JP2005103610A - Brazing composite material and brazing product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazing composite material having good brazing characteristics and having good heat resistance and corrosion resistance of a brazed joint, and brazing products having good reliability of the brazed joint and low manufacturing cost. Is to provide.
A brazing composite material 10 according to the present invention brazes members to be brazed together, and a Ni or Ni alloy layer is formed on the surface of a base material 11 made of an alloy containing Ni. A brazing layer 15 having a multilayer structure in which 13 and Ti or a Ti alloy layer 12 are laminated is integrally provided. The weight W1 of the Ni component contained in the brazing layer 15 and the weights of the Ni component and the Ti component The ratio W1 / W2 to the total sum W2 is 0.58 to 0.64.
[Selection] Figure 1

Description

  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 a heat exchanger and a fuel cell member and a brazing product using the same.

  Stainless steel-based clad materials are used as joining materials for automobile oil coolers. In this case, 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.

  Further, as a brazing material for members made of stainless steel, Ni-base or Co-base alloy, various Ni brazing materials having excellent corrosion resistance at the brazed joint are defined by JIS standards.

  Further, 4 to 22 wt% of metal powder selected from Ni, Cr, Ni—Cr alloy, or stainless steel is added to the powdered Ni brazing material as the Ni brazing material used for joining the heat exchanger. A powder Ni brazing material is proposed (see, for example, Patent Document 1).

  Further, there is a self-brazing composite material having a brazing layer made of Ni and Ti on the surface of stainless steel as a base material, that is, having a brazing layer structure of Ni / Ti / stainless steel (for example, Patent Document 2). reference).

JP 2000-107883 A Japanese Patent Laid-Open No. 7-299592

  By the way, a conventional brazing material or a brazing composite material is subjected to a heat exchanger (cooler for a fuel cell reformer, exhaust gas recirculation device (hereinafter referred to as EGR (Exhaust Gas)) exposed to a highly corrosive gas or liquid at high temperature. When used as a brazing filler metal for a recirculation)), there are 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 bonding material for an EGR cooler, the exhaust gas is circulated at a high temperature and highly corrosive in the EGR cooler. (Cu material) has a problem that heat resistance and corrosion resistance are not sufficient.

  (2) Since the powder Ni brazing material described in Patent Document 1 and various Ni brazing materials specified in JIS standards are in the form of powder, the work of applying the powder Ni brazing material to each brazed joint is performed. I need it. 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.

  (3) Since the amorphous Ni brazing material similarly stipulated by the JIS standard is very fragile, handling (handling) at the time of brazing material manufacture and brazing product assembly is difficult, and there has been a problem that the work cost becomes high.

  (4) Although the self-brazing composite material described in Patent Document 2 is sufficient in heat resistance and corrosion resistance, the brazing material itself is not good in brazing and wettability during brazing. Since it is brittle, there has been a problem that the performance (strength and fatigue properties) of the product after brazing is greatly reduced.

  One object of the present invention created in view of the above circumstances is to provide a brazing composite material having good brazing characteristics and good heat resistance and corrosion resistance of a brazed joint. .

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

  In order to achieve the above object, a brazing composite material according to the present invention is a brazing composite material for brazing members to be brazed to each other on the surface of a base material composed of an alloy containing Ni. A brazing layer having a multilayer structure in which an alloy layer and Ti or a Ti alloy layer are laminated is integrally provided, and the weight W1 of the Ni component contained in the brazing layer and the total weight of the Ni component and the Ti component The ratio W1 / W2 with W2 is 0.58 to 0.64.

  Further, the brazing composite material according to the present invention is a brazing composite material for brazing members to be brazed, and a Ni or Ni alloy layer is formed on the surface of a base material composed of an alloy containing no Ni. A brazing layer having a multilayer structure in which a Ti or Ti alloy layer is laminated is integrally provided. The weight W1 of the Ni component contained in the brazing layer and the total weight W2 of the weights of the Ni component and the Ti component The ratio W1 / W2 is 0.64 to 0.68.

  Here, it is preferable that at least one of the Ni or Ni alloy layer or the Ti or Ti alloy layer contains P. Thereby, the hot-water flow property when brazing the brazing material or the brazing layer and the oxidation resistance of the brazed joint can be further improved.

  Moreover, it is preferable that at least one of Ni or Ni alloy layer or Ti or Ti alloy layer contains at least one of Cu, Mn, Al, or Cr. Thereby, the hot water flow property when brazing the brazing material or the brazing layer and the corrosion resistance of the brazed joint can be further improved.

  According to the above, a brazing characteristic is good and a brazing joint portion is obtained by integrating a substrate obtained by clad a Ti or Ti alloy layer and a Ni or Ni alloy layer at a predetermined weight ratio. A brazing composite material having good heat resistance and corrosion resistance can be obtained.

  According to the present invention, it is possible to braze a Ni—Ti brazing material at a relatively low temperature, and exhibit an excellent effect that the reliability of the brazed joint is high.

