WO2018123984A1

WO2018123984A1 - Heat exchanger and manufacturing method therefor

Info

Publication number: WO2018123984A1
Application number: PCT/JP2017/046465
Authority: WO
Inventors: 上田　薫; 加奈荻原
Original assignee: 株式会社Uacj
Priority date: 2016-12-28
Filing date: 2017-12-25
Publication date: 2018-07-05
Also published as: JP2018105572A

Abstract

The present invention provides a heat exchanger having excellent hydrophilicity and hydrophilic sustainability and a manufacturing method therefor. Provided are: a heat exchanger (1) that is provided with a metal pipe (2), an aluminum fin (3), and a brazed part (4) where the metal pipe (2) and the aluminum fin (3) are joined; and a manufacturing method therefor. In the X-ray fluorescence spectrum of the fin (3), an Si-derived peak intensity (I_Si), a Zr-derived peak intensity (I_Zr), an F-derived peak intensity (I_F), and an Al-derived peak intensity (I_Al) satisfy a predetermined relationship. The fin (3) has a predetermined high-content section in the range from the surface thereof to a depth of 100 nm.

Description

Heat exchanger and manufacturing method thereof

The present invention relates to a heat exchanger including a metal tube, an aluminum fin, and a brazing part to which both are connected, and a method for manufacturing the heat exchanger.

Generally, a heat exchanger has a metal tube made of aluminum or the like through which a refrigerant flows and an aluminum fin for performing heat exchange between air outside the metal tube, and the metal tube and the fin The brazing parts are connected. 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 having such a hydrophilic coating film and the metal tube, for example, brazing joining is used.

However, since a general resin-based or inorganic coating film is altered or decomposed at the heating temperature during brazing, there is a possibility that sufficient hydrophilicity cannot be exhibited after brazing. Therefore, for the purpose of improving hydrophilicity, for example, Patent Document 1 proposes a fin material having a coating film containing silicate as a main component as a fin material pre-coated with a coating film. Further, Patent Document 2 proposes a method of manufacturing a heat exchanger using a fin in which a film containing a support such as xylene or a silicon-based binder such as silicone oil is previously formed before brazing. Yes.

JP 2013-137153 A Special table 2008-508103 gazette

However, even if the fin in the state before joining with the metal tube has excellent hydrophilicity, the hydrophilicity of the fin and its sustainability are not obtained in the heat exchanger obtained after joining the fin and the metal tube. May decrease. As described above, even if a fin material having a coating film containing silicate as a main component is used, or a fin in which a coating film including a support or a silicon-based binder is formed in advance is used, a heat exchanger after bonding In this case, the fins may not be able to exhibit sufficient hydrophilicity and hydrophilic sustainability. Therefore, development of a heat exchanger excellent in hydrophilicity and its sustainability is desired.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a heat exchanger excellent in hydrophilicity and hydrophilic sustainability and a manufacturing method thereof.

One aspect of the present invention is a metal tube;
Aluminum fins,
A brazing part to which the fin and the metal pipe are connected,
In the fluorescent X-ray spectrum of the fin, the peak intensity I _Si derived from _Si , the peak intensity I _Zr derived from _Zr , the peak intensity I _F derived from _F, and the peak intensity I _Al derived from _Al are 0.05. ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴
The fin has a total value C _Si + C _zr at% of the Si atom content C _Si at% and the Zr atom content C _Zr at% within a range from the surface of the fin to a depth of 100 nm. The heat exchanger has a high content portion that is twice or more the total value at a position of 200 nm.

Another aspect of the present invention is the above heat exchanger production method,
An abutting step for abutting an aluminum fin and a metal tube;
An application step of applying a flux liquid containing at least a fluoride-based flux on the surface of the fin and the contact portion between the fin and the metal tube;
A joining step of forming the brazed portion by brazing the fin and the metal tube at the abutting portion;
At least one of the surfaces of the flux liquid and the fins is in a method for manufacturing a heat exchanger, containing at least one of a Si source and a Zr source.

The heat exchanger has fins in which each peak intensity in the fluorescent X-ray spectrum satisfies the predetermined relationship. Further, the fin has a high content portion having a high total content of Si and Zr as described above in a range from the surface to a depth of 100 nm as compared with a position at a depth of 200 nm. Therefore, in the heat exchanger, the fin exhibits excellent hydrophilicity, and the excellent hydrophilicity is maintained for a long time. That is, the heat exchanger is excellent in hydrophilicity and hydrophilic sustainability.

