JP6169333B2 - Surface-treated metal material, method for producing surface-treated metal material, and bonded structure - Google Patents

Description

  The present invention relates to a surface-treated metal material, a method for producing the surface-treated metal material, and a bonded structure.

  In the field of transport machinery such as automobiles and railway vehicles, members and parts that are partially joined by welding or the like in a state where different kinds of metal materials are in contact with each other are widely used. However, there are many cases where different metal contact corrosion (galvanic corrosion) occurs in a member brought into contact with a different metal material. This dissimilar metal contact corrosion is a phenomenon in which a metal material having a low corrosion potential serves as an anode and a noble metal material serves as a cathode to constitute a battery, and corrosion of the base metal material is promoted. For example, when a steel material and an aluminum alloy material are brought into contact as different kinds of metal materials, corrosion of the aluminum alloy material is promoted. In this case, the corrosion rate is much higher than when the aluminum alloy material is used alone, and damage such as perforation is caused at an early stage. Therefore, when using a member or the like in contact with different kinds of metal materials, it is important to reduce the occurrence of such different metal contact corrosion.

  As a means for reducing the occurrence of this different metal contact corrosion, a method of forming a corrosion prevention layer containing a specific organic acid salt or the like on the surface of an aluminum alloy material (Japanese Patent Application Laid-Open No. 2010-144223 and Japanese Patent Application Laid-Open No. 2010-242195). And a method for forming a resin film containing a specific resin (see Japanese Patent Application Laid-Open No. 2011-140067) has been developed. However, even in each of the above methods, it is difficult to say that the sustainability of the anticorrosion function is sufficient, for example, pitting corrosion can occur due to corrosion concentration from coating defects.

JP 2010-144223 A JP 2010-242195 A JP 2011-140067 A

  The present invention has been made on the basis of the above-mentioned circumstances, has a surface-treated metal material and a joined structure having excellent contact corrosion resistance and excellent in this durability, and such a surface. It aims at providing the manufacturing method of a processing metal material.

  The inventor has found that an oxide film containing a Group 4 element such as titanium has high contact corrosion resistance with excellent sustainability, and has completed the present invention.

That is, the invention made to solve the above problems is
An aluminum base material made of aluminum or an aluminum alloy, and an oxide film formed on the surface of the aluminum base material, and joined with a counterpart metal material having a metal base material having a corrosion potential nobler than that of the aluminum base material. A surface-treated metal material used,
The oxide film contains a Group 4 element.

  The surface-treated metal material is provided with an oxide film containing a Group 4 element, thereby having excellent contact corrosion resistance and excellent sustainability. Although the reason why the surface-treated metal material has such a property is not certain, for example, the group 4 element reduces the potential difference between aluminum and the other base metal, or the oxidation of the group 4 element. It is presumed that the product has a high bonding property with aluminum and a strong oxide film is formed.

  It is preferable that the oxide film is formed by contact of the acidic solution containing the Group 4 element with the surface of the aluminum base material. By doing in this way, the oxide film which contains a group 4 element and is excellent in the sustainability of a function can be formed comparatively easily.

  It is preