing sheet described in Patent Document 2, Patent Document 4 and Patent Document 5 is used as a fin material, with a brazing material on one side of the core material and a sacrificial anode material clad on the surface opposite to the brazing material. Thus, in the heat exchanger obtained by brazing and joining it to the heat transfer tube, since the Zn addition amount of the sacrificial anode material is low, it is difficult to obtain an effective sacrificial anode action for preventing corrosion of the heat transfer tube. There's a problem. Further, the brazing sheet described in Patent Document 3 having a brazing material on one side of the core material and a sacrificial anode material clad on the surface opposite to the brazing material is brazed and joined to the heat transfer tube. In the heat exchanger obtained, the Zn content of the sacrificial anode material is diffused in the thickness direction of the fin plate during brazing heating because the Zn content of the sacrificial anode material will be too high. Due to the preferential corrosion of the joint portion due to the concentration in the portion, there is a problem that the fins peel off early.

  Therefore, the object or problem of the present invention is a brazing fin material made of aluminum alloy in which a brazing material is clad on one side of the core material and a sacrificial anode material is clad on the core material surface opposite to the brazing material. In addition, by effectively improving the corrosion resistance of the joints between the fins and heat transfer tubes formed using this fin material, it is made of an aluminum alloy that provides heat exchanger fins with extremely excellent ability to prevent heat transfer tubes It is to provide a brazing fin material.

  And as a result of earnestly examining this invention to solve said subject, the concentration of Zn component to the junction part after brazing is suppressed by regulating the Zn concentration of the core material and the brazing material in the brazing fin material. However, by using a brazing fin material clad with an Al-Zn alloy (hereinafter referred to as a sacrificial anode material) on the core material surface opposite to the brazing material, the potential of the fin after brazing is advantageously reduced. The present invention has been completed on the basis of the finding that it is possible to suppress the lowering of the potential of the junction and to suppress the preferential corrosion of the junction.

  Therefore, the gist of the present invention is to clad the Al—Si brazing material on one surface of the core material, and clad the Al—Zn based sacrificial anode material on the other surface surface of the core material. A brazing fin material for a heat exchanger, wherein the core material contains Mn: 0.5 to 2.0% by mass and Zn: 0.1% by mass or less, and the balance is made of Al and inevitable impurities. It is composed of an aluminum alloy, and the brazing material contains Si: 6.5 to 12.5% by mass, Zn: 0.1% by mass or less, and Cu: 0.001 to 0.5% by mass, with the balance being It is composed of an aluminum alloy composed of Al and inevitable impurities, and the sacrificial anode material contains Zn: 7 to 15% by mass, and the balance is composed of an aluminum alloy composed of Al and inevitable impurities. Characteristic heat exchange In use an aluminum alloy brazing the fin material.

  According to one of desirable aspects of the aluminum alloy brazing fin material for a heat exchanger according to the present invention, the core material further contains Cu: 0.1% by mass or less, and the sacrificial anode material comprises: Furthermore, Cu: 0.1 mass% or less is contained.

  According to still another preferred aspect of the present invention, the sacrificial anode material further contains Si: 8% by mass or less.

  Furthermore, according to another desirable aspect of the present invention, the brazing material further contains Sr: 0.1% by mass or less.

  Still further, according to a different aspect of the present invention, advantageously, the core material further comprises: Si: 1.5 mass% or less, Fe: 0.5 mass% or less, Mg: 1.0 mass% or less, Cr : 0.3% by mass or less, Zr: 0.3% by mass or less, and Ni: 1.5% by mass or less, and the sacrificial anode material further contains Mn: One or two of 2.0% by mass or less and Fe: 1.0% by mass or less are contained.

  In addition, in the brazing fin material according to the present invention, preferably, the core material further contains Ti: 0.3% by mass or less, and the sacrificial anode material further contains Ti: 0.35 mass. % Or less, Sn: 0.05% by mass or less, and In: 0.05% by mass or less.

  The present invention also provides a fin member made of a brazing fin material in which a brazing material is clad on at least one side of a core material and a sacrificial anode material is coated on a surface opposite to the brazing material, and a heat transfer tube made of an aluminum alloy Is a heat exchanger obtained by brazing and heating the assembled body, and the potential of the fin formed by the fin member by brazing and the potential of the junction between the fin and the heat transfer tube Further, the present invention also provides a heat exchanger having a potential configuration in which the potential on the fin surface is the most basic with respect to the surface potential of each surface of the heat transfer tube, and then the junction surface and the surface of the heat transfer tube become noble.

  Specifically, it is an aluminum heat exchanger obtained by brazing a fin member obtained by molding from an aluminum alloy brazing fin material for heat exchanger according to the present invention as described above and an aluminum heat transfer tube. The natural potential of the fin surface of the heat exchanger, the natural potential of the surface of the joint between the fin and the aluminum heat transfer tube, and the natural potential of the surface of the aluminum heat transfer tube are represented by fin surface <joint surface <transfer The gist of the heat exchanger is an aluminum heat exchanger characterized in that it becomes noble in the order of the heat tube surface, or in the order of fin surface <heat transfer tube surface <joint surface.

  Thus, according to the present invention, a brazing material made of a specific aluminum alloy is provided on one side of a core material made of a specific aluminum alloy, and a sacrificial anode material made of a specific aluminum alloy is formed on the core material surface opposite to the brazing material. In the brazing heating for producing the heat exchanger by using the clad brazing fin material, the preferential corrosion of the joint between the heat exchanger fin and the heat transfer tube produced by using the brazing fin material. Thus, it is possible to effectively improve the peeling of the fins and to provide a heat exchanger with excellent corrosion resistance to the heat transfer tube. Further, by using such brazing fin material, it is possible to advantageously provide a heat exchanger imparted with characteristics excellent in corrosion resistance.

