JPH1058134A - Joining method using sprayed coating, and joined body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining method where a sprayed coating with excellent adhesivity and a joined body with excellent joining strength of a joined part and excellent ductility are obtained, and a joined body in performing the joining using a sprayed coating of Ni-based alloy containing Cr and/or Si excellent in heat resistance and strength. SOLUTION: In a joining method using sprayed film where a sprayed coating is formed on a surface of a base plate, the base plate is brought into contact with a work through the sprayed coating, the sprayed coating is heated and melted to join the base plate with the work, Ni-based alloy containing Cr and/or Si is used for the sprayed coating, and the relationship between the surface roughness Ra (μm) and the quantity of oxide mOx (mass %) contained in the sprayed coating simultaneously satisfies the inequalities of Ra+mOx<=5.5 and Ra<2> ×mOx>=0.2 when the surface roughness Ra is <=2μm, or the inequality of Ra+mOx<=5.5 when the surface roughness Ra is >2μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method using a sprayed coating for joining a substrate and a member to be joined by spraying a sprayed material onto a substrate and melting the sprayed coating, and a joined body thereof. In particular, the present invention relates to a bonding method using a Ni-based alloy containing Cr or / and Si for a thermal spray coating and a bonded body thereof. In particular, C
The Ni-based alloy containing r and / or Si is applied to a self-fluxing alloy and a Ni solder.

[0002]

2. Description of the Related Art Brazing is used as a method for joining metals. Also, when brazing a joint having a complicated shape such as a curved surface, it may be difficult to install the brazing material using a foil or a powder brazing material. Therefore, a method has been proposed in which a brazing material or the like is sprayed on the joint to form a sprayed coating, and then brazing is performed. As a method of brazing using a thermal spray coating, a method using a thermal spray coating of a self-fluxing alloy (Japanese Patent Laid-Open No.
2-118988), a method using a thermal spray coating of a brazing material or a component similar thereto (Japanese Patent Publication No. 6-7165).
No. 1), a method using a coating obtained by spraying a copper braze with an arc or plasma (see Japanese Patent Publication No. 8-15656).
Etc. In particular, a Ni-based alloy containing Cr and Si is used for brazing requiring heat resistance and high strength.

[0003]

However, in the brazing method using the sprayed coating of the Ni-based alloy, the sprayed coating of the Ni-based alloy may peel off from the substrate, and there is a problem that brazing cannot be performed. In addition, Cr and Si oxides, which are easily oxidized in the thermal spray coating of the Ni-based alloy, are mixed into the thermal spray coating at the time of thermal spraying, and there is a problem that the bonding strength and elongation of the bonded portion after brazing are reduced.

Accordingly, the present invention provides a thermal spray coating having excellent adhesion when brazing a Ni-based alloy containing Cr and Si having excellent properties of heat resistance and high strength by using a thermal spray coating. An object of the present invention is to provide a bonding method and a bonded body that obtain a bonded body having high bonding strength and excellent elongation by using a film.

[0005]

Means for Solving the Problems The inventors of the present invention have made it possible to achieve the above-mentioned object by using Cr and / or Si.
And the adhesion between the thermal spray coating of the Ni-based alloy and the substrate,
Intensive research was conducted on the bonding strength and elongation of a brazed joint using this thermal spray coating. In particular, the effects of the surface roughness Ra of the substrate and the oxide amount of the thermal spray coating, which are considered to have a great effect on the adhesion of the thermal spray coating and the bonding strength and elongation of the joined body, were investigated. As a result, it has been found that when the surface roughness Ra of the substrate is 2 μm or less in the adhesion between the thermal spray coating and the substrate, peeling of the thermal spray coating from the substrate is promoted. However, when the surface roughness Ra was 2 μm or less, a remarkable finding was obtained that peeling of the sprayed coating could be prevented by the presence of the oxide in the sprayed coating. Further, the inventors have found that the bonding strength and elongation of the bonded body tend to be higher as the surface roughness Ra of the substrate is smaller and the oxide amount of the thermal spray coating is smaller, and the present invention has been completed. Hereinafter, the progress of completing the present invention will be described.