As described above, the heat exchanger can be manufactured by performing the contact step, the coating step, and the joining step. In the coating step, a flux liquid containing a fluoride-based flux is applied to the contact portion between the metal tube and the fin brought into contact in the coating step and the surface of the fin. This fluoride-based flux becomes the F source, and F remains in the fins of the heat exchanger. At least one of the Si source and the Zr source is contained in at least one of the flux liquid and the fin. That is, for example, a flux liquid containing at least one of a Si source and a Zr source can be used, or a fin in which at least one of the Si source and the Zr source is supplied to the surface as a coating film or the like can be used. Thereby, at least one of Si and Zr remains in the fin of the heat exchanger. As described above, each peak intensity satisfies the predetermined relationship, and it is possible to obtain a heat exchanger including fins having a high content portion.

Explanatory drawing of the heat exchanger in Example 1. FIG. The perspective view of the core part of the heat exchanger in Example 1. FIG. Sectional drawing of the core part of the heat exchanger in Example 1. FIG. In Example 1, (a) The expanded sectional view of the fin of a heat exchanger, (b) The expanded sectional view of the coating-film surface of a fin. In Example 1, (a) Explanatory drawing which shows the cross-sectional structure of the contact part of the fin and tube before brazing, (b) Explanatory drawing which shows the cross-sectional structure of the brazing part of a fin and a tube. (A) The expanded sectional view of the fin of a heat exchanger in Example 2, (b) The expanded sectional view of the fin surface. The figure which shows the relationship between the depth direction from the surface of the board | plate material of the sample E2, and the content rate of each element in an experiment example. The figure which shows the relationship between the depth direction from the surface of the board | plate material of the sample C1, and the content rate of each element in an experiment example.

Next, preferred embodiments of the heat exchanger and the manufacturing method thereof will be described. In the present specification, “aluminum” is a concept including not only pure aluminum but also an aluminum alloy. Specifically, as the aluminum, A1000 series pure aluminum, A3000 series aluminum alloy, or the like can be used.

The heat exchanger has a metal tube, aluminum fins, and a brazing part for connecting the fins and the metal tube. The metal tube is preferably made of a metal having excellent thermal conductivity, and examples of such a metal include aluminum, copper, and copper alloy. More preferably, the metal tube is made of aluminum.

As the metal tube, for example, a tube formed by processing a brazing sheet into a round tube shape or a flat tube shape can be used. The brazing sheet is made of, for example, a core material made of aluminum and clad with a brazing material, and may be single-sided clad or double-sided clad. When using a metal tube formed by processing such a brazing sheet, it is not necessary to use a separate brazing material when joining the fin. That is, a clad tube having a surface clad with a brazing material can be used as the metal tube. As the brazing material clad on the core material, for example, Al—Si alloy powder, Si powder, Al—Si—Zn alloy powder or the like is used. Of the brazing filler metal powders, the Si powder can exert its function as a brazing filler metal by forming Al and an Al—Si alloy in the metal tube and / or fin during brazing heating. it can. Moreover, flux and binder resin can also be mixed with the above-mentioned brazing material. As the flux, for example, fluoride-based flux powders such as potassium fluoroaluminate and potassium fluorozincate are used. As the binder resin, for example, an acrylic resin is used. Further, as the metal tube, a bare tube in which a brazing material or the like is not clad can be used.

A shape such as a corrugated fin, a plate fin, or a pin fin can be adopted as the fin. In order to improve heat exchange performance, the fin may have a slit. Further, as the fin, a clad fin with a brazing material clad on the surface can be used, a pre-coated fin with a coating film formed on the surface, or a brazing material or a coating film is formed. Not bare fins can be used. When the clad fin is used, as the brazing material, the same material as the above-mentioned powder can be used, and the above-mentioned flux and binder resin can be mixed into the brazing material. The clad fin may be single-sided clad or double-sided clad. When using pre-coated fins, the coating film can be formed by applying and drying a paint containing at least one of colloidal silica and zirconia, for example. The paint for forming a coating film may further contain water glass and / or an organic resin. The coating film in the precoat fin may be formed on one side or may be formed on both sides. The coating film can be formed, for example, with an adhesion amount of 100 to 2000 mg / m ² per side of the substrate. When a coating material containing colloidal silica is used, a coating film in which amorphous silica particles are dispersed can be formed. Further, when a paint containing zirconia is used, a coating film in which zirconia is dispersed can be formed.

