Joint body

Abstract

To provide a joint body that can extend a corrosion life by maintaining a joint strength even when corrosion in a sacrificial anticorrosive layer proceeds.SOLUTION: A joint body 1 includes: a first joint material 100 including a core material 110 having one surface 111, a sacrificial anticorrosive layer 120 coating the one surface 111 of the core material 110 and having an electrical potential that is lower than that of the core material 110, and a coating layer 130 provided on the sacrificial anticorrosive layer 120; and a second joint material 200 joined to the coating layer 130 of the first joint material 100. The coating layer 130 of the first joint material 100 has an electrical potential that is higher than that of the sacrificial anticorrosive layer 120.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a conjugate. [Background technology]

[0002] Conventionally, a metal material comprising a base material, a sacrificial metal layer adhered to the surface of the base material via an insulating adhesive layer, and a protective layer formed on the surface of the sacrificial metal layer has been proposed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-001944 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have investigated a structure in which a sacrificial protection layer, which is more susceptible to corrosion than the substrate, is provided on a substrate and another bonding material is bonded to the sacrificial protection layer. As a result, they have found that corrosion products are generated when part of the sacrificial protection layer corrodes, and that the corrosion products grow within the sacrificial protection layer.

[0005] Furthermore, it was found that as the volume of the corrosion products increases, the stress of the corrosion products concentrates at the bonded interface between the sacrificial protection layer and another bonded material, pushing up the bonded portion between the sacrificial protection layer and the other bonded material. This causes a gap to form between the sacrificial protection layer and the other bonded material, accelerating crevice corrosion. Alternatively, the application of an external force to the bonded body generates peeling stress at the bonded portion. This causes the sacrificial protection layer to peel off from the other bonded material early.

[0006] In view of the above, an object of the present invention is to provide a joined body that can improve corrosion life by maintaining joint strength even if corrosion of the sacrificial anticorrosion layer progresses. [Means for solving the problem]

[0007] To achieve the above object, in the invention described in claim 1, the joined body includes a first joining material (100) including a core material (110) having one surface (111), a sacrificial protection layer (120) covering the one surface of the core material and having a lower potential than the core material, and a coating layer (130) provided on the sacrificial protection layer, and a second joining material (200) joined to the coating layer of the first joining material. The coating layer of the first joining material has a higher potential than the sacrificial protection layer.

[0008] According to this, a coating layer having a more noble potential than the sacrificial protection layer is provided on the sacrificial protection layer. Therefore, even if corrosion progresses in the sacrificial protection layer, the coating layer prevents the corrosion products from progressing to the joint (131) between the coating layer and the second bonding material. Therefore, stress from the corrosion products is less likely to concentrate at the joint, making it less likely that the joint and the second bonding material will peel off early. Therefore, even if corrosion progresses in the sacrificial protection layer, the bonding strength between the first bonding material and the second bonding material can be maintained, and the corrosion life of the bonded structure can be improved.

[0009] The symbols in parentheses for each means described in this section and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view of the bonded body according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] 10 is a diagram showing the relationship between the potential difference between the sacrificial anticorrosion layer and the coating layer and whether or not peeling occurs between the coating layer and the adhesive. FIG. [Figure 4] FIG. 4 is a cross-sectional view showing another example of the bonded body in the first embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a bonded body according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing another example of the bonded body in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts are designated by the same reference numerals in the drawings.

[0012] (First embodiment) The bonded body according to this embodiment is formed by bonding a first bonding material and a second bonding material together, and is used, for example, to bond burred portions through which cooling water passes in a heat exchanger.

[0013] Fig. 1 is a plan view of a bonded body 1. Fig. 2 is a cross-sectional view of the bonded body 1 shown in Fig. 1. As shown in Figs. 1 and 2, the bonded body 1 includes a first bonding material 100, a second bonding material 200, and an adhesive 300.

[0014] The first bonding material 100 includes a core material 110, a sacrificial anticorrosion layer 120, and a coating layer 130. The core material 110 is, for example, a plate-shaped component having one surface 111 and another surface 112 opposite to the one surface 111. The core material 110 is made of, for example, a metal material such as pure aluminum or an aluminum alloy.

[0015] The shape of the first bonding material 100 is not limited to a plate shape, and various shapes such as a block, a pipe, etc. The core material 110 is not limited to an aluminum-based metal, and any metal material that may corrode can be used.

[0016] The sacrificial protection layer 120 covers one surface 111 of the core material 110. In other words, the first bonding material 100 is a clad material in which one surface 111 of the core material 110 is covered with the sacrificial protection layer 120. The sacrificial protection layer 120 has a lower potential than the core material 110, that is, a lower potential than the core material 110. As a result, the sacrificial protection layer 120 corrodes preferentially to the core material 110, thereby preventing corrosion of the core material 110. The sacrificial protection layer 120 is made of, for example, an aluminum alloy such as an Al-Zn alloy.

