JP2004291077A - Brazing heat treatment method and brazed product using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brazing heat treatment method which brings low product manufacturing cost and superior resistance against heat, corrosion and high temperature oxidation in a brazed joined part, and also to provide a brazed product having improved reliability in brazed joined parts. <P>SOLUTION: In this brazing heat treatment method, a brazing material 10 having a brazing layer 15 on the surface of a base material 11 is heated in a high vacuum state for the brazing heat treatment. The brazing material 10 is arranged in a vacuum heating furnace together with Cr or a Cr alloy. Then, at a heat treatment temperature T in the range of 900≤T≤1,200°C, the brazing heat treatment is performed under conditions in which the degree of vacuum V satisfies an expression, V≤4×10<SP>ä(T/100)-13}</SP>(Pa), with the brazing layer 15 fused, and with chromium components of Cr or a Cr alloy evaporated in the vacuum heating furnace. Subsequently, the vacuum heating furnace is cooled to vapor-deposit a Cr or Cr alloy layer on the surface of the brazing layer 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００６３】
表１に示すように、本発明に係るろう付け熱処理方法を用いた実施例１，２は、熱処理温度Ｔが９００≦Ｔ≦１２００℃の範囲の時、真空度Ｖが、
Ｖ≦４×１０^{｛（Ｔ／１００）−１３｝}（Ｐａ）…▲１▼
▲１▼式を満足する条件でろう付け熱処理を行っている（つまり、図２中の斜線領域（ろう付け熱処理条件域Ａ）内である）ため、ろう付け熱処理中、炉内に十分な量のＣｒが蒸発する。その結果、ろう合金層にＣｒを蒸着させることができ、高温酸化試験時に、ろう付け接合部の表面に、十分な厚さの酸化クロム被膜が形成される。よって、耐高温酸化性が極めて良好となった。
【００６４】
これに対して、比較例１，２は、ろう付け熱処理時の真空度Ｖが、上記▲１▼式を満足していない（つまり、図２中の斜線領域（ろう付け熱処理条件域Ａ）外である）ため、ろう付け熱処理中、炉内にＣｒを全く（又は殆ど全く）蒸発させることができない。その結果、高温酸化試験時に、ろう付け接合部の表面に酸化クロム被膜が全く（又は殆ど全く）形成されず、耐高温酸化性は不良となった。
【００６５】
また、従来例１，２は、ろう付け熱処理時に、加熱炉内にクロム単体を配置していないため、高温酸化試験時に、ろう付け接合部の表面に酸化クロム被膜が全く形成されず、耐高温酸化性は不良となった。
【００６６】
以上、本発明に係るろう付け熱処理方法を用いた実施例１，２は、ろう付け接合部の耐高温酸化性がいずれも良好であることから、ろう付け接合部の信頼性に優れたろう付け熱処理方法であることがわかる。
【００６７】
【発明の効果】
以上要するに本発明によれば、次のような優れた効果を発揮する。
（１） 本発明に係るろう付け熱処理方法によれば、熱処理温度Ｔが９００≦Ｔ≦１２００℃の範囲の時、真空度Ｖが、
Ｖ≦４×１０^{｛（Ｔ／１００）−１３｝}（Ｐａ）…▲１▼
▲１▼式を満足する条件でろう付け熱処理を行うことで、耐熱性、耐食性、及び耐高温酸化性が良好なろう付け接合部を、安価に得ることができる。
（２） （１）のろう付け用複合材を用いてろう付けすることで、ろう付け接合部の信頼性が良好で、製造コストが安価なろう付け製品を得ることができる。
【図面の簡単な説明】
【図１】本発明に係るろう付け熱処理方法に用いるろう付け用複合材の一例を示す断面図である。
【図２】ろう付け熱処理時における温度と真空度との関係を示す図である。
【図３】図１のろう付け用複合材に、本発明に係るろう付け熱処理方法を用いたろう付け熱処理を行った後の断面図である。
【図４】本発明に係るろう付け熱処理方法に用いるろう付け用複合材の他の一例を示す断面図である。
【図５】図２のろう付け用複合材に、本発明に係るろう付け熱処理方法を用いたろう付け熱処理を行った後の断面図である。
【符号の説明】
１０，４０ ろう付け用複合材（ろう付け材）
１１ 基材
１２ Ｔｉ又はＴｉ合金層
１３ａ，１３ｂ，４３ Ｃｕ又はＣｕ合金層
１５，４５ ろう付け層
３０，５０ ろう付け製品
３５，５５ ろう付け接合部
３６，５６ ろう合金層
３７，５７ 酸化クロム層
４４ Ｎｉ又はＮｉ合金層[0001]
TECHNICAL 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 a heat exchanger and a member for a fuel cell, and a brazing product using the same.
