WO2018047970A1

WO2018047970A1 - Precoated fin material and heat exchanger using same

Info

Publication number: WO2018047970A1
Application number: PCT/JP2017/032782
Authority: WO
Inventors: 幸平塩見; 涼子藤村; 貴彦水田
Original assignee: 株式会社Uacj
Priority date: 2016-09-12
Filing date: 2017-09-12
Publication date: 2018-03-15
Also published as: JP2018044693A; JP7096638B2

Abstract

Provided are: a precoated fin material which has excellent hydrophilicity sustainability for fins, and which enables a fin and an aluminum pipe to be bonded with each other without separately supplying a brazing material thereto, thereby enabling the production of a heat exchanger that has excellent bonding properties; and a heat exchanger which uses this precoated fin material. A precoated fin material (1) which comprises a brazing sheet (11) and a coating film (12) that is formed on the surface of the brazing sheet (11); and a heat exchanger comprising a fin that is formed from this precoated fin material (1). The brazing sheet (11) comprises: a core material (111) that is formed from an aluminum alloy; and a brazing material (112) that is laminated on the core material (11). The brazing material (112) has a chemical composition that contains 5-10% by mass of Si, with the balance being made up of Al and unavoidable impurities. The amount of Si in the coating film (12) is 10-300 mg/m².

Description

Pre-coated fin material and heat exchanger using the same

The present invention relates to, for example, a precoated fin material having a brazing sheet and a coating film, and a heat exchanger using the same.

Generally, an all-aluminum heat exchanger has an aluminum tube through which a refrigerant flows and an aluminum fin for exchanging heat between air outside the tube, and the tube and the fin are joined to each other. ing. Since the hydrophilicity of the fin greatly affects the heat exchange performance of the heat exchanger, a fin having a hydrophilic coating film formed on the surface is often used. For joining the fin and the pipe having such a hydrophilic coating film, a method of mechanically joining the two by expanding the pipe inserted into the hole provided in the fin (patent) Reference 1 and Patent Reference 2).

As a joining method, in addition to the above-described mechanical joining, brazing joining is assumed. However, since a general resin-based or inorganic coating film is altered or decomposed at the heating temperature at the time of brazing, it cannot sufficiently exhibit hydrophilicity after brazing. Further, when flux is used for brazing, the flux action is hindered by the presence of the coating film, and brazing joining may be insufficient. Therefore, when manufacturing a heat exchanger by brazing, the coating film is generally formed after brazing (refer patent document 3). However, in this case, there is a problem that the manufacturing cost increases because a dedicated coating film forming facility is required. In this case, it is difficult to cope with an increase in the size of the heat exchanger.

Therefore, a fin material having a coating film mainly composed of silicate has been proposed as a fin material having a coating film pre-coated before brazing (see Patent Document 4). Further, in the production of a heat exchanger, a method for producing a fin in which a film containing a support such as xylene or a silicon-based binder such as silicone oil is formed before brazing has been proposed (Patent Document 5). reference).

JP-A-4-278189 JP 2012-052747 A JP 2004-347314 A JP 2013-137153 A Special table 2008-508103 gazette

However, fin films pre-coated with conventional coatings and films have insufficient hydrophilic sustainability after brazing and insufficient brazing function. That is, the conventional fin material did not have excellent hydrophilic sustainability and excellent brazing function. Therefore, it is necessary to supply a brazing material separately when manufacturing the heat exchanger using the fin material. As a result, a decrease in manufacturability due to an increase in the manufacturing process and an increase in manufacturing cost due to member procurement are expected. In addition, the pre-coated coating film or coating film adversely affects the brazing joint between the fin using the brazing material and the aluminum tube, and there is a possibility that the joining property is insufficient. Therefore, development of a pre-coated fin material that can maintain a superior hydrophilic sustainability and can produce a heat exchanger that can be joined without using a brazing material and has excellent joining properties between the fin and the aluminum tube. Is desired.

The present invention has been made in view of such a background, and is excellent in the hydrophilic sustainability of the fins, can be joined between the fins and the aluminum pipe without separately supplying a brazing material, and has excellent joining properties. An object of the present invention is to provide a pre-coated fin material capable of producing an exchanger, and a heat exchanger using the pre-coated fin material.

One aspect of the present invention is a brazing sheet having a core material made of an aluminum alloy, and a brazing material laminated on the core material,
A coating film formed on the surface of the brazing sheet,
The brazing material contains Si: 5 to 10% by mass, and the balance has a chemical component consisting of Al and inevitable impurities,
The pre-coated fin material has a Si content in the coating film of 10 to 300 mg / m ² .

Another aspect of the present invention resides in a heat exchanger having a core portion made of a fin made of the pre-coated fin material and an aluminum tube joined to the fin.

The pre-coated fin material has a brazing sheet having a core material made of an aluminum alloy and a brazing material laminated on the core material, wherein the brazing material contains Si in the specific range, with the balance being Al and inevitable impurities. It has a chemical component consisting of Therefore, the pre-coated fin material can be joined to another member such as an aluminum tube by the brazing material laminated on the core material. Therefore, it is possible to join without using a separate joining member such as a brazing material, and it is possible to ensure sufficient joining properties. Furthermore, since it is possible to join without separately using a joining member such as a brazing material, it is possible to prevent an increase in the manufacturing process, and it is not necessary to procure a joining member separately, thereby meeting the demand for cost reduction. Moreover, the brazing material having the specific composition can prevent the performance of the coating film formed on the brazing sheet from being impaired.

In addition, the coating film in which the Si amount is adjusted as described above is unlikely to deteriorate in coating film performance due to heating or the like. Therefore, the coating film can exhibit excellent hydrophilicity even after heating at the time of joining with another member such as an aluminum tube, and can maintain the initial excellent hydrophilicity for a long period of time. Moreover, a coating film hardly inhibits joining with other aluminum members, such as an aluminum pipe, and a precoat fin material, for example. Therefore, although the said precoat fin material has a coating film, sufficient joining with an aluminum pipe, for example is possible.

