JP2006334605A - Brazing filler metal, and brazed product using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily treatable brazing filler metal having sufficient heat resistance and corrosion resistance, and to provide a brazed product using the same. <P>SOLUTION: The brazing filler metal 10 used for brazing members to be brazed is composed of a composite body with at least two layer structure, and also, a combination of a first layer 11 and the other layer 12 is the one of metallic layers capable of obtaining an alloy having a melting point lower than those of metals or an alloy constituting the respective layers 11, 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brazing material for brazing members to be brazed such as a heat exchanger and a member for a fuel cell, and a brazed product using the brazing material.

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

  In addition, as a brazing material for parts made of stainless steel, Ni-base alloy or Co-base alloy, various Ni brazing materials with excellent corrosion resistance in brazed joints can be selected from Ni, Cr, or Ni-Cr alloys There has been proposed a powdered Ni brazing material obtained by adding 4 to 22 wt% of a metal powder (see, for example, Patent Document 1).

  Further, as a brazing material having high corrosion resistance, there is an amorphous foil-shaped Ni brazing material having a composition conforming to JIS standards and mainly composed of Ni and Cr.

JP 2000-107883 A

  By the way, the conventional brazing material or brazing clad material is heated at a high temperature and exposed to highly corrosive gas or liquid (cooler for fuel cell reformer, exhaust gas recirculation device (hereinafter referred to as EGR (Exhaust Gas)). When used as a brazing filler metal for a recirculation)), there have been the following problems.

  (1) When the aforementioned stainless steel-based clad material is used as a joining material for an oil cooler for automobiles, there is no problem with respect to heat resistance and corrosion resistance. However, when this stainless steel-based clad material is used as a joining material for a fuel cell heat exchanger or an EGR cooler, there are problems in heat resistance and corrosion resistance. This is because high temperature and highly corrosive solutions and exhaust gases are circulated in the heat exchanger for fuel cells and the EGR cooler. There was a problem that the property and corrosion resistance were not sufficient and could not be used.

  (2) The powder Ni brazing material described in Patent Document 1 and the various Ni brazing materials specified by JIS standards are in the form of powder. Is required. That is, since much work is required for the brazing work, the productivity of the brazed product is remarkably lowered, resulting in an increase in manufacturing cost. In addition, the powder brazing material uses an organic binder when it is applied to the brazed joint, so a binder evaporation process is required. The problem that the inside becomes polluted arises.

  (3) Since the above-mentioned commercially available amorphous foil Ni brazing material is brittle, it is difficult to handle (handling) at the time of brazing material manufacture and assembly of a brazed product, resulting in a high manufacturing cost.

  An object of the present invention created in view of the above circumstances is to provide a brazing material that is easy to handle and has sufficient heat resistance and corrosion resistance, and a brazed product using the same.

  In order to achieve the above object, the brazing material according to the present invention is composed of at least two kinds of metals in the brazing material for brazing members to be brazed, and a combination of the first metal and the other metal, This is a combination of metals from which an alloy having a melting point lower than the melting point of each metal is obtained.

  Here, the first metal may be Ni or a Ni alloy, and the second metal may be Ti or a Ti alloy. The first metal may be Ni or Ni alloy, the second metal may be Ti or Ti alloy, and the third metal may be Ni or Ni alloy. Further, the first metal may be an Fe—Ni alloy, the second metal may be Ti or Ti alloy, and the third metal may be Ni or Ni alloy.

  Further, the brazing material according to the present invention is a brazing material for brazing members to be brazed, and is composed of a composite having at least a two-layer structure, and a combination of the first layer and the other layers is used for each layer. It is a combination of metal layers that provides an alloy having a melting point lower than the melting point of the constituent metal or alloy.