It is a section explanatory view showing an example of an aluminum alloy brazing fin material for heat exchangers according to the present invention. It is an isometric view explanatory drawing which shows an example of the plate fin member obtained by press-working the brazing fin material made from the aluminum alloy for heat exchangers according to this invention. It is a perspective partial explanatory view showing typically a part of an assembly core formed by assembling a plate fin member and a heat transfer tube. FIG. 5 is a partial explanatory view schematically showing an enlarged cross section of a contact portion between a plate fin member and a heat transfer tube before brazing heating. It is a partial explanatory view which expands and shows typically a section of a joined part of a fin and a heat exchanger tube in an assembly core after brazing heating.

  By the way, the brazing fin material made of an aluminum alloy for a heat exchanger according to the present invention clads the Al—Si brazing material 4 on the surface on one side of the core material 2 as shown in FIG. The other side surface is a brazing fin material 8 made of an aluminum alloy for a heat exchanger that is clad with an Al—Zn-based sacrificial anode material 6 and has a plate shape as a whole. The core material 2 contains Mn: 0.5 to 2.0% by mass and Zn: 0.1% by mass or less, and the balance is made of an aluminum alloy composed of Al and unavoidable impurities. 4 is an aluminum alloy containing Si: 6.5 to 12.5% by mass, Zn: 0.1% by mass or less and Cu: 0.001 to 0.5% by mass with the balance being Al and inevitable impurities. The sacrificial anode material 6 contains Zn: 7 to 15% by mass, and the balance is made of an aluminum alloy composed of Al and inevitable impurities. The significance of each alloy component in the three types of aluminum alloys constituting the brazing fin material 8 made of aluminum alloy is as follows.

  First, the significance and reasons for limitation of the alloy components in the aluminum alloy that gives the core material 2 constituting the aluminum alloy brazing fin material 8 for heat exchanger according to the present invention will be described.

[Mn: 0.5 to 2.0% by mass]
Mn is an alloy component that functions to improve the strength of the core material 2 and improve the high temperature buckling resistance. The required content of Mn is in the range of 0.5 to 2.0% by mass. When the Mn content is less than 0.5% by mass, the effect is small and exceeds 2.0% by mass. If it becomes like this, a coarse compound will produce | generate at the time of casting, rolling workability will fall, troubles, such as a crack, will generate | occur | produce, and it will become difficult to obtain a healthy board | plate material. In addition, preferable content of such Mn is 1.0-1.5 mass%.

[Zn: 0.1% by mass or less]
Zn lowers the potential of the core material 2 and diffuses into the brazing material 4, and lowers the potential of the brazing material 4 to promote preferential corrosion of the joint. Therefore, its content is 0.1 mass. % Or less is required. If the Zn content exceeds 0.1% by mass, preferential corrosion of the joint is promoted. Further, the more preferable content of Zn is 0.001 to 0.05% by mass.

  In the present invention, in addition to the essential alloy components in the aluminum alloy that provides the core material 2 as described above, the following various alloy components can be appropriately contained alone or in combination. is there.

[Cu: 0.1% by mass or less]
Cu in the core material 2 improves the strength of the fin material before brazing and the fin after brazing, but if the content increases, the intergranular corrosion resistance may be reduced. For this reason, it is desirable that the Cu content in the core material 2 is 0.1% by mass or less, and more preferably 0.02 to 0.08% by mass. Note that if the Cu content in the core material 2 exceeds the above range, the potential of the fin becomes noble, the sacrificial anode effect of the fin tends to decrease, and the intergranular corrosion resistance also tends to decrease.

[Si: 1.5% by mass or less]
The Si in the core material 2 forms fine precipitates with other additive elements such as Mn or Fe, thereby improving the strength of the core material 2 and reducing the solid solution amount of Mn. Degree). For this reason, it is desirable that the Si content in the core material 2 is in the range of 0.1 to 1.5% by mass. If the content is less than 0.1% by mass, the effect is not sufficient, and 1 If it exceeds 0.5 mass%, the corrosion resistance is lowered, the melting point of the core material 2 is lowered, and local melting is likely to occur during brazing. In addition, the more preferable range of Si content is 0.3-1.1 mass%.

[Fe: 0.5% by mass or less]
Fe in the core material 2 coexists with Mn and improves the strength of the fin material before and after brazing and the fins resulting therefrom. The Fe content in the core material 2 is preferably 0.5% by mass or less, particularly preferably in the range of 0.1 to 0.5% by mass, and the effect decreases as the content decreases. When it exceeds 5% by mass, the crystal grains become finer, and the molten brazing is likely to be eroded into the core material 2, the high temperature buckling resistance is likely to be lowered, and the self-corrosion property is likely to be increased. There is. In addition, the more preferable range of Fe content is 0.1-0.3 mass%.

[Mg: 1.0% by mass or less]
Mg in the core material 2 has a function of improving the strength of the fin material and fins before and after brazing by forming a precipitate with Si. The content of Mg in the core material 2 is preferably 1.0% by mass or less, more preferably 0.05 to 1.0% by mass. When the Mg content in the core material 2 exceeds the above range, the melting point of the core material 2 is lowered, and deformation during brazing and local melting are likely to occur.