Thus, in the pre-coated fin material, the components of the coating film and the brazing material are optimized as described above. Therefore, it is possible to manufacture a heat exchanger that is excellent in hydrophilic sustainability of the fins, can join the fins to the aluminum pipe without separately supplying a brazing material, and has excellent joining properties.

Moreover, the said heat exchanger has a core part which consists of the fin which consists of a precoat fin material excellent in the above-mentioned hydrophilic sustainability and joining property, and the aluminum pipe joined to the fin.
Therefore, in the heat exchanger, since fins exhibit excellent hydrophilic sustainability, an increase in ventilation resistance can be suppressed, and good heat exchange performance can be stably exhibited for a long period of time. Further, in the heat exchanger, for example, an aluminum tube and a fin are sufficiently joined, so that the heat exchange performance between the aluminum tube and the fin is improved.

Sectional drawing of the precoat fin material in Example 1. FIG. The perspective view of the core part (specifically minicore) of the heat exchanger in Example 1. FIG. Sectional drawing of the core part (specifically minicore) of the heat exchanger in Example 1. FIG. The expanded sectional view of the fin of the heat exchanger in Example 1. FIG. The fragmentary sectional view of the contact part of the fin and aluminum pipe before joining in Example 1. FIG. The front view of the heat exchanger in Example 2. FIG. The perspective view of the principal part of the heat exchanger in Example 3. FIG. The partial expanded sectional view of the contact part vicinity in FIG. FIG. 8 is a cross-sectional view taken along line III-III in FIG.

The pre-coated fin material is used for joining a fin made of the pre-coated fin material and an aluminum tube to obtain a heat exchanger. In the present specification, the “aluminum tube” is a concept including not only a pure aluminum tube but also an aluminum alloy tube. Specifically, A1000 series pure aluminum, A3000 series aluminum alloy, or the like can be used.

The pre-coated fin material has a brazing sheet having a core material made of an aluminum alloy and a brazing material laminated on the core material. The brazing sheet is, for example, a clad material, and an aluminum alloy (ie, core material) is clad with an Al—Si alloy (ie, brazing material). The thickness of the brazing sheet is preferably, for example, 0.15 mm or less from the viewpoint that the precoat fin material is used for fins that require heat exchange performance. In addition, the thickness of the brazing sheet is, for example, from the viewpoint that the fin material remains large even when the corrosion rate is high, and the sacrificial anode effect continues for a certain period of time, so corrosion resistance is not a problem. 0.05 mm or more is preferable.

The chemical component of the core aluminum alloy is selected from the group consisting of Si, Fe, Mn, Zn, Mg, Cu, In, Sn, Ti, V, Zr, Cr, and Ni in addition to Al and inevitable impurities. At least one additional element can be further contained.

The chemical composition of the core aluminum alloy contains, for example, Si: 0.05 to 0.8 mass%, Fe: 0.05 to 0.8 mass%, and Mn: 0.8 to 2 mass%, with the balance being It preferably consists of Al and inevitable impurities. When the Mn content of the core exceeds the above range, coarse crystallized products are generated during casting, rolling workability is impaired, and the production of the clad material tends to be difficult.

Si in the core material forms fine precipitates with other additive elements such as Mn or Fe, improving the strength of the core material, and reducing the solid solution amount of Mn to reduce thermal conductivity (electrical conductivity). To improve. The Si content of the core material is preferably 0.05 to 0.8% by mass as described above. When the Si content is less than 0.05% by mass, the effect of addition becomes insufficient. When the Si content exceeds 0.8% by mass, the melting point of the core material is lowered, and deformation during brazing and local melting occur. It tends to occur. From the viewpoint of sufficiently obtaining the effect of addition of Si and sufficiently preventing deformation and local melting, the Si content is more preferably 0.1 to 0.8% by mass, and still more preferably 0.3 to 0%. 0.5% by mass.

Fe in the core material coexists with Mn and improves the strength of the fin material before and after brazing. The Fe content of the core material is preferably 0.05 to 0.8% by mass as described above. If the Fe content of the core material is less than 0.05% by mass, the effect of addition becomes insufficient, and if it exceeds 0.8% by mass, the crystal grains become fine and the molten brazing core material It becomes easy to erode inside, the high temperature buckling resistance tends to decrease, and the self corrosion property tends to increase. From the viewpoint of sufficiently obtaining the effect of addition of Fe, further suppressing the decrease in high-temperature buckling resistance and further suppressing the increase in self-corrosion, the Fe content is more preferably 0.1 to 0.00. It is 8% by mass, more preferably 0.3 to 0.5% by mass.

Mn in the core material functions to improve the strength of the core material and improve high temperature buckling resistance. The Mn content of the core material is preferably 0.8 to 2% by mass as described above. When the Mn content of the core material is less than 0.8% by mass, the effect of addition becomes insufficient, and when it exceeds 2% by mass, a coarse crystallized product is generated at the time of casting, and the rollability is low. The clad material is likely to be difficult to manufacture. From the viewpoint of sufficiently obtaining the addition effect of Mn and further suppressing the reduction in rolling workability, the Mn content is more preferably 0.9 to 2% by mass, and still more preferably 1 to 1.7% by mass. It is.

The core material may further contain Zn: 0.3 to 3% by mass. That is, the chemical component of the core aluminum alloy contains, for example, Si: 0.05 to 0.8 mass%, Fe: 0.05 to 0.8 mass%, Mn: 0.1 to 2 mass%, Further, Zn: 0.3 to 3% by mass, the balance being Al and inevitable impurities. Zn in the core material can lower the potential and increase the sacrificial anode effect, and can improve the corrosion resistance of the pre-coated fin material. When the Zn content of the core material is less than 0.3% by mass, the effect of addition becomes insufficient. When the Zn content exceeds 3% by mass, the self-corrosion resistance of the core material itself tends to be deteriorated, and it is susceptible to intergranular corrosion. It becomes easy to increase. From the viewpoint of sufficiently obtaining the effect of adding Zn and further improving the corrosion resistance, the Zn content of the core material is more preferably 1 to 2.5% by mass, and further preferably 2 to 2.3% by mass.