The coating film can further contain water glass and / or an organic resin. In this case, the coating property at the time of forming the coating film is improved, the retention of the amorphous silica particles in the coating film is improved, and the falling off of the amorphous silica particles can be prevented. In addition, although water glass generally shows the aqueous solution of silicate, the above-mentioned water glass contained in a coating film is solid content of water glass, ie, silicate.

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 during brazing, and the organic resin can be lost from the coating film. As a result, since the organic resin in the coating film after brazing decreases, it is possible to prevent the brazing performance from being inhibited.

The fin is made of aluminum, and a coating film may be formed on the surface or may not be formed. Moreover, the fin may have a chemical conversion film between the board | substrate which consists of aluminum, and a coating film. The chemical conversion film can be formed by, for example, phosphoric acid chromate treatment, zirconium phosphate treatment, boehmite treatment, and the like. The chemical conversion film can improve the adhesion between the substrate and the coating film.

In the fluorescent X-ray spectrum of the fin, the peak intensity I _Si derived from _Si , the peak intensity I _Zr derived from _Zr , the peak intensity I _F derived from _F, and the peak intensity I _Al derived from _Al are 0.05. ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ . Each peak intensity is an intensity at the peak top. If this relationship is not satisfied, the hydrophilicity or hydrophilic sustainability of the fins may be insufficient. Further, in the case of (I _Si + I _Zr ) / I _F > 10, the brazing property may be hindered and the strength of the brazed portion may be insufficient. In the case of (I _Si + I _Zr ) / I _F <0.05, hydrophilic sustainability may be insufficient. In the above relationship, either I _Si or I _Zr may be 0. Further, the relationship of I _F / I _Al ≧ 1 × 10 ⁻⁴ indicates that a predetermined amount or more of F exists on the surface of the fin, and such F is, for example, a fluoride system used during brazing. Derived from flux and the like.

Moreover, it is preferable that the peak intensity I _Si , the peak intensity I _Zr, and the peak intensity I _F satisfy the relationship of 0.1 ≦ (I _Si + I _Zr ) / I _F ≦ 5. In this case, the hydrophilic durability of the fin can be further improved.

The fin has a total value of Si atom content C _Si at% and Zr atom content C _Zr at% in the range from the surface to a depth of 100 nm, which is twice the above total value at a position 200 nm deep from the surface. It has the high content part which becomes the above. Either C _Si or C _Zr may be zero. When the high content portion is not present, that is, when the total value is less than twice, the hydrophilicity or hydrophilic sustainability becomes insufficient.

As described above, a fin satisfying the relationship of 0.05 ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ and having a high content portion is, for example, This can be realized by supplying at least one of a Si source and a Zr source and an F source to the surface and adjusting the supply amount thereof. Supply of the Si source, the Zr source, and the F source can be performed by various timings and methods. For example, the flux liquid used at the time of brazing can contain a Si source, a Zr source, and an F source, or a fin having a coating film on the surface is used and a Si source, a Zr source, and an F source are contained in the coating film. You can also. These supply methods will also be described in the following production methods and examples.

In manufacturing the heat exchanger, the contact process, the application process, and the bonding process are performed as described above. In the contact step, the fin and the metal tube are brought into contact. As described above, as described above, a fin with a coating film formed on the surface (that is, a pre-coated fin) may be used, or a fin without a coating film (that is, a bare fin) may be used. In addition, the bare fin may have a chemical conversion film on the surface, and does not need to have it.

In the case of a pre-coated fin, the coating film can contain at least one of a Si source and a Zr source. In this case, at least one of Si and Zr derived from the coating film is supplied to the surface of the fin, each peak intensity in the fluorescent X-ray spectrum satisfies the above relationship, and a fin having a high content portion is formed. Is possible. The contents of the Si source and the Zr source in the coating film can be appropriately adjusted. The Si source in the coating is preferably amorphous silica derived from colloidal silica. In this case, hydrophilicity and hydrophilic sustainability can be further improved. The Zr source preferably contains zirconia. Also in this case, hydrophilicity and hydrophilic sustainability can be further improved.