[Cr: 0.3% by mass or less]
Cr in the core material 2 is a component that improves the high-temperature buckling property as well as improving the strength of the fin material and the fin before brazing and after brazing. The Cr content in the core material 2 is desirably 0.3% by mass or less. On the other hand, if it exceeds 0.3% by mass, coarse crystallized products are generated during casting, and rolling is performed. Workability is likely to be impaired, and production of a plate material is likely to be difficult. In addition, the more preferable range of Cr content is 0.02-0.2 mass%.

[Zr: 0.3 mass% or less]
Zr in the core material 2 is a component that improves the high-temperature buckling property as well as improving the strength of the fin material and the fin before and after brazing. The Zr content in the core material 2 is desirably 0.3% by mass or less, and when it exceeds 0.3% by mass, coarse crystallized products are generated during casting, which impairs the rolling processability. It becomes easy and manufacture of a board | plate material becomes easy to become difficult. In addition, the more preferable range of Zr content is 0.02-0.2 mass%.

[Ni: 1.5% by mass or less]
Ni in the core material 2 is a component that improves the strength of the fin material and the fin before brazing and after brazing. The Ni content in the core material 2 is preferably 1.5% by mass or less, more preferably 0.05 to 1.5% by mass. In addition, when the Ni content in the core material 2 exceeds 1.5 mass%, the crystal grains become finer, and the molten brazing is easily eroded in the core material, and the high temperature buckling resistance is likely to be reduced. Self-corrosion tends to increase.

[Ti: 0.3% by mass or less]
Ti in the core material 2 is a component that mitigates local corrosion by making the corrosion of the fin material and the fin before brazing and the corrosion of the fin into a layered corrosion form. The Ti content in the core material 2 is preferably 0.3% by mass or less. In addition, when Ti content exceeds 0.3 mass%, a coarse crystallization thing will produce | generate at the time of casting, it will become easy to impair rolling workability, and it will become difficult to manufacture a board | plate material. A more preferable range of the Ti content is 0.02 to 0.2% by mass.

  Moreover, each alloy component in the aluminum alloy which gives the brazing material 4 constituting the brazing fin material 8 according to the present invention has the following significance and reasons for limitation.

[Si: 6.5 to 12.5% by mass]
Si is an element that lowers the melting point of the brazing material 4, increases the fluidity of the brazing material 4, and exhibits an effective function as a brazing material. The Si content is in the range of 6.5 to 12.5% by mass. On the other hand, when the Si content is less than 6.5% by mass, the fluidity is lowered, causing a problem that the solder does not act effectively, and when it exceeds 12.5% by mass, cracks are caused by rolling. This causes a problem that it becomes difficult to produce a sound plate material.

[Zn: 0.1% by mass or less]
Since Zn lowers the potential of the brazing material 4 and promotes preferential corrosion of the joint, the Zn content needs to be 0.1% by mass or less. On the other hand, when the Zn content exceeds 0.1% by mass, preferential corrosion of the joint portion may be promoted. In addition, preferable content of Zn is 0.001-0.05 mass%.

[Cu: 0.001 to 0.5% by mass]
Cu in the brazing material 4 is a component that improves the corrosion resistance of the joint by making the potential of the fillet after brazing noble. For this reason, Cu content in the brazing material 4 needs to be 0.001-0.5 mass%, More preferably, it is 0.01-0.3 mass%. If the Cu content in the brazing material 4 is less than 0.001% by mass, the effect of the addition cannot be fully exhibited, while if it exceeds 0.5% by mass, the potential of the fin material Becomes noble and causes a problem that the sacrificial anode effect of the fin is likely to be lowered.

  And in this invention, in addition to the essential alloy component in the aluminum alloy which gives the brazing filler metal 4 as mentioned above, it is desirable that the following predetermined amount of Sr is further contained as required.

[Sr: 0.1% by mass or less]
This Sr has an effect of finely and uniformly dispersing the Si particles in the brazing material 4. Then, when the Si particles are finely and uniformly dispersed, the melting of the brazing becomes uniform and the brazing property is improved, and the existence form of the Si particles after brazing is also fine and uniform. Therefore, the corrosion resistance of the outer surface can be improved. The preferable content of Sr that performs such an action is 0.1% by mass or less, particularly in the range of 0.005 to 0.1% by mass, and the content exceeds 0.1% by mass. Then, the effect of addition becomes saturated. The more preferable content of Sr is 0.01 to 0.03% by mass. In addition, even if it replaces with this Sr and Na: 1-100ppm or Sb: 0.001-0.5 mass% is added, the effect equivalent to Sr can be acquired.

  Furthermore, the significance and reasons for limitation of each alloy component in the aluminum alloy that provides the sacrificial anode material 6 constituting the brazing fin material 8 according to the present invention are as follows.

[Zn: 7 to 15% by mass]
Zn has the effect of preventing the pitting corrosion of the heat transfer tube by lowering the potential of the sacrificial anode material 6 and exerting the sacrificial anode effect by the fins on the heat transfer tube of the heat exchanger. For this reason, it is necessary to make Zn content into the range of 7-15 mass%. If the Zn content is less than 7% by mass, the effect is small. If the Zn content exceeds 15% by mass, the self-corrosion amount of the brazing fins increases. Further, the more preferable content of Zn is 7.5 to 12% by mass.

  In addition, the aluminum alloy that provides the sacrificial anode material 6 constituting the brazing fin material 8 according to the present invention includes the above-described Zn as an essential component as an alloy component, and the following various alloy components alone or in combination. It will be contained appropriately.