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

  The present inventors have good brazing characteristics (such as hot metal flowability and brazing productivity of the brazing material), good heat resistance and corrosion resistance of the brazed joint, and greatly reduce the brazing cost. Various studies were made on the composition of the brazing composite. As a result, conventionally, Ni metal alone has a high melting point of about 1455 ° C., and as such (single), it was difficult to use it as a brazing material for joining stainless steel materials. It was found that the melting point can be lowered by cladding at a weight ratio and alloying these at the time of brazing, and brazing at around 1200 ° C. is possible.

(First embodiment)
A cross-sectional view of a brazing composite material according to a preferred embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, the brazing composite material 10 according to the present embodiment is a thin plate and on the surface of a base material 11 made of an alloy containing Ni (only the upper surface in FIG. 1). A brazing layer 15 is provided in which a Ti or Ti alloy layer 12 and a Ni or Ni alloy layer 13 are clad so as to overlap each other. The surface of the base material 11 here refers to all surfaces exposed to the outside.

  Examples of the alloy containing Ni constituting the base material 11 include austenitic stainless steel, such as SUS304 (JIS standard).

  In the composite material 10, the ratio (W1 / W2) of the weight W1 of the Ni component contained in the brazing layer 15 and the total weight W2 of the Ni component and the Ti component was adjusted to 0.58 to 0.64. Is. In other words, the composite material 10 is adjusted so that the composition of the entire brazing layer 15 is Ni-36 to 42 wt% Ti. These adjustments are made by adjusting the layer thickness of the layers 12 and 13, adjusting the alloy composition of the layers 12 and 13, and the like.

  Here, if W1 / W2 is less than 0.58, since the Ni component contained in the brazing layer 15 is too small (because the Ti component is excessive), the melting point of the brazing layer 15 becomes higher than necessary. . Therefore, the melting point cannot be sufficiently lowered even by the alloying action of the Ni component contained in the brazing layer 15 and the Ni component supplied from the base material 11 and the Ti component of the layer 12, and the hot water flow of the brazing material Will get worse. At this time, when the Ni component is sufficiently supplied from the base material 11, the melting point of the brazing layer 15 can be sufficiently lowered, but in this case, the reduction amount of the thickness of the base material 11 becomes extremely large. This is not preferable. On the other hand, when W1 / W2 exceeds 0.64, the Ni component is excessively combined with the Ni component supplied from the base material 11, the melting point of the brazing layer 15 is increased, and the liquid phase and the solid phase are increased. And the coexisting temperature range becomes wide, and the hot water flowability is deteriorated.

  Moreover, at least one of the layer 12 or the layer 13 may contain P. By containing P in the brazing layer 15 in an amount of 0.02 to 10 wt%, preferably 0.02 to 5.0 wt%, the hot metal flow and oxidation resistance of the brazing material can be remarkably improved. Here, the reason why the P content is limited to 0.02 to 10 wt% is that if it is less than 0.02 wt%, improvement in hot water flow cannot be expected, and conversely if it exceeds 10 wt%, brazing is performed. This is because the strength is lowered depending on the type of brazed member to be used.

  Moreover, at least one of the layer 12 or the layer 13 may contain at least one of Cu, Mn, Al, or Cr. By containing Cu and / or Mn in the brazing material 15, the hot water flow property of the brazing material 15 can be further improved. Here, the Cu concentration contained in the brazing material 15 is 0.2 to 30 wt%. This is because if the Cu concentration is less than 0.2 wt%, the effect of Cu addition cannot be obtained sufficiently, and conversely if it exceeds 30 wt%, the corrosion resistance decreases. On the other hand, the inclusion of Al and / or Cr in the brazing material 15 can further improve the corrosion resistance and high-temperature oxidation resistance of the brazed joint.

  A composite material for brazing (final product) having a desired thickness is obtained by appropriately rolling the composite material 10 according to the present embodiment. A brazed product is obtained by bringing the final products into contact with each other or with a brazing member (not shown) for joining with the final product and performing a brazing process by heating.

  In the present embodiment, the case where the brazing layer 15 is formed only on one side (the upper surface in FIG. 1) of the base material 11 has been described, but not only the single side of the base material 11 but both surfaces of the base material 11. (Upper and lower surfaces in FIG. 1) may be formed.

  Moreover, in this Embodiment, although demonstrated using the composite material 10 which exhibited the thin plate shape, the shape of a composite material is not specifically limited to a thin plate shape. As shown in FIG. 2, a brazing layer 25 formed by laminating the layers 12 and 13 in order from the inner layer side is formed on the surface of a rod-like or wire-like base material 31 as shown in FIG. The composite material 20 may be used. In this case, the layers 12 and 13 are formed by a plating method, an extrusion method, a pipe making method, or the like.

  Next, the operation of the composite material 10 (or 20) according to the present embodiment will be described.

