JP2003117686A - Composite material for brazing, and brazed product obtained by using the composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material for brazing which has satisfactory brazing properties, and in which the ratio of the erosion of a base material on brazing is low, and to provide a brazed product which has satisfactory reliability in joined parts, and whose production cost is low. SOLUTION: The composite material 10 for brazing is obtained, on the surface of a base material 11, by forming a brazed layer 15 consisting of the three layers, from the side of the base material 11, of a first Ni or Ni alloy layer 12, a Ti or Ti alloy layer 13, and a second Ni or Ni alloy layer 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing composite material and a brazing product using the same, and more particularly to a composite material used for brazing heat exchangers and fuel cell members and brazing using the same. It is about products.

[0002]

2. Description of the Related Art Stainless steel based clad materials are used as joining materials for automobile oil coolers. In this, a Cu material having a function as a brazing material is clad on one side or both sides of a stainless steel plate which is a base material.

As a brazing material for members made of stainless steel, Ni-based or Co-based alloys, various Ni brazing materials having excellent oxidation resistance and corrosion resistance at the joint are specified by the JIS standard.

Further, Ni used for joining heat exchangers.
As a brazing filler metal, a powdered Ni brazing filler metal and a metal powder selected from Ni, Cr, or a Ni—Cr alloy is used in an amount of 4 to 2
A powdered Ni brazing material added with 2 wt% has been proposed (see Japanese Patent Laid-Open No. 2000-107883).

Further, N is formed on the surface of the stainless steel which is the base material.
with a brazing layer consisting of i and Ti, ie Ni / T
There is a self-brazing composite material having a brazing layer structure of i / stainless steel (see Japanese Patent Laid-Open No. 7-299592).

[0006]

However, a conventional brazing material or brazing composite material is exposed to a high temperature and highly corrosive gas or liquid (heat exchanger (exhaust gas recirculation device (hereinafter referred to as EGR (Exhaust Gas Recirculation When used as a brazing filler metal for ()))), there were the following problems.

When the above-mentioned stainless steel-based clad material is used as a joining material for an oil cooler for automobiles, there is no problem in heat resistance, oxidation resistance, and corrosion resistance.
When this stainless steel-based clad material is used as a joining material for an EGR cooler, a brazing material (Cu material) of the stainless steel-based clad material is used because the exhaust gas with high temperature and high corrosiveness is circulated in the EGR cooler. ), Heat resistance,
There is a problem that the oxidation resistance and the corrosion resistance are not sufficient.

Since the various Ni brazing materials described above are powdery, it is necessary to apply the powder Ni brazing material to each joint. That is, there is a problem that the brazing work requires a great deal of labor, so that the productivity of the brazing product is extremely low, resulting in an increase in manufacturing cost.

Although the above-described self-brazing composite material exerts a sufficient effect on heat resistance and corrosion resistance, when brazing, the stainless steel of the base material is severely eroded by the molten brazing layer and There has been a problem that the performance (strength, fatigue characteristics) of the subsequent product is greatly reduced. Specifically, the Ni layer and the Ti layer are melted by the heat treatment during brazing, but the reactivity of Ti with the base material stainless steel becomes excessive because the reactivity of Ti is extremely high. This is because the Fe component of the base material stainless steel reacts with Ti, and the Fe-rich solid solution phase and Fe ₂ Ti,
This is because intermetallic compounds such as FeTi are likely to occur.
As a result, the Fe component of the base material elutes (melts / disperses) into the brazing layer, causing significant erosion in the base material, and the thickness / volume of the base material before brazing cannot be secured. , The joint strength of the joint part is lowered, that is, the reliability of the brazed product is lowered.

An object of the present invention, which was devised in view of the above circumstances, is to provide a brazing composite material having good brazing characteristics and having a low base material erosion rate during brazing. Especially.

Another object of the present invention is to provide a brazed product having a good joint reliability and a low manufacturing cost.

[0012]

In order to achieve the above object, a brazing composite material according to the present invention is a brazing composite material in which a brazing layer is formed on the surface of a base material. A brazing layer composed of three layers of a first Ni or Ni alloy layer, a Ti or Ti alloy layer, and a second Ni or Ni alloy layer is formed in this order from the base material side.

Here, the second Ni or Ni alloy layer is
Ni-P containing at least 0.02 to 10 wt% P
It may be formed of an alloy.

