JP2006239745A - Method for joining aluminum member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for joining aluminum members through a zinc coating layer by surely forming the layer in a quantity sufficient for the joining face of the members to be joined composed of an aluminum material. <P>SOLUTION: The joining face in each aluminum member 1a, 1b is provided with a zinc coating layer 2 by electroplating, both aluminum members 1a, 1b are superposed through the zinc coating layers 2, 2 and heated at or above the solidus temperature of aluminum and zinc, desirably, at not less than the melting point of zinc. In superposing and heating both aluminum members 1a, 1b, a pressurizing load is imparted to them. The joining face of each aluminum member 1a, 1b, after being processed for oxide film removal, is provided with the zinc coating layer 2 by the electroplating. In superposing both aluminum members 1a, 1b through the zinc coating layers 2, 2, tin is interposed between the layers 2, 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum-based member joining method in which two members to be joined made of an aluminum-based material such as pure aluminum or an aluminum alloy are joined to each other.

  Conventionally, a brazing method is known in order to join two members to be joined made of an aluminum-based material such as pure aluminum or an aluminum alloy. As the brazing material used for the brazing, for example, an Al—Si alloy brazing material, an Al—Zn alloy brazing material, and the like are known. Further, in order to enable brazing at a lower temperature or to improve wettability with respect to a member to be joined made of the aluminum-based material (hereinafter sometimes simply referred to as an aluminum-based member), the Al—Zn-based An alloy brazing material added with Ti or Si is also known (see, for example, Patent Documents 1 and 2).

  However, since the aluminum-based member has a stable oxide film formed on the surface, the wettability is poor even when Si is added, and it is necessary to mechanically remove the oxide film for joining by brazing. There is. The oxide film can be removed by using a flux during brazing, but it is difficult to bond in a large area when using a flux, and the heat treatment furnace used for brazing is contaminated by the flux. There is also a problem.

  Therefore, a method has been proposed in which a zinc coating layer is formed on the bonding surface of the aluminum-based member, and the aluminum-based members are bonded to each other via the zinc coating layer. In the method, the aluminum-based member is immersed in a zinc alloy solder bath, and the bonding surface of the aluminum-based member is coated with zinc alloy solder.

  In the method, the aluminum-based members coated with the zinc alloy solder are butted together with a predetermined gap, the gap is immersed in a zinc alloy solder bath, and the gap is filled with the zinc alloy solder. Thereafter, it is said that the aluminum-based members can be joined by pulling up from the zinc alloy solder bath and uniformly pressurizing the joint surface to cool and solidify the zinc alloy solder (see Patent Document 3).

  Further, instead of immersing the gap portion in a zinc alloy solder bath and filling the gap portion with zinc alloy solder, a method of sandwiching a zinc alloy solder sheet in the gap portion and uniformly pressing the joint surface Is also known (see Patent Document 4).

However, when the aluminum-based member is immersed in the zinc alloy solder bath, an oxide film is formed on the surface of the aluminum-based member due to the heat of the zinc alloy solder bath, which makes it difficult to coat the zinc alloy solder itself. is there. Further, even if the zinc alloy solder coating is formed, there is a disadvantage that the amount of zinc increases.
JP-A-10-5994 (paragraph numbers 0003 and 0006) JP-A-9-94689 (Claims 1 and 2) JP-A-9-323166 (Claim 1, paragraph number 0020) JP-A-9-323167 (Claim 1, paragraph number 0018)

  The present invention eliminates such inconveniences, and reliably forms a necessary and sufficient amount of a zinc coating layer on the joining surface of a member to be joined made of an aluminum-based material, and the aluminum-based members are connected to each other via the zinc coating layer. It aims at providing the method of joining.

  In order to achieve this object, the present invention provides a method for joining aluminum members to join two members to be joined made of an aluminum material to each other, and a zinc coating layer formed by electrolytic plating on the joining surfaces of the members to be joined. And both the members to be joined are overlapped through the zinc coating layer and heated to a temperature equal to or higher than the solidus temperature of aluminum and zinc.