The core material may further contain at least one of Mg: 1 mass% or less and Cu: 0.5 mass% or less. That is, the chemical composition of the core aluminum alloy is, for example, Si: 0.05 to 0.8 mass%, Fe: 0.05 to 0.8 mass%, Mn: 0.1 to 2 mass%, Zn: 0 3 to 6% by mass, further containing at least one of Mg: 1% by mass or less and Cu: 0.5% by mass or less, with the balance being Al and inevitable impurities.

Mg in the core material improves the strength of the fin material before and after brazing by forming precipitates with Si. The content of Mg in the core material is preferably 1% by mass or less as described above. When the Mg content exceeds 1% by mass, the melting point of the core material is lowered, and deformation during brazing and local melting are likely to occur. From the viewpoint of sufficiently obtaining the effect of adding Mg, the content of Mg in the core material is more preferably 0.05 to 1% by mass, still more preferably 0.3 to 1% by mass.

Cu in the core material improves the strength of the fin material before and after brazing, but reduces intergranular corrosion resistance. The Cu content in the core material is preferably 0.5% by mass or less as described above. When the Cu content exceeds 0.5% by mass, the potential of the fin material becomes noble and the sacrificial anode effect of the fin material tends to decrease, and the intergranular corrosion resistance also tends to decrease. From the viewpoint of sufficiently obtaining the effect of adding Cu, the content of Cu in the core material is more preferably 0.05 to 0.5% by mass.

The core material can further contain at least one of In: 0.3 mass% or less and Sn: 0.3 mass% or less. That is, the chemical composition of the core aluminum alloy is, for example, Si: 0.05 to 0.8 mass%, Fe: 0.05 to 0.8 mass%, Mn: 0.1 to 2 mass%, Zn: 0 3 to 6% by mass, further containing In: 0.3% by mass or less and Sn: 0.3% by mass, with the balance being Al and inevitable impurities.

Sn in the core material lowers the surface potential and lowers the potential to increase the sacrificial anode effect. The Sn content of the core material is preferably 0.3% by mass or less as described above. When the Sn content of the core material exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of sufficiently obtaining the effect of adding Sn, the Sn content of the core material is more preferably 0.005 to 0.3% by mass.

In in the core material lowers the surface potential and lowers the potential to increase the sacrificial anode effect. The In content of the core material is preferably 0.3% by mass or less as described above. When the In content exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of obtaining a sufficient effect of adding In, the In content of the core material is more preferably 0.005 to 0.3% by mass.

The core material is further selected from Ti: 0.3 mass% or less, V: 0.3 mass% or less, Zr: 0.3 mass% or less, Cr: 0.3 mass% or less, and Ni: 2 mass% or less. At least one kind can be contained. That is, the chemical composition of the core aluminum alloy is, for example, Si: 0.05 to 0.8 mass%, Fe: 0.05 to 0.8 mass%, Mn: 0.1 to 2 mass%, Zn: 0 3 to 6% by mass, Ti: 0.3% by mass or less, V: 0.3% by mass or less, Zr: 0.3% by mass or less, Cr: 0.3% by mass or less, and Ni: It contains at least one selected from 2% by mass or less, and the balance is Al and inevitable impurities.

Ti in the core material mitigates local corrosion by using the corrosion of the fin material before brazing and after brazing as a layered corrosion form. Moreover, Ti improves the strength of the fin material before and after brazing and improves high temperature buckling. The Ti content of the core material is preferably 0.3% by mass or less as described above. When the Ti content of the core material exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of sufficiently obtaining the effect of adding Ti, the Ti content of the core material is more preferably 0.01 to 0.3% by mass.

V in the core material is dissolved in the matrix of the aluminum alloy structure to improve the strength, and is also distributed in layers to prevent the progress of corrosion in the thickness direction. Further, V improves the strength of the fin material before and after brazing and improves high temperature buckling. The V content of the core material is preferably 0.3% by mass or less as described above. When the V content of the core material exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of sufficiently obtaining the effect of adding V, the V content of the core material is more preferably 0.01 to 0.3% by mass.

Zr in the core material improves the strength of the fin material before and after brazing and improves the high temperature buckling. The Zr content of the core material is preferably 0.3% by mass or less as described above. When the Zr content of the core material exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of obtaining a sufficient effect of adding Zr, the Zr content of the core material is more preferably 0.01 to 0.3% by mass.

Cr in the core material improves the strength of the fin material before and after brazing and improves the high temperature buckling. The Cr content of the core material is preferably 0.3% by mass or less as described above. When the Cr content of the core material exceeds 0.3% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of sufficiently obtaining the effect of addition of Cr, the content of Cr in the core material is more preferably 0.01 to 0.3% by mass.

Ni in the core material improves the strength of the fin material before and after brazing. The Ni content of the core material is preferably 2% by mass or less as described above. When the Ni content of the core material exceeds 2% by mass, the crystal grains become fine, and the molten brazing is likely to erode in the core material, high temperature buckling resistance is likely to decrease, and self-corrosion property is likely to increase. Become. From the viewpoint of sufficiently obtaining the effect of adding Ni, the Ni content in the core material is more preferably 0.05 to 2% by mass, still more preferably 0.1 to 2% by mass.

The brazing material contains Si: 5 to 10% by mass, and the balance has chemical components composed of Al and inevitable impurities. Si in the brazing material contributes to bonding by increasing the flowability of the molten brazing during brazing heating. When the Si content of the brazing material is less than 5% by mass, the effect of addition becomes insufficient. When the Si content exceeds 10% by mass, the molten brazing becomes excessive, and the coating is washed away by the molten brazing and becomes hydrophilic. Sustainability decreases. From the viewpoint of obtaining a sufficient effect of adding Si and further suppressing the decrease in hydrophilic sustainability, the brazing filler metal content is more preferably 7 to 9% by mass.

The brazing material can further contain Sr: 0.1% by mass or less. That is, the chemical component of the aluminum alloy of the brazing material contains, for example, Si: 5 to 10% by mass, further contains Sr: 0.1% by mass or less, and the balance is Al and inevitable impurities.