The layer thickness of the first Ni or Ni alloy layer may be made thicker than the layer thickness of the second Ni or Ni alloy layer.

The substrate may be made of stainless steel.

According to the above, it is possible to obtain a brazing composite material having good brazing characteristics and having a low base material erosion rate during brazing.

On the other hand, the brazing product according to the present invention is obtained by joining the brazing composite material.

According to the above, the reliability of the joint is good,
A brazed product with a low manufacturing cost is obtained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

The inventors of the present invention have the same heat resistance, oxidation resistance and heat resistance as the conventional self-brazing composite material (Ni-Ti type brazing material).
In addition, it has corrosion resistance, little corrosion of Ti, which is the base material of stainless steel (melting / dispersion into the brazing layer) during brazing, and various brazing composite materials that are easy to braze. As a result of examination, brazing satisfying the above-mentioned characteristics by forming the brazing layer from three layers of a first Ni or Ni alloy layer, a Ti or Ti alloy layer, and a second Ni or Ni alloy layer in order from the base material side. The composite material could be obtained.

FIG. 1 is a sectional view of a first embodiment of a brazing composite material according to the present invention, and FIG. 1 shows a first modified example, a second modified example,
2 and 3 and 4 are sectional views of the third modification.

As shown in FIG. 1, the brazing composite material 10 according to the first embodiment has a base material 11 made of a stainless steel plate, and a surface (only an upper surface in FIG. 1) of the base material 11 in order from the base material 11 side. 1 Ni or Ni alloy layer 12, Ti or Ti alloy layer 13,
Also, a brazing layer 15 composed of three layers of the second Ni or Ni alloy layer 14 is formed, and a Ti layer is sandwiched between Ni layers. The surface of the base material 11 mentioned here indicates all the surfaces exposed to the outside.

Here, the constituent material of the base material 11 is preferably an Fe-based alloy containing Fe as a main component, and particularly preferably stainless steel.

First (or second) Ni or Ni alloy layer 12
As the Ni alloy constituting (or 14), a Ni-P alloy or a Ni-Cr-Fe corrosion-resistant heat-resistant superalloy (for example,
Inconel (registered trademark) or the like) is preferable. By using these alloys, it is possible to improve the flowability and wettability of the molten metal during brazing, and when an Fe-based alloy (for example, stainless steel) is used as the base material 11, F
It is possible to reduce elution of the e component into the brazing layer 15.

The second Ni or Ni alloy layer 14, which is the outermost layer of the brazing layer 15 (or 25), may be made of a Ni alloy containing at least one selected from P, B, and Si. The melting point, the wettability, the toughness, and the bonding strength of the brazing filler metal can be adjusted by making the Ni alloy contain these elements and adjusting the contents of these elements. In particular, by containing 0.02 to 10 wt% of P in the Ni alloy, it is possible to remarkably improve the molten metal flowability, the wettability, and the corrosion resistance of the brazing material. P content of 0.0
The reason for defining 2 to 10 wt% is that if it is less than 0.02 wt%, the inconvenience that the improvement of the flowability of the molten metal cannot be expected occurs, while if it exceeds 10 wt%, the brazing layer becomes brittle and vibration fatigue occurs. This is because the disadvantage that the characteristics and the bonding strength are significantly reduced occurs, and the preferable content is 0.
It is 5 to 8 wt%.

The Ti concentration of the entire brazing layer 15 is not particularly limited, but is preferably 20 to 60 wt%,
More preferably 30 to 50 wt%, particularly preferably 40
It is around wt%.

The method for forming the brazing layer 15 is not particularly limited, and examples thereof include a method in which plate materials are laminated and then integrated by rolling.

The brazing composite material 10 of the present embodiment shown in FIG. 1 has a first Ni or Ni alloy layer 12 and a second Ni layer.
Alternatively, the Ni alloy layer 14 is formed to have the same layer thickness, but as shown in FIG. 2, the layer thickness of the first Ni or Ni alloy layer 12 on the base material 11 side is set to the layer of the second Ni or Ni alloy layer 14. It may be formed thicker than the thickness.