[0002]
[Prior art]
Stainless steel-based clad materials are used as joining materials for automotive oil coolers. In this method, a Cu material having a function as a brazing material is clad on one or both surfaces of a stainless steel plate as a base material.
[0003]
In addition, as brazing materials for members made of stainless steel, Ni-based or Co-based alloys, various Ni brazing materials having excellent oxidation resistance and corrosion resistance of brazed joints are specified by JIS standards.
[0004]
Further, as a Ni brazing material used for joining the heat exchanger, a powder obtained by adding 4 to 22 wt% of a metal powder selected from Ni, Cr, or a Ni-Cr alloy to a powdery Ni brazing material. A Ni brazing material has been proposed (for example, see Patent Document 1).
[0005]
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).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-107883 [Patent Document 2]
JP-A-7-299592
[Problems to be solved by the invention]
However, a conventional brazing material or a brazing composite material is exposed to a high-temperature, highly corrosive gas or liquid and is used in a heat exchanger (cooler for an exhaust gas recirculation device (hereinafter referred to as EGR (Exhaust Gas Recirculation))). When used as a brazing filler metal, there are the following problems.
[0008]
{Circle around (1)} When the above-mentioned stainless base clad material is used as a joining material for an automotive oil cooler, there is no problem in terms of heat resistance and corrosion resistance, but when this stainless base clad material is used as a joining material for an EGR cooler. Since the EGR cooler has a high temperature and highly corrosive exhaust gas is circulated, the brazing material (Cu material) of the stainless base clad material has high temperature corrosion resistance (high temperature oxidation resistance) and corrosion resistance. There was a problem that it was not enough.
[0009]
{Circle over (2)} Since the above-mentioned various Ni brazing materials are in a powder form, it is necessary to apply a powder Ni brazing material to each brazing joint. That is, since a large amount of labor is required for the brazing operation, the productivity of the brazed product is extremely low, and as a result, there is a problem that the manufacturing cost is increased.
{Circle around (3)} Although the self-brazing composite material described above has sufficient corrosion resistance in a low-temperature and humid environment, there is a problem that the corrosion resistance (high-temperature oxidation resistance) in a high-temperature oxygen atmosphere is insufficient.
[0010]
SUMMARY OF THE INVENTION One object of the present invention, which has been made in view of the above circumstances, is to provide a brazing heat treatment method that has low manufacturing cost and good heat resistance, corrosion resistance, and high-temperature oxidation resistance of a brazed joint. Is to do.
[0011]
It is another object of the present invention to provide a brazed product having good brazed joint reliability.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a brazing heat treatment method according to the present invention comprises heating a brazing material having a brazing layer on the surface of a base material under a high vacuum, and performing a brazing heat treatment. Or placed in a vacuum heating furnace together with a Cr alloy, and then, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above-mentioned brazing heat treatment is performed under the conditions satisfying the following equation to melt the brazing layer, evaporate the chromium component of Cr or a Cr alloy in a vacuum heating furnace, and then cool the vacuum heating furnace to perform the brazing. A Cr or Cr alloy layer is deposited on the surface of the layer.
[0013]
Further, in a method of heating a brazing material having a brazing layer on the surface of a base material under a high vacuum and performing a brazing heat treatment, the brazing layer of the brazing material includes a Ti or Ti alloy layer and a Cu or Cu alloy. The brazing material is placed in a vacuum heating furnace together with Cr or a Cr alloy, and then, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above brazing heat treatment is performed under the conditions satisfying the formula to melt the brazing layer, and the chromium component of Cr or Cr alloy is evaporated in a vacuum heating furnace, and then the vacuum heating furnace is cooled, and each metal component is cooled. Cr or a Cr alloy layer is vapor-deposited on the surface of the brazing layer formed by diffusion and alloying.