[Cu: 0.1% by mass or less]
Cu in the sacrificial anode material 6 improves the strength of the fin material and the fin before brazing and after brazing, but makes the potential of the sacrificial anode material 6 noble and reduces the effect of sacrificial anode action by the fins. Therefore, the Cu content in the sacrificial anode material 6 is adjusted to be 0.1 mass% or less. When the Cu content in the sacrificial anode material 6 exceeds the above range, the potential of the fin becomes noble, the sacrificial anode effect of the fin is likely to be lowered, and intergranular corrosion resistance is also liable to be lowered. The problem of becoming. In addition, the more preferable range of such Cu is 0.01-0.08 mass%.

[Si: 8.0% by mass or less]
Si, together with Mn and Fe, causes a large amount of Al-Mn-Fe-Si-based compounds to crystallize and suppress excessive coarsening of the crystal grains of the sacrificial anode material 6, and in addition to Al-Mn-Fe-Si. A system compound serves as a starting point of corrosion and exhibits a function of improving corrosion resistance by dispersing pitting corrosion. The preferable content of Si is 8.0% by mass or less, and when the content exceeds 8.0% by mass, there arises a problem that the corrosion resistance is lowered. In addition, the more preferable content range of this Si is 0.3-4 mass%.

[Mn: 2.0% by mass or less]
Mn is a component that functions to improve the strength of the sacrificial anode material 6. A preferable content range of Mn is 2.0% by mass or less, and when the content exceeds 2.0% by mass, a coarse compound is generated at the time of casting, rolling workability is impaired, cracking, etc. This causes the problem that it becomes difficult to obtain a sound clad plate. The more preferable content of Mn is 0.2 to 1.3% by mass.

[Fe: 1.0% by mass or less]
Fe functions to crystallize a large amount of Al-Mn-Fe-Si compound together with Mn and Si and improve the strength of the sacrificial anode material 6, and in addition to Al-Mn-Fe-Si compound Is the starting point of corrosion and exhibits the feature of improving corrosion resistance by dispersing pitting corrosion. The preferable content of Fe is 1.0% by mass or less, and when it exceeds 1.0% by mass, there is a problem that the corrosion resistance is lowered. In addition, the more preferable content range of Fe is 0.1-0.5 mass%.

[Ti: 0.35 mass% or less]
Ti is divided into a high Ti concentration region and a low Ti region in the thickness direction of the sacrificial anode material 6 and functions so that these regions are alternately distributed in layers. And since the region where the Ti concentration is low corrodes preferentially compared to the region where the Ti concentration is high, the corrosion form becomes layered, and the progress of corrosion in the thickness direction is hindered, resulting in improved pitting corrosion resistance. Demonstrate. The preferable content of Ti is 0.35% by mass or less, particularly in the range of 0.01 to 0.35% by mass, and the effect decreases as the content decreases, and 0% If it exceeds .35% by mass, casting becomes difficult, workability deteriorates, defects such as cracks occur, and it becomes difficult to produce a sound clad plate material. In addition, the more preferable content range of this Ti is 0.1-0.2 mass%.

[Sn: 0.05% by mass or less]
Sn exerts the function of preventing the occurrence of pitting corrosion of the core material 2 by sacrificing anode effect by making the potential of the sacrificial anode material 6 low by adding a small amount thereof. The preferable content range of such Sn is 0.05 mass% or less. On the other hand, the inclusion of Sn in a proportion exceeding 0.05% by mass causes a problem that the amount of self-corrosion of the sacrificial anode material increases. In addition, the more preferable content of Sn is 0.01 to 0.03% by mass.

[In: 0.05% by mass or less]
In, like the above-described Sn, the potential of the sacrificial anode material 6 is reduced by adding a small amount, and the sacrificial anode effect exhibits the function of preventing the occurrence of pitting corrosion of the core material. A preferable content range of such In is 0.05% by mass or less. On the other hand, the inclusion of In in a proportion exceeding 0.05% by mass causes a problem that the amount of self-corrosion of the sacrificial anode material 6 increases. A more preferable content of In is 0.01 to 0.03% by mass.

  In addition, in each aluminum alloy which provides the core material 2, brazing material 4 and sacrificial anode material 6 constituting the brazing fin material 8 according to the present invention, the remainder other than the alloy components described above is composed of aluminum and inevitable impurities. It becomes. Therefore, the content of the inevitable impurities is preferably as small as possible so that the characteristics as the brazing fin material are not deteriorated, and generally the content is not more than the upper limit value of the impurity component defined by the JIS standard or the like. Will be adjusted.

  Further, in the plate-like brazing fin material 8 constituted integrally by the core material 2, the brazing material 4 and the sacrificial anode material 6 made of each aluminum alloy having the alloy components described above, the brazing material 4 and the sacrificial anode material 6. In consideration of the relationship between the surface potential on the sacrificial anode material 6 side after brazing, the surface potential on the surface side of the brazing filler metal 4 side, the surface potential of the joint, etc. Although it will be selected appropriately, it is preferably 7 μm or more, more preferably 7 to 40 μm. In addition, when the thickness of the brazing material 4 and the sacrificial anode material 6 is less than 7 μm, it may be difficult to effectively exhibit the brazing action and the sacrificial anode effect, and the potential of the joint portion is easily reduced, This causes a problem that the corrosion resistance of the joint becomes inferior. On the other hand, when the thickness of the brazing material 4 and the sacrificial anode material 6 exceeds 40 μm, the brazing material 4 and the sacrificial anode material 6 are within a range of 50 to 200 μm, which is the thickness of a general fin material. It becomes difficult to join the core material 2 to the core material 2, which may hinder the production of a sound clad plate.

