JPH06318417A - Welding part using phosphor copper blazing filler metal - Google Patents

Abstract

PURPOSE:To maintain a long lifetime by making a welding part using phosphor copper blazing filler metal difficult to be corroded in the environment of sulfur gas atmosphere. CONSTITUTION:An Sn plating layer 8 is formed on at least one main surface of phosphor copper blazing filler metal to be used, where a thickness of the Sn plating layer 8 is made 5-40% in total with respect to a thickness of a phosphor copper blazing filler metal plate 4. Or, the Sn plating layer 8 is formed not on the phosphor copper blazing filler metal plate 4 but on a side of a member, where a thickness of the Sn plating layer 8 is made 10-30mum. Consequently, a fillet which is formed by resistance heat welding includes a large quantity of Sn in either case and this Sn is difficult to generate sulfidity corrosion, thus restraining corrosion of Cu singly by sulfur gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to parts joined by resistance heating brazing using phosphor copper brazing.

[0002]

2. Description of the Related Art A brazing technique is widely used for joining members such as copper alloys in electric equipment. For example, joining of members such as copper or brass, joining of terminals of these metals and silver alloy contacts, brazing of these metallic members and mesh copper wire, and the like. Sn brazing may be applied to such brazed members,
It is as thin as about 1 to 3 μm.

Here, for example, a case will be described in which a contact material such as Ag-CdO is joined to a contact base made of a conductive alloy of electric equipment by brazing. Two methods are commonly used when joining contacts to a contact base by brazing. One is a method in which Ag brazing filler metal and an anti-oxidation flux are used for direct heating with a gas flame for joining. The other is resistance brazing in which a copper copper brazing material is placed between the electrodes together with these members, and a large current is applied while heating while heating.

FIG. 6 is a schematic view seen from the side, for explaining the arrangement of each member when performing the resistance heating brazing. In FIG. 6, for example, a contact 1 made of AgCdO alloy or the like, to which an Ag plate has been pasted, in advance.
With the Ag surface facing the contact base 3 having the Sn plating layer 2 formed on the surface thereof, for example, 80% Cu-15% Ag-5% P
The copper-copper brazing plate 4 having the above composition is sandwiched and placed on the contact base 3, and these members are sandwiched by the upper electrode 5 and the lower electrode 6, and a large current is applied while applying pressure.

FIG. 7 is a partial cross-sectional view showing the main part after brazing. The phosphor copper brazing plate 4 and the Sn plating layer 2 between the contact 1 and the contact base 3 are melted by heating, and at this time, the upper electrode. Since the pressing force from 5 and the lower electrode 6 is working, the excess copper braze plate 4 is formed around the joint between the contact 1 and the contact base 3.
And the melt of the Sn plating layer 2 is extruded, and this is cooled and solidified to form the fillet 7.

As described above, the joining method of heating by applying a large current while pressurizing is higher in productivity than the joining method of heating with a gas flame or the like. Further, as the brazing material, phosphor copper brazing is cheaper than Ag brazing, and since brazing can be done without flux, the brazing time is shortened and the flux is removed after brazing. The process can be omitted and the manufacturing cost can be reduced. When the copper-copper brazing plate 4 is used, the flux is not necessary because the brazing filler metal melts and phosphorus contained in the brazing filler metal prevents oxidation of the brazing filler metal and at the same time activates the surface of the contact base 3 This is because it has a role of preventing the surface of 3 from being oxidized.

[0007]

However, there are also the following problems in an electric device or the like having a joining part using phosphor copper braze, which is inexpensive to manufacture. This is because when electrical equipment having joint parts using phosphor copper braze is used in an environment where sulfide gas exists, such as in hot springs and sewage treatment plants, phosphorus with high vapor pressure in the brazing filler metal It vaporizes, and holes are created there, and CuS is generated by the holes,
This is to cause a situation in which the joint portion is sulfide-corroded, the joint strength is reduced, and the contact eventually comes off.