Sr in the brazing material reduces the Si particle diameter in the brazing material after brazing. The Sr content of the brazing material is preferably 0.1% by mass or less as described above. When the Sr content of the brazing material exceeds 0.1% by mass, a coarse crystallized product is generated at the time of casting, and the rolling processability is liable to be impaired, and the production of the plate material is likely to be difficult. From the viewpoint of sufficiently obtaining the effect of adding Sr, the content of Sr in the brazing material is more preferably 0.001 to 0.1% by mass.

The brazing material can further contain at least one of Zn: 0.3% by mass or less and Cu: 0.3% by mass or less. That is, the chemical components of the brazing aluminum alloy include, for example, Si: 5 to 10 mass%, Sr: 0.1 mass% or less, Zn: 0.3 mass% or less, and Cu: 0.3 mass%. It contains at least one of mass% or less, and the balance is Al and inevitable impurities.

Zn in the brazing material functions to enhance the sacrificial anode effect. The Zn content of the brazing material is preferably 0.3% by mass or less as described above. When the Zn content of the brazing material exceeds 0.3% by mass, the workability at the time of production tends to be lowered, and the natural potential becomes base and the self-corrosion property tends to increase. From the viewpoint of obtaining a sufficient effect of adding Zn, the content of Zn in the brazing material is more preferably 0.05 to 0.3% by mass.

Cu in the brazing material improves the corrosion resistance of the joint by making the potential of the fillet after brazing noble. The Cu content of the brazing material is preferably 0.3% by mass or less as described above. When the Cu content of the brazing material exceeds 0.3% by mass, the potential of the fin material becomes noble and the sacrificial anode effect of the fin tends to decrease. From the viewpoint of sufficiently obtaining the Cu addition effect and further suppressing the decrease in the sacrificial anode effect of the fin, the Cu content in the brazing material is more preferably 0.05 to 0.3% by mass, and still more preferably. 0.1 to 0.2% by mass.

The thickness of the brazing material is appropriately selected depending on the Si content in the brazing material, the joining shape of the fin and the aluminum tube, the fin pitch, etc., and is preferably 7 μm or more, more preferably 7 to 30 μm.

In the brazing sheet, the brazing material may be clad only on one side of the core material, or may be clad on both sides. The clad rate of the brazing material is applicable as long as it is in a common sense range and is appropriately selected, but is preferably 3 to 25%. If the clad rate of the brazing material is less than the above range, the amount of the brazing material melted during brazing heating tends to be small, and a fillet may not be sufficiently formed. The core material may melt because there is too much brazing material.

The brazing sheet is obtained by cladding a brazing material on one or both sides of the core material. As a method of cladding the brazing material on the core material, an alloy ingot for the core material having the same composition as each element in the core material or the brazing material and an alloy ingot for the brazing material are cast, and then the alloy for the core material The ingot is homogenized according to the usual method for the ingot, the alloy ingot for the brazing material is hot-rolled, and then the ingot for the core material and the alloy ingot for the brazing material are subjected to the homogenization treatment. A hot rolled product is piled up and hot rolled to produce a clad plate. Thereafter, cold rolling is performed, intermediate annealing is performed as necessary, and finish cold rolling is performed to obtain a brazing sheet. After finishing cold rolling, it is cut into product widths to form a brazing sheet as a fin material. Before or after the strip cutting, the coating film described later can be formed on the brazing sheet.

Next, the coating film formed on the surface of the brazing sheet will be described.
The coating film may be formed on one side of the brazing sheet or may be formed on both sides. The coating film is formed of, for example, an oxide containing silicon (Si), a composite oxide, or the like, and contains Si. The amount of Si in the coating film is 10 to 300 mg / m ² . When the amount of Si is less than 10 mg / m ² , hydrophilic sustainability may be reduced. From the viewpoint of further suppressing the decrease in hydrophilic durability, the amount of Si in the coating film is more preferably 100 mg / m ² or more. On the other hand, when the amount of Si exceeds 300 mg / m ² , there is a possibility that the bondability at the time of brazing may be impaired by the coating film. In addition, Si amount is the amount per one side of the coating film. Further, when the Si amount in the coating film is 10 to 300 mg / m ² , the adhesion amount of the coating film is preferably 20 to 800 mg / m ² .

The coating film preferably contains at least one of silicate and amorphous silica. In this case, the hydrophilic durability of the coating film is further improved. From the viewpoint of further improving hydrophilic sustainability, the coating film more preferably contains at least silicate. Silicate is, for example, sodium silicate or lithium silicate. The coating film containing silicate can be formed by coating an aqueous solution containing silicate such as water glass on the surface of the brazing sheet and drying. From the viewpoint of further improving the hydrophilic sustainability, the silicate is more preferably derived from water glass.

Further, as the amorphous silica, for example, there is an aggregate formed by drying amorphous colloidal silica, and from the viewpoint that hydrophilic sustainability can be further improved, amorphous silica is derived from amorphous colloidal silica. It is preferable. The coating film containing amorphous silica can be formed by coating amorphous colloidal silica on the surface of the brazing sheet and drying. Moreover, a coating film containing amorphous silica and silicate is formed by coating a mixture of amorphous colloidal silica and an aqueous solution containing silicate on the surface of the brazing sheet and drying. Can do.

The coating film can further contain a fluoride flux. The fluoride flux content may be zero. The content of the fluoride flux is preferably 0 or more and 5000 mg / m ² or less. In this case, the flux effect can be obtained and the hydrophilic sustainability can be further improved. If the content of the fluoride flux is too small, the effect of adding the flux may not be sufficiently obtained. Therefore, the content of the fluoride flux is more preferably 40 mg / m ² or more, further preferably 500 mg / m ² or more, and further preferably 1000 mg / m ² or more. On the other hand, when there is too much content of fluoride flux, there exists a possibility that hydrophilic sustainability may fall. From the viewpoint of suppressing a decrease in hydrophilic durability, the content of the fluoride flux is preferably 5000 mg / m ² or less, more preferably 3000 mg / m ² or less, as described above, and 2000 mg / m ^2. More preferably, it is as follows. When the coating film contains fluoride flux in the above range, the coating amount is preferably 50 to 6000 mg / m ² .