The composite material 10 (or 20) shown in FIG. 1 (or FIG. 2) is one side of the base material 11 (upper surface in FIGS. 1 and 2).
The brazing layer 15 (or 25) is formed only on
As shown in FIG. 3, brazing layers 15 and 15 may be formed on both surfaces (upper and lower surfaces in FIG. 3) of the base material 11 to form the brazing composite material 30.

These composite materials 10, 20, 30 (hereinafter,
Composite materials 10 to 30) are clad materials, but the forming method is not particularly limited, and any conventional method for forming a clad material can be applied. Examples thereof include a method of repeatedly forming, a method of laminating all plate materials and then rolling together.

The composite materials 10 to 30 shown in FIGS. 1 to 3 are
The brazing layer 15 (or 25 or 15, 15) is formed on the surface of the plate-shaped substrate 11, but as shown in FIG.
The brazing layer 15 may be formed on the surface of the rod-shaped or wire-shaped base material 41 to form the brazing composite material 40. In this case, the brazing layer 15 is formed by a plating method, an extrusion method, a pipe forming method, or the like.

Next, the operation of this embodiment will be described.

The composite materials 10, 20, 30 of the present embodiment
In 40 (hereinafter referred to as composite materials 10 to 40), in order to suppress the reaction between the Fe component (stainless steel) of the base material 11 and the Ti component of the brazing layer 15 or the Ti component of the Ti alloy layer 13 as much as possible, Ti Or Ni on both sides of the Ti alloy layer 13
Alternatively, the Ni alloy layers 12 and 14 are provided, and the first Ni or Ni is used as a barrier layer between the base material 11 and the Ti or Ti alloy layer 13.
By forming the alloy (for example, Ni—Cr—Fe based alloy) layer 12, direct contact between the base material 11 and the Ti or Ti alloy layer 13 is prevented. Here, the Ni layer is formed between the base material 11 and the Ti layer because the diffusion rate of Ni and Fe (stainless steel) (the diffusion rate of Fe with respect to Ni) is T
i and diffusion rate of Fe (stainless steel) (F to Ti)
This is because the reaction of the Ti component in the molten brazing layer 15 and the Fe component in the stainless steel is suppressed, and by extension, the base material 11 and the Ti or Ti alloy. It is possible to prevent the formation of intermetallic compounds between the layers 13.

Further, in the composite material 20 shown in FIG. 2, among the Ni or Ni alloy layers 22 and 14 formed on both sides of the Ti or Ti alloy layer 13, the first Ni or Ni alloy layer 22 on the base material 11 side is formed. Is formed thicker than the layer thickness of the second Ni or Ni alloy layer 14, the Fe component of the base material 11 is Ti in the brazing layer 25 or Ti of the Ti alloy layer 13.
It is possible to further suppress the reaction with the components. That is, due to the heat treatment during brazing, the Ti component of the Ti or Ti alloy layer 13 is Ni or Ni adjacent to both surfaces thereof.
Although it diffuses into the alloy layers 22 and 14 at the same diffusion rate, the first Ni or the Ni alloy layer 22 on the base material 11 side is the second Ni.
Alternatively, since the layer thickness is larger than that of the Ni alloy layer 14, diffusion is less likely to proceed, and as a result, corrosion of stainless steel is less likely to occur.

Further, the composite materials 10 to 40 are composed of the base material 11,
Since the brazing layer 15 (or 25) is integrally provided on the surface of 41, it is necessary to apply powdered Ni brazing material to each joint at the time of brazing, like various conventional Ni brazing materials. It is not necessary and does not require much labor for the brazing work (the brazing workability is good). As a result, the yield and productivity of brazed products are improved,
As a result, the manufacturing cost can be reduced.

The composite materials 10 to 40 are made of Ni or Ni.
The brazing layer 15 is formed by appropriately adding an additional element to the Ni alloy forming the alloy layers 12 and 14 (or 22 and 14).
(Or 25) has good flowability. Therefore, when the composite materials 10 to 40 are applied to brazing of a brazing member having a complicated brazing joint shape,
A good joint surface and a sufficient joint strength can be obtained, which in turn increases the reliability of the joint portion of the brazed product.