  In the composite material 10 (or 20) according to the present embodiment, the brazing layer 15 is composed of a Ti or Ti alloy layer 12 and a Ni or Ni alloy layer 13. For this reason, during brazing, the Ti component of the Ti brazing material and the Ni component of the Ni brazing material in the brazing layer 15 diffuse together to form an alloy.

  At this time, the Ni component alone contained in the Ni brazing material is not sufficient to lower the melting point of the brazing layer 15, that is, the melting point of the Ni—Ti alloy to around 1200 ° C. The Ni component contained in the substrate 11 diffuses into the brazing layer 15 together with the Ni component contained in the brazing layer. In composite material 10 (or 20) according to the present embodiment, it is anticipated that Ni component contained in substrate 11 will diffuse into brazing layer 15, and the ratio of Ti component and Ni component in brazing layer 15 Is adjusted.

  As a result, the melting point of the brazing material containing Ni or Ni alloy, which has been difficult to function as a brazing material due to its high melting point, can be lowered to around 1200 ° C., and brazing using the composite material 10 can be carried out at around 1200 ° C. Can be performed.

  As a result, the composite material 10 (or 20) according to the present embodiment can be used as a brazing material for joining an EGR cooler that is exposed to a highly corrosive gas or liquid at a high temperature. As a result, it is possible to obtain a Ni—Ti brazed joint having excellent brazing characteristics and excellent heat resistance and corrosion resistance.

  Further, by containing Al or Cr in at least one of the Ti or Ti alloy layer 12 and the Ni or Ni alloy layer 13 of the brazing layer 15, the surface of the brazed joint is made of aluminum oxide or chromium oxide. Thus, a dense oxide film is formed, and the high-temperature oxidation resistance can be remarkably improved. As a result, it becomes difficult for the joint strength of the brazed joint to decrease due to high-temperature (about 600 to 800 ° C.) oxidation, and the joint of the brazed product has good reliability.

  Moreover, the viscosity of the brazing layer 15 is reduced by adding Cu or Mn to at least one of the Ti or Ti alloy layer 12 and the Ni or Ni alloy layer 13 of the brazing material 15. As a result, the hot water flow property of the brazing layer 15 is further improved, and the brazing characteristics are improved.

  Moreover, the composite material 10 (or 20) is integrally provided with a brazing layer 15 on the surface of the base material 11. For this reason, a brazed product can be obtained simply by bringing the brazing layer 15 of the composite material 10 (or 20) into contact with the member to be brazed and performing brazing. That is, in the brazed product using the composite material 10 (or 20) according to the present embodiment, the composite material 10 using at least one brazed member as a base material 11 among a set of brazed members to be joined. (Or 20) is formed, and this composite material 10 (or 20) and the other brazed member are superposed and heated.

  Therefore, the composite material 10 (or 20) according to the present embodiment does not need to be coated with a powdered Ni brazing material at each brazed joint, unlike various conventional Ni brazing materials. As a result, a great amount of labor is not required for the brazing work (the brazing workability is improved), the yield and productivity of the brazed product are improved, and the manufacturing cost can be reduced.

  From the above, by brazing using the composite material 10 (or 20) according to the present embodiment, a brazed joint excellent in heat resistance and corrosion resistance can be obtained easily and inexpensively, and corrosion is caused at a high temperature. It is optimal as a brazing material for brazed joints such as EGR coolers that are exposed to highly gas or liquid.

  Next, another embodiment of the present invention will be described with reference to the accompanying drawings.

(Second Embodiment)
FIG. 3 shows a cross-sectional view of a brazing composite material according to another preferred embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to FIG. 1, and detailed description is abbreviate | omitted about these members.

  The composite material 10 according to the first embodiment is integrally provided with a brazing layer 15 formed by superposing two layers of a Ti or Ti alloy layer 12 and a Ni or Ni alloy layer 13 on the surface of the base material 11. It was.

  On the other hand, as shown in FIG. 3, the composite material 30 according to the second embodiment is a thin plate-like surface of the base material 11 made of an alloy containing Ni (the upper surface in FIG. 3). Only), a brazing layer 35 in which a Ti or Ti alloy layer 12 and a Ni or Ni alloy layer 13 are alternately layered on a layer 13, a layer 12, and a layer 13.

  Also in the composite material 30 according to the present embodiment, the same effects as those of the composite material 10 according to the previous embodiment can be obtained.

  In the present embodiment, the case where the brazing layer 35 is formed only on one surface (the upper surface in FIG. 3) of the base material 11 has been described, but not only one surface of the base material 11 but both surfaces of the base material 11. (Upper and lower surfaces in FIG. 3) may be formed.

  In the present embodiment, the case where the brazing layer has a three-layer structure has been described. However, the present invention is not limited to this. For example, as shown in FIG. 4, the first modification of FIG. 3 is a thin plate and Ti or Ti alloy on the surface of the base material 11 made of an alloy containing Ni (only the upper surface in FIG. 4). The composite material 40 may be formed by forming a brazing layer 45 in which the layer 12 and the Ni or Ni alloy layer 13 are alternately overlapped with the layer 13, the layer 12, the layer 13, the layer 12, and the layer 13. Further, a brazing layer having a four-layer structure or a structure having six or more layers may be formed on the surface of the base material 11 to form a composite material.