As fluoride flux, KAlF ₄ , K ₂ AlF ₅ , K ₂ AlF ₅ .H ₂ O, K ₃ AlF ₆ , AlF ₃ , KZnF ₃ , K ₂ SiF ₆ , Cs ₃ AlF ₆ , CsAlF ₄ .2H ₂ O , Cs ₂ AlF ₅ .H ₂ O, and the like. When the coating film contains a fluoride flux, the coating film may have a Si content of 10 to 300 mg / m ² , and may be formed by a single layer containing a fluoride flux. May be formed of a laminate of a layer having a thickness of 10 to 300 mg / m ² and a layer mainly composed of fluoride flux. Specifically, in the case of a single layer, the coating film is formed of a layer containing, for example, at least one of silicate and amorphous silica and a fluoride flux. In the case of a laminate having a two-layer structure, the coating film is formed of, for example, a layer mainly containing at least one of silicate and amorphous silica and a layer mainly containing fluoride flux.

The coating film can further contain an organic resin. In this case, the coating property at the time of forming the coating film is improved. Moreover, it can prevent that Si components, such as a silicate and an amorphous silica, fall off from a coating film.

The organic resin is preferably made of a water-soluble acrylic resin and / or polyoxyethylene alkylene glycol (PAE). In this case, the organic resin is easily decomposed by heating at the time of bonding, for example, and the organic resin can be lost from the coating film. As a result, since the organic resin in the coating film after bonding decreases, it is possible to prevent the bondability from being inhibited by the organic resin.

Moreover, the precoat fin material may have a base treatment layer made of a chemical conversion film formed between the brazing sheet and the coating film. The base treatment layer made of the chemical conversion film can be formed by, for example, phosphoric acid chromate treatment, zirconium phosphate treatment, boehmite treatment, or the like. The ground treatment layer only needs to improve the adhesion between the brazing sheet and the coating film, and may be formed by other treatments.

In the heat exchanger, shapes such as insertion fins and corrugated fins can be adopted as the fins made of the pre-coated fin material. In order to improve the heat exchange performance, the fin material may have a slit.

The shape of the aluminum tube is not particularly limited as long as it is a refrigerant passage tube through which a refrigerant flows, and a round tube, a flat tube, or the like can be adopted. An inner column that divides the interior into a plurality of passages may be formed in the pipe. More specifically, for example, a flat multi-hole tube can be adopted as the aluminum tube. The aluminum tube may or may not have a brazing material clad on the surface.

Next, a method of joining the fin made of the pre-coated fin material and the aluminum tube will be described. In the joining, the joining ability of the brazing material laminated on the core material in the brazing sheet can be used without separately using the brazing material. Considering the use of heat exchangers as fins, it is desirable to avoid deformation of the fin material itself, and for this reason, the bonding heating conditions can be managed. The brazing heating temperature is, for example, 590 ° C. to 605 ° C., and the brazing heating time is, for example, 1 to 10 minutes. The atmosphere during brazing heating is an inert gas atmosphere such as a nitrogen gas atmosphere, a helium gas atmosphere, or an argon gas atmosphere.

As described above, the precoat fin material has a brazing material and a coating film on the core material. As described above, the coating film can be formed on the core material or can be formed on the brazing material. At the time of brazing heating, at least a part of the brazing material is softened or melted, and a fillet that contributes to joining can be formed at the contact portion with the aluminum tube. At this time, even if a coating film is formed on the brazing material, the fin of the heat exchanger can exhibit excellent hydrophilic sustainability. This is considered to be because even if the brazing material is softened or melted, Si components (silicate, amorphous silica, etc.) in the coating film are retained on the fin.

The heat exchanger has a core portion made of a fin made of a pre-coated fin material and an aluminum tube joined to the fin. Although the specific example of a heat exchanger is demonstrated using drawing in the below-mentioned Example, a heat exchanger is manufactured by attaching a header, a side support, an entrance / exit pipe | tube, etc. to a core part.

The heat exchanger can be used for an air conditioner and a refrigerator, for example. It can also be used for automobile condensers, evaporators, radiators, heaters, intercoolers, oil coolers, and the like. Furthermore, it can also be used for a cooling device for cooling a heating element such as an IGBT (Insulated Gate Bipolar Transistor) provided in an inverter unit for controlling a drive motor of a hybrid vehicle or an electric vehicle.

(Example 1)
This example is an example in which a plurality of pre-coated fin materials according to Examples and Comparative Examples are manufactured and their performances are compared. In this example, as shown in Tables 1 to 11 described later, a plurality of pre-coated fin materials (Sample E1-1 to Sample E9-2, Samples C1-1 to C9-2) are prepared. And using each of these precoat fin materials, the core part for heat exchangers is produced, and hydrophilicity sustainability and bondability are compared and evaluated. In this example, a test mini-core is manufactured as the core portion.

As illustrated in FIG. 1, the precoat fin material 1 has a brazing sheet 11 and a coating film 12 formed on the surface thereof. The brazing sheet 11 includes a core material 111 made of an aluminum alloy and a brazing material 112 formed on both surfaces of the core material 111. The coating film 12 is formed on both surfaces of the brazing sheet 11. Specifically, the coating film 12 is laminated on the brazing material 112 via a base treatment layer made of a chemical conversion film (not shown). Yes. The formation of the base treatment layer is optional and may not be formed.

The brazing filler metal 112 contains additive components (elements) shown in Table 1 to be described later, and the remainder has chemical components composed of Al and inevitable impurities. In this example, the brazing materials of Sample A1 to Sample A10 having different compositions shown in Table 1 are used. The core material 111 contains additive components (elements) shown in Table 2 to be described later, and the remainder has chemical components composed of Al and inevitable impurities. In this example, core materials of samples B1 to B34 having different compositions shown in Table 2 are used. The coating film 12 contains Si derived from lithium silicate in the contents shown in Tables 3 to 11 to be described later, and further contains a water-soluble acrylic resin in such an amount that the coating property can be improved. Moreover, in a part of the precoat fin material 1 produced in this example, the coating film 12 further contains a flux in an amount shown in a table described later.

As shown in FIGS. 2 and 3, the mini-core 2 has a fin 3 made of the pre-coated fin material 1 and an aluminum tube 4, and the corrugated fin 3 is sandwiched between the aluminum tubes 4. In FIG. 2, one of the two aluminum tubes 4 sandwiching the fin 3 is indicated by a broken line in order to clearly show the corrugated shape of the fin 2.