In the coating step, a flux solution containing at least a fluoride-based flux is applied to the contact portion between the fin and the metal tube and the surface of the fin. In this coating process, F derived from the fluoride-based flux is supplied to the surface of the fin and can remain on the surface of the fin even after brazing heating described later. The flux liquid can contain at least one of a Si source and a Zr source. In this case, at least one of a flux-derived Si source and a Zr source is supplied to the surface of the fin in the coating step, and can remain on the surface of the fin even after brazing heating described later. Thereby, each peak intensity of the fluorescent X-ray spectrum satisfies the above relationship, and a fin having a high content portion can be formed. The contents of fluoride flux, Si source, and Zr source in the flux liquid can be adjusted as appropriate. The Si source in the flux liquid is preferably colloidal silica. In this case, hydrophilicity and hydrophilic sustainability can be further improved. The flux liquid preferably contains zirconia as a Zr source. Also in this case, hydrophilicity and hydrophilic sustainability can be further improved.

In the joining process, a brazing part is formed by brazing the fin and the metal tube at the contact part. Brazing can be performed by heating, for example. Heating at the time of brazing is performed at a maximum temperature of 570 ° C. to 610 ° C., for example. By this heating, the brazing material is melted at the contact portion between the fin and the metal tube, and the molten brazing material is cured by the subsequent cooling. Thereby, the brazing part in which the fin and the metal tube are connected is formed. Furthermore, in the heating at the time of brazing, the F source supplied in the coating process can be baked on the surface of the fin. Moreover, when the flux liquid containing at least one of Si source and Zr source is used, Si source and Zr source can be baked at the time of brazing heating.

In the joining step, brazing is preferably performed using a flux liquid containing a fluoride-based flux. In this case, the brazing performance is further improved by the flux action, and the strength of the brazing portion where the fin and the metal tube are connected is further improved. In order to obtain a sufficient flux effect, brazing heating is preferably performed in a non-oxidizing atmosphere such as a nitrogen atmosphere or a hydrogen atmosphere.

As the fluoride flux, potassium fluoroaluminate such as KAlF ₄ , K ₂ AlF ₅ , K ₃ AlF ₆ can be used. Further, as the fluoride flux, potassium fluorozincate such as KZnF ₃ can be used. As the fluoride-based flux, the above-mentioned compounds can be used alone or in combination. As the fluoride flux, for example, one having an average primary particle diameter of 1 to 50 nm can be used. The average primary particle diameter of the fluoride-based flux means the particle diameter at a volume integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

The heat exchanger has a core part composed of fins, metal tubes, and brazing parts connecting them. Specific examples of the heat exchanger will be described with reference to the drawings in the following embodiments, but the heat exchanger is manufactured by assembling a header, a side support, an inlet / outlet pipe, and the like to the core portion.

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
Next, the heat exchanger according to the embodiment will be described with reference to FIGS. As illustrated in FIG. 1, the heat exchanger 1 has a large number of core portions 10 including metal tubes 2, fins 3, and brazed portions 4 to which these are connected. The core portion 10 is formed by alternately laminating corrugated fins 3 and metal tubes 2, and the fins 3 and the metal tubes 2 are connected by brazing portions 4.

2, each core portion 10 has a metal tube 2 and fins 3, and the corrugated fins 3 are sandwiched between the metal tubes 2. In FIG. 2, one of the two metal tubes 2 sandwiching the fin 3 is indicated by a broken line in order to clearly show the corrugated shape of the fin 3. As illustrated in FIGS. 2 to 4, the fin 3 is a pre-coated fin having a fin material 31 made of, for example, an aluminum plate formed in a corrugated shape, and a coating film 32 formed on both surfaces of the fin material 31. is there. In addition, although illustration is abbreviate | omitted, between the fin material 31 and the coating film 32, the chemical conversion film formed by the below-mentioned phosphoric acid chromate process exists.

2 and 3, the metal tube 2 includes a core material 21 made of, for example, a flat multi-hole tube made of an aluminum alloy, and a brazing material layer 22 formed on the surface of the core material 21. The core material 21 has a large number of refrigerant flow paths 211 for circulating the refrigerant. In the core part 10, as illustrated in FIG. 5B, the fins 3 and the metal pipe 2 are connected by brazing, and a brazing part 4 is formed between them.