  In the method of the present invention, first, a necessary and sufficient amount of the zinc coating layer can be reliably formed by performing an electroplating process on the joint surface of each member to be joined. Then, both the members to be joined on which the zinc coating layer is formed are overlapped with each other via the zinc coating layer, and heated to a temperature equal to or higher than the solidus temperature of aluminum and zinc. This zinc can be dissolved and diffused inside each member to be joined. Therefore, according to the method of the present invention, both members to be joined can be firmly joined.

  The heating may be performed at a temperature equal to or higher than the solidus temperature of aluminum and zinc. However, when the heating is performed at a temperature equal to or higher than the melting point of zinc, both members to be bonded can be more firmly bonded.

  Moreover, it is preferable to apply a pressing load to both the members to be bonded when the two members to be bonded are overlaid and heated. By applying the pressing load, it is possible to reliably join both the members to be joined.

  In the method of the present invention, it is preferable that the zinc coating layer is provided by the electrolytic plating process after the oxide film removing process is performed on the bonding surface of each member to be bonded. By performing the oxide film removal treatment, the zinc coating layer can be more reliably formed. The oxide film removal process can be performed, for example, by pickling with nitric acid.

  In the method of the present invention, it is preferable to interpose tin between the zinc coating layers when the two members to be bonded are overlapped via the zinc coating layer. Since the melting point of the zinc coating layer is lowered by superimposing and heating the members to be bonded with tin interposed in the zinc coating layer, the members to be bonded can be firmly bonded at a lower temperature. Can do.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view showing a joining method according to the present embodiment, and FIG. 2A is a plan view showing a test method for joining strength of aluminum-based members joined by the joining method according to the present embodiment. FIG. 2B is a side view of FIG.

  In the method of the present embodiment, first, as shown in FIG. 1A, the zinc coating layer 2 is formed by subjecting the joint surfaces of aluminum-based members 1a and 1b made of pure aluminum or aluminum alloy to electrolytic plating. Form. As a result, zinc-coated aluminum-based members 3a and 3b having a zinc coating layer 2 having a thickness of 5 to 40 μm on the joint surface are obtained.

  Next, as shown in FIG. 1B, the zinc-coated aluminum-based members 3a and 3b are overlapped via the zinc-coated layers 2 and 2, and a pressing load is applied. Then, the overlapped zinc-coated aluminum-based members 3a and 3b are heated to a temperature not lower than the solidus temperature of aluminum and zinc, preferably to a temperature not lower than the melting point of zinc. The solidus temperature of aluminum and zinc is 381 ° C., and the melting point of zinc is 419.58 ° C.

  By heating to the above temperature, the zinc coating layers 2 and 2 are melted, and are dissolved and diffused in the aluminum-based members 1a and 1b. Therefore, the zinc-coated aluminum-based members 3a and 3b can be joined by heating and holding at the above temperature for 1 to 3 hours and then cooling.

The electrolytic plating treatment can be performed by a method known per se, for example, in a plating bath comprising zinc chloride 0.5 g / l, sodium cyanide 0.5 g / l, and sodium hydroxide 10 g / l. It can be carried out under conditions of a density of 0.5 to 10 A / dm ² and a normal temperature of 5 to 10 minutes. However, the plating bath used does not contain a component that forms an intermetallic compound with a metal component in aluminum or an aluminum alloy. When the plating bath includes a component that forms an intermetallic compound with a metal component in aluminum or an aluminum alloy, the metal is formed when the formed zinc coating layer 2 reacts with the metal component in aluminum or the aluminum alloy. It may solidify simultaneously with the formation of the intermetallic compound, and sufficient strength may not be obtained when the zinc-coated aluminum-based members 3a and 3b are joined.