  Here, the first layer may be a Ni or Ni alloy layer, and the second layer may be a Ti or Ti alloy layer. The first layer may be a Ni or Ni alloy layer, the second layer may be a Ti or Ti alloy layer, and the third layer may be a Ni or Ni alloy layer. Further, the first layer may be a Fe—Ni alloy layer, the second layer may be a Ti or Ti alloy layer, and the third layer may be a Ni or Ni alloy layer.

  The brazing material may contain at least one element selected from P, Cu, Mn, Al, or Cr. The brazing material preferably contains Fe in a concentration range of 50% by weight or less. Further, the brazing material may be any of a foil material, a bar material, and a wire material.

  On the other hand, the brazed product according to the present invention is obtained by brazing and joining brazed members using the brazing material described above.

  According to the present invention, it is possible to obtain an excellent effect that a brazing material that can be brazed at a temperature of about 1200 ° C. with Ni and Ti as main components can be obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

  A cross-sectional view of a brazing filler metal according to a preferred embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, a brazing material 10 according to the present embodiment brazes members to be brazed, and is composed of a composite having at least a two-layer structure. Specifically, the brazing material 10 includes a Ni or Ni alloy layer (hereinafter referred to as Ni layer) 11 as a first layer and a Ti or Ti alloy layer (hereinafter referred to as Ti layer) 12 as a second layer. It is comprised by the laminated body (composite body) of 2 layer structure.

  If the weight of Ni in the entire brazing filler metal 10 is W1, and the total weight of Ni and Ti is W2, W1 / W2 is 0.58 to 0.68, preferably 0.62 to 0.67. If W1 / W2 is less than 0.58 (or exceeds 0.68), the melting point of the brazing material 10 becomes extremely high, and brazing treatment at around 1200 ° C. becomes impossible.

  The Ni alloys constituting the Ni layer 11 are roughly classified into those containing an Fe component and those not containing an Fe component. Examples of the Ni alloy containing the Fe component include an Fe—Ni alloy, preferably Invar (registered trademark) and 42 alloy.

  The brazing filler metal 10 may contain at least one element selected from P, Cu, Mn, Al, or Cr. For example, when P is contained in the brazing material 10 in a ratio of 0.02 to 10.0% by weight, preferably 0.02 to 5.0% by weight, the hot water flow and oxidation resistance of the brazing material can be improved. Here, the content of P is limited to 0.02 to 10% by weight because if it is less than 0.02% by weight, improvement in hot water flow cannot be expected, and conversely if it exceeds 10.0% by weight, brazing is performed. This is because the strength is lowered depending on the type of brazing member to be performed. Moreover, when Cu and Mn are contained in the brazing material 10, the hot water flowability of the brazing material can be improved. Furthermore, when Al and Cr are contained in the brazing material 10, the corrosion resistance of the brazing material can be improved.

  Further, when brazing members to be brazed of iron-based alloys such as stainless steel, it is desirable to add Fe to the brazing material. This is because the biting of the member to be brazed can be reduced by adding Fe. The Fe content is 50% by weight or less, preferably 15 to 50% by weight or less. Here, if the Fe concentration exceeds 50% by weight, the corrosion resistance of the brazed joint and the hot water flow of the brazing material are lowered, which is not preferable.

  In the present embodiment, the brazing material 10 having the two-layer structure of the Ni layer 11 and the Ti layer 12 has been described. However, the layer structure of the brazing material is not particularly limited to this, and may be a structure of three or more layers. For example, a brazing material 20 having a three-layer structure as shown in FIG. 2 and a brazing material 30 having a five-layer structure as shown in FIG. The brazing material 20 is a composite formed by laminating the Ni layer 11a (first layer), the Ti layer 12 (second layer), and the Ni layer 11b (third layer) in this order. Ni layer 11a (first layer), Ti layer 12a (second layer), Ni layer 11b (third layer), Ti layer 12b (fourth layer), Ni layer 11c (fifth layer) It is a composite formed by sequentially laminating.