  Furthermore, in the brazing fin material 8 for a heat exchanger according to the present invention, the brazing material 4 and the sacrificial anode material 6 are clad only on one side of the core material 2, respectively. The clad rate is applicable as long as it is in a common sense range and is appropriately selected. Preferably, the clad rate is about 3 to 25% with respect to the entire thickness of the fin material 8. In these cladding ratios, for example, when the cladding ratio of the brazing material is less than the above range, the brazing filler metal is likely to decrease during brazing heating, and the fillet may not be sufficiently formed, while the above range is exceeded. Then, since too much brazing material is melted during brazing heating, the core material may be melted.

  The brazing fin material 8 made of aluminum alloy for heat exchanger shown in FIG. 1 as described above clads the brazing material 4 on one surface of the core material 2, while the sacrificial anode is disposed on the surface of the core material 2 opposite to the brazing material 4. The clad material 6 is obtained by cladding the brazing material 4 and the sacrificial anode material 6 on the core material 2 as the core material 2, brazing material 4 and An aluminum alloy ingot for core material, an aluminum alloy ingot for brazing material, and an aluminum alloy ingot for sacrificial anode material having the same composition as each alloy element in the sacrificial anode material 6 are cast, and then the core material For aluminum alloy ingots for sacrificial anodes and aluminum alloy ingots for sacrificial anode materials, homogenization is performed according to a conventional method, while for aluminum alloy ingots for brazing filler metals, With the aluminum alloy ingot for sacrificial anode material subjected to the homogenization treatment, hot rolling is performed, and aluminum for brazing material is formed on one side of the aluminum alloy ingot for core material after the homogenization treatment. The hot rolled material of the ingot of the alloy ingot, and the hot rolled material of the aluminum alloy ingot for the sacrificial anode material are superposed on the other side surface, respectively, and hot clad rolling is performed, whereby aluminum is obtained. A technique for producing an alloy clad material will be adopted. Thereafter, the clad material is cold-rolled, further subjected to intermediate annealing as necessary, and then subjected to finish cold-rolling to produce the intended aluminum alloy brazing fin material 8. It is done. The brazing fin material 8 is subjected to finish cold rolling and then cut into product widths to be used as fin materials.

  Thereafter, the brazing fin material (fin material) 8 obtained in this way is assembled by a known process such as a press process for assembling with a predetermined heat transfer tube, for example, as shown in FIG. The fin member 10 is molded. The fin member 10 shown in FIG. 2 provides plate fins in a plate fin type heat exchanger, and opens at one end in the width direction (vertical direction in the figure) of the fin body 12 having a rectangular plate shape. A plurality of assembly holes 14 made of U-shaped slits extending to the end side are arranged in the longitudinal direction of the fin body 12 at a predetermined interval. A collar portion 16 having a predetermined height is integrally formed with the fin main body 12 around the assembly hole 14 as in the prior art. Here, as shown in FIG. 3, a known flat aluminum multi-hole pipe 20 is fitted into the assembly hole 14 and assembled into the assembly core 30, and the fin member 10 is used in the brazing process. It has come to be offered. That is, as shown in the drawing, here, two flat multi-hole tubes 20 and 20 are formed on the fin member 10 with respect to the plurality of fin members 10 arranged in parallel to each other and at a predetermined distance. It is inserted into the slit-like assembly hole 14 and assembled. As is well known, the flat multi-hole tube 20 made of aluminum is formed by extrusion or the like using a metal material made of aluminum or an aluminum alloy. Here, the flat multi-hole tubes 20 are parallel to each other and extend in the tube axis direction. It is a multi-hole tube having a flat shape in which seven holes 22 are formed.

  The heat exchanger according to the present invention is an assembly in which at least the fin member 10 obtained by processing the aluminum alloy brazing fin material 8 according to the present invention and the aluminum heat transfer tube 20 are assembled. The assembly core 30 is manufactured by brazing and heating in the same manner as in the prior art. That is, the target heat exchanger is formed by brazing and heating the assembly core 30 obtained by assembling at least the fin member 10 and the heat transfer tube 20 at a predetermined temperature and time. At this time, the fin member 10 is joined to the heat transfer tube 20 from the form shown in FIG. 4 through the joint portion 41 in which the fillet 41a is formed by melting the brazing material 4 constituting the fin member 10 as shown in FIG. Then, the heat exchanger 40 is fixed and an integral heat exchanger 40 is formed. Further, when the brazing material 4 is melted by the brazing heating, the fins 18 substantially composed of the core material 2 and the sacrificial anode material 6 are formed in a state where they are erected with respect to the heat transfer tube 20. Will be. In this case, the brazing heating temperature is generally about 590 to 605 ° C., and the brazing heating time is about 1 to 10 minutes. Furthermore, an inert gas atmosphere such as a nitrogen gas atmosphere, a helium gas atmosphere, or an argon gas atmosphere is adopted as the atmosphere during brazing heating.

  Thus, when manufacturing a plate fin type heat exchanger, the shape of the fin is basically a plate shape. In the plate-like fin, for example, a brazing fin material made of an aluminum alloy is provided with an inner wall called a fin collar at a portion where the heat transfer tube is disposed, and a plurality of through holes are opened (FIG. 2). Reference) and a flat portion between the through-holes are manufactured by providing a plurality of slits for promoting air turbulence. At this time, the front end of the collar is formed to have a predetermined height or is flared and expanded. And, in order to braze and join the heat transfer tube and the plate-like fin, the surface on the brazing material side of the plate-like fin is the inner surface side of the collar, that is, the surface in contact with the heat transfer tube (see FIG. 4). A strong metal bond is obtained (see FIG. 5), the heat transfer performance between the refrigerant and the air is increased, and the strength as a heat exchanger is also improved. As the heat transfer tube, a conventionally used copper tube or the like can be used in addition to the exemplified aluminum tube. Then, a large number of plate-like fins are stacked at intervals, the heat transfer tubes are inserted through the through holes, the fins and the heat transfer tubes are assembled, and other members are assembled as necessary. (See FIG. 3). The assembly is then brazed and heated to produce the intended plate fin heat exchanger.