  Further, in the method of this embodiment, when the plating bath contains a brightener, a smoothing agent, etc., the brightener, organic components in the smoothing agent form bubbles at the bonding interface, or impurities segregate. However, when the zinc-coated aluminum-based members 3a and 3b are joined, sufficient strength may not be obtained. Accordingly, the plating bath does not contain a brightener, a smoothing agent, or the like. Since the zinc coating layer 2 is interposed between the aluminum-based members 1a and 1b and used for joining the two, it is not necessary to have glossiness, smoothness and the like.

  In the electrolytic plating process, it is preferable that an oxide film removing process is performed on the joint surfaces of the aluminum-based members 1a and 1b in advance. The oxide film removal process can be performed at room temperature using, for example, 50% by volume nitric acid.

  By performing the oxide film removal treatment, the oxide film formed on the surfaces of the aluminum-based members 1a and 1b can be thinned, and the adhesion of the zinc coating layer 2 to the aluminum-based members 1a and 1b is increased. Formation of the zinc coating layer 2 can be performed reliably. In addition, by performing the oxide film removal treatment, when the zinc-coated aluminum-based members 3a and 3b on which the zinc coating layer 2 is formed are superposed and heated to the temperature, the reaction between aluminum and zinc easily proceeds. Moreover, the effect that the zinc covering aluminum-type members 3a and 3b can be joined more firmly can also be acquired.

  In the method of this embodiment, tin may be interposed between the zinc coating layers 2 and 2 when the zinc coating aluminum-based members 3a and 3b are overlapped via the zinc coating layers 2 and 2, respectively. By heating with zinc interposed between the zinc coating layers 2 and 2, the melting point of the zinc coating layer 2 can be lowered, and the zinc-coated aluminum-based members 3a and 3b can be firmly bonded at a lower temperature. it can.

  In order to interpose tin between the zinc coating layers 2 and 2, for example, the zinc coating layer 2 can be subjected to electrolytic plating to form a tin coating layer. The electroplating treatment for forming the tin coating layer can be performed by a method known per se, for example, consisting of sodium stannate 90 g / l, sodium hydroxide 7.5 g / l, and sodium acetate 10 g / l. It can be performed using a plating bath.

  Next, examples and comparative examples of the present invention are shown.

  In this embodiment, first, a pure aluminum plate (Al 99.5% or more) having a size of 20 mm × 100 mm and a thickness of 1 mm is used as aluminum members 1a and 1b, and the aluminum members 1a and 1b are degreased and washed with water, and then 50% by volume. It pickled at normal temperature using nitric acid, and the oxide film removal process was performed. Next, after the zincate treatment was performed on the surfaces of the aluminum-based members 1a and 1b, the electrolytic plating treatment was performed to obtain the zinc-coated aluminum-based members 3a and 3b including the zinc coating layer 2 having a thickness of about 20 μm.

The zincate treatment is an electroless activation treatment, in which the aluminum-based members 1a and 1b are immersed in a bath composed of 9 g / l zinc and 120 g / l sodium hydroxide at 15 to 25 ° C. for 30 to 60 seconds. It went on condition of. In addition, the electrolytic plating treatment is performed using the aluminum-based members 1a and 1b subjected to the zincate treatment with zinc chloride 0.5g / l, sodium cyanide 0.5g / l, and sodium hydroxide 10g / l. It was immersed in a plating bath not containing an agent and a smoothing agent, and the current density was 0.5 to 10 A / dm ² and the conditions were 5 to 10 minutes at room temperature.

  Next, as shown in FIG. 2 (a), the zinc-coated aluminum-based members 3a and 3b are overlapped with an area of 20 mm × 20 mm through the zinc-coated layers 2 and 2, and a pressing load of 2 MPa is applied. After heating and holding in a vacuum atmosphere for 1 hour, bonding was performed by cooling. The heating temperature was 400 ° C., 450 ° C., and 500 ° C.