As illustrated in FIG. 1, in the heat exchanger 1, headers 5 are assembled at both ends of the metal tube 2, and side plates 6 are disposed at both ends (outermost sides) in the stacking direction of the core portion 10. It is assembled. In addition, a tank 7 is assembled to the header 5. The header 5, the side plate 6, and the tank 7 can be joined by, for example, brazing, similarly to the joining of the metal pipe 2 and the fin 3 described above.

The core unit 10 is manufactured as follows. Specifically, first, a core material 21 made of a flat multi-hole tube made of an aluminum alloy was produced by extrusion (see FIGS. 1 and 2). And the brazing filler metal layer 22 was formed by apply | coating the brazing filler metal which consists of Si powder to the surface of the core material 21. FIG. In this way, a metal tube 2 was obtained.

Further, degreasing treatment and phosphoric acid chromate treatment were performed on an aluminum plate material having a JIS standard A1050 composition. The degreasing treatment was performed by heating at 60 ° C. for 30 seconds using a 2% by mass solution of EC760 manufactured by Nippon Paint Co., Ltd. The phosphoric acid chromate treatment was performed under the conditions of a temperature of 45 ° C. and a treatment time of 20 seconds using a 1.2 mass% solution of Alchrome 702SK / ACK manufactured by Nihon Parkerizing Co., Ltd. Next, using a bar coater, a coating material containing colloidal silica was applied to the plate material and dried to form a coating film. Thereafter, the plate material on which the coating film was formed was processed into a corrugated shape. In this way, a corrugated fin 3 having a coating film 32 formed on the surface of the fin material 31 was obtained (see FIGS. 2 to 4).

Next, a corrugated fin 3 was sandwiched between the two metal tubes 2 to produce an assembly (see FIGS. 2 and 3). At this time, the brazing material layer 22 of each metal tube 2 was opposed to each other, and the fins 3 were sandwiched between the two so that each vertex 30 of the corrugated fin 3 and the brazing material layer 22 were brought into contact with each other. . Next, as shown in FIG. 5A, a flux liquid 101 prepared by dispersing a fluoride-based flux in water was sprayed on the entire assembly composed of the metal tube 2 and the fins 3.

Thereafter, the assembly was held for 3 minutes in a furnace at a temperature of 600 ° C. in a nitrogen gas atmosphere, and then cooled to room temperature (specifically, 25 ° C.). The brazing filler metal layer 22 is melted during heating in the furnace, and the molten brazing filler metal layer 22 is cured during cooling. By melting and hardening the brazing material layer 22, the metal tube 2 and the fin 3 are connected to form the brazing portion 4 (see FIG. 5B). Thus, the core part 10 is obtained as shown in FIGS. The heat exchanger 1 having the configuration illustrated in FIG. 1 can be obtained by a known assembly method using the core portion 10.

In this example, the fin 3 has the coating film 32 which has Si source derived from colloidal silica, and the fluoride type flux is used at the time of brazing joining. Accordingly, the Si source derived from the coating film 32 and the F source derived from the flux are present on the surface of the fin 3. And as shown as sample E1 of the below-mentioned experimental example, the fin 3 of this example has a peak intensity I _Si derived from _Si , a peak intensity I _Zr derived from _Zr, and a peak intensity derived from F in the fluorescent X-ray spectrum. I _F and the peak intensity I Al derived from _Al satisfy the relationship of 0.05 ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ . Further, the fin 3 has a Si atom content C _Si at% and a Zr atom content C _Zr at% in a range from the surface 33 to a depth of 100 nm, and the total value of C _{Si at} a position 200 nm deep from the surface 33. It has the high content part 34 which becomes 2 times or more of the total value of at% and _CZrat % (refer FIG.4 (b)). In FIG. 4B, D ₁ = 100 nm and D ₂ = 200 nm, and the same applies to FIG. 6B referred to in Example 2 described later. The high content part 34 should just exist in the range of depth 100nm from the surface 33 surface of the fin 3, and may be exposed to the surface 33, or a depth direction rather than the surface 33 without exposing at least one part. It may be formed inside.

As will be described in detail in the experimental examples to be described later, since the peak intensity satisfies the predetermined relationship and has a high content portion, the fin 3 exhibits excellent hydrophilicity and the excellent hydrophilicity is maintained for a long time. The That is, the heat exchanger 1 of this example is excellent in the hydrophilicity and hydrophilic sustainability of the fins 3.