[0014]
Further, in a method of heating a brazing material having a brazing layer on a base material surface under a high vacuum and performing a brazing heat treatment, the brazing layer of the brazing material may be a Ti or Ti alloy layer, Cu or a Cu alloy. When the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the brazing material is arranged together with Cr or the Cr alloy in a vacuum heating furnace. , The degree of vacuum V
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above brazing heat treatment is performed under conditions satisfying the formula (1) to melt the brazing layer, evaporate the chromium component of Cr or a Cr alloy in a vacuum heating furnace, and then cool the vacuum heating furnace. A Cr or Cr alloy layer is deposited on the surface of the brazing layer in which the metal component is diffused and alloyed.
[0015]
More specifically, a cooling means for cooling the stage itself is provided on a stage on which the brazing material is mounted in the vacuum heating furnace, and the brazing material is provided on the stage of the vacuum heating furnace. Is preferably mounted.
[0016]
In addition, it is preferable that a portion of the vacuum heating furnace other than the brazing material is covered with a heat-resistant material, and that the brazing material is disposed in the vacuum heating furnace.
[0017]
According to the brazing heat treatment method according to the present invention, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is:
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
By performing the brazing heat treatment under the conditions satisfying the formula (1), a brazed joint having good heat resistance, corrosion resistance, and high-temperature oxidation resistance can be obtained at low cost.
[0018]
On the other hand, the brazed product according to the present invention is one that has been joined using the above-described brazing heat treatment method.
[0019]
Thereby, a brazed product having good reliability of the brazed joint is obtained.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.
[0021]
(First Embodiment)
FIG. 1 shows an example of a brazing composite material used in the brazing heat treatment method according to the present invention.
[0022]
As shown in FIG. 1, a brazing composite material 10 includes a Cu or Cu alloy layer 13 a, a Ti or Ti alloy layer 12, and a Cu or Cu alloy layer 13 a on a surface of a thin plate-shaped base material 11 (only the upper surface in FIG. 1). The brazing layer 15 is formed by stacking three layers of the Cu alloy layer 13b. The surface of the substrate 11 referred to here indicates all surfaces exposed to the outside.
[0023]
By appropriately rolling the composite material 10, a composite material for brazing (final product) having a desired thickness is obtained.
[0024]
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.
[0025]
Also, when the brazing layer 15 contains P in an amount of 0.02 to 10% by weight, preferably 5 to 10% by weight, the flowability of the brazing material and the oxidation resistance can be remarkably improved. The reason why the content of P is limited to 0.02 to 10 wt% is that if the content is less than 0.02 wt%, improvement in the flowability of the molten metal cannot be expected. Conversely, if the content exceeds 10 wt%, the brazing layer 15 This is because the material becomes brittle and the vibration fatigue characteristics and the joining strength are significantly reduced.
[0026]
In the brazing composite material 10 shown in FIG. 1, the brazing layer 15 is formed only on one surface (the upper surface in FIG. 1) of the substrate 11, but on both surfaces (the upper and lower surfaces in FIG. 1) of the substrate 11. ) May be formed with the brazing layers 15.
[0027]
Further, in the present embodiment, the description has been given using the composite material 10 having the brazing layer 15 having a three-layer structure, but the present invention is not limited to this, and a brazing material having a two-layer structure or a structure having four or more layers is used. It may be an attachment layer.
[0028]
Next, a brazing heat treatment method according to the present embodiment using the composite material 10 will be described.
[0029]
First, the composite material 10 (brazing material) is placed in a vacuum heating furnace together with Cr or a Cr alloy. The composite material 10 is mounted on a stage provided with cooling means. The stage can be cooled from the inside by air cooling or water cooling by the cooling means. More preferably, the peripheral portion of the composite material 10 on the wall surface and the stage surface in the vacuum heating furnace (other than the brazing material mounting portion in the vacuum heating furnace) is made of a heat-resistant material for preventing Cr deposition (described later). To prevent Cr deposition from occurring except for the composite material 10.
[0030]
Next, the brazing layer 15 is maintained at a constant temperature in a substantially vacuum at a temperature at which the brazing layer 15 is sufficiently melted, and a brazing heat treatment is performed. Specifically, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V becomes
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
A brazing heat treatment is performed under conditions satisfying the equation (1). For example, when the heat treatment temperature is 900 ° C., the degree of vacuum is 4 × 10 ⁻⁴ Pa or less. When the heat treatment temperature is 1000 ° C., the degree of vacuum is 4 × 10 ⁻³ Pa or less. When the heat treatment temperature is 1100 ° C., the degree of vacuum is 4 × 10 ^−2. At 1200 ° C. or less, the degree of vacuum is set to 4 × 10 ⁻¹ Pa or less. In other words, as shown in FIG. 2, in the brazing heat treatment condition area (shaded area in FIG. 2) A, the lower the heat treatment temperature, the higher the degree of vacuum (the lower the pressure), and the higher the heat treatment temperature, the lower the degree of vacuum ( The pressure increases). By performing the brazing heat treatment under these conditions, it becomes possible to evaporate the chromium component of Cr or a Cr alloy in the vacuum heating furnace.