First, the influence of the surface roughness Ra of the substrate was investigated. The adhesion between the thermal spray coating and the substrate depends on the anchoring (mechanical bite) effect. It has been found that the anchoring effect increases as the surface roughness of the substrate increases, and that the adhesion between the thermal spray coating and the substrate increases. Therefore, it has been found that it is necessary to increase the surface roughness of the substrate in order to obtain excellent adhesion of the thermal spray coating. On the other hand, it has been found that it is effective to reduce the surface roughness Ra of the substrate in order to increase the joining strength and elongation of the brazed joint. With such improved adhesion between the thermal spray coating and the substrate,
It has been found that the surface roughness Ra of the substrate has a contradictory effect on the improvement of the joining strength and elongation of the brazed joined body. For the surface roughness Ra, the center line average roughness was determined by a stylus method (JIS B0601).

Next, the influence of the oxide amount mOx of the thermal spray coating was investigated. When a film is formed by thermal spraying, a reaction occurs between the thermal spray material and the thermal spray atmosphere because the thermal spray material is in a molten or semi-molten state during thermal spraying. At the time of thermal spraying, Cr, Si, etc. in the thermal spray material are oxidized, and the generated oxide is contained in the thermal spray coating. The effect of this oxide was investigated in detail. As a result, in the adhesion between the thermal spray coating and the substrate, it was found that the oxide was effective in preventing the thermal spray coating from peeling off when the surface roughness Ra of the substrate was 2 μm or less. . On the other hand, the joining strength and elongation of the joined body are such that when brazing is performed using a thermal spray coating containing an oxide, the oxide remains at the joint. As a result, it was found that destruction occurred from the oxide of the joint as a starting point, the joining strength of the joined body was reduced, and the elongation was significantly reduced.

As described above, the surface roughness Ra of the substrate to be sprayed and the amount of oxide mOx of the sprayed coating of the Ni-based alloy containing Cr and / or Si are determined by the adhesion between the sprayed coating and the substrate, It has been found that this has a great effect on the bonding strength and elongation of the steel. In order to investigate this effect in more detail, a thermal spray material of a Ni-based alloy containing Cr or / and Si (Ni braze, self-fluxing alloy, etc.)
Thermal spraying (gas flame spraying, plasma spraying) was performed on the metal substrate having the changed surface roughness. At this time, the spraying conditions were changed to change the oxide amount of the sprayed coating. The surface roughness Ra of the used substrate is in the range of about 0.2 to 8.0 μm, and the oxide amount of the thermal spray coating is in the range of about 0.1 to 19% by mass. The thermal spray coating thus obtained was subjected to an adhesion test.
Next, the substrate and the material to be joined were brought into contact with each other via the thermal spray coating, and the thermal spray coating was heated and melted to join the substrate and the material to be joined, and brazing was performed. Thereafter, a tensile test was performed on the joints of these joined bodies to measure joint strength and elongation. Based on these measurement results, a numerical analysis was performed on the relationship between the surface roughness of the substrate and the amount of oxide in the thermal spray coating. The results are shown in FIGS.

FIG. 1 shows a surface roughness Ra (μm) of a substrate to be sprayed and a Ni containing Cr and / or Si to which a bonding method and a bonded body using the thermal spray coating of the present invention are applied.
It is a figure which shows the relationship with the oxide amount mOx (mass%) of the thermal spray coating of a base alloy, and the range (shaded part) of this invention. FIG.
Describes the effects of the surface roughness Ra (μm) of the substrate and the oxide amount mOx (mass%) of the thermal spray coating on the properties of the thermal spray coating of the Ni-based alloy containing Cr and / or Si used in the present invention. FIG.

FIG. 1 shows the surface roughness Ra of the substrate sprayed on the horizontal axis.
(Μm), and the ordinate represents the oxide amount mOx (mass%) of the thermal spray coating. Surface roughness Ra (μm) of substrate to be sprayed
FIG. 1 shows a relational expression between the thermal spray coating and the oxide amount mOx (% by mass). These are shown below. Ra + mOx = 5.5 Ra ² × mOx = 0.2 mOx = 0 The portion (shaded portion) surrounded by the above relational expression is the scope of the present invention. Here, in the portion below Ra + mOx = 5.5 (formula), the joint strength of the joined body is 300 MPa or more,
It is a region where the elongation is 10% or more. When the bonding strength and elongation of the bonded body satisfy these values, the mechanical strength and reliability of the product obtained by the brazing method of the present invention are enhanced.

When the surface roughness Ra of the substrate is 2 μm or less, the upper part of Ra ² × mOx = 0.2 (formula) is a region where the thermal spray coating does not peel off from the substrate. The upper part of mOx = 0 (formula) where the surface roughness Ra exceeds 2 μm does not cause the thermal spray coating to peel off from the substrate. These will be described below.

The relationship between Ra ² × mOx = 0.2 (expression) and mOx = 0 (expression) will be described, and the meaning of Ra ² × mOx = 0.2 (expression) will be described in detail. . First, Ra ² × mOx = 0.2 (formula) and m
The relationship with Ox = 0 (expression) will be described with reference to FIG. In FIG. 2, the horizontal axis indicates the surface roughness Ra (μm) of the substrate, and the vertical axis indicates the oxide amount mOx (mass%) of the thermal spray coating on a logarithmic scale, and the characteristics of the thermal spray coating of the Ni-based alloy are obtained.
FIG. 2 shows the results of the following adhesion test of the thermal spray coating. Using a stainless steel SUS304 and SUS316 for the substrate 1, a thermal spray coating 2 of Ni-based powder brazing material BNi-2 and BNi-5 was formed (see FIG. 3).
Thereafter, as an adhesion test, a visual inspection of the sprayed coating and, if necessary, a scratch test of the sprayed coating were performed.

In FIG. 2, black circles and black triangles indicate points where the sprayed coating has peeled off from the substrate, and white circles and white triangles indicate points where the sprayed coating is in close contact. The oblique straight line in FIG. 2 is a straight line that separates the area to be peeled from the area that is in close contact:
Ra ² × mOx = 0.2 (formula). When the surface roughness Ra of the substrate is 2 μm or less, the portion (Ra)
^{At 2} × mOx <0.2), the thermal spray coating peeled off from the substrate. On the other hand, if the surface roughness Ra of the substrate exceeds 2 μm, the mOx calculated from Ra ² × mOx = 0.2 (formula)
Is less than 0.05% by mass, the surface roughness Ra of the substrate is increased, and mOx is further reduced. Therefore, when the surface roughness Ra of the substrate exceeds 2 μm, Ra
Instead of ² × mOx = 0.2 (formula), mOx = 0
It is considered that (Expression) may be used. That is, in the region where the surface roughness Ra of the substrate exceeds 2 μm, it is considered that the thermal spray coating adheres to the substrate regardless of the amount of oxide in the thermal spray coating.

The above-mentioned mOx 0.05% by mass is
In the present invention, the lower limit of the measurement in the method for measuring the amount of oxide in the thermal spray coating (Br ₂ -methanol decomposition method) is 0.1% by mass or less. If it is less than 05% by mass, it is regarded as substantially 0% by mass.

Next, the meaning of Ra ² × mOx = 0.2 (formula) will be described. Conventionally, when the amount of oxides in the thermal spray coating is large, metallurgical reactions such as adhesion between the oxide and the substrate do not easily occur during thermal spraying, so that the oxide reduces the adhesion between the thermal spray coating and the substrate, It has been thought that it promotes the peeling of the thermal spray coating from the substrate. However, a surprising fact was confirmed when the surface roughness Ra of the substrate was 2 μm or less. As shown in FIG. 2, unlike the conventional knowledge, the presence of an oxide in the thermal spray coating suppresses the separation of the thermal spray coating from the substrate (Ra ² × mOx = 0.2).
(Upper part of (expression)). That is, the presence of the oxide in the thermal spray coating allows the thermal spray coating to be bonded to the substrate. Investigation of this cause is for further study.