  Moreover, in this Embodiment, although demonstrated using the composite material 30 which exhibited the thin plate shape, the shape of a composite material is not specifically limited to a thin plate shape. As shown in FIG. 5, a brazing layer 55 is formed on the surface of the rod-like or wire-like base material 31 by laminating the layer 13, the layer 12, and the layer 13 in this order from the inner layer side. Alternatively, the brazing composite material 50 may be used. Further, as shown in FIG. 6, the layer 13, the layer 12, the layer 13, the layer 12, and the layer 13 are laminated on the surface of the rod-like or wire-like base material 31 in order from the inner layer side as shown in FIG. A brazing layer 65 may be formed to form a brazing composite material 60. Also in the composite materials 50 and 60, the same effect as the composite material 20 according to the previous embodiment can be obtained.

  In the present embodiment, the case where the material (composition) of the layer 12 or the layer 13 is the same has been described. However, the present invention is not limited to this, and the material (composition) of the layer 12 or the layer 13 is changed to each layer. Each may be different.

(Third embodiment)
FIG. 7 shows a cross-sectional view of a brazing composite material according to another preferred embodiment of the present invention.
In addition, the same code | symbol is attached | subjected to the member similar to FIG. 1, and detailed description is abbreviate | omitted about these members.

  As shown in FIG. 7, the brazing composite material 70 according to the present embodiment is a thin plate and on the surface of the base material 71 made of an alloy not containing Ni (only the upper surface in FIG. 7). A brazing layer 75 is provided in which a Ti or Ti alloy layer 12 and a Ni or Ni alloy layer 13 are laminated in two layers and clad. The surface of the base material 21 here refers to all surfaces exposed to the outside.

  Examples of the alloy that does not contain Ni constituting the base material 71 include ferritic stainless steel and martensitic stainless steel, and examples thereof include SUS430 (JIS standard). Ferritic stainless steel is preferred.

  Further, in the composite material 70, the ratio (W1 / W2) of the weight W1 of the Ni component contained in the brazing layer 75 and the total weight W2 of the Ni component and the Ti component was adjusted to 0.64 to 0.68. Is. In other words, the composite material 70 is adjusted so that the composition of the entire brazing layer 75 is Ni-32 to 36 wt% Ti. These adjustments are made by adjusting the layer thickness of the layers 12 and 13, adjusting the alloy composition of the layers 12 and 13, and the like.

  Here, when W1 / W2 is less than 0.64, since the Ni component contained in the brazing layer 75 is too small (because the Ti component is excessive), the melting point of the brazing layer 75 becomes extremely high. Therefore, the melting point cannot be lowered sufficiently even by the alloying action of the Ni component and the Ti component contained in the brazing layer 75, and the hot metal flowability of the brazing material is deteriorated. On the other hand, if W1 / W2 exceeds 0.68, the Ni component becomes excessive, the melting point of the brazing layer 75 cannot be lowered sufficiently, and the temperature range in which the liquid phase and the solid phase coexist is increased. It becomes wider and the hot water flowability deteriorates. In an extreme case, the brazing layer 75 is not melted.

  Next, the operation of the composite material according to the present embodiment will be described.

  Also in the composite material 70 according to the present embodiment, the same effects as those of the composite material 10 according to the first embodiment can be obtained.

  Further, when brazing is performed using the composite material 70 according to the present embodiment, the Ti component of the Ti brazing material and the Ni component of the Ni brazing material diffuse to each other to form a Ni—Ti alloy.

  At this time, the Ni component contained in the Ni brazing material and the Ti component contained in the Ti brazing material are adjusted to an optimum ratio for lowering the melting point of the brazing material, that is, the melting point of the Ni-Ti alloy to around 1200 ° C. . Here, if the Ni component is contained in the base material 71, the Ni component diffuses into the brazing layer 75, and the optimally adjusted ratio of Ni and Ti is disturbed, and the melting point of the brazing material is reduced. It cannot be lowered to around 1200 ° C. However, since the composite material 70 according to the present embodiment uses the base material 71 that does not contain the Ni component, the Ni component diffuses from the base material 71 to the brazing layer 75 during brazing. There is no.

  Thereby, the melting point of the brazing material containing Ni or Ni alloy, which has been difficult to function as a brazing material due to the high melting point, can be lowered to around 1200 ° C., and the composite material 70 according to the present embodiment is used. Brazing can be performed near 1200 ° C.

  In the composite material 70 according to the present embodiment, the case where the brazing layer 15 has a two-layer structure has been described. However, a brazing layer having a structure of three or more layers may be used (see FIGS. 3 and 4). ). Moreover, in the composite material which concerns on this Embodiment, although the case where the thin plate-shaped base material 71 was used was demonstrated, the shape of the base material 21 is not specifically limited to a thin plate shape, A rod shape or wire shape (See FIGS. 2, 5, and 6).