  Moreover, in this Embodiment, although demonstrated using the brazing material (foil material) 10 which exhibited foil shape (thin plate shape), the shape of a brazing material is not specifically limited to foil shape, for example, It may be rod-shaped or wire-shaped. For example, as shown in FIG. 4, a brazing material (bar material, wire material) 40 provided with a first layer made of Ni layer 11 around a core material made of Ti layer 12 (second layer), or FIG. As shown in FIG. 4, a brazing material (bar material, wire) in which a second layer made of a Ti layer 12 and a first layer made of a Ni layer 11a are sequentially provided around a core material made of a Ni layer 11b (third layer). Material) 50. In this case, the layer provided around the core material is formed by a plating method, an extrusion method, a pipe making method, or the like.

  Next, a brazing method using the brazing material 10 according to the present embodiment will be described.

  By appropriately rolling the brazing material 10 according to the present embodiment, the layers 11 and 12 are clad, and a brazing material (final product) having a desired thickness is obtained. This final product is arranged in a portion to be brazed (hereinafter referred to as a brazed portion) between brazed members (not shown) to be joined.

  Next, the brazing process is performed by heating the brazed member with the brazed portion as the main. By this brazing process, a melting reaction of the brazing material 10 occurs at the brazing point. The temperature of this brazing process is, for example, 1150 to less than 1250 ° C, preferably around 1200 ° C.

  By this brazing treatment, first, a diffusion reaction proceeds between the Ni layer 11 and the Ti layer 12 in the brazing material 10 and melting starts at the interface between the Ni layer 11 and the Ti layer 12. That is, in the brazing filler metal 10, the Ni component and the Ti component are mixed and contacted to cause alloying. As a result, the melting point of the brazing material 10 is lower than the melting points of Ni and Ti (1455 ° C. and 1670 ° C.), and brazing treatment at a lower temperature is possible. As a result, the brazing filler metal 10 begins to melt at a temperature of around 1200 ° C. (less than about 1150 to 1250 ° C.), the brazing filler metal 10 flows, and the brazing filler metal 10 melts to form a brazing melt part.

  In particular, when the Ni layer 11 of the brazing filler metal 10 according to the present embodiment contains an Fe component, when the melting starts at the interface between the Ni layer 11 and the Ti layer 12, the Fe component contained in the brazing filler metal 10 is brazing. Since it diffuses throughout the material 10, the melting of the brazing material 10 is further facilitated. That is, in the brazing filler metal 10, the Ni component, Ti component, and Fe component are mixed and contacted to cause alloying. As a result, the melting point of the brazing material 10 is further reduced as compared with the case where the brazing material composed of only Ni and Ti is melted, so that brazing treatment at a lower temperature is possible. As a result, the brazing filler metal 10 starts to melt at a temperature below about 1200 ° C.

  Further, when the Ni layer 11 contains an Fe component, the brazing material 10 melts and flows during the brazing process, and the Fe component sufficiently diffuses throughout the brazing material 10 before the melting and flow. For this reason, the Fe concentration of the entire brazing filler metal 10 is 50% by weight or less which is the same as the Fe concentration of the entire brazing filler metal 10 before melting.

  During the brazing process, the Fe component of the member to be brazed may dissolve into the brazing melt part, but the melting occurs until the Fe concentration in the brazing melt part reaches saturation, and the Fe that can be melted. There is a limit to the amount. Since a sufficient concentration of the Fe component is present in the brazing molten portion of the brazing material 10, the Fe component of the brazed member is suppressed from being dissolved into the brazed molten portion, and the brazed member is eroded. Occurrence can be greatly reduced. Further, the Fe concentration in the brazing melt part is adjusted to 50% by weight or less so as not to inhibit the hot water flowability. For this reason, the hot metal flowability of the brazing melt part is good. As a result, after the brazing process, there is no reduction in strength at the brazed joint of the brazed product, and the reliability of the brazed joint is good.

  Thereafter, when the brazing material 10 is completely melted, rapid cooling is performed to solidify the brazed molten portion into a brazed joint, and the brazed members are joined to each other via the brazed joint. Is obtained.