(Example 2)
This example is an example of a heat exchanger that has fins that do not have a coating film on the surface, and that uses a flux liquid that contains at least one of a Si source and a Zr source as well as a fluoride flux during brazing. It is. As illustrated in FIGS. 6A and 6B, the fin 3 in the heat exchanger of this example does not have a coating film on the surface 33 unlike the first embodiment. In addition, although illustration is abbreviate | omitted, the chemical conversion film is formed in the surface. The heat exchanger of this example uses the fin 3 produced without forming a coating film, and uses a flux liquid in which at least one of a Si source and a Zr source and a fluoride-based flux are dispersed in water. Except for this, it is manufactured in the same manner as in Example 1.

As illustrated in FIG. 6B, the fin 3 does not have a coating film on the surface 33, but on the surface of the fin 3, at least one of the Si source and the Zr source derived from the flux liquid and the F source And exist. And as shown as samples E2 to E4 in the experimental examples described later, the fin 3 of this example has a peak intensity I _Si derived from _Si , a peak intensity I _Zr derived from _Zr, and a peak derived from F in the fluorescent X-ray spectrum. and the peak intensity I _F, and the peak intensity I _Al from Al satisfies _{_{0.05 ≦ (I Si + I Zr}} ) / I F ≦ 10, and the relationship _{_{I F / I Al ≧ 1 ×}} 10 -4. Further, the fin 3 has a total value of Si atom content C _Si and Zr atom content C _Zr within a range from the surface 33 to a depth of 100 nm, and C _Si and C _{Zr at} a position 200 nm deep from the surface 33. And a high-content portion 34 that is twice or more the total value (see FIG. 6B).

Therefore, like the fin of Example 1, the fin 3 in the heat exchanger of this example also exhibits excellent hydrophilicity, and the excellent hydrophilicity is maintained for a long time. Details thereof will be shown in an experimental example described later. Of the reference numerals used in the second embodiment, the same reference numerals as those used in the above-described embodiments represent the same components as those in the above-described embodiments unless otherwise indicated.

(Experimental example)
In this example, a plurality of plate material samples (sample E1 to sample E4, sample C1 to sample C3) used as fins for a heat exchanger are prepared, and their hydrophilicity and hydrophilic sustainability are evaluated.

Sample E1 is a plate material sample having an aluminum plate and a coating film formed on the surface thereof, and was prepared as follows. First, degreasing treatment and phosphoric acid chromate treatment were performed on an aluminum plate material having an A1050 composition according to JIS standards. The degreasing treatment was performed by heating at 60 ° C. for 30 seconds using a 2% by mass solution of EC760 manufactured by Nippon Paint Co., Ltd. The phosphoric acid chromate treatment was performed under the conditions of a temperature of 45 ° C. and a treatment time of 20 seconds using a 1.2% by mass solution of Alchrome 702SK / ACK manufactured by Nippon Parkerizing Co., Ltd. Subsequently, the coating material was apply | coated to the board | plate material using the bar coater, it dried, and the coating film was formed. The paint was prepared by dispersing silicate, binder and colloidal silica in water. The adhesion amount of the coating film is 500 mg / m ² . Next, assuming brazing heating, a flux solution was applied to the plate material on which the coating film was formed, and then this plate material was heated at a temperature of 600 ° C. for 3 minutes in a nitrogen atmosphere. The plate material sample for fin thus obtained is designated as sample E1. The flux liquid was prepared by dispersing fluoride-based flux in water.

Sample E2 to Sample E4 are plate material samples having no coating film, and were prepared as follows. First, similarly to the sample E1, a degreasing treatment and a phosphoric acid chromate treatment were performed on an aluminum plate material having an A1050 composition according to JIS standards. Next, assuming brazing heating, a flux solution was applied to the plate material on which the coating film was formed, and then the plate material was heated at a temperature of 600 ° C. for 3 minutes in a nitrogen atmosphere. In preparing the sample E2, a flux liquid prepared by dispersing fluoride-based flux and colloidal silica in water was used. In preparing the sample E3, a flux liquid prepared by dispersing fluoride-based flux and zirconia in water was used. In preparing the sample E4, a flux liquid prepared by dispersing fluoride-based flux, colloidal silica, and zirconia in water was used.