The fin 3 is made of a pre-coated fin material 1 formed into a corrugated shape. More specifically, as shown in FIG. 4, the fin 3 has a brazing sheet 11 composed of a core material 111 and a brazing material 112 formed on both surfaces thereof, and a coating film 12 formed on both surfaces thereof.

2 and 3, the aluminum tube 4 is a flat multi-hole tube made of an aluminum alloy. The aluminum tube 4 has a large number of refrigerant flow paths 411 for circulating the refrigerant. In the mini-core 2, the corrugated fin 3 is joined to the aluminum tube 4 at each vertex 30.

Hereinafter, a method for manufacturing the mini-core 1 of this example will be described. Specifically, first, by continuous casting, an aluminum alloy for core material having the composition shown in Table 2 and an aluminum alloy for brazing material having the composition shown in Table 1 are ingoted, and homogenized according to a conventional method, The aluminum alloy ingot for brazing material is further hot-rolled and clad at a ratio of 10% brazing filler metal on one side of the aluminum alloy ingot for core material, then hot-rolled, and then cold-rolled. After performing intermediate annealing, the brazing sheet 11 was manufactured through final cold rolling. Components other than the additive components shown in each table, that is, the balance is Al and inevitable impurities.

Next, a base treatment layer made of a chemical conversion film (not shown) was formed on both surfaces of the brazing sheet 11 by performing a base treatment. As the base treatment, phosphoric acid chromate treatment was performed. The thickness of the base treatment layer is, for example, about 1 μm.

Next, using a bar coater, a predetermined amount of water glass, a water-soluble acrylic resin, and a coating containing KAlF ₄ which is a fluoride flux added as needed is applied on the base treatment layer, and the temperature is 200 ° C. The coating film 12 was formed by drying with (refer FIG. 1). In this manner, precoated fin material 1 having coating film 12 containing water glass-derived Si at the contents shown in Tables 3 to 11 on brazing sheet 11 was produced. The coating film 12 was formed on both surfaces of the brazing sheet 11.

The amount of Si in the coating film 12 was measured by fluorescent X-ray analysis. The fluorescent X-ray analysis was performed using a ZSX Primus II manufactured by Rigaku under the conditions of atmosphere: vacuum, tube: Rh, output: 50 kV-60 mA. Quantification of Si in the coating film was performed by a calibration curve method using a standard Si sample.

Next, the pre-coated fin material 1 was processed into a corrugated shape. In this way, a corrugated fin 3 having the coating film 12 formed on both surfaces of the brazing sheet 11 was obtained (see FIGS. 2 to 4). These fins 3 are respectively used for manufacturing the mini-core 1.

Next, as the aluminum tube 4, a flat multi-hole tube made of 3000 series aluminum alloy was produced by extrusion (see FIGS. 2 and 3). A corrugated fin 3 was sandwiched between two aluminum tubes 4 to produce an assembly (see FIGS. 2 and 3). At this time, as shown in FIG. 5, each vertex 30 of the corrugated fin 3 and the aluminum tube 4 were brought into contact with each other. Next, the assembly was held in a furnace at a temperature of 600 ° C. in a nitrogen gas atmosphere for 3 minutes, and then cooled to room temperature (25 ° C.). The brazing filler metal 112 of the fin 3 softens or melts during heating in the furnace, and the brazing filler solidifies during cooling. By softening, melting, or solidifying the brazing material, each vertex 30 of the corrugated fin 3 and the aluminum tube 4 are joined at the contact portion (not shown). In this way, as illustrated in FIGS. 2 and 3, the mini-core 2 in which the fin 3 and the aluminum tube 4 are joined is obtained.

Next, the precoat fin material 1 and the mini-core 2 of each sample obtained as described above were evaluated for hydrophilic sustainability, bondability, strength, corrosion resistance, deformation rate, and manufacturability as follows. The results are shown in Tables 3 to 11.

<Hydrophilic sustainability>
The hydrophilic durability was evaluated using the precoated fin material of each sample. Each sample is heated under the assumption of fin bonding performed after the formation of the coating film. Specifically, the pre-coated fin material was heated for 3 minutes in a furnace having a temperature of 600 ° C. in a nitrogen gas atmosphere. Next, the pre-coated fin material was immersed in pure water for 2 minutes and then air-dried for 6 minutes. This cycle of immersion in pure water and air drying was repeated 300 times. Subsequently, the contact angle of the water droplet on the coating film of each test plate was measured. The contact angle was measured using a FACE automatic contact angle meter “CA-Z” manufactured by Kyowa Interface Chemical Co., Ltd. Specifically, a water drop was dropped on the coating film at room temperature, and the contact angle of the water drop after 30 seconds was measured. When the contact angle is less than 10 °, it is evaluated as “A”, when it is 10 ° or more and less than 20 °, it is evaluated as “B”, and when it is 20 ° or more and less than 30 °, it is evaluated as “C”. The case of 30 ° or more was evaluated as “D”.

<Jointability>
The joined portion in each mini-core after joining is cut with a cutter knife, and the value obtained by dividing the joining length L ₁ of the fin by the sum of the lengths L ₂ of the ridges of the fin (100/100) (L ₁ / L ₂ × 100) was defined as a bonding rate (%). The case where the joining rate is 90% or more is evaluated as “A”, the case where the joining rate is 80% or more and less than 90% is evaluated as “B”, and the case where the joining rate is 70% or more and less than 80%. The case was evaluated as “D”, and the case of less than 70% was evaluated as “D”.

<Strength>
The strength was measured by a tensile test using the precoated fin material of each sample. Each sample is heated under the assumption of fin bonding performed after the formation of the coating film. Specifically, the pre-coated fin material was heated for 3 minutes in a furnace having a temperature of 600 ° C. in a nitrogen gas atmosphere. The tensile test was carried out at room temperature according to JIS Z2241 (2011) under the conditions of a tensile speed of 10 mm / min and a gauge length of 50 mm for each sample.