The present invention has been made in view of the above points, and an object thereof is a joining component using phosphor copper brazing material capable of maintaining a long life even in an environment of an atmosphere containing a sulfurizing gas. To provide.

[0009]

In order to solve the above-mentioned problems, a copper-copper brazing plate is sandwiched between two members to perform resistance heating. Sn plating layer is formed on one main surface, and Sn
The thickness of the plating layer is 5 to 40% in total with respect to the thickness of the phosphor copper brazing plate, and the Sn plating layer may be formed not on the phosphor copper brazing plate surface but on the member side. Sn
The thickness of the plating layer is 10 to 30 μm.

[0010]

Since the joined part of the present invention is joined as described above, the molten material of the copper-copper brazing plate and the Sn-plated layer is spread around the joined part due to the pressing force and the heat of the electric current at the time of joining. Although it is extruded and formed into a fillet shape, this melt contains a large amount of Sn and forms a CuSn alloy to be solidified. Therefore, even if the phosphorus contained in the copper-copper brazing material is vaporized, Sn is unlikely to be corroded by sulfidation, so that Cu can be suppressed from being corroded alone by the sulfidizing gas.

[0011]

EXAMPLES The present invention will be described below based on examples. In the present invention, firstly, an Sn plating layer is applied to the surface of the phosphor copper brazing plate. FIG. 1 is a schematic diagram showing an arrangement relationship of each member in resistance heating brazing of a joint component at that time in accordance with FIG. 6, and the same parts as those in FIG. 6 are denoted by the same reference numerals. 1 is different from FIG. 6 in that a Sn plating layer 8 is formed on both upper and lower surfaces of a phosphor copper brazing plate 4 placed between the contact 1 and the contact base 3, and a Sn plating layer is formed on the contact base 3. There is something wrong with it. FIG. 1 shows the case where the Sn plating layers 8 are formed on both surfaces of the phosphor copper brazing plate 4, but in the present invention, the Sn plating layer 8 is formed only on one of the upper and lower surfaces of the phosphor copper brazing plate 4, that is, on one side. You may form.

When the Sn plating layer 8 is applied to the surface of the phosphor copper brazing plate 4, the Sn plating layer 6 having a thickness of 3 μm and 10 μm is formed on one surface of the phosphor copper brazing plate 4 having a thickness of 0.2 mm.
And two types of Sn, which are 20 μm thick and 40 μm thick, on both upper and lower surfaces of the copper-copper brazing plate 3 having a thickness of 0.2 mm.
A total of four types of samples, two types with the plated layer 8 formed, were prepared, sandwiched between the contact 1 and the contact base 3, and resistance heating brazing was performed by a usual method to obtain the contact parts. Was used to carry out a sulfide corrosion test. When performing this test, for comparison, a conventional unplated phosphor copper braze plate 4 was also added.

The second aspect of the present invention is the same as that of FIG.
The plating layer 2 is formed on the surface of the contact base 3 to be thicker than before. Here, the thickness of the Sn plating layer 2 is set to 10 μm, but for comparison, three types of samples are prepared, including a Sn plating thickness of 3 μm and one without plating, and phosphor copper braze The plate 4 and the contact 1 were placed, resistance heating brazing was carried out in the same manner as described above, and a sulfidation corrosion test was carried out using the obtained contact part.

In any of the above cases, the test conditions were H ₂ S gas concentration 3 ppm, temperature 40 ° C., relative humidity 85%, leaving days 10, 20, 30 days, and shearing of the joint before and after the sulfidation corrosion test. This is a measurement of the strength reduction rate. The shear strength reduction rate is calculated by the following equation. However, W ₀ : Shear strength before sulfidation corrosion test (Kgf / mm ² ) W ₁ : Shear strength after sulfidation corrosion test (Kgf / mm ² ) The obtained test results are shown in Table 1.