(Fourth embodiment)
A brazing composite material according to still another preferred embodiment of the present invention is a brazing layer obtained by laminating a Ti or Ti alloy layer and a Ni or Ni alloy layer in two layers on the surface of a base material. And the ratio (W1 / W2) between the weight W1 of the Ni component contained in the brazing layer and the total weight W2 of the Ni component and the Ti component is 0.62 to 0.66, preferably 0. .63 to 0.65. In other words, the composite material is adjusted so that the composition of the entire brazing layer is Ni-34 to 38 wt% Ti. These adjustments are made by adjusting the layer thickness of each layer, adjusting the alloy composition of each layer, or the like.

  The constituent material of the substrate is not particularly limited as long as it is conventionally used as a member to be brazed, and any of an alloy containing Ni and an alloy not containing Ni may be used.

  Here, if W1 / W2 is less than 0.62, the Ni component contained in the brazing layer is too small (because the Ti component is excessive), so the melting point of the brazing layer becomes higher than necessary. The hot water flow of the material will deteriorate. On the other hand, if W1 / W2 exceeds 0.66, the Ni component becomes excessive, the melting point of the brazing layer cannot be lowered sufficiently, and the hot water flowability is deteriorated.

  Also in the composite material according to the present embodiment, the same effects as those of the composite material 10 according to the first embodiment can be obtained. Further, the brazing layer of the composite material according to the present embodiment may have a structure of three or more layers (see FIGS. 3 and 4). Furthermore, the base material of the composite material according to the present embodiment may be rod-shaped or wire-shaped (see FIGS. 2, 5, and 6).

  As mentioned above, it cannot be overemphasized that embodiment of this invention is not limited to embodiment mentioned above, and various things are assumed in addition.

  Next, embodiments of the present invention will be described based on examples, but the embodiments of the present invention are not limited to these examples.

(Example 1)
Made of SUS304 (JIS standard), on the surface of a 2.5 mm thick stainless steel strip, in order from the stainless steel strip side, a 1.0 mm thick Ti strip, a 0.76 mm thick Ni strip Was laminated by a rolling method to produce a composite material having a laminated structure of Ni / Ti / SUS304 and a composition of the entire brazing layer of Ni-40 wt% Ti (W1 / W2 = 0.60). Thereafter, the composite material was repeatedly rolled to produce a brazing composite material having a total brazing layer thickness of 70 μm. The composite material was heated in a 1200 ° C. tubular furnace to evaluate the characteristics of the brazing composite material.

(Example 2)
On the surface of the same stainless steel strip as in Example 1, in order from the stainless steel strip side, a Ni strip having a thickness of 0.35 mm, a Ti strip having a thickness of 1.0 mm, and a Ni strip having a thickness of 0.35 mm. The material was clad by a rolling method to produce a composite material having a laminated structure of Ni / Ti / Ni / SUS304 and a brazing layer composition of Ni-42 wt% Ti (W1 / W2 = 0.58). Thereafter, in the same manner as in Example 1, the characteristics of the brazing composite material were evaluated.

(Example 3)
The composite material for brazing was the same as in Example 2 except that the thickness of each Ni strip was 0.45 mm and the composition of the entire brazing layer was Ni-36 wt% Ti (W1 / W2 = 0.64). Characteristics were evaluated.

(Comparative Example 1)
A Ni strip having a thickness of 0.5 mm was clad by the rolling method on the surface of the same stainless steel strip as in Example 1 to produce a composite material having a laminated structure of Ni / SUS304 and the entire brazing layer made of Ni. Thereafter, in the same manner as in Example 1, the characteristics of the brazing composite material were evaluated.

(Comparative Example 2)
The composite material for brazing was the same as in Example 2 except that the thickness of each Ni strip was 0.32 mm and the composition of the entire brazing layer was Ni-44 wt% Ti (W1 / W2 = 0.56). Characteristics were evaluated.

(Comparative Example 3)
The composite material for brazing was the same as in Example 2 except that the thickness of each Ni strip was 0.49 mm and the composition of the entire brazing layer was Ni-34 wt% Ti (W1 / W2 = 0.66). Characteristics were evaluated.

(Comparative Example 4)
The stainless steel strip is composed of SUS430 (JIS standard), the thickness of each Ni strip is 0.41 mm, and the composition of the entire brazing layer is Ni-38 wt% Ti (W1 / W2 = 0.62). In the same manner as in Example 2, the characteristics of the brazing composite material were evaluated.

(Conventional example 1)
On the surface of the same stainless steel strip as in Example 1, a Cu strip was clad by a rolling method to produce a composite material in which the laminated structure was Cu / SUS304 and the entire brazing layer was Cu. Thereafter, in the same manner as in Example 1, the characteristics of the brazing composite material were evaluated. The brazing temperature was 1120 ° C.