<Corrosion resistance>
A CASS test was conducted for 500 hours to confirm the corrosion state of the fins. In the cross-sectional observation with an optical microscope, the case where the remaining amount of fin is 70% or more is evaluated as “A”, the case where it is 50% or more and less than 70% is evaluated as “B”, and the case where it is 30% or more and less than 50% Was evaluated as “C”, and the case of less than 30% was evaluated as “D”.

<Deformation rate>
The fin height of the mini-core before and after joining was measured and the deformation rate due to fin buckling was also evaluated. That is, the case where the ratio of the fin height change before and after joining to the fin height before joining is 5% or less is evaluated as “A”, and the case where it exceeds 5% and is 10% or less is evaluated as “B”. The case where it exceeded 10% and 15% or less was evaluated as “C”, and the case where it exceeded 15% was evaluated as “D”.

<Manufacturability>
When the aluminum alloy was rolled, for example, a case where surface cracking occurred and a good plate material could not be produced was evaluated as “x”, and a case where a good plate material could be produced was evaluated as “◯”. In addition, when the manufacturability was “x”, the other evaluations described above were omitted.

As shown in Tables 1 to 3, Sample E1-1 and Sample E1-2 are superior in hydrophilic sustainability and have a high bonding rate compared to Sample C1-1 and Sample C1-2. Therefore, in the pre-coated fin material 1 having the brazing sheet 11 and the coating film 12, the brazing material 112 of the brazing sheet 11 contains 5 to 10% by mass of Si, and the balance contains chemical components composed of Al and inevitable impurities. It turns out that it is preferable to have. Sample E1-3 and Sample E1-4 are superior in hydrophilic sustainability and have a higher bonding rate than Samples C1-3 and C1-4. Therefore, it can be seen that the Si amount in the coating film 12 is preferably 10 to 300 mg / m ² .

In addition, as can be seen by comparing Sample E2-1 and Sample E-2 with Sample E2-3 and Sample E-4 in Table 4, the coating film can contain fluoride flux. By adjusting the content of to 40 to 5000 mg / m ² , the hydrophilic sustainability can be further improved.

Further, as is known from Tables 1, 2 and 5, the core aluminum alloy contains Si: 0.05 to 0.8% by mass, Fe: 0.05 to 0.8% by mass, and Mn: 0 Samples E3-1 to E3-6 containing 0.8 to 2% by mass have higher strength or corrosion resistance than Samples C3-1 to C3-6, respectively, in which the content of these additive components is outside the above range. It was better.

Further, as is known from Table 1, Table 2, and Table 6, Sample E4-1 and Sample 4-2, which contain Zn: 0.3 to 3 mass% in the aluminum alloy of the core material, have Zn content. Compared to Samples C4-1 and C4-2 outside the above range, the corrosion resistance was more excellent.

Further, as is known from Table 1, Table 2, and Table 7, Sample E5-1 and Sample 5-2 containing at least one of Mg: 1 mass% or less and Cu 0.5 mass% or less in the aluminum alloy of the core material Compared with sample C5-1 to sample C5-2, the contents of these additive components were outside the above range, the corrosion resistance and the bondability were more excellent.

Further, as known from Table 1, Table 2, and Table 8, the sample E6-1 containing at least one of In: 0.3% by mass or less and Sn: 0.3% by mass or less in the aluminum alloy of the core material and Sample 6-2 had improved corrosion resistance. On the other hand, when the content of these additive components is out of the above range, manufacturability is impaired.

Further, as known from Tables 1, 2 and 9, the core aluminum alloy includes Ti: 0.3% by mass or less, V: 0.3% by mass or less, Zr: 0.3% by mass or less, Cr : Sample E7-1 to Sample 7-5 containing at least one selected from 0.3% by mass or less and Ni: 2% by mass or less were improved with a reduced deformation rate. On the other hand, when the content of these additive components is out of the above range, the manufacturability is impaired or the deformation rate is increased.

Further, as is known from Tables 1, 2, and 10, Sample E8-1, which contains Sr: 0.1% by mass or less in the brazing material aluminum alloy, had a low deformation rate and was improved. On the other hand, when the content of Sr exceeds the above range, productivity was impaired.

Further, as is known from Tables 1, 2 and 11, Sample E9-1 containing at least one of Zn: 0.3 mass% or less and Cu: 0.3 mass% or less in the aluminum alloy of the brazing material And sample E9-2 was improved in corrosion resistance as compared with sample C9-1 and sample C9-2, in which the content of these additive components was outside the above range.

(Example 2)
Next, the example of the heat exchanger which has a core part using the precoat fin material shown in Example 1 is demonstrated. As shown in FIG. 6, the heat exchanger 5 has a core portion 2 having a number of configurations similar to those of the mini-core of the first embodiment. Specifically, the core portion 2 is formed by alternately laminating a large number of fins 3 made of a corrugated pre-coated fin material 1 and aluminum tubes 4, and the fins 3 and the aluminum tubes 4 are the mini-cores of the first embodiment. They are joined in the same way.

The header 51 is assembled | attached to the both ends of the aluminum pipe 4, and the side plate 52 is assembled | attached to the both ends (outermost side) in the lamination direction of the core part 2. As shown in FIG. In addition, a tank 53 is assembled to the header 51. These header 51, side plate 52, and tank 53 can be joined by brazing, for example.

In the heat exchanger 5, the precoat fin material 1 similar to the samples E1-1 to E9-2 shown in the above Tables 3 to 11 can be used. That is, the heat exchanger 5 has the core part 2 which consists of the fin 3 which consists of the precoat fin material 1 excellent in the above-mentioned hydrophilic sustainability, joining property, etc., and the aluminum tube 4 joined to the fin 3. Therefore, since the fin 3 exhibits excellent hydrophilic durability, the heat exchanger 5 can suppress an increase in ventilation resistance and can stably exhibit good heat exchange performance for a long period of time. Further, in the heat exchanger 5, for example, the aluminum tube 4 and the fin 3 are sufficiently joined, so that the heat exchange performance between the aluminum tube 4 and the fin 3 is improved.