[0015]

[Table 1] From the results shown in Table 1, the Sn plating layer 8 was formed on the phosphor copper brazing plate 4,
By forming the total thickness of the phosphor-copper brazing plate 4 in the range of 5% to 40%, the shear strength reduction rate of the joint portion in the sulfidation corrosion test can be significantly reduced. FIG. 2 shows a cross-sectional photomicrograph of the end portion of the contact 1 after the joining at a magnification of 300 times. According to FIG. 2, in the phosphor copper brazing plate 4 which melts between the contact 1 and the contact base 3, the Sn plating layer 8 facilitates the formation of an alloy of Cu and Sn, and the alloy 9 containing a large amount of Sn. Is formed into a fillet shape. Therefore, Cu is not selectively corroded in the fillet, and micropores are not generated.
The contact component used in this example is suppressed in corrosion due to sulfide gas even when used in an environment where sulfide gas is present, and has a life of at least 2 before the contact 1 peels off.
It has become twice as long.

The thickness of the Sn plating layer 8 formed on the copper-phosphorus brazing plate 4 in this embodiment is as follows.
When the total thickness is 40% or more with respect to the thickness, the phosphorous copper brazing plate 4 does not melt at the time of bonding, only the Sn plating layer 8 melts, and the melted Sn rises on the peripheral surface of the contact 1. A phenomenon occurs, and it becomes impossible to obtain a healthy joint state. Further, in consideration of productivity in terms of efficiency of the plating process, it is appropriate that the upper limit of the thickness of the Sn plating layer 8 is 40% in total with respect to the thickness of the phosphor copper brazing plate 4. . On the other hand, if the Sn plating layer 8 is too thin, a sufficient CuSn alloy cannot be formed in the fillet, and in order to maintain the corrosion resistance even if phosphorus is vaporized, the lower limit of the thickness of the Sn plating layer 8 is required. Is preferably 5% with respect to the thickness of the phosphor copper brazing plate 4.

Further, from the results shown in Table 1, when the Sn plating layer 2 is formed thickly on the surface of the contact base 3 instead of the phosphor copper brazing plate 4, the thickness of the Sn plating layer 2 is set to 10 μm or more. The life of the contact 1 can be almost doubled as compared with the conventional one. When the thickness of the Sn plating layer 2 is increased to 10 μm or more, the fillet 7 is Ag-Cu-P containing a large amount of Sn after brazing using the phosphor copper brazing plate 4.
-Sn, and the interface between the phosphor copper brazing plate 4 and the contact base 3 is S
It becomes a quaternary alloy containing n. When the amount of Sn in the Ag-Cu-P-Sn quaternary alloy increases, Cu and Sn easily form an alloy, and the state in which Cu alone disperses is small, and Cu is selective even when the phosphorus component vaporizes. It will be suppressed from being corroded by.

However, the thickness of the Sn plating layer 2 is 10 μm.
If the thickness is too high, the brazing material does not melt and only the Sn plating layer 2 melts when a large current is applied during brazing.
The phenomenon that n rises to the contact surface comes to occur, and it becomes impossible to obtain a sound joint state. Taking into consideration the productivity of the plating process, the limit plating thickness is 30.
It is preferable that the thickness is about μm. Therefore, phosphor copper brazing board 4
In order to suppress sulfide corrosion by using, the thickness range of the Sn plating layer 2 formed only on the contact base 3 is 10 to 30 μm.
A value of m is suitable.

FIGS. 3, 4 and 5 show the fillet 7 formed after the sulfidation corrosion test and a magnification of 150 times in the vicinity thereof for the above-mentioned three kinds of samples in which the Sn plating layer 2 was formed on the surface of the contact base 3. FIG. 3 is a cross-sectional photomicrograph for comparison. FIG. 3 is a Sn-plated thickness of the joining component of the present invention of 10 μm, FIG.
It shows the case without plating.

In the fillet 7 shown in FIGS. 4 and 5, a large number of minute pores due to corrosion are generated inside the phosphor copper brazing plate 4, and a thick Cu sulfide 10 is formed on the surface of the fillet 7. There is. On the other hand, in FIG. 3, the Sn plating thickness is set to 10 μm and a large amount of CuSn alloy is left in the fillet 7, so that Cu is not selectively corroded, and many of those shown in FIGS. No microscopic holes are generated. Further, the thickness of the Cu sulfide 10 formed on the fillet 7 is also extremely thin as compared with FIGS. 4 and 5.