(Conventional example 2)
A composite material for brazing was applied to the surface of the same stainless steel strip as in Example 1 by applying a kneaded material prepared by dissolving a commercially available powdered Ni brazing material (composition: Ni-19Cr-10Si (wt%)) with a synthetic resin binder. Was made. Thereafter, in the same manner as in Example 1, the characteristics of the brazing composite material were evaluated. The brazing temperature was 1180 ° C.

  About each composite material of Examples 1-3, Comparative Examples 1-4, and Conventional Examples 1 and 2, evaluation of characteristics, specifically, fillet formation state (hot water flowability), presence or absence of corrosion occurrence (corrosion resistance), Evaluation of brazing productivity (workability) and comprehensive evaluation of these characteristics were performed. The evaluation results of the brazing characteristics are shown in Table 1. The evaluation was evaluated as 極 め て for very good, ◯ for good, △ for insufficient (insufficient), and × for poor.

  Here, the evaluation of the hot water flow is carried out by placing a stainless steel pipe made of SUS304 on the surface of the brazing layer of each composite material, and brazing it by heating to 1200 ° C. Evaluation was performed by the cross-sectional area.

  Corrosion resistance is evaluated by immersing each composite material after brazing in a corrosive solution containing chlorine ions, nitrate ions and sulfate ions for 1000 hours, and then performing a corrosion test. This was done by examining the structure of the brazed part and examining the occurrence of corrosion. 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, in the composite materials of Examples 1 to 3 which are the composite materials for brazing according to the present invention, the base material is an alloy containing Ni (SUS304), and the brazed layer is a Ti layer and a Ni layer. The composition of the brazing layer is adjusted to Ni-36 to 42 wt% Ti (W1 / W2 = 0.58 to 0.64). The composition of the brazing layer alone cannot lower the melting point of the brazing layer to around 1200 ° C. However, at the time of brazing, the Ni component diffuses from the base material into the brazing layer, whereby the melting point of the brazing layer can be lowered to around 1200 ° C.

  As a result, the composite materials of Examples 1 to 3 can be brazed at about 1200 ° C. As a result, the composite materials of Examples 1 to 3 have extremely high hot water flowability and brazing productivity. It was good. In addition, none of the composite materials of Examples 1 to 3 was corroded. Therefore, the overall evaluation was extremely good.

  In contrast, although the brazing productivity of the composite material of Comparative Example 1 was good, the brazing layer was composed of Ni alone, so that the brazing layer did not melt at a brazing temperature of 1200 ° C. It did not function as a brazing material. From the above, the overall evaluation was poor.

  The composite material of Comparative Example 2 did not cause corrosion and had a very good brazing productivity, but the Ni content in the brazing layer was too small (Ni-44 wt% Ti (W1 / W2 = 0.56). Therefore, the melting point of the brazing layer itself is high, and even when the Ni component diffuses from the base material into the brazing layer, the melting point cannot be lowered sufficiently. For this reason, although brazing is possible, the hot metal flowability of the brazing was not good (bad), and as a result, the overall evaluation was bad. In addition, even if a sufficient amount of Ni component diffuses from the base material into the brazing layer and the melting point can be sufficiently lowered, the base material is eroded (thickness reduction increases). Not practical.

  The composite material of Comparative Example 3 was free from corrosion and the brazing productivity was very good, but the Ni content in the brazing layer was too high (Ni-34 wt% Ti (W1 / W2 = 0.66)). Therefore, the melting point of the brazing layer itself has increased due to the diffusion of the Ni component from the base material into the brazing layer. For this reason, although brazing is possible, the hot water flowability is not good (bad), and as a result, the overall evaluation is bad.

  In the composite material of Comparative Example 4, the proportion of Ni in the brazing layer is also appropriate (Ni-38wt% Ti (W1 / W2 = 0.62)), there is no corrosion, and the brazing productivity is extremely good. However, since the base material is SUS430 that does not contain Ni, the Ni component cannot be diffused from the base material into the brazing layer. For this reason, the flowability of brazing water is insufficient, and as a result, the overall evaluation is also insufficient.

  Although the composite material of Conventional Example 1 had very good hot metal flow and brazing productivity, the brazing layer was composed of Cu alone, so that the corrosion resistance was not good and corrosion occurred. As a result, the overall evaluation was poor.

  The composite material of Conventional Example 2 has very good hot-water flow properties and no corrosion, but the brazing material of the brazing layer is a powder Ni brazing material. Therefore, an organic binder is used for forming the brazing layer. The brazing productivity was poor. As a result, the overall evaluation was poor.

  As mentioned above, since the composite material of Examples 1 to 3 which is a composite material for brazing according to the present invention has good hot metal flowability, corrosion resistance of a brazed joint, and brazing productivity, It can be seen that the composite material for brazing is excellent in brazing characteristics and reliability of the brazed joint.