Further, in the composite materials 10 to 40, the brazing layer 15 (or 25) is replaced with the Ni or Ni alloy layer 12
(Or 22), 14 and Ti or the Ti alloy layer 13, the Ni element of the Ni brazing material mixes (melts) into the Ti brazing material during brazing. As a result, although Ti and Ti are excellent in heat resistance and corrosion resistance, it is difficult to function as a brazing material due to their high melting point.
The melting point of Ti brazing material made of alloy can be lowered, and T
Brazing using the i brazing material can be performed at around 1200 ° C. As a result, a Ti-based brazing part (joint part) having excellent heat resistance and corrosion resistance equivalent to those of the conventional self-brazing composite material (Ni-Ti type brazing material) and having excellent brazing property is obtained. Obtainable.

A brazing product using the composite materials 10 to 40 is a brazing layer 15 (or 2) of the composite materials 10 to 40.
5) and a brazing member (not shown) for joining are superposed and heated, or one of the brazing members for joining is joined to the base material 11 (or 4).
As 1), composite materials 10 to 40 are formed.
-40 and the other brazing member are overlapped and heated.

The composite materials 10 to 40 of this embodiment are EG
The use is not limited to heat exchangers such as R coolers that are exposed to high temperature and highly corrosive gases or liquids, and in addition, for example, coolers for reformers of fuel cells and fuel cell members. It is also applicable to various uses such as.
In particular, the composite material 40 is applicable to an EGR cooler, a heat exchanger such as a cooler for a reformer of a fuel cell, a fuel cell member, an oil cooler, a radiator, a secondary battery member, and the like. .

It is needless to say that the embodiments of the present invention are not limited to the above-mentioned embodiments but various other embodiments are possible.

[0041]

Example 1 A first Ni sheet made of SUS304 (JIS standard) and having a thickness of 2.5 mm and a width of 150 mm is formed on the surface of a stainless steel strip material in order from the stainless steel strip side to have a thickness of 0.076 mm. Strip material, Ti with a thickness of 0.2 mm
A strip material and a second Ni strip material having a thickness of 0.076 mm are clad by a rolling method, and the weight ratio of each layer of the brazing layer (second N
A composite substrate in which i / Ti / first Ni) was 30Ni-40Ti-30Ni (wt%) was prepared. After that, rolling is repeatedly performed on the composite base material so that the entire brazing layer has a thickness of 70 μm.
A (0.07 mm) brazing composite material was produced.

(Example 2) On the surface of the same stainless steel strip as in Example 1, the first Ni strip having a thickness of 0.1 mm, the Ti strip having a thickness of 0.2 mm, in this order from the stainless steel strip side, And a second Ni strip having a thickness of 0.05 mm is clad by a rolling method, and the weight ratio of each brazing layer (second Ni /
A composite substrate was prepared in which Ti / first Ni) was 20Ni-40Ti-40Ni (wt%). After that, rolling is repeatedly performed on the composite base material so that the entire brazing layer has a thickness of 70 μm.
A (0.07 mm) brazing composite material was produced.

Comparative Example 1 On the surface of the same stainless steel strip as in Example 1, a Ni strip having a thickness of 0.152 mm and a Ti strip having a thickness of 0.2 mm were rolled in order from the stainless steel strip side. A composite base material was produced in which the brazing layer was clad by the method and the weight ratio (Ni / Ti) of the brazing layers was 60Ni-40Ti (wt%). Then, rolling is repeatedly performed on the composite base material so that the entire brazing layer has a thickness of 70 μm (0.0
7 mm) of a brazing composite material was prepared.

(Conventional Example 1) A Cu base material having a thickness of 0.3 mm was clad on the surface of the same stainless steel base material as in Example 1 by a rolling method to prepare a composite base material. After that, rolling is repeatedly performed on the composite base material so that the brazing layer (Cu
A brazing composite material having a layer thickness of 70 μm was produced.

(Prior Art Example 2) A commercially available powdered Ni brazing material (average particle size: 35 μm) was formed on the surface of the same stainless steel strip as in Example 1.
The kneaded material in which m) was melted with a binder of synthetic resin (polymer resin) was applied to prepare a brazing composite material.

Examples 1 and 2, Comparative Example 1, and Conventional Example 1,
Table 1 shows the layer structure of the composite material of No. 2 and the weight ratio of each layer of the brazing layer.

[0047]

[Table 1]

Next, each of the composite materials was heated in a vacuum furnace to melt the brazing layer, and their brazing performances were evaluated. The brazing performance was evaluated by a comprehensive evaluation of the corrosion rate of the stainless steel strip as the base material, the corrosion resistance, the wettability of the brazing material, the brazing productivity (workability), and the evaluation thereof. The evaluation results are shown in Table 2.