[0031]
Thereafter, the heating is stopped and the vacuum heating furnace is cooled (furnace cooling). In this cooling process, by using the cooling means provided on the stage, the composite material 10 is preferentially cooled to a low temperature. As a result, Cr is vapor-deposited on the surface of the brazing alloy layer (the brazing layer 15 in which each metal component (Cu and Ti) is diffused and alloyed), and the vapor-deposited Cr partially mixes with the brazing alloy layer, and A brazed product having a brazed joint is obtained. Here, the surface of the brazing alloy layer does not mean the outermost surface, but means the surface layer portion including the outermost surface. That is, Cr is not only deposited on the outermost surface of the brazing alloy layer, but also partially incorporated into the brazing alloy layer.
[0032]
By exposing this brazing product to a high-temperature oxygen atmosphere, the chromium component mixed in the brazing alloy layer diffuses to the surface of the brazing joint and is oxidized. As shown in FIG. A brazed product 30 having a brazed joint 35 with the surface of layer 36 covered with a chromium oxide layer 37 is obtained. Since the chromium oxide layer 37 is a dense oxide film and is extremely chemically stable, the heat resistance, corrosion resistance, and high-temperature oxidation resistance of the brazed joint 35 can be significantly improved. As a result, it is possible to sufficiently prevent the brazing alloy layer 36 from being oxidized in a high-temperature (about 600 to 800 ° C.) oxidizing atmosphere, and it is difficult to reduce the joining strength of the brazing joint 35 due to the high-temperature oxidation. The reliability of the joint of the attachment 30 is improved.
[0033]
Therefore, by performing the brazing heat treatment using the brazing heat treatment method according to the present embodiment, a brazed joint excellent in heat resistance, corrosion resistance, and high-temperature oxidation resistance can be obtained easily and at a low manufacturing cost. This method is optimal as a brazing heat treatment method for a brazing joint such as an EGR cooler exposed to a high-temperature, highly corrosive gas or liquid.
[0034]
In the composite material 10 used in the brazing heat treatment method of the present embodiment, the brazing layer 15 is composed of the Ti or Ti alloy layer 12 and the Cu or Cu alloy layers 13a and 13b. At the time of attachment, the Cu component of the Cu brazing material is mixed (dissolved) into the Ti brazing material. Thus, the melting point of the brazing material containing Ti or a Ti alloy can be lowered, and brazing using this brazing material can be performed at around 980 to 1200 ° C. As a result, even when the composite material 10 is used as a brazing material, a brazed joint having excellent brazing properties can be obtained.
[0035]
Further, since the composite material 10 has the brazing layer 15 integrally provided on the surface of the base material 11, the powdered Ni brazing material is applied to each brazing joint at the time of brazing, as in various conventional Ni brazing materials. And it is not necessary to apply much to the brazing operation (the brazing workability is improved). That is, the brazing product 30 obtained by brazing using the composite material 10 forms the composite material 10 using one of the brazing materials as the base material 11 among a set of brazing materials to be joined, The composite material 10 and the other material to be brazed are obtained by overlapping and heating. As a result, the yield and productivity of the brazed product 30 are improved, and the production cost can be reduced.
[0036]
Further, in the composite material 10, the innermost layer and the outermost layer (the lowermost layer and the uppermost layer in FIG. 1) of the brazing layer 15 are not the Ti or Ti alloy layer 12, but the Cu or Cu alloy layers 13a and 13b. Therefore, at the time of brazing, it is possible to suppress the reaction between the base material 11 made of stainless steel and Ti, and as a result, the reliability of the brazed joint is further improved.
[0037]
Therefore, by brazing using the composite material 10, a brazed joint having good brazing characteristics and excellent heat resistance, corrosion resistance, and high-temperature oxidation resistance can be easily and inexpensively obtained.
[0038]
Next, another embodiment of the present invention will be described with reference to the accompanying drawings.
[0039]
(Second embodiment)
FIG. 4 shows another example of the brazing composite material used in the brazing heat treatment method according to the present invention. The same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description of these members will be omitted.