(Example 3)
This example is an example of a heat exchanger having a configuration in which an aluminum tube made of a flat multi-hole tube is inserted into an assembly hole formed in a fin. As illustrated in FIG. 7, the heat exchanger 6 includes an aluminum tube 7 and fins 8. As illustrated in FIGS. 7 and 9, the fin 8 has an assembly hole 81 into which the aluminum tube 7 is inserted. As illustrated in FIGS. 7 and 8, the aluminum tube 7 is in contact with the fin 8 at the contact portion 61. As illustrated in FIGS. 7 to 9, in the contact portion 61, a fillet 600 is formed between the aluminum tube 7 and the fin 8 to join both.

As illustrated in FIG. 7, the heat exchanger 6 of this example includes a large number of fins 8 arranged at intervals in the plate thickness direction, and a plurality of aluminum tubes 7 extending in the plate thickness direction of the fins 8. And have. The fin 8 has a substantially rectangular shape in plan view as viewed from the thickness direction.

As illustrated in FIG. 8 and FIG. 9, the fin 8 is made of the precoated fin material 1 having the same brazing sheet 11 as in Example 1 and the coating film 12 formed on both surfaces thereof, but the brazing sheet 11. The brazing material 112 is formed on one side of the core material 111. More specifically, the brazing material 112 is formed on the abutting portion 61 side with the aluminum tube 7, and the brazing material 112 is not formed on the opposite side. The coating film 12 is laminated on the brazing material 112 on the surface on which the brazing material 112 is formed, and is laminated on the core material 111 on the non-forming surface side of the brazing material. The method for forming the brazing material and the coating film is the same as in Example 1.

The assembly hole 81 in the fin 8 is a notch 811 provided in the outer peripheral edge portion of the fin 8. The notch 811 extends in the plate width direction from the outer peripheral edge of the fin 8 and has a U shape in plan view. The notch 811 is configured such that the aluminum tube 7 can be press-fitted from an open portion 812 provided at the outer peripheral edge of the fin 8.

7 and 9, the fin 8 has a collar portion 82 protruding from the peripheral edge of the assembly hole 81. Although the height of the color part 82 is not specifically limited, For example, it can be 200 micrometers or more.

7, the aluminum tube 7 is a flat multi-hole tube in which a cross section in the longitudinal direction has an oval shape and a plurality of flow paths 711 are formed therein. The flat multi-hole tube is arranged so that the width direction thereof is parallel to the plate width direction of the fin plate. As illustrated in FIGS. 7 and 8, the aluminum tube 7 made of a flat multi-hole tube has a collar portion 82 at one end 712 in the width direction, that is, a portion where the surface is curved. Abut. One end portion 712 of the aluminum tube 7 and the tip portion 821 of the U-shape of the collar portion 82 constitute a contact portion 61. Although illustration is omitted, in the contact portion 61, the brazing material 112 of the fin 8 joins the fin 8 and the aluminum tube 7 by heating and cooling at the time of joining described later.

The heat exchanger 6 of this example can be manufactured as follows, for example. First, the pre-coated fin material 1 is produced in the same manner as in Example 1 except that the brazing material 112 is formed on one side of the core material 111, and the fin 8 is produced by a conventional method using this fin material. Then, the plurality of fins 8 are arranged at intervals in the plate thickness direction. Next, an aluminum tube 7 made of a flat multi-hole tube prepared by a conventional method is press-fitted into the assembly hole 81 of the fin 8, and at least one end 712 of the aluminum tube 7 and the tip 821 of the collar portion 82 are brought into contact with each other. Make contact. Thereafter, for example, the substrate is heated at 600 ° C. for 3 minutes in a nitrogen gas atmosphere and then cooled. The fin 8 and the aluminum tube 7 are joined at the contact portion 61 by softening or melting the brazing material 112 of the fin 8 by heating and condensing the brazing material by cooling. In this way, the heat exchanger 6 having a core portion in which the aluminum tube 7 and the fins 8 are joined can be manufactured. Also in the heat exchanger of this example, there can exist an effect similar to Example 2. FIG.

As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the above-mentioned each Example, A various change is possible within the range which does not impair the meaning of this invention. .

Claims

A brazing sheet having a core made of an aluminum alloy and a brazing material laminated on the core;
A coating film formed on the surface of the brazing sheet,
The brazing material contains Si: 5 to 10% by mass, and the balance has a chemical component consisting of Al and inevitable impurities,
A pre-coated fin material, wherein the amount of Si in the coating film is 10 to 300 mg / m 2 .
The pre-coated fin material according to claim 1, wherein the coating film contains at least one of silicate and amorphous silica.
The pre-coated fin material according to claim 1 or 2, wherein the coating film contains lithium silicate.
The precoated fin material according to any one of claims 1 to 3, wherein the coating film further contains 40 to 5000 mg / m 2 of a fluoride flux.
The core material contains Si: 0.05 to 0.8% by mass, Fe: 0.05 to 0.8% by mass, and Mn: 0.8 to 2% by mass with the balance being Al and inevitable impurities. The precoated fin material according to any one of claims 1 to 4, which has a chemical component:
The precoated fin material according to claim 5, wherein the core material further contains Zn: 0.3 to 3% by mass.
The pre-coated fin material according to claim 5 or 6, wherein the core material further contains at least one of Mg: 1 mass% or less and Cu: 0.5 mass% or less.
The precoated fin material according to any one of claims 5 to 7, wherein the core material further contains at least one of In: 0.3 mass% or less and Sn: 0.3 mass% or less.
The core material is further selected from Ti: 0.3 mass% or less, V: 0.3 mass% or less, Zr: 0.3 mass% or less, Cr: 0.3 mass% or less, and Ni: 2 mass% or less. The precoated fin material according to any one of claims 5 to 8, comprising at least one selected from the group consisting of:
The pre-coated fin material according to any one of claims 1 to 9, wherein the brazing material further contains Sr: 0.1% by mass or less.
The precoated fin material according to any one of claims 1 to 10, wherein the brazing material further contains at least one of Zn: 0.3% by mass or less and Cu: 0.3% by mass or less.
A heat exchanger having a core portion made of a fin made of the pre-coated fin material according to any one of claims 1 to 11 and an aluminum tube joined to the fin.