  In the present invention, the heat transfer tube is made of pure aluminum having an aluminum content of 99.0% by mass or more, JIS A3003 alloy, and pure aluminum containing Cu and Mn in an amount of 0.1 to 0.00. An aluminum alloy added with about 5% by mass is preferably employed. Moreover, the coating film which has a Zn component is provided to the surface of such a heat exchanger tube, and provision of the coating film which has this Zn component will be implemented by thermal spraying, a clad, or painting. Furthermore, a well-known thing, such as a flat multi-hole tube and a round tube, will be employ | adopted for a heat exchanger tube.

  And, in the aluminum heat exchanger obtained by brazing the fin member obtained by processing the brazing fin material made of aluminum alloy according to the present invention and the aluminum heat transfer tube obtained as described above, The natural potential of the surface of the fin formed from the brazing fin material (fin member), the natural potential of the surface of the joint between such a fin and the aluminum heat transfer tube, and the natural potential of the surface of the aluminum heat transfer tube However, in order of fin surface <joint surface <heat transfer tube surface or in order of fin surface <heat transfer tube surface <joint surface, the corrosion resistance of the heat exchanger is advantageously enhanced. You will get.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying. In addition to the following examples, in addition to the specific description described above, the present invention includes various changes, modifications, and modifications based on the knowledge of the parties without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

(1) Production of brazing fin material Various known aluminum alloys for core materials having the alloy composition shown in Table 1 below, various aluminum alloys for brazing material having the alloy composition shown in Table 2 below, and Ingots of various aluminum alloys for sacrificial anode materials having the alloy compositions shown in Table 3 were cast. Of these ingots, the aluminum alloy ingot for the core material and the aluminum alloy ingot for the sacrificial anode material were each subjected to a homogenization treatment. Thereafter, the homogenized aluminum alloy ingot for sacrificial anode material is hot-rolled together with the aluminum alloy ingot for brazing material, respectively, and is heated to a predetermined thickness (2 to 6 mm). A rolled plate was obtained. Subsequently, the obtained aluminum alloy for brazing material No. And aluminum alloy No. for sacrificial anode material (sacrificial material). Together with the hot-rolled plate of the brazing material symbol and the sacrificial material symbol respectively corresponding to the aluminum alloy No. In the various combinations shown in Tables 4 to 6 below, a hot rolled sheet for brazing material is placed on one side of the homogenization material for core material using the homogenization material for core material having a core material symbol corresponding to Overlap, on the other side, a hot rolled plate for sacrificial material is overlapped to make a laminated material, and the laminated material is hot-rolled (clad rolled) to obtain various clad materials having a three-layer structure. Obtained. Thereafter, the clad materials are cold-rolled, intermediate-annealed, and cold-rolled, respectively, to obtain a plate material (H14) having a thickness of 0.1 mm, and finally, the structure as shown in FIG. Various brazing fin materials: X1 to X56 and Y1 to Y26 were produced. The clad ratio of each member in each of the obtained brazing fin materials was such that the core material was 0.06 mm, the sacrificial anode material was 0.02 mm, and the brazing material was 0.02 mm.

(2) Production of assembly core Various brazing fin materials obtained above were press-molded to produce various plate fin members 10 having assembly holes 14 as shown in FIG. Each of the plate fin members 10 had a width of 20 mm and a length of 100 mm, and the assembly holes 14 had a width of 17 mm and a length of 2 mm and were provided at a pitch of 10 mm. Next, the plate fin member obtained above was used by using a heat transfer tube comprising a flat multi-hole tube 20 made of pure aluminum and having a coating with a Zn component of 8 g / m ² attached to the surface by Zn spraying. An assembly core 30 as shown in FIG. 3 having a size of 100 mm × 100 mm was produced by inserting and assembling 10 into a group of fins laminated at a pitch of 1.5 mm. Note that the plate fin member 10 has a flat flat shape in a form in which the collar 16 is formed at the time of pressing so that the surface on the brazing material 4 side contacts the flat multi-hole tube 20 as shown in FIG. The hole tube 20 was assembled.

  Thereafter, a known fluoride-based flux is sprayed onto the assembled core 30 and then heated to 600 ° C. (maximum temperature reached) in an inert atmosphere and held at 600 ° C. for 3 minutes, followed by brazing heating As shown in FIG. 5, the fin 18, which is substantially composed of the core material 2 and the sacrificial anode material 6, forms a fillet 41 a between the flat multi-hole tube 20 and the molten brazing material 4. On the other hand, an assembly core was integrally brazed through the joint 41. In addition, the core preparation examples: X1 to X56 and Y1 to Y26 shown in Tables 7 to 9 are respectively matched with the symbols of the fin material used. For example, in the core preparation example X1, the fin material It is shown that an assembly core is manufactured using X1.