Further, in order to increase the bonding strength and elongation of the bonded body, the surface roughness Ra of the substrate has been reduced. However, when the surface roughness Ra of the substrate is reduced and the surface roughness Ra becomes 2 μm or less, a problem of peeling of the thermal spray coating from the substrate occurs. In the present invention, when the surface roughness Ra of the substrate is 2 μm or less, Ra ² × mOx ≧
This suggests that the problem can be solved by using a sprayed coating having an oxide amount satisfying 0.2 (formula). That is, the surface roughness Ra of the substrate and the amount of oxide in the thermal spray coating are properly adjusted by the relational expression (expression, equation) between the surface roughness Ra of the substrate and the amount of oxide in the thermal spray coating obtained in the present invention. By doing so, a sprayed coating with even better adhesion,
It is possible to obtain a joining method and a joined body for obtaining a joined body having higher joining strength and more excellent elongation of a joining portion.

As is apparent from the above description, in the invention according to the first aspect of the present invention, a sprayed film is formed on the surface of the substrate, and the substrate and the material to be joined are brought into contact with each other via the sprayed film. In a bonding method using a thermal spray coating for heating and melting a thermal spray coating to bond a substrate and a material to be bonded, the thermal spray coating uses a Ni-based alloy containing Cr or / and Si, and has a surface roughness Ra ( μm) and the amount of oxide mOx (% by mass) contained in the thermal spray coating, when the surface roughness Ra is 2 μm or less, the following expressions and expressions are simultaneously satisfied: Ra + mOx ≦ 5.5 Ra ² × mOx ≧ 0.2 If the surface roughness Ra exceeds 2 μm, Ra + mOx ≦ 5.5.

As described above, when the formula is satisfied, the joined body has high joining strength and excellent elongation in brazing using a thermal spray coating of a Ni-based alloy containing Cr and / or Si. be able to. When the surface roughness Ra of the substrate is 2 μm or less, by satisfying the expression, it is possible to prevent the thermal spray coating of the Ni-based alloy containing Cr and / or Si from peeling off from the substrate.

The Ni-based thermal spray material used in the present invention is often used as a powder from the viewpoint of moldability, but it can be applied to a wire or a rod as long as it can be molded. Furthermore, the thermal spray material used in the present invention is not particularly limited as long as it is a powder of a Ni-based alloy component containing Cr and / or Si. Tables 1 and 2 exemplify the Ni-based alloy components used in the present invention without limitation. Components other than Cr and Si contained in these Ni-based alloys (C,
B, Fe, Co, Mo, Cu, W, P, etc.) may be included in the thermal spray material used in the present invention.

[0020]

[Table 1]

[0021]

[Table 2]

The material of the substrate on which the thermal spraying is performed is not particularly limited, and may be a mild steel, a stainless steel, a Ni-based alloy, or the like.
Any material can be used as long as it can be joined using an i-based thermal spray coating. As for the material of the joined body, the same material as that of the substrate can be used.

The control of the surface roughness in the present invention includes a grit blast method, a machining method, an arc method, and an etching method. As a method of controlling the amount of oxide, there are a method of controlling a spraying atmosphere such as a degree of vacuum and a shielding gas, a method of adjusting a temperature of a heat source, and a method of adjusting the particle size of a sprayed powder. In particular, in gas flame spraying, it is possible to adjust the atmosphere in the combustion flame and the temperature of the heat source by adjusting the mixing ratio and flow rate of acetylene-oxygen, for example.

According to a second aspect of the present invention, the Ni-based alloy containing Cr and / or Si according to the first aspect is a brazing material. By using a brazing material that has a wider range of application than a self-fluxing alloy and is inexpensive, it can be applied to products that require a high cost for installation of the brazing material due to the large number of joints.

According to a third aspect of the present invention, the Ni-based alloy containing Cr and / or Si according to the first aspect is a self-fluxing alloy. By using a self-fluxing alloy, the joining portion has excellent heat resistance and strength, which are characteristics of the self-fluxing alloy, and can be applied to a member particularly requiring heat resistance and strength.

According to a fourth aspect of the present invention, there is provided a joined body formed by using any one of the first to third aspects. The joined body joined by any one of the methods according to any one of claims 1 to 3 has high joining strength and excellent elongation.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. 3 to 5 are schematic views illustrating a joining method according to an embodiment of the present invention.