  Since the brazing material 10 according to the present embodiment is excellent in corrosion resistance and mainly contains high melting point Ni and Ti, the brazed joint portion of the brazed product using the brazing material 10 has sufficient heat resistance. And has corrosion resistance.

  Further, the brazing material 10 according to the present embodiment is mainly composed of high melting point Ni and Ti, but can be brazed at a low temperature of around 1200 ° C., and the brazing productivity is good. .

  Furthermore, since the brazing material 10 according to the present embodiment is sufficiently clad with each of the layers 11 and 12, workability such as bending and pressing is good, and the brazed portion of the brazed member has a shape. Accordingly, the shape can be freely deformed. Therefore, the brazing filler metal 10 according to the present embodiment can be manufactured at a lower cost than the conventional amorphous foil Ni brazing filler metal, and as a result, the manufacturing cost of the brazed product is also reduced.

  Further, since the brazing material 10 according to the present embodiment is a foil material, a rod material, or a wire material, it does not require an organic binder as in the case of a conventional powdery brazing material, and the brazing process is performed. Is easy to handle.

  Brazing products using the brazing filler metal 10 according to the present embodiment include heat exchangers exposed to high-temperature, highly corrosive gases or liquids such as EGR coolers, fuel cell reformer coolers, fuel cell members, An oil cooler, a radiator, a secondary battery member, etc. are mentioned. Moreover, the brazing material 10 according to the present embodiment can be applied to all brazing products that require high corrosion resistance at the brazed joint.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

Example 1
A Ni plate (Ni strip) having a thickness of 0.90 mm and a Ti plate (Ti strip) having a thickness of 1.0 mm were laminated in order to form a laminate having a two-layer structure. The laminate was repeatedly subjected to rolling treatment to produce a clad material (brazing material) having a thickness of 50 μm.

  After this clad material was placed on a stainless steel (SUS304) plate, a stainless steel (SUS304) pipe was placed on the clad material. Thereafter, the member arranged in such a state was heated in a tubular furnace at 1200 ° C. to perform brazing treatment, and a brazed product was produced. The Fe concentration of the brazing material was 0 wt%.

(Example 2)
A laminate with a three-layer structure is formed by sequentially stacking a 0.45 mm thick Ni plate (Ni strip), a 1.0 mm thick Ti plate (Ti strip), and a 0.45 mm thick Ni plate (Ni strip). Formed. A brazed product was produced in the same manner as in Example 1 except that this laminate was used. The Fe concentration of the brazing material was 0 wt%.

(Example 3)
A three-layer structure in which an Invar (registered trademark) plate (Invar strip) with a thickness of 0.72 mm, a Ti plate (Ti strip) with a thickness of 1.0 mm, and a Ni plate (Ni strip) with a thickness of 0.52 mm are stacked in order. A laminate was formed. A brazed product was produced in the same manner as in Example 1 except that this laminate was used. The Fe concentration of the brazing material was 25 wt%.

Example 4
A three-layer structure in which an Invar (registered trademark) plate (invar strip) with a thickness of 2.26 mm, a Ti plate (Ti strip) with a thickness of 1.0 mm, and a Ni plate (Ni strip) with a thickness of 0.06 mm are stacked in order. A laminate was formed. A brazed product was produced in the same manner as in Example 1 except that this laminate was used. The Fe concentration of the brazing material was 50 wt%.

(Comparative Example 1)
After placing a Ni foil rolled to a thickness of 50 μm on the same stainless steel plate as in Example 1, the same stainless steel pipe as in Example 1 was placed on the Ni foil. Thereafter, the member arranged in such a state was heated in a tubular furnace at 1200 ° C. to perform brazing treatment, and a brazed product was produced. The Fe concentration of the brazing material was 0 wt%.