Also, three types of plate material samples were prepared for comparison with the samples E1 to E4. These plate material samples are designated as Sample C1 to Sample C3. In preparing the sample C1, first, an aluminum plate material having a JIS standard A1050 composition was prepared. Next, assuming brazing heating, a flux solution was applied to the plate material, and then the plate material was heated in a nitrogen atmosphere at a temperature of 600 ° C. for 3 minutes. The flux liquid was prepared by dispersing fluoride-based flux in water.

In preparing the sample C2, first, similarly to the sample E1, a degreasing treatment and a phosphoric acid chromate treatment were performed on an aluminum plate material having a JIS standard A1050 composition. Next, assuming the brazing heating, the plate was heated at a temperature of 600 ° C. for 3 minutes in a nitrogen atmosphere. In the sample C2, no flux liquid is used.

In preparing the sample C3, first, similarly to the sample E1, a degreasing treatment and a phosphoric acid chromate treatment were performed on an aluminum plate material having a JIS standard A1050 composition. Subsequently, the coating material was apply | coated to the board | plate material using the bar coater, it dried, and the coating film was formed. As the paint, the same paint as sample E1 was used. The adhesion amount of the coating film is 500 mg / m ² . Next, assuming the brazing heating, the plate was heated at a temperature of 600 ° C. for 3 minutes in a nitrogen atmosphere. In the sample C3, no flux liquid is used.

In the preparation of each sample, NOCOLLOK manufactured by Solvay is used as the fluoride flux, and the content of the fluoride flux in the flux liquid is 3% by mass. As the colloidal silica, Cataloid SI-550 which is an amorphous colloidal silica manufactured by JGC Catalysts & Chemicals Co., Ltd. was used. As the zirconia, B-2000, an aqueous coating agent manufactured by Nikken Co., Ltd., was used.

Next, by performing surface X-ray fluorescence analysis on each sample, Si-derived peak intensity I _Si , Zr-derived peak intensity I _Zr , F-derived peak intensity I _F , and Al-derived peak intensity I Seeking relationship with _Al . Specifically, (I _Si + I _Zr ) / I _F , I _Si / I _F , I _Zr / I _F , and I _F / I _Al were determined. Each peak intensity is an intensity at the peak top. The measurement apparatus and measurement conditions are as follows.
Measuring device: Rix3100 manufactured by RIGAKU
Tube voltage: 30-50kV
Tube current: 80-130mA

Next, the content of each element in the depth direction from the surface of each sample was measured by glow discharge emission analysis (GD-OES). As a representative example, the result of the sample E2 is shown in FIG. 7, and the result of the sample C1 is shown in FIG. In these figures, C _Al indicates the content of Al atoms, C 2 _O indicates the content of O atoms, C _Si indicates the content of Si atoms, and C _N indicates the content of N atoms. C _Si is shown at 10 times. GD-OES measuring equipment and measuring conditions are as follows.
Measuring device: GDA750 manufactured by RIGAKU
Sputtering gas: Ar gas Pressure: 3.5 hPa
Anode diameter: φ2.5mm
Sputter rate: 20 nm / s (standard aluminum metal)

Based on the content of each element in the depth direction measured by GD-OES, the total value C _Si + C _Zr of the Si atom content C _Si and the Zr atom content C _Zr within a depth of 100 nm from the surface The maximum value (peak top in GD-OES) was determined. This is C _max . Furthermore, the total value C _Si + C _Zr of the Si atom content C _Si and the Zr atom content C _{Zr at} a position 200 nm deep from the surface was determined. This is referred to as C _200. Then, the ratio of C _max / C ₂₀₀ is calculated, and the value is shown in Table 1 as the C _Si + C _Zr ratio. Similarly, the ratio of the Si atom content rate at the position of the above-mentioned maximum value with respect to the position of the depth of 200 nm is calculated, and the value is shown in Table 1 as the C _Si ratio. Similarly, the ratio of the Zr atom content rate at the position of the above-mentioned maximum value with respect to the position at a depth of 200 nm is calculated, and the value is shown in Table 1 as the C _Zr ratio.

Each sample was evaluated for hydrophilicity and hydrophilicity sustainability as follows. The results are shown in Table 1.