(Embodiment 1) In Embodiment 1, a Ni solder (BNi
-2), the surface roughness Ra of the substrate to be sprayed is 1.80.
This is an example in which brazing was performed by changing the amount of oxide of the thermal spray coating to a constant value of μm. As shown in FIG. 3, stainless steel SUS304 was used for the substrate 1. SUS304
The surface roughness Ra of the substrate 1 was adjusted by blasting using an alumina grid, and the sprayed surface of the substrate 1 was adjusted to have a surface roughness Ra of 1.80 μm. The surface roughness Ra was confirmed by a surface roughness test using a stylus method. For thermal spray material,
Ni brazing filler metal powder BNi-2 (Ni-6.9 mass% Cr-
3.1% by mass B-4.4% by mass Si-3.0% by mass F
e) was used. The change in the amount of oxide in the thermal spray coating was carried out by adjusting the particle size of the Ni brazing filler metal powder (see Japanese Patent Application No. 8-217608). Thermal spraying is a mixed gas of acetylene and oxygen (C ₂ H ₂ gas flow rate: 1.70 m ³ / h)
, An O ₂ gas flow rate of 2.70 m ³ / h) to form a sprayed coating having a thickness of 250 μm to 350 μm on the blasted surface of the substrate 1 of SUS304. An analysis of the amount of oxide in these sprayed films and an adhesion test of the sprayed films were performed. Next, a material 3 to be joined made of stainless steel SUS304 was set on the substrate 1 on which the thermal spray coating 2 was formed so as to be in contact therewith. In this state, by heating to 1175 ° C. in a vacuum, the thermal spray coating 2 is formed.
And brazing the substrate 1 and the material 3 to be joined,
A joined body was manufactured. After brazing, a tensile test piece (JIS No. 14A test piece, parallel part diameter: 6 mm) was cut out of these bonded bodies so that the bonded portion was at the center. After this,
A tensile test was performed to measure the joint strength and elongation of the joined body. These, the oxide amount of the thermal spray coating, the adhesion of the thermal spray coating,
Table 3 shows the measurement results of the joining strength and the elongation of the joined body.

[0029]

[Table 3]

As shown in Table 3, the bonding strength and the elongation increase as the amount of oxide in the thermal spray coating decreases. The amount of oxide in the thermal spray coating is 0.1% by mass and the bonding strength is 400M
Pa and elongation were 20%. On the other hand, the bonding strength of the joined body in which the amount of oxide in the sprayed coating in which the value on the left side of the formula exceeds 5.5 was 4.1% by mass was 260 MPa, and the elongation was significantly reduced to 4%. When the value of the oxide on the left side of the formula is less than 0.2 and the amount of oxide in the thermal spray coating is 0.0% by mass (no oxide in the thermal spray coating is detected), the thermal spray coating shows peeling from the substrate. Was done. Brazing could not be performed by peeling. As shown in the present embodiment, the surface roughness of the thermal sprayed surface of the substrate and the amount of oxide in the thermal spray coating, the formula, by performing brazing under conditions that simultaneously satisfy the formula, without causing peeling of the thermal spray coating from the substrate It was confirmed that a joined body having high strength and excellent elongation was obtained.

(Embodiment 2) In Embodiment 2, a Ni solder (BNi
-2), the surface roughness Ra of the substrate to be sprayed is 0.50
This is an example in which brazing was performed by changing the amount of oxide of the thermal spray coating to a constant value of μm. Brazing was performed under the same conditions as in Example 1, and the adhesion of the thermal spray coating, the bonding strength and the elongation of the bonded body were measured. Table 4 shows the results.

[0032]

[Table 4]

In the same manner as in Example 1, the thermal spray coating is peeled off from the substrate by brazing under the condition that the surface roughness Ra of the thermal sprayed surface of the substrate and the amount of oxide mOx in the thermal spray coating simultaneously satisfy the following expressions. It was confirmed that a bonded body having high strength and excellent elongation could be obtained without occurrence of cracks.