Example 4
Made of SUS430 (JIS standard), on the surface of a 2.5 mm thick stainless steel strip, in order from the stainless steel strip side, a 1.0 mm thick Ti strip, a 0.90 mm thick Ni strip Was laminated by a rolling method to prepare a composite material having a laminated structure of Ni / Ti / SUS430 and a composition of the entire brazing layer of Ni-36 wt% Ti (W1 / W2 = 0.64). Thereafter, the composite material was repeatedly rolled to produce a brazing composite material having a total brazing layer thickness of 70 μm. The composite material was heated in a 1200 ° C. tubular furnace to evaluate the characteristics of the brazing composite material.

(Example 5)
On the surface of the same stainless steel strip as in Example 4, in order from the stainless steel strip side, a 0.45 mm thick Ni strip, a 1.0 mm thick Ti strip, and a 0.45 mm thick Ni strip. The material was clad by a rolling method to produce a composite material having a laminated structure of Ni / Ti / Ni / SUS430 and a composition of the entire brazing layer of Ni-36 wt% Ti (W1 / W2 = 0.64). Thereafter, the characteristics of the brazing composite material were evaluated in the same manner as in Example 4.

(Example 6)
The composite material for brazing was the same as in Example 5 except that the thickness of each Ni strip was 0.54 mm and the composition of the entire brazing layer was Ni-32 wt% Ti (W1 / W2 = 0.68). Characteristics were evaluated.

(Comparative Example 5)
On the surface of the same stainless steel strip as in Example 4, a Ni strip having a thickness of 0.5 mm was clad by a rolling method to produce a composite material having a laminated structure of Ni / SUS304 and the entire brazing layer made of Ni. Thereafter, the characteristics of the brazing composite material were evaluated in the same manner as in Example 4.

(Comparative Example 6)
The composite material for brazing was the same as in Example 5 except that the thickness of each Ni strip was 0.41 mm and the composition of the entire brazing layer was Ni-38 wt% Ti (W1 / W2 = 0.62). Characteristics were evaluated.

(Comparative Example 7)
The composite material for brazing was the same as in Example 5 except that the thickness of each Ni strip was 0.59 mm and the composition of the entire brazing layer was Ni-30 wt% Ti (W1 / W2 = 0.70). Characteristics were evaluated.

(Comparative Example 8)
The stainless steel strip is composed of SUS304 (JIS standard), the thickness of each Ni strip is 0.49 mm, and the composition of the entire brazing layer is Ni-34 wt% Ti (W1 / W2 = 0.66). In the same manner as in Example 5, the characteristics of the brazing composite material were evaluated.

(Conventional example 3)
On the surface of the same stainless steel strip as in Example 4, a Cu strip was clad by a rolling method to produce a composite material in which the laminated structure was Cu / SUS430 and the entire brazing layer was Cu. Thereafter, the characteristics of the brazing composite material were evaluated in the same manner as in Example 4. The brazing temperature was 1120 ° C.

(Conventional example 4)
A kneaded material prepared by dissolving a commercially available powdered Ni brazing material (composition: Ni-19Cr-10Si (wt%)) with a synthetic resin binder is applied to the surface of the same stainless steel strip as in Example 4, and a composite material for brazing. Was made. Thereafter, the characteristics of the brazing composite material were evaluated in the same manner as in Example 4. The brazing temperature was 1180 ° C.

  About each composite material of Examples 4-6, Comparative Examples 5-8, and Conventional Examples 3 and 4, evaluation of characteristics, specifically, fillet formation state (hot water flowability), presence or absence of corrosion occurrence (corrosion resistance), Evaluation of brazing productivity (workability) and comprehensive evaluation of these characteristics were performed. Table 2 shows the evaluation results of the brazing characteristics.

  Here, each evaluation is performed in the same manner as in [Example 1] except that a stainless steel pipe made of SUS430 is used for evaluating the hot water flow. What is being done (insufficient) is indicated by Δ, and those that are defective are indicated by ×.

  As shown in Table 2, in the composite materials of Examples 4 to 6 which are the composite materials for brazing according to the present invention, the base material is an alloy not containing Ni (SUS430), and the brazed layer is a Ti layer and an Ni layer. And the composition of the brazing layer is adjusted to Ni-32 to 36 wt% Ti (W1 / W2 = 0.64 to 0.68).

  In the composite materials of Examples 4 to 6, the composition of the brazing layer is adjusted so that the melting point of the brazing layer is lowered to around 1200 ° C. In the composite materials of Examples 4 to 6, since the base material is composed of an alloy that does not contain Ni, the Ni component does not diffuse from the base material into the brazing layer during brazing.

  As a result, the composite materials of Examples 4 to 6 can be brazed at about 1200 ° C. As a result, the composite materials of Examples 4 to 6 have extremely high hot water flowability and brazing productivity. It was good. Moreover, all the composite materials of Examples 4 to 6 did not generate corrosion. Therefore, the overall evaluation was extremely good.

  In contrast, the composite material of Comparative Example 5 had good brazing productivity, but the brazing layer was composed of Ni alone, so the brazing layer did not melt at a brazing temperature of 1200 ° C. It did not function as a brazing material. From the above, the overall evaluation was poor.