[0040]
The composite material 10 used in the brazing heat treatment method according to the previous embodiment includes a brazing layer 15 in which a Ti or Ti alloy layer 12 is sandwiched by the same kind of metal, that is, Cu or Cu alloy layers 13a and 13b. Was to be done.
[0041]
On the other hand, as shown in FIG. 4, in the composite material 40 used in the brazing heat treatment method according to the present embodiment, the Ti or Ti alloy layer 12 is made of a dissimilar metal, that is, the Cu or Cu alloy layer 43, It is composed of a brazing layer 45 sandwiched between Ni or Ni alloy layers 44.
[0042]
Further, in the present embodiment, the description has been given using the composite material 40 having the brazing layer 45 having a three-layer structure. However, the present invention is not limited to this, and a brazing material having a two-layer structure or a structure having four or more layers is used. It may be an attachment layer.
[0043]
In the brazing heat treatment method according to the present embodiment using the composite material 40, the same operation and effect as in the previous embodiment can be obtained.
[0044]
In the composite material 40 used in the brazing heat treatment method of the present embodiment, the brazing layer 45 is composed of the Ti or Ti alloy layer 12, the Cu or Cu alloy layer 43, and the Ni or Ni alloy layer 44. Therefore, at the time of brazing, the Cu component of the Cu brazing material and the Ni component of the Ni brazing material are mixed (dissolved) into the Ti brazing material. Thus, the melting point of the brazing material containing Ti or a Ti alloy can be lowered, and brazing using this brazing material can be performed at around 980 to 1200 ° C. As a result, even when the composite material 40 is used as a brazing material, a brazed joint having excellent brazing properties can be obtained.
[0045]
In addition, since the composite material 40 has the brazing layer 45 integrally provided on the surface of the base material 11, the yield of the brazed product 50 obtained by brazing using the composite material 40 is similar to the composite material 10. The productivity is improved, and the production cost can be reduced.
[0046]
In the composite material 40, the innermost layer and the outermost layer (the lowermost layer and the uppermost layer in FIG. 4) of the brazing layer 45 are not the Ti or Ti alloy layer 12, but the Cu or Cu alloy layer 43 and the Ni or Ni alloy. Since the layer 44 is used, the reaction between the base material 11 made of stainless steel and Ti during brazing can be suppressed, and as a result, the reliability of the brazed joint can be further improved.
[0047]
Therefore, by brazing using the composite material 40, a brazed joint having good brazing characteristics and excellent heat resistance, corrosion resistance, and high-temperature oxidation resistance can be easily and inexpensively obtained.
[0048]
The brazed products 30 and 50 joined using the brazing heat treatment methods according to the first and second embodiments are limited to a heat exchanger such as an EGR cooler that is exposed to a high-temperature and highly corrosive gas or liquid. However, the present invention is not limited to its use, and can be applied to various other uses such as a cooler for a reformer of a fuel cell, a fuel cell member, an oil cooler, a radiator, and a secondary battery member.
[0049]
As described above, the embodiments of the present invention are not limited to the above-described embodiments, and it is needless to say that various other embodiments are also possible.
[0050]
【Example】
(Example 1)
A pure Cu strip having a thickness of 0.5 mm, a pure Ti strip having a thickness of 2.0 mm, and a pure Cu strip having a thickness of 0.5 mm are overlapped so that the laminated structure becomes Cu / Ti / Cu, Clad by hot rolling to produce a clad plate having a thickness of 1.4 mm. This clad plate was continuously cold-rolled to produce a clad plate having a thickness of 1.0 mm.
[0051]
This clad plate is placed on a SUS304 (JIS standard) strip having a thickness of 2.5 mm (Cu / Ti / Cu / SUS), clad by hot rolling, and subsequently cold rolled to reduce the thickness of the plate. A 0.5 mm braze composite was made.
[0052]
This composite material is placed in a batch external heating vacuum heating furnace together with 30 g of chromium alone. Then, after holding at a heat treatment temperature T of 900 ° C. and a degree of vacuum of 2.0 × 10 ⁻⁴ Pa for 10 minutes, cooling was performed and brazing heat treatment was performed. During cooling, the stage is preferentially cooled by injecting and discharging air into the stage. In addition, a heat-resistant material is lined around the composite material on the wall surface and the stage surface in the heating furnace to prevent Cr deposition.