(Comparative Example 2)
After placing a Ti foil rolled to a thickness of 50 μm on the same stainless steel plate as in Example 1, the same stainless steel pipe as in Example 1 was placed on the Ti foil. Thereafter, the member arranged in such a state was heated in a tubular furnace at 1200 ° C. to perform brazing treatment, and a brazed product was produced. The Fe concentration of the brazing material was 0 wt%.

(Comparative Example 3)
A three-layer structure in which an Invar (registered trademark) plate (Invar strip) with a thickness of 2.36 mm, a Ti plate (Ti strip) with a thickness of 1.0 mm, and a Ni plate (Ni strip) with a thickness of 0.03 mm are stacked in order. A laminate was formed. A brazed product was produced in the same manner as in Example 1 except that this laminate was used. The Fe concentration of the brazing material was 51 wt%.

(Conventional example 1)
After placing a Cu foil (brazing material) rolled to a thickness of 50 μm on the same stainless steel plate as in Example 1, the same stainless steel pipe as in Example 1 was placed on the Cu foil. Thereafter, the member arranged in such a state was heated in a tubular furnace at 1120 ° C. to perform brazing treatment, and a brazed product was produced. The Fe concentration of the brazing material was 0 wt%.

(Conventional example 2)
After applying a commercially available powdered Ni brazing filler metal equivalent to JIS standard BNi-5 with a synthetic resin binder to one side of the same stainless steel plate as in Example 1, the same as in Example 1 was applied to the coating film. A stainless steel pipe was placed. Thereafter, the member arranged in such a state was heated in a tubular furnace at 1180 ° C. to perform brazing treatment, and a brazed product was produced. The Fe concentration of the brazing material was 0 wt%.

(Conventional example 3)
After placing a commercially available amorphous foil Ni brazing material corresponding to JIS standard BNi-5 on one side of the same stainless steel plate as in Example 1, the same stainless steel pipe as in Example 1 was placed on the foil. After that, the member arranged in such a state was heated in a tubular furnace at 1180 ° C. and subjected to brazing treatment to produce a brazed product. The Fe concentration of the brazing material was 0 wt%.

  Table 1 shows the structures of the brazing materials of Examples 1 to 4, Comparative Examples 1 to 3, and Conventional Examples 1 to 3 (layer structure, ratio of Fe concentration in the entire brazing material). Moreover, about each brazing product of Examples 1-4, Comparative Examples 1-3, and Conventional Examples 1-3, workability, the presence or absence of corrosion generation | occurrence | production, brazing productivity (handleability) are evaluated, and those A comprehensive evaluation was performed based on the evaluation. These results are also shown in Table 1.

  For the evaluation of workability, a 180 ° bending test was performed on each brazing material in the form of a plate (foil), and the presence or absence of material breakage and the presence or absence of cracks were observed by visual observation and optical microscope observation.

  The presence or absence of corrosion was determined by immersing each brazed product after brazing treatment in a corrosive solution containing chlorine ions, nitrate ions, and sulfate ions for 1000 hours, and then performing each of these brazed products. Was taken out of the solution, and the structure of the brazed joint was observed to examine whether or not corrosion occurred. In addition, the solution after the corrosion test was analyzed, and the amount of the eluate from the brazing material was quantitatively compared to determine the degree of corrosion.

  As shown in Table 1, each brazing material of Examples 1 to 4 is formed by combining Ni and Ti by combining a Ni layer and a Ti layer, or a Ni alloy layer (Invar (registered trademark) layer), a Ti layer, and a Ni layer. Compared with each melting point (1455 ° C, 1670 ° C), the melting point was significantly reduced, and brazing at 1200 ° C was possible. Moreover, from the evaluation of each brazing material in Examples 3 and 4, it was found that sufficiently high corrosion resistance can be obtained if the Fe concentration in the brazing material is 50% by weight or less. Furthermore, since each brazing material of Examples 1-4 was plate-shaped, it turned out that workability is favorable and brazing productivity is also favorable.