<Hydrophilicity>
The hydrophilicity was evaluated by measuring the contact angle of water droplets on each sample. 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 sample at room temperature, and the contact angle of the water drop after 30 seconds was measured. The case where the contact angle was 20 ° or less was evaluated as “A”, and the case where the contact angle exceeded 20 ° was evaluated as “B”.

<Hydrophilic sustainability>
Each sample was immersed in pure water for 2 minutes and then air-dried for 6 minutes. This immersion and air drying were repeated for a total of 300 cycles. Thereafter, the contact angle with water droplets was measured in the same manner as the hydrophilicity evaluation described above. The case where the contact angle after 300 cycles was 25 ° or less was evaluated as “A”, and the case where the contact angle exceeded 25 ° was evaluated as “B”.

As shown in Table 1, the samples E1 to E4 have a peak intensity I _Si derived from _Si , a peak intensity I _Zr derived from _Zr , a peak intensity I _F derived from _F, and a peak intensity I _Al derived from _Al. 0.05 ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ . Further, Sample E1 to Sample E4 have a C _Si + C _Zr ratio of 2 or more, and within a range from the fin surface to a depth of 100 nm, the Si atom content C _Si at% and the Zr atom content C _Zr at% And the total value C _Si + C _Zr at% of the above-mentioned surface has a high content part that is at least twice the total value at a position 200 nm deep from the surface. Therefore, as shown in Table 1, Sample E1 to Sample E4 are excellent in hydrophilicity and hydrophilic sustainability. Note that it is considered that the colloidal silica and zirconia present on the surfaces of the samples E1 to E4 are partially reduced during heating.

In contrast, the sample C1 satisfies the relationship of 0.05 ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ , but the samples E1 to E4 are satisfied. The high content part like does not exist. Therefore, the hydrophilic sustainability was insufficient. In Sample C2 and Sample C3, since a fluoride-based flux is not used, the relationship of 0.05 ≦ (I _Si + I _Zr ) / I _F ≦ 10 and I _F / I _Al ≧ 1 × 10 ⁻⁴ Is not satisfied, and the sample C2 does not have a higher content. As a result, both hydrophilicity and hydrophilic sustainability were insufficient.

Claims

A metal tube,
Aluminum fins,
A brazing part to which the fin and the metal pipe are connected,
In the fluorescent X-ray spectrum of the fin, the peak intensity I Si derived from Si , the peak intensity I Zr derived from Zr , the peak intensity I F derived from F, and the peak intensity I Al derived from Al are 0.05. ≦ (I Si + I Zr ) / I F ≦ 10 and I F / I Al ≧ 1 × 10 −4
The fin has a total value C Si + C zr at% of the Si atom content C Si at% and the Zr atom content C Zr at% within a range from the surface of the fin to a depth of 100 nm. A heat exchanger having a high content portion that is at least twice the total value at a position of 200 nm.
2. The heat exchanger according to claim 1, wherein the peak intensity I Si , the peak intensity I Zr, and the peak intensity I F satisfy a relationship of 0.1 ≦ (I Si + I Zr ) / I F ≦ 5. .
The heat exchanger according to claim 1 or 2, wherein the metal tube is made of aluminum.
The method of manufacturing a heat exchanger according to any one of claims 1 to 3,
An abutting step for abutting the fin made of aluminum and the metal tube;
An application step of applying a flux liquid containing at least a fluoride-based flux to the abutment portion between the fin and the metal tube, and the surface of the fin;
A joining step of forming the brazed portion by brazing the fin and the metal tube at the abutting portion;
The method for manufacturing a heat exchanger, wherein at least one of the surfaces of the flux liquid and the fin contains at least one of a Si source and a Zr source.
The method for producing a heat exchanger according to claim 4, wherein the fin has a coating film on the surface, and the coating film contains at least one of the Si source and the Zr source.
The method for producing a heat exchanger according to claim 5, wherein the Si source in the coating film is amorphous silica derived from colloidal silica.
The method for producing a heat exchanger according to claim 5 or 6, wherein the Zr source in the coating film is zirconia.
The method for manufacturing a heat exchanger according to any one of claims 4 to 7, wherein the Si source in the flux liquid is colloidal silica.
The method for manufacturing a heat exchanger according to any one of claims 4 to 8, wherein the Zr source in the flux liquid is zirconia.