Example 3 In Example 3, a self-fluxing alloy was used.
The surface roughness Ra of the substrate to be sprayed is kept constant at 3.10 μm.
And brazed by changing the amount of oxide in the thermal spray coating
This is an example. Use mild steel for the substrate and adjust the surface roughness of the substrate.
Adjustment by blasting using a steel grid.
The sprayed surface of the mild steel substrate has a surface roughness Ra of 3.10 μm.
Was adjusted. Ni-based self-fluxing alloy powder (Ni-
13.0% by mass Cr-4.5% by mass Si-2.9% by mass
B-4.0 mass% Fe-0.03 mass% C).
The change in the amount of oxide in the thermal spray coating was the same as in Example 1, except that
This was performed by adjusting the particle size of the self-fluxing alloy powder.
Next, thermal spraying is performed using an acetylene-oxygen mixed gas (C_TwoH _TwoMoth
Flow rate: 1.70m^Three/ H, O_TwoGas flow rate: 2.70
m^Three/ H) by gas flame spraying
A film having a thickness of 200 μm to 350 μm
A thermal spray coating of a Ni-based self-fluxing alloy was formed. These thermal spray coatings
The analysis of the amount of oxides and the adhesion test of the thermal spray coating were carried out in Example 1.
The same conditions were used.

Next, as shown in FIG. 4, a material 3 to be joined made of mild steel was set next to the substrate 1 on which the thermal spray coating 2 was formed. In this state, in vacuum at 1110 ° C.
Then, the thermal sprayed coating 1 was melted, and the substrate 1 and the material to be joined 3 were brazed to produce a joined body. The joining strength and elongation of these joined bodies were measured under the same conditions as in Example 1. Table 5 shows the results.

[0036]

[Table 5]

The sprayed coating of the self-fluxing alloy of Example 3 did not peel off from the substrate. This is because the surface roughness Ra of the substrate of Example 3 is in a region exceeding 2 μm (also a region satisfying the formula). The bonding strength and elongation of the bonded body are such that the amount of oxide in the sprayed coating whose value on the left side of the equation exceeds 5.5 exceeds 2.5.
The joint strength of the joined body of mass% was 260 MPa, and the elongation was significantly reduced to 6%. As described above, even when brazing using a sprayed film of a self-fluxing alloy or when the set of the sprayed film of the substrate and the object to be bonded is laid horizontally as shown in FIG. It was confirmed that the result was obtained.

Further, the influence of the surface roughness of the substrate when the amount of oxide in the thermal spray coating was 0.1% by mass was investigated in more detail. In addition, 0.1 mass% is the lower limit of the analysis of the oxide amount of the thermal spray coating of the Ni-based alloy.

(Embodiment 4) In Embodiment 4, a Ni solder (BNi
This is an example in which brazing was performed by changing the surface roughness Ra of the substrate while keeping the amount of oxide in the thermal spray coating constant at 0.1% by mass using -5). For the thermal spraying material, Ni brazing material powder BNi-5 (Ni-18.0% by mass Cr-9.9% by mass)
Si-0.7 mass% C) was used. The substrate 1 was made of stainless steel SUS316. The surface roughness of the substrate used for the test was determined by machining and finishing with a paper file (120, 4
No. 00, 800), blasting (alumina grid,
By using a steel grid), the surface roughness Ra was 0.3 to 7.7 μm. Surface roughness Ra
Was measured by a surface roughness test using a stylus method.

The spraying is performed by Ar-H ₂ plasma spraying to form a sprayed coating having a thickness of 250 μm to 350 μm by SU.
It was formed on the substrate of S316. By controlling the spraying conditions, a sample having an oxide content of 0.1% by mass in the sprayed coating was obtained. The amount of oxide was confirmed by analysis. Next, as shown in FIG. 3, the thermally sprayed substrate 1 and the object 3 were set via the thermal spray coating 2. In this state, the thermal spray coating 1 was melted by heating to 1185 ° C. in a vacuum, and the substrate 1 and the workpiece 3 were brazed to produce a joined body.
The adhesion of these thermal spray coatings and the joint strength and elongation of the joined body were measured. Table 6 shows the results.