(3) Measurement of natural potential About the assembly core (heat exchanger 40) after the various brazing heating obtained above, after cooling, as shown in FIG. Surface 42, brazing material (4) arrangement side surface 43, surface (fillet surface) 44 of joint 41 between fin 18 and heat transfer tube (flat multi-hole tube 20), and heat transfer tube (flat multi-hole tube 20) The respective natural potentials of the surface 45 were measured, and the results are shown in Tables 7 to 9 below.

  In measuring the natural potential, first, a test material masked with a silicon sealant in a form in which only the measurement site of the core (40) after brazing heating is exposed, is a sample for measuring natural potential. It was. Acetic acid is added to a 5% NaCl aqueous solution, and the above-mentioned sample for measuring natural potential is immersed in a measurement solution prepared to pH 3 and kept at room temperature for 24 hours, and then measured using a potentiostat. Measurements were made on the parts (fin brazing material side, fin sacrificial material side, fillet and heat transfer tube surface), and the average value of data collected every 10 minutes was taken as the value of the natural potential of each part. The potentiostat used was HAL-3001 manufactured by Hokuto Denko Corporation.

(4) SWAAT corrosion test For various cores (40) obtained by brazing and heating according to various core production examples, the openings (refrigerant inlet / outlet) of each flat multi-hole tube 20 were masked with silicon sealant. Thereafter, a SWAAT corrosion test for 500 hours was performed by a method based on the ASTM standard (G85 A3). And after such a corrosion test, after removing a corrosion product with phosphoric acid chromic acid and making it dry, the joining state of the fin 18 and the flat multi-hole tube 20 was observed and evaluated. Regarding the bonding state between the fin 18 and the flat multi-hole tube 20 after the SWAAT test, the bonding area of the core that has not been subjected to the corrosion test and the remaining bonding area of the core that has been subjected to the corrosion test Was measured by image analysis, and the bonding area remaining rate was determined. The bonding area was determined as the bonding area where the number of plate fins 10 was 20 pieces. Further, when the residual ratio of the bonding area is 80% or more, “◎”, 60% or more and less than 80% “◯”, 20% or more and less than 60% “Δ”, and less than 20% “×”, this SWAAT corrosion The joining state after the test was evaluated. In addition, the evaluation of the brazing property indicating the brazed joint state of the core is made by visually confirming the presence or absence of the unjoined portion, and setting the one without the unjoined portion as “O”, When defects such as fin melting occurred, this was indicated. The evaluation results are shown in Tables 7 to 9 below.

(5) Characteristic evaluation of the fin material (1) About the various brazing fin materials obtained in the production of the brazing fin material, each of them is cut into a size of width: 100 mm and length: 300 mm. A heat treatment corresponding to brazing was performed. That is, a heat treatment was carried out by hanging the fin material cut to a predetermined size in a brazing furnace and heating it to 600 ° C. (maximum temperature reached) in an inert atmosphere. And the No. 5 test piece of JIS-Z2201 was produced from the fin material after this heat treatment, and a tensile test was performed at room temperature according to JIS-Z2241, and the results are shown in Tables 7 to 9 below. In the production of each brazing fin material, “○” is indicated when a fin material capable of brazing heating is obtained, and “△” is indicated when a problem occurs in brazing property, and the fin material cannot be produced. When it became, it was set as "x" and the possibility of manufacture was evaluated and the result was combined with following Table 7-Table 9, and was shown.

  As is clear from the results of Tables 7 to 9, all of the core production examples X1 to X56 in which the assembled cores are produced using the brazing fin materials X1 to X56 according to the present invention are brazed. Manufacturing as a fin material is advantageously realized, the tensile strength after brazing is sufficient, the brazing property is also good, and the state of fin bonding after 500 hours of SWAAT test is also good. It is recognized that And also about the natural potential in the assembly core (heat exchanger 40) obtained by brazing heating, the natural potential of the sacrificial material side surface 42 and the brazing material side surface 43 of the fin 18 is the lowest, and then basically It is recognized that the result that the potential becomes noble in the order of the surface 44 of the fillet 41a and the tube surface which is the surface of the flat multi-hole tube 20 can provide excellent corrosion resistance. It was.

On the other hand, when trying to manufacture brazing fin materials Y1 to Y26 in the clad configuration shown in Table 6 that is outside the scope of the present invention, various problems were caused in the manufacturing and the obtained results were obtained. It has been clarified that the following various problems occur in the core manufacturing examples Y1 to Y26 in which the respective cores are manufactured using the fin material.
That is, in the core production example Y1, since the Mn amount of the core material is small, the fin strength is lowered, the fin is deformed when the core is assembled, and the joint is buckled after brazing heating. Further, in the core production example Y3, since the amount of Zn in the core material is large, the amount of Zn diffusing into the brazing material increases, the junction potential becomes lower than that of the fin material, and the bonding area ratio after the SWAAT test decreases. . Furthermore, in the core production example Y4, since the amount of Cu in the core material is large, the potential of the fin surface became nobler than the potential of the joint, and the joint area ratio after the SWAAT test decreased. In the core production example Y5, the core material has a large amount of Si, and in the core production example Y10, the core material has a large amount of Ni, the core material crystal grains are refined, and the brazing material penetrates into the core material, so that the fins are seated. Bowed. Further, in the core production example Y6, since the amount of Fe in the core material is large, the crystal grains of the core material are refined and the brazing material penetrates into the core material, so that the fin is buckled. Further, in the core production example Y7, the amount of Mg in the core material is large, the melting point of the core material is lowered, and the problem that the fin melts during brazing heating is caused. In addition, the core production example Y2 has a large amount of Mn in the core material, the core production example Y8 has a large amount of Cr in the core material, the core production example Y9 has a large amount of Zr in the core material, and the core production example Y11. In No. 1, since the amount of Ti in the core material is large, cracks occurred during rolling, and a sound plate material could not be obtained.