[0053]
(Example 2)
Except for stacking a pure Ni strip material having a thickness of 1.0 mm, a pure Ti strip material having a thickness of 2.0 mm, and a pure Cu strip material having a thickness of 0.5 mm so that the laminated structure becomes Ni / Ti / Cu. In the same manner as in Example 1, a composite material for brazing was produced.
[0054]
Using this composite material, together with 30 g of chromium alone, it is placed in the same batch type external heating vacuum heating furnace as in Example 1. Then, after holding at a heat treatment temperature T of 1000 ° C. and a degree of vacuum of 2.0 × 10 ⁻³ Pa for 10 minutes, cooling was performed and brazing heat treatment was performed.
[0055]
(Comparative Example 1)
The brazing heat treatment was performed in exactly the same manner as in Example 1 except that the heat treatment temperature T was 900 ° C. and the degree of vacuum was 3.0 × 10 ⁻³ Pa.
[0056]
(Comparative Example 2)
The brazing heat treatment was performed in exactly the same manner as in Example 2 except that the heat treatment temperature T was 1000 ° C. and the degree of vacuum was 1.0 × 10 ⁻¹ Pa.
[0057]
(Conventional example 1)
Except that a pure Cu strip having a thickness of 1.0 mm, a pure Ti strip having a thickness of 2.0 mm, and a pure Cu strip having a thickness of 1.0 mm are overlapped so that the laminated structure becomes Cu / Ti / Cu. In the same manner as in Example 1, a composite material for brazing was produced.
[0058]
The composite material is placed in a batch type external heating vacuum heating furnace. Then, after holding for 10 minutes under the conditions of a heat treatment temperature T of 900 ° C. and a degree of vacuum of 8.0 × 10 ⁻² Pa, cooling was performed and brazing heat treatment was performed.
[0059]
(Conventional example 2)
The same composite material as in Example 2 is placed in the same batch type external heating vacuum heating furnace as in Example 1. Then, after holding for 10 minutes under the conditions of a heat treatment temperature T of 1000 ° C. and a degree of vacuum of 4.0 × 10 ⁻² Pa, cooling was performed and brazing heat treatment was performed.
[0060]
The composite materials of Examples 1 and 2, Comparative Examples 1 and 2, and Conventional Examples 1 and 2 were evaluated for high-temperature oxidation resistance of a brazed joint after brazing heat treatment. Table 1 shows the specifications (laminated structure of the brazing layer, heat treatment temperature T (° C.), and degree of vacuum (Pa)) of each composite material, and the evaluation results of each composite material.
[0061]
Here, the evaluation of the high-temperature oxidation resistance was performed by holding the composite materials of Examples 1 and 2, Comparative Examples 1 and 2, and Conventional Examples 1 and 2 at 600 ° C. for 72 hours in the atmosphere of 1 atm. A high-temperature oxidation test was performed, and the high-temperature oxidation resistance was evaluated based on the change in weight before and after the test and the thickness of the oxide film by cross-sectional observation.
[0062]
[Table 1]

[0063]
As shown in Table 1, in Examples 1 and 2 using the brazing heat treatment method according to the present invention, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is:
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
Since the brazing heat treatment is performed under the condition satisfying the formula (1) (that is, in the shaded region (brazing heat treatment condition region A) in FIG. 2), a sufficient amount of the brazing heat treatment is performed in the furnace during the brazing heat treatment. Cr evaporates. As a result, Cr can be deposited on the brazing alloy layer, and a sufficiently thick chromium oxide film is formed on the surface of the brazing joint during the high-temperature oxidation test. Therefore, the high temperature oxidation resistance was extremely good.
[0064]
On the other hand, in Comparative Examples 1 and 2, the degree of vacuum V during the brazing heat treatment does not satisfy the above equation (1) (that is, outside the shaded region (brazing heat treatment condition region A) in FIG. 2). Therefore, no (or almost no) Cr can be evaporated in the furnace during the brazing heat treatment. As a result, at the time of the high-temperature oxidation test, no (or almost no) chromium oxide film was formed on the surface of the brazed joint, and the high-temperature oxidation resistance was poor.
[0065]
In addition, in the conventional examples 1 and 2, chromium alone was not placed in the heating furnace during the brazing heat treatment, so that no chromium oxide film was formed on the surface of the brazed joint at the time of the high-temperature oxidation test. Oxidation became poor.