[0041]

[Table 6]

As shown in Table 6, the joining strength and elongation of the joined body increase as the surface roughness Ra of the substrate decreases. The substrate has a surface roughness Ra of 1.5 μm and a bonding strength of 37
It showed 0 MPa and an elongation of 21%. On the other hand, the bonding strength of the bonded body having a surface roughness Ra of 7.7 μm of the substrate whose value on the left side of the expression exceeds 5.5 was 95 MPa, and the elongation was significantly reduced to 1%. In addition, when the surface roughness Ra of the substrate whose value on the left side of the equation was less than 0.2 was 1.3, 0.6, or 0.3 μm, peeling of the sprayed coating from the substrate was observed in all cases. As shown in the present embodiment, the surface roughness of the thermal sprayed surface of the substrate and the amount of oxide in the thermal spray coating, the formula, by performing brazing under conditions that simultaneously satisfy the formula, without causing peeling of the thermal spray coating from the substrate It was confirmed that a joined body having high strength and excellent elongation was obtained.

(Example 5) In Example 5, a self-fluxing alloy (MSF
Using Ni3), the amount of oxide in the thermal spray coating is 0.1% by mass.
This is an example in which brazing was performed while changing the surface roughness Ra of the substrate while keeping the surface constant. Self-fluxing alloy powder MSFNi3 (Ni-14.2% by mass Cr-3.8% by mass Si-2.5% by mass B-0.6% by mass C) was used as the thermal spraying material. Stainless steel SUS403 was used for the substrate. By adjusting in the same manner as in Example 4, the surface roughness Ra of the substrate used for the test was 0.3 to 7.8 μm. Thermal spraying is an acetylene-oxygen mixed gas (C ₂ H ₂ gas flow rate:
1.70 m ³ / h, O ₂ gas flow rate: 2.70 m ³ / h)
A gas sprayed film was used to form a sprayed coating having a thickness of 250 μm to 350 μm on the SUS403 substrate. Also in this example, a sample in which the amount of oxide in the thermal spray coating was 0.1% by mass was obtained by adjusting the thermal spraying conditions and the particle size of the thermal spray powder. These were confirmed by analysis of the amount of oxide.

Next, as shown in FIG.
The substrate 1 and the object 3 were set via the thermal spray coating 2 with the object 3 facing down and the object 3 placed below. In this state, the thermal spray coating 1 was melted by heating to 1120 ° C. in a vacuum, and the substrate 1 and the workpiece 3 were brazed to produce a bonded body. The adhesion of these thermal spray coatings and the joint strength and elongation of the joined body were measured. Table 7 shows the results.

[0045]

[Table 7]

As in the first embodiment, the brazing is performed under the condition that the surface roughness of the thermal sprayed surface of the substrate and the amount of oxide in the thermal spray coating simultaneously satisfy the formulas, and the thermal spray coating is separated from the substrate. Thus, it was confirmed that a joined body having high strength and excellent elongation was obtained. Thus, the same results as in Example 4 were obtained even when brazing using a self-fluxing alloy thermal spray coating or changing the set of the thermal spray coating on the substrate and the object to be joined during brazing.

FIG. 5 is a schematic diagram showing the influence of the surface roughness Ra of the substrate and the amount of oxide mOx of the thermal spray coating on the bonding strength and elongation of the bonded body, based on the results of Examples 1 to 5 described above. 6 is shown. As shown in FIG. 6, the bonding strength and elongation of the bonded body are such that the smaller the surface roughness Ra of the substrate is,
Also, the smaller the amount of oxide in the thermal spray coating, the higher the value tends to be. By controlling the surface roughness Ra of the substrate and the amount of oxide mOx of the thermal sprayed coating within the range (shaded portion) of the present invention shown in FIG. 6, a joined body with further enhanced joint strength and elongation is obtained. It is possible.

According to the method of the present invention, since the joining surface has a complicated shape such as a curved surface, a product (for example, a centrifugal compressor impeller or the like) having a portion where it is difficult to install a brazing material such as foil or powder, or a large number of joining portions is used. Therefore, by using a product (for example, a plate fin type heat exchanger or the like) which requires a cost for installation of the brazing material, the above-described effect can be obtained.