In the above, the joining parts using the phosphor copper braze of the present invention have been described by taking the case of joining the contacts to the contact base as an example, but using the phosphor copper braze having the Sn plating layer formed as described above, Alternatively, the effectiveness of brazing using a joining member having a thick Sn plating layer is not limited to joining contacts, and other machines and devices are also joined using phosphor copper solder. It can be applied to many parts and can be sufficiently achieved.

[0022]

EFFECTS OF THE INVENTION In the joining component using the phosphor copper braze plate of the present invention, an Sn plating layer having a thickness of 5 to 40% of the thickness of the phosphor copper braze plate is formed on at least one surface of the phosphor copper braze plate. What you have done, or 1
The formation of the Sn plating layer of 0 to 30 μm facilitates the formation of an alloy of Cu and Sn in the molten brazing material during resistance heating brazing in any case. for that reason,
When this part is used in an environment where sulfide gas is present, the vaporized pores of phosphorus contained in the brazing material cause Cu
The sulfide gas attack alone is suppressed, and the life until the joining member comes off due to sulfide corrosion at the connection interface is at least twice as long as the conventional life.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a positional relationship of each member when a Sn plating layer is applied to a phosphor copper brazing plate at the time of brazing a contact according to the present invention.

FIG. 2 is a cross-sectional photomicrograph of the fillet and its vicinity after brazing from the state shown in FIG.

FIG. 3 is a cross-sectional photomicrograph of the fillet and its vicinity after brazing when the Sn plating layer thickness of the contact base is 10 μm.

FIG. 4 is a cross-sectional photomicrograph of the fillet and its vicinity after brazing when the Sn plating layer thickness of the contact base is 3 μm.

FIG. 5 is a cross-sectional photomicrograph of the fillet and its vicinity after brazing when the contact base is not Sn-plated.

FIG. 6 is a schematic diagram showing a positional relationship of each member during conventional brazing of contacts.

FIG. 7 is a schematic cross-sectional view showing a main part after conventional contact brazing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 contact point 2 Sn plating layer 3 contact point 4 phosphor copper brazing plate 5 upper electrode 6 lower electrode 7 fillet 8 Sn plating layer 9 alloy 10 containing a large amount of Sn 10 sulfide

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[Procedure amendment]

[Submission date] May 27, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

FIG. 2 is a photograph showing a metal structure of a cross section of the fillet and its vicinity after brazing from the state shown in FIG.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is a photograph showing a metallographic structure of the fillet after brazing and a cross section in the vicinity thereof after the Sn plating layer of the contact base has a thickness of 10 μm.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 4

[Correction method] Change

[Correction content]

FIG. 4 is a photograph showing the metallographic structure of the fillet after brazing and the cross section in the vicinity thereof when the thickness of the Sn plating layer of the contact base is 3 μm.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

FIG. 5 is a photograph showing the metallographic structure of the cross section of the fillet and its vicinity after brazing when the contact base is not Sn-plated.

Claims (4)

[Claims] 1. A joint part using phosphor copper braze in which a plate-shaped phosphor copper braze is sandwiched between two members and joined by resistance heating, wherein at least one main surface of the phosphor copper braze is provided. A joint part using phosphor copper brazing, characterized in that a Sn plating layer is formed. 2. The joint component according to claim 1, wherein the thickness of the Sn plating layer is 5 to 5 in total with respect to the thickness of the phosphor copper brazing plate.
A joint part using phosphor copper brazing, characterized in that it is 40%. 3. A joint component using a phosphor copper braze in which one member having an Sn plating layer formed on the surface is brazed to the other member by resistance heating, wherein the Sn plating layer has a thickness of 10
A joined part using phosphor copper solder characterized by having a thickness of up to 30 μm. 4. The joint component according to claim 1, wherein the fillet produced after brazing contains a large amount of Sn, and the joint component uses phosphorous copper brazing.