  In contrast, each brazing material of Comparative Examples 1 and 2 has good workability and handleability, but the brazing material is composed of a single high-melting point metal such as Ni foil and Ti foil. The melting point of the brazing material is high. For this reason, each brazing material of Comparative Examples 1 and 2 was not melted by the brazing treatment at 1200 ° C. and did not function as a brazing material.

  The brazing material of Comparative Example 3 has the same structure as the brazing materials of Examples 3 and 4, but the Fe concentration in the brazing material is 51% by weight, and the specified range (50% by weight or less). Therefore, there was a slight problem with corrosion resistance. From this, it is understood that the Fe concentration in the brazing material is desirably 50% by weight or less.

  On the other hand, the brazing material of Conventional Example 1 has good workability and handleability, and since the melting point of the brazing material is relatively low, it can function as a brazing material alone. However, since the brazing material is composed of Cu alone, the corrosion resistance is insufficient and significant corrosion occurs, which indicates that it cannot be used in a high corrosion resistance environment.

  Although the brazing material of Conventional Example 2 has good corrosion resistance, it is a powder brazing material, so it cannot be bent and further requires an organic binder, so that it is easy to handle. Not. In addition, it was found that the brazing material peels off from the stainless steel plate (member to be brazed) and falls off when vibration is applied in the state after the brazing material is applied.

  Although the brazing material of Conventional Example 3 has good corrosion resistance, it is a brittle amorphous foil brazing material, so it cannot be bent and is difficult to handle.

1 is a cross-sectional view of a brazing material according to a preferred embodiment of the present invention. It is a figure which shows the 1st modification of the brazing material of FIG. It is a figure which shows the 2nd modification of the brazing material of FIG. It is a figure which shows the 3rd modification of the brazing material of FIG. It is a figure which shows the 4th modification of the brazing material of FIG.

Explanation of symbols

10 Brazing material 11 Ni layer (first layer)
12 Ti layer (second layer)

Claims (13)

  A brazing material for brazing members to be brazed, which is made of at least two kinds of metals and in which an alloy having a melting point lower than the melting point of each metal is obtained by combining the first metal and the other metal. A brazing material characterized by being a combination of each other.   The brazing material according to claim 1, wherein the first metal is Ni or a Ni alloy, and the second metal is Ti or a Ti alloy.   The brazing material according to claim 1, wherein the first metal is Ni or a Ni alloy, the second metal is Ti or a Ti alloy, and the third metal is Ni or a Ni alloy.   The brazing material according to claim 1, wherein the first metal is an Fe-Ni alloy, the second metal is Ti or Ti alloy, and the third metal is Ni or Ni alloy.   A brazing material for brazing members to be brazed, which is composed of a composite having at least a two-layer structure, and the combination of the first layer and the other layers has a melting point higher than the melting point of the metal or alloy constituting each layer. A brazing material characterized in that it is a combination of metal layers from which a low-alloy alloy can be obtained.   The brazing material according to claim 5, wherein the first layer is a Ni or Ni alloy layer, and the second layer is a Ti or Ti alloy layer.   6. The brazing material according to claim 5, wherein the first layer is a Ni or Ni alloy layer, the second layer is a Ti or Ti alloy layer, and the third layer is a Ni or Ni alloy layer.   The brazing material according to claim 5, wherein the first layer is a Fe-Ni alloy layer, the second layer is a Ti layer or a Ti alloy, and the third layer is a Ni or Ni alloy layer.   The brazing material according to any one of claims 1 to 8, wherein the brazing material contains at least one element selected from P, Cu, Mn, Al, and Cr.   The brazing material according to any one of claims 1, 4, 5, 8, and 9, wherein the brazing material contains Fe in a concentration range of 50% by weight or less.   The brazing material according to any one of claims 1 to 10, wherein the brazing material is a foil material.   The brazing material according to any one of claims 1 to 10, wherein the brazing material is a bar material or a wire material. A brazing product comprising the brazing material according to any one of claims 1 to 12 and brazing and joining members to be brazed.

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