[0066]
As described above, in Examples 1 and 2 using the brazing heat treatment method according to the present invention, since the high-temperature oxidation resistance of the brazing joint is good, the brazing heat treatment with excellent reliability of the brazing joint is performed. It turns out that it is a method.
[0067]
【The invention's effect】
In short, according to the present invention, the following excellent effects are exhibited.
(1) According to the brazing heat treatment method according to the present invention, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V becomes
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
By performing the brazing heat treatment under the condition satisfying the formula (1), a brazed joint having good heat resistance, corrosion resistance, and high-temperature oxidation resistance can be obtained at low cost.
(2) By brazing using the brazing composite material of (1), it is possible to obtain a brazed product in which the reliability of the brazed joint is good and the production cost is low.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a brazing composite material used in a brazing heat treatment method according to the present invention.
FIG. 2 is a diagram showing the relationship between temperature and degree of vacuum during brazing heat treatment.
FIG. 3 is a cross-sectional view after performing a brazing heat treatment using the brazing heat treatment method according to the present invention on the brazing composite material of FIG. 1;
FIG. 4 is a cross-sectional view showing another example of the brazing composite material used in the brazing heat treatment method according to the present invention.
5 is a cross-sectional view after the brazing composite material of FIG. 2 has been subjected to a brazing heat treatment using the brazing heat treatment method according to the present invention.
[Explanation of symbols]
10,40 Brazing composite (brazing material)
Reference Signs List 11 base material 12 Ti or Ti alloy layer 13a, 13b, 43 Cu or Cu alloy layer 15, 45 brazing layer 30, 50 brazing product 35, 55 brazing joint 36, 56 brazing alloy layer 37, 57 chromium oxide layer 44 Ni or Ni alloy layer

Claims (6)

In a method of heating a brazing material having a brazing layer on a substrate surface under a high vacuum and performing a brazing heat treatment, the brazing material is placed in a vacuum heating furnace together with Cr or a Cr alloy, and then the heat treatment temperature is set. When T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above brazing heat treatment is performed under the conditions satisfying the formula (1) to melt the brazing layer, and the chromium component of Cr or a Cr alloy is evaporated in a vacuum heating furnace. A brazing heat treatment method comprising depositing a Cr or Cr alloy layer on the surface of the brazing layer. In a method of heating a brazing material having a brazing layer on a substrate surface under a high vacuum and performing a brazing heat treatment, the brazing layer of the brazing material includes a Ti or Ti alloy layer and a Cu or Cu alloy layer. And the brazing material is placed together with Cr or a Cr alloy in a vacuum heating furnace. Thereafter, when the heat treatment temperature T is in the range of 900 ≦ T ≦ 1200 ° C., the degree of vacuum V is
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above brazing heat treatment is performed under conditions satisfying the formula (1) to melt the brazing layer, evaporate the chromium component of Cr or a Cr alloy in a vacuum heating furnace, and then cool the vacuum heating furnace. A brazing heat treatment method comprising depositing a Cr or Cr alloy layer on the surface of the brazing layer in which the metal component is diffused and alloyed. In a method of heating a brazing material having a brazing layer on a substrate surface under a high vacuum and performing a brazing heat treatment, the brazing layer of the brazing material includes a Ti or Ti alloy layer, a Cu or Cu alloy layer, And a brazing material together with Cr or a Cr alloy are placed in a vacuum heating furnace, and when the heat treatment temperature T is in a range of 900 ≦ T ≦ 1200 ° C., the vacuum Degree V
V ≦ 4 × 10 ^{{(T / 100) −13}} (Pa) ... ▲ 1 ▼
The above brazing heat treatment is performed under conditions satisfying the formula (1) to melt the brazing layer, evaporate the chromium component of Cr or a Cr alloy in a vacuum heating furnace, and then cool the vacuum heating furnace. A brazing heat treatment method comprising depositing a Cr or Cr alloy layer on the surface of the brazing layer in which the metal component is diffused and alloyed. 4. The vacuum heating furnace according to claim 1, wherein cooling means for cooling the stage itself is provided on a stage on which the brazing material is placed, and the brazing material is placed on the stage of the vacuum heating furnace. Brazing heat treatment method. The brazing heat treatment method according to any one of claims 1 to 4, wherein a portion of the vacuum heating furnace other than the portion where the brazing material is placed is covered with a heat-resistant material, and the brazing material is disposed in the vacuum heating furnace. A brazed product obtained by joining using the brazing heat treatment method according to claim 1.

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