Next, as shown in FIG. 2B, a tensile test was performed to pull the zinc-coated aluminum-based members 3a and 3b joined at the respective temperatures in opposite directions to measure the joining strength. The results are shown in Table 1.
[Comparative Example 1]
In this comparative example, the zinc-coated aluminum-based members 3a and 3b were joined in exactly the same manner as in Example 1 except that the heating temperature was set to 350 ° C., but the two could not be joined. The results are shown in Table 1.

  In this example, the same procedure as in Example 1 was performed except that the zinc-coated aluminum-based member 3b on which the zinc coating layer 2 was formed was subjected to an electrolytic plating process to form a tin coating layer (not shown) on the zinc coating layer 2. Zinc-coated aluminum-based members 3a and 3b were joined in exactly the same manner.

In the electroplating treatment, the zinc-coated aluminum-based member 3b is made of sodium stannate 90 g / l, sodium hydroxide 7.5 g / l, sodium acetate 10 g / l in a plating bath that does not contain a brightener and a smoothing agent. Immersion was performed at a current density of 0.5 to 3 A / dm ² at 70 ° C. for 1 to 5 minutes to form a tin coating layer having a thickness of about 2 μm on the zinc coating layer 2. The results are shown in Table 1.
[Comparative Example 2]
In this comparative example, the zinc-coated aluminum-based members 3a and 3b were joined in exactly the same manner as in Example 2 except that the heating temperature was 350 ° C., but the two could not be joined. The results are shown in Table 1.

  In the present embodiment, the zinc-coated aluminum-based members 3a and 3b on which the zinc coating layer 2 was formed were subjected to an electrolytic plating process, and a tin coating layer (not shown) was formed on the zinc coating layer 2. The zinc-coated aluminum-based members 3a and 3b were joined in exactly the same manner as in FIG.

The electrolytic plating treatment was performed in exactly the same manner as in Example 2, and a tin coating layer having a thickness of about 2 μm was formed on the zinc coating layer 2 of each of the zinc-coated aluminum-based members 3a and 3b. The results are shown in Table 1.
[Comparative Example 3]
In this comparative example, the zinc-coated aluminum-based members 3a and 3b were joined in exactly the same manner as in Example 3 except that the heating temperature was set to 350 ° C., but the two could not be joined. The results are shown in Table 1.
[Comparative Example 4]
In this comparative example, except that the zinc coating layer 2 is not formed on the surfaces of the aluminum-based members 1a and 1b, the zinc-coated aluminum-based members 3a and 3b are used, and the heating temperatures are 600 ° C. and 650 ° C. Attempts were made to join the zinc-coated aluminum-based members 3a and 3b in exactly the same manner as in Example 1, but they could not be joined. The results are shown in Table 1.

However, the two could not be joined. The results are shown in Table 1.
[Comparative Example 5]
In this comparative example, except that the zinc coating layer 2 was not formed, but only the tin coating layer was formed as zinc-coated aluminum-based members 3a and 3b, and the heating temperatures were 400 ° C., 500 ° C., and 600 ° C. The zinc-coated aluminum-based members 3a and 3b were tried in exactly the same manner as in Example 1, but they could not be joined. The tin coating layer was formed in exactly the same way as in Example 2. The results are shown in Table 1.
[Comparative Example 6]
In this comparative example, the zinc coating layer 2 is formed only on the aluminum-based member 1a to form the zinc-coated aluminum-based member 3a, and the aluminum-based member 1b is not formed with the zinc coating layer 2 to form the zinc-coated aluminum-based member 3b. The zinc-coated aluminum members 3a and 3b were joined in exactly the same manner as in Example 1 except that the heating temperatures were 500 ° C., 600 ° C., and 650 ° C., but they could not be joined. . The results are shown in Table 1.