  Further, in the core manufacturing example Y12, since the amount of Si in the brazing material is small, a sufficient brazing joint cannot be obtained, and in the core manufacturing example Y13, the amount of Si in the brazing material is too large. Caused the problem of melting. Further, in the core production example Y14, there is a problem that the amount of Zn in the brazing material is large, the potential of the joint portion is lower than the potential of the fin material, and the joint area ratio after the SWAAT test is lowered. Causes a problem that the amount of Cu in the brazing material is small, the junction potential is lower than the potential of the fin material, and the bonding area ratio after the SWAAT test is lowered. On the other hand, in the core production example Y16, It was found that the bonding area ratio after the SWAAT test was lowered by the amount of Cu being large and the potential of the fin being nominated more than the tube surface potential and preferentially corroding from the tube surface. In addition, in the core production example Y17, the amount of Sr of the brazing material was large, cracking occurred during rolling, and a sound plate material could not be produced.

  Furthermore, in the core production example Y18, there is a problem that the Zn of the sacrificial anode material is small, the junction potential becomes lower than the fin potential, and the junction area ratio after the SWAAT test is lowered, while in the core production example Y19 Since the sacrificial anode material has a large amount of Zn, the bonding portion becomes lower than the fin potential, causing a problem that the bonding area ratio after the SWAAT test is lowered. Further, in the core production example Y20, there is a problem that the amount of Cu in the sacrificial anode material is large, so that the bonding site is lower than the fin potential, and the bonding area ratio after the SWAAT test is also reduced. Has a large amount of Si in the sacrificial anode material, which increases the amount of Si diffused into the core material, causing the problem of fin melting during brazing. Furthermore, in the core production example Y22, the amount of Fe in the sacrificial anode material was large, and therefore, the bonding site became lower than the fin potential, and the bonding area ratio after the SWAAT test also decreased. In addition, in the core manufacturing example Y23, the Mn amount of the sacrificial anode material is large, in the core manufacturing example Y24, the Ti amount of the sacrificial anode material is large, and in the core manufacturing example Y25, the Sn amount of the sacrificial anode material. Furthermore, in the core preparation example Y26, since the amount of In in the sacrificial anode material was large, cracking occurred during rolling, and a good plate material could not be obtained.

2 Core material 4 Brazing material 6 Sacrificial anode material 8 Brazing fin material 10 Fin member 12 Fin body 14 Assembly hole 16 Collar portion 18 Fin 20 Flat multi-hole tube 22 Refrigerant flow channel 30 Assembly core 40 Heat exchanger 41 Joint portion 41a Fillet 42 Sacrificial material side surface 43 Brazing material side surface 44 Joint surface 45 Heat transfer tube surface

Claims (7)

  It is a brazing fin material for a heat exchanger in which an Al—Si brazing material is clad on one surface of a core material and an Al—Zn based sacrificial anode material is clad on the other surface of the core material. The core material contains Mn: 0.5 to 2.0% by mass and Zn: 0.1% by mass or less, and the balance is made of an aluminum alloy composed of Al and inevitable impurities, and the brazing material is Si: 6.5 to 12.5% by mass, Zn: 0.1% by mass or less and Cu: 0.001 to 0.5% by mass, with the balance being made of an aluminum alloy consisting of Al and inevitable impurities In addition, the sacrificial anode material contains Zn: 7 to 15% by mass, and the balance is made of an aluminum alloy composed of Al and inevitable impurities. Down material.   2. The heat according to claim 1, wherein the core material further contains Cu: 0.1% by mass or less, and the sacrificial anode material further contains Cu: 0.1% by mass or less. Aluminum alloy brazing fin material for exchangers.   The said sacrificial anode material contains Si: 8 mass% or less further, The brazing fin material made from aluminum alloy for heat exchangers of Claim 1 or Claim 2 characterized by the above-mentioned.   The brazing fin material for an aluminum alloy for a heat exchanger according to any one of claims 1 to 3, wherein the brazing material further contains Sr: 0.1 mass% or less.   The core material is further Si: 1.5 mass% or less, Fe: 0.5 mass% or less, Mg: 1.0 mass% or less, Cr: 0.3 mass% or less, Zr: 0.3 mass% or less Ni: 1.5% by mass or less, and the sacrificial anode material further comprises Mn: 2.0% by mass or less and Fe: 1.0% by mass or less. The brazing fin material made of aluminum alloy for a heat exchanger according to any one of claims 1 to 4, wherein one or two of them are contained.   The core material further contains Ti: 0.3% by mass or less, and the sacrificial anode material further contains Ti: 0.35% by mass or less, Sn: 0.05% by mass or less, and In: 0.00%. The brazing fin material made of aluminum alloy for a heat exchanger according to any one of claims 1 to 5, wherein one or more of 05 mass% or less is contained.   An aluminum heat exchanger obtained by brazing a fin member obtained by molding the aluminum alloy brazing fin material for heat exchanger according to any one of claims 1 to 6 and an aluminum heat transfer tube. The natural potential of the fin surface of the heat exchanger, the natural potential of the surface of the joint between the fin and the aluminum heat transfer tube, and the natural potential of the surface of the aluminum heat transfer tube are expressed as follows: fin surface <joint surface < An aluminum heat exchanger characterized by being noble in the order of the heat transfer tube surface, or in the order of fin surface <heat transfer tube surface <joint surface.

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