Here, the rate of erosion is evaluated by heating each composite material in a vacuum furnace to melt the brazing layer, and then observing the cross section of each composite material, the stainless steel strip material as the base material. The remaining plate thickness (plate thickness after heat treatment × 100 / plate thickness before heat treatment (%)) was measured.

The corrosion resistance was evaluated by immersing the laminate or each composite material in a corrosive solution containing chlorine ions, nitrate ions, and sulfate ions for 1000 hours to carry out a corrosion test. Each composite material was taken out of the solution, the structure of the brazed portion was observed, and the presence or absence of corrosion was examined.

Further, the wettability of the brazing material was evaluated by placing a stainless steel pipe made of SUS304 on the surface of the brazing layer of each composite material and heating at 1150 ° C. to perform brazing. The fillet (chamfer) shape was used for evaluation.

[0052]

[Table 2]

As shown in Table 2, in the composite materials of Examples 1 and 2 which are the brazing composite materials according to the present invention, the plate thickness residual ratio of the stainless steel strip is high at 95% and 98%, and The corrosion resistance, wettability, and brazing productivity of the brazing layer were all good, and the overall evaluation was good. In particular, the composite material of Example 2 in which the Ni layer thickness on the stainless steel strip side in the brazing layer was increased had a very high plate thickness residual rate.

On the other hand, the composite material of Comparative Example 1 has good corrosion resistance, wettability and brazing productivity of the brazing layer, but the Ti layer in the brazing layer and the stainless steel strip are Since they were in direct contact, the stainless steel strip was significantly corroded (residual thickness was 65%), and the overall evaluation was poor.

The composite material of Conventional Example 1 had good brazing wettability and brazing productivity, but since the brazing layer was formed of only the Cu brazing material, the corrosion resistance of the brazing layer was poor. The overall evaluation was poor.

The composite material of Conventional Example 2 had good corrosion resistance of the brazing layer and good wettability of the brazing material, but the brazing material of the brazing layer was powdered Ni brazing material, so that the brazing productivity was high. It was bad and the overall evaluation was poor.

As described above, the composite materials of Examples 1 and 2 which are the brazing composite material according to the present invention have a low rate of corrosion of the stainless steel strip (base material) during brazing and the brazing. Since the corrosion resistance of the layer, the wettability of the brazing material, and the brazing productivity are all good, it can be seen that the brazing composite material has excellent brazing layer reliability.

[0058]

In summary, according to the present invention, the following excellent effects are exhibited. (1) It is possible to obtain a brazing composite material having good brazing characteristics and having a low base material erosion rate during brazing. (2) It is possible to obtain a brazed product having a good joint reliability and a low manufacturing cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a brazing composite material according to the present invention.

FIG. 2 is a sectional view showing a first modification of FIG.

FIG. 3 is a sectional view showing a second modification of FIG.

FIG. 4 is a sectional view showing a third modification of FIG.

[Explanation of symbols]

10, 20, 30, 40 Brazing composite material 11,41 Base material 12,22 First Ni or Ni alloy layer 13 Ti or Ti alloy layer 14 Second Ni or Ni alloy layer 15,25 Brazing layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideyuki Sagawa             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. (72) Inventor Masayoshi Aoyama             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. (72) Inventor Shirai Kaku             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd.

Claims (5)

[Claims] 1. A brazing composite material having a brazing layer formed on the surface of a base material, wherein a first Ni or Ni alloy layer, a Ti or Ti alloy layer, and a first Ni or Ni alloy layer are formed on the base material surface in this order from the base material side. A brazing composite material having a brazing layer formed of three layers of 2Ni or Ni alloy layers. 2. The brazing composite material according to claim 1, wherein the second Ni or Ni alloy layer is formed of a Ni—P alloy containing at least 0.02 to 10 wt% of P. 3. The layer thickness of the first Ni or Ni alloy layer,
The brazing composite material according to claim 1 or 2, wherein the brazing composite material is formed thicker than the second Ni or Ni alloy layer. 4. The brazing composite material according to claim 1, wherein the base material is formed of stainless steel. 5. A brazing product using a brazing composite material, which is joined by using the brazing composite material according to claim 1.