  From Table 1, the zinc-coated aluminum-based members 3a and 3b are overlapped via the zinc-coated layer 2 and heated to a temperature equal to or higher than the solidus temperature of aluminum and zinc (381 ° C.), whereby the zinc-coated aluminum-based member 3a. 3b can be joined, and it is clear that the zinc-coated aluminum-based members 3a and 3b can be joined more firmly by heating to a temperature equal to or higher than the melting point of zinc (419.58 ° C.) (Example) 1).

  Further, from Table 1, when the zinc-coated aluminum-based members 3a and 3b are overlapped via the zinc coating layer 2, a tin coating layer is interposed between the zinc coating layers 2 and 2 (Examples 2 and 3). It is clear that the zinc-coated aluminum-based members 3a and 3b can be bonded more firmly than in the first embodiment even at the same temperature as in the first embodiment.

  On the other hand, even if the zinc-coated aluminum-based members 3a and 3b are overlapped with each other via the zinc-coated layer 2, or even if a tin-coated layer is interposed between the zinc-coated layers 2 and 2, the heating temperature is aluminum and zinc. When the temperature is lower than the solidus temperature (Comparative Examples 1, 2, and 3), it is apparent that the zinc-coated aluminum-based members 3a and 3b cannot be joined.

Further, when the zinc coating layer 2 is not provided at all on both the zinc coating aluminum members 3a and 3b (Comparative Example 4), only the tin coating layer is used instead of the zinc coating layer 2 on both the zinc coating aluminum members 3a and 3b. (Comparative Example 5), when the zinc coating layer 2 is provided only on one zinc-coated aluminum-based member 3a (Comparative Example 6), the heating temperature is higher than the solidus temperature of aluminum and zinc. Even in terms of temperature, it is clear that the zinc-coated aluminum-based members 3a and 3b cannot be joined.
[Comparative Example 7]
In this comparative example, the zinc-coated aluminum-based members 3a and 3b are formed on the surfaces of the aluminum-based members 1a and 1b without the zinc coating layer 2, and the zinc-coated aluminum-based members 3a and 3b are zinc sheets having a thickness of 25 μm. The zinc-coated aluminum-based members 3a and 3b were tried to be joined in exactly the same manner as in Example 1 except that they were overlapped with each other, but the two could not be joined. The results are shown in Table 2.

  From Table 2, in the case of zinc-coated aluminum-based members 3a and 3b that are not provided with the zinc-coated layer 2 formed in close contact with the aluminum-based members 1a and 1b, a zinc sheet is interposed between the two, It is apparent that bonding is not possible even when heated to a temperature higher than the solidus temperature (381 ° C.) with zinc.

Explanatory sectional drawing which shows the joining method of this invention. The top view and side view which show the test method of the joining strength of the aluminum-type member joined by the joining method of this invention.

Explanation of symbols

  1a, 1b ... members to be joined, 2 ... zinc coating layer.

Claims (5)

In the joining method of the aluminum type member which joins two to-be-joined members which consist of aluminum type materials mutually,
A zinc coating layer by electrolytic plating is provided on the bonding surface of each member to be bonded, and both the members to be bonded are overlapped via the zinc coating layer and heated to a temperature equal to or higher than the solidus temperature of aluminum and zinc. A method for joining aluminum members, which is characterized.   The said heating is performed at the temperature more than melting | fusing point of zinc, The joining method of the aluminum-type member of Claim 1 characterized by the above-mentioned.   3. The method for joining aluminum-based members according to claim 1, wherein a pressing load is applied to both of the members to be joined when the two members to be joined are overlaid and heated.   The aluminum system according to any one of claims 1 to 3, wherein the zinc coating layer is provided by the electrolytic plating process after the oxide film removing process is performed on the bonding surface of each member to be bonded. Member joining method.   5. The aluminum-based member according to claim 1, wherein tin is interposed between the zinc coating layers when the both members to be bonded are overlapped via the zinc coating layer. Joining method.

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