  The composite material of Comparative Example 6 had no corrosion and extremely good brazing productivity, but the Ni content in the brazing layer was too small (Ni-38 wt% Ti (W1 / W2 = 0.62)). Therefore, although brazing is possible, the flow of brazing metal was insufficient. As a result, the overall evaluation was insufficient.

  The composite material of Comparative Example 7 did not cause corrosion, and the brazing productivity was very good, but the proportion of Ni in the brazing layer was too large (Ni-30 wt% Ti (W1 / W2 = 0.70) Therefore, the melting point of the brazing layer could not be lowered sufficiently and brazing was possible, but the hot-water flowability was not good (bad). As a result, the overall evaluation was poor.

  In the composite material of Comparative Example 8, the proportion of Ni in the brazing layer is also appropriate (Ni-34 wt% Ti (W1 / W2 = 0.66)), there is no corrosion, and the brazing productivity is extremely good. However, since the base material was SUS304 containing Ni, the Ni component diffused from the base material into the brazing layer, and the melting point of the brazing layer increased. For this reason, although brazing was possible, the hot-water flow property was not good (defect). As a result, the overall evaluation was poor.

  Although the composite material of Conventional Example 3 had extremely good hot-water flow and brazing productivity, the brazing layer was composed of Cu alone, so that the corrosion resistance was not good and corrosion occurred. As a result, the overall evaluation was poor.

  The composite material of Conventional Example 4 has very good hot-water flow properties and no corrosion, but the brazing material of the brazing layer is a powder Ni brazing material. Therefore, an organic binder is used for forming the brazing layer. The brazing productivity was poor. As a result, the overall evaluation was poor.

  As mentioned above, since the composite material of Examples 4 to 6 which is a composite material for brazing according to the present invention has good hot metal flowability, corrosion resistance of a brazed joint, and brazing productivity, It can be seen that the composite material for brazing is excellent in brazing characteristics and reliability of the brazed joint.

  The composite material according to a preferred embodiment of the present invention is not limited to a heat exchanger that is exposed to a highly corrosive gas or liquid at a high temperature such as an EGR cooler. For example, the present invention can be applied to various uses such as a fuel cell reformer cooler and a fuel cell member. In particular, a rod-like or wire-like composite material (see FIGS. 2, 5, and 6) has a small diameter size and good handleability, so that it can be used for EGR coolers, fuel cell reformer coolers, and the like. In addition to heat exchangers and fuel cell members, the present invention can also be applied to oil coolers, radiators, secondary battery members, and the like.

1 is a cross-sectional view of a brazing composite material according to a preferred embodiment of the present invention. It is sectional drawing which shows the modification of FIG. It is sectional drawing of the composite material for brazing which concerns on other preferable one Embodiment of this invention. It is sectional drawing which shows the 1st modification of FIG. It is sectional drawing which shows the 2nd modification of FIG. It is sectional drawing which shows the 3rd modification of FIG. It is sectional drawing of the composite material for brazing which concerns on another suitable one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Brazing composite material 11 Base material 12 Ti or Ti alloy layer 13 Ni or Ni alloy layer 15 Brazing layer

Claims (9)

  A brazing composite material for brazing members to be brazed, having a multilayer structure in which a Ni or Ni alloy layer and a Ti or Ti alloy layer are laminated on the surface of a base material made of an alloy containing Ni. The ratio W1 / W2 between the weight W1 of the Ni component contained in the brazing layer and the total weight W2 of the Ni component and the Ti component is 0.58 to 0.64. A composite material for brazing characterized by being.   The brazing composite material according to claim 1, wherein the base material is made of austenitic stainless steel.   In a brazing composite material for brazing members to be brazed, a multilayer structure in which a Ni or Ni alloy layer and a Ti or Ti alloy layer are stacked on the surface of a base material composed of an alloy not containing Ni. A brazing layer is integrally provided, and a ratio W1 / W2 between the weight W1 of the Ni component contained in the brazing layer and the total weight W2 of the Ni component and the Ti component is 0.64 to 0.68. A composite material for brazing, characterized in that   The brazing composite material according to claim 3, wherein the base material is made of ferritic stainless steel.   The brazing composite material according to any one of claims 1 to 4, wherein at least one of the Ni or Ni alloy layer or the Ti or Ti alloy layer contains P.   The composite material for brazing according to claim 5, wherein the P concentration contained in the brazing layer is 0.02 to 10 wt%.   The brazing composite material according to any one of claims 1 to 6, wherein at least one of the Ni or Ni alloy layer or the Ti or Ti alloy layer contains at least one of Cu, Mn, Al, and Cr.   The composite material for brazing according to claim 7, wherein the concentration of Cu contained in the brazing layer is 0.2 to 30 wt%. A brazed product using the brazing composite material, wherein the brazing composite material is joined using the brazing composite material according to any one of claims 1 to 8.

Images