[0049]

As described above, according to the first aspect of the present invention, a thermal sprayed material of a Ni-based alloy containing Cr and / or Si, which is excellent in heat resistance and high strength, is formed on a substrate by thermal spraying. Formed on the surface, by contacting the substrate and the material to be joined via the thermal spray coating, when the thermal spray coating is heated and fused to join the substrate and the material to be joined, a thermal spray coating having excellent adhesion It is possible to obtain a joined body having high joining strength and excellent elongation. Since the adhesion between the thermal spray coating and the substrate is excellent, the handleability during assembly is good, and the efficiency of the brazing process can be improved. Further, by using a thermal sprayed coating having excellent adhesion, it is possible to obtain a bonded body having high bonding strength and excellent elongation.

The invention according to claim 2 can be applied to a product which requires a wide range of application and is inexpensive to install because of the large number of joints. It is possible to obtain a great effect. In addition, the invention according to claim 3 has a greater effect than being applied to a member particularly requiring heat resistance and strength by having a joint having heat resistance and strength which are excellent properties of the self-fluxing alloy. It is possible to obtain.

The bonded article according to the fourth aspect of the present invention is characterized in that the surface roughness of the substrate is obtained by the relational expression (expression, expression) between the surface roughness Ra of the substrate obtained in the present invention and the amount of oxide mOx in the thermal spray coating. By properly adjusting the Ra and the amount of oxides mOx in the thermal spray coating, it is possible to obtain a thermal spray coating with better adhesion and a bonded body with higher bonding strength and better elongation at the bonding part. It is assumed that.

[Brief description of the drawings]

FIG. 1 shows a surface roughness Ra (μm) of a substrate to be sprayed to which a bonding method and a bonded body using a sprayed coating of the present invention are applied.
FIG. 2 is a graph showing the relationship between the oxide amount of a thermal sprayed coating of a Ni-based alloy containing Cr and / or Si and mOx (% by mass) and the range of the present invention (shaded portion).

FIG. 2 shows Cr and / or Si used in the present invention.
Of the surface roughness Ra (μm) of the substrate on the properties of the thermal spray coating of a Ni-based alloy containing Ni and the oxide amount mOx of the thermal spray coating
It is a figure which shows the influence of (mass%).

FIG. 3 is a schematic view showing a joining method according to a first embodiment, a second embodiment, and a fourth embodiment of the present invention.

FIG. 4 is a schematic view showing a joining method according to a third embodiment of the present invention.

FIG. 5 is a schematic view showing a joining method according to a fifth embodiment of the present invention.

FIG. 6 is a schematic diagram showing the influence of the surface roughness Ra (μm) of the substrate and the amount of oxide mOx (% by mass) on the bonding strength and elongation of the joined body using the thermal spray coating of the present invention. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Thermal spray coating 3 Material to be joined

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C23C 4/18 C23C 4/18

Claims (4)

[Claims] 1. A thermal spray coating for forming a thermal spray coating on the surface of a substrate, bringing the substrate into contact with the material to be joined through the thermal spray coating, heating and melting the thermal spray coating to join the substrate and the material to be joined. In the joining method using Ni, the thermal sprayed coating contains Ni containing Cr or / and Si.
Using a base alloy, the relationship between the surface roughness Ra (μm) of the substrate and the amount of oxide mOx (mass%) contained in the thermal spray coating is as follows: When the surface roughness Ra is 2 μm or less, the following equation is obtained. Ra + mOx ≦ 5.5 Ra ² × mOx ≧ 0.2 When the surface roughness Ra exceeds 2 μm, Ra + mOx ≦ 5.5. A bonding method using a thermal spray coating. 2. The joining method using a thermal spray coating according to claim 1, wherein the Ni-based alloy containing Cr and / or Si is a brazing material. 3. The joining method using a thermal spray coating according to claim 1, wherein the Ni-based alloy containing Cr and / or Si is a self-fluxing alloy. 4. A joined body joined by using the method according to claim 1.