[0017] The coating layer 130 is provided on the sacrificial corrosion protection layer 120. In this embodiment, the coating layer 130 is a bare material clad on the sacrificial corrosion protection layer 120. As a result, the first bonding material 100 is a three-layer clad material consisting of the core material 110, the sacrificial corrosion protection layer 120, and the coating layer 130.

[0018] The covering layer 130 is made of a metal material such as pure aluminum or an aluminum alloy, similar to the core material 110. Of course, the covering layer 130 may be made of a metal material different from that of the core material 110.

[0019] The coating layer 130 has a more noble potential than the sacrificial protection layer 120, that is, a higher potential than the sacrificial protection layer 120. This makes the coating layer 130 less susceptible to corrosion than the sacrificial protection layer 120.

[0020] The inventors investigated the relationship between the potential difference between the sacrificial protection layer 120 and the coating layer 130 and the presence or absence of peeling between the coating layer 130 and the adhesive 300. The potential difference between the sacrificial protection layer 120 and the coating layer 130 is calculated by subtracting the potential of the sacrificial protection layer 120 from the potential of the coating layer 130.

[0021] As a corrosion test, a SWAAT test (Sea Water Acidified Test) was conducted. The SWAAT test conforms to ASTM G85 A3. In this embodiment, the state of the assembly 1 was examined 480 hours after the start of the test. The results are shown in FIG. 3. FIG. 3 shows the relationship between the potential difference obtained by subtracting the potential of the sacrificial anticorrosion layer 120 from the potential of the coating layer 130, and the presence or absence of peeling between the coating layer 130 and the adhesive 300. In the right column of FIG. 3, an "x" indicates that peeling occurred, and an "o" indicates that peeling did not occur.

[0022] 3, when the potential difference between the sacrificial protection layer 120 and the coating layer 130 was 10 mV, the coating layer 130 and the adhesive 300 peeled off. However, when the potential difference between the sacrificial protection layer 120 and the coating layer 130 was 20 mV or more, the coating layer 130 and the adhesive 300 did not peel off. From this result, it is preferable that the sacrificial protection layer 120 has a potential that is 20 mV or more more base than the coating layer 130, that is, a potential that is 20 mV or more lower than the coating layer 130. This makes it possible to make the coating layer 130 and the adhesive 300 less likely to peel off.

[0023] The thickness of the sacrificial protection layer 120 and the coating layer 130 is, for example, several tens of μm to several hundreds of μm. Since the sacrificial protection layer 120 and the coating layer 130 are each clad, the thickness of the sacrificial protection layer 120 and the coating layer 130 is uniform. Of course, there will be some difference in thickness depending on the position, but it is sufficient if the thickness of the sacrificial protection layer 120 and the coating layer 130 is uniform. In other words, the thickness of the sacrificial protection layer 120 and the coating layer 130 does not have to be completely uniform.

[0024] The second bonding material 200 is a material to be bonded to the coating layer 130 of the first bonding material 100. In this embodiment, the second bonding material 200 is a metal plate such as pure aluminum or an aluminum alloy.

[0025] The second bonding material 200 is not limited to an aluminum-based metal material, and may be made of other metal materials. The shape of the second bonding material 200 is not limited to a plate, and various shapes such as a block or a pipe can be adopted. Of course, the second bonding material 200 may be a clad material consisting of a core material and a sacrificial anticorrosion layer, similar to the first bonding material 100.

[0026] The adhesive 300 is a component that bonds the first bonding material 100 and the second bonding material 200. Specifically, the adhesive 300 bonds the bonding portion 131 of the coating layer 130 and the end portion 210 of the second bonding material 200. The adhesive 300 is made of, for example, an epoxy resin. The adhesive 300 bonds the first bonding material 100 and the second bonding material 200 without heating, i.e., without causing solid-state diffusion of elements.

[0027] The adhesive 300 is continuously provided from one end 113 to the other end 114 of the core material 110 along one direction parallel to one surface 111 of the core material 110. If a direction parallel to one surface 111 of the core material 110 and perpendicular to the one direction and the vertical direction is defined as the other direction, the adhesive 300 overflows from between the first bonding material 100 and the second bonding material 200. Of course, the adhesive 300 does not have to overflow from the end 210 of the second bonding material 200 in the other direction.

[0028] Next, a method for manufacturing the bonded body 1 will be described. First, a first bonding material 100 and a second bonding material 200 are prepared, each having a coating layer 130 formed on a sacrificial protection layer 120. Next, an adhesive 300 is applied to a portion of the coating layer 130 of the first bonding material 100 that corresponds to the bonding portion 131. Alternatively, the adhesive 300 may be applied to the second bonding material 200. Then, the first bonding material 100 and the second bonding material 200 are brought relatively close to each other in a vertical direction perpendicular to one surface 111 of the core material 110, so that the second bonding material 200 comes into contact with the adhesive 300. Thereafter, the first bonding material 100 and the second bonding material 200 are held in place until the adhesive 300 hardens. In this manner, the bonded body 1 is completed.

[0029] Next, we will explain the potential relationship between each part of the joined body 1. In the above configuration, the potential of the core material 110 is defined as V11, the potential of the sacrificial protection layer 120 as V12, the potential of the coating layer 130 as V13, and the potential of the second joining material 200 as V20. The potentials of the core material 110, the sacrificial protection layer 120, the coating layer 130, and the second joining material 200 satisfy the condition V11 ≧ V20 ≧ V13 > V12.

[0030] According to this, the potential of the coating layer 130 provided on the sacrificial protection layer 120 is more noble than that of the sacrificial protection layer 120. In other words, the coating layer 130 is less susceptible to corrosion than the sacrificial protection layer 120. For this reason, even if corrosion occurs in the priority sacrificial portion 121 and progresses within the priority sacrificial portion 121, the corrosion products cannot progress to the joint portion 131 of the coating layer 130 with the second bonding material 200. In other words, the corrosion products cannot progress to the joint interface between the coating layer 130 and the second bonding material 200.

[0031] Therefore, stress from the corrosion products is less likely to concentrate at the bonding interface between the coating layer 130 and the second bonding material 200, making it less likely that the bonding portion 131 of the first bonding material 100 and the second bonding material 200 will peel off early. Therefore, even if corrosion progresses to the sacrificial corrosion protection layer 120, the bonding strength between the first bonding material 100 and the second bonding material 200 can be maintained. Furthermore, the corrosion resistance of the bonding portion 131 of the first bonding material 100 can be improved, and the corrosion life of the bonded body 1 can be improved.

[0032] For example, if the core material 110 is the part that is most undesirable from corrosion, the potential V11 of the core material 110 can be set to be the highest, as in the above potential conditions. Also, for example, by setting the potential V11 of the core material 110, the potential V20 of the second bonding material 200, and the potential V13 of the coating layer 130 to the same potential, the entire joined body 1 can be protected from corrosion in a well-balanced manner. Of course, the potential V11 of the core material 110, the potential V20 of the second bonding material 200, and the potential V13 of the coating layer 130 may be set to different potentials.

[0033] As another example, the coating layer 130 may not be clad on the sacrificial protection layer 120. For example, as shown in FIG. 4 , the coating layer 130 may be partially provided on the sacrificial protection layer 120 by a method such as vapor deposition. To partially provide the coating layer 130, for example, a mask is used. In this case, the adhesive 300 may be applied to the entire coating layer 130 partially provided on the sacrificial protection layer 120, or may be applied to only a portion of the coating layer 130.

[0034] (Second embodiment) In this embodiment, differences from the first embodiment will be mainly described. As shown in Fig. 5, the coating layer 130 is directly bonded to the second bonding material 200. That is, in this embodiment, the bonded body 1 does not include the adhesive 300.

[0035] As a method for joining the coating layer 130 and the second joining material 200, for example, ultrasonic joining, FSW (Friction Stir Welding), laser welding, etc. can be adopted. In the configuration according to this embodiment, the same effects as in the first embodiment can be obtained.

[0036] 6, the coating layer 130 may be provided on a part of the sacrificial protection layer 120. In this case, the second bonding material 200 may be bonded to the entire coating layer 130, or may be bonded to a part of the coating layer 130.

[0037] (Other embodiments) The configuration of the joined body 1 shown in each of the above embodiments is merely an example, and the present invention is not limited to the above configuration, and other configurations that can realize the present invention may be adopted. For example, the joined body 1 is not limited to being used in a heat exchanger. The joined body 1 may be any structure that is used in an environment exposed to corrosion. [Explanation of symbols]

[0038] 100 1st bonding material 110 Core material 111 One side 120 Sacrificial corrosion protection layer 130 Covering layer 200 Second bonding material

Claims

1. A first bonding material (100) including a core material (110) having one surface (111), a sacrificial corrosion protection layer (120) that covers the one surface of the core material and has a lower potential than the core material, and a coating layer (130) provided on the sacrificial corrosion protection layer; A second bonding material (200) bonded to the coating layer of the first bonding material; Including, A bonded body, wherein the coating layer of the first bonding material has a more noble potential than the sacrificial protection layer.

2. If the potential of the core material is defined as V11, the potential of the sacrificial protection layer as V12, the potential of the coating layer as V13, and the potential of the second bonding material as V20, then: The joined body according to claim 1 , wherein the potentials of the core material, the sacrificial anticorrosion layer, the coating layer, and the second joining material satisfy the condition V11≧V20≧V13>V12.

3. 3. The joined body according to claim 1, wherein the potential of the sacrificial protection layer is at least 20 mV lower than the potential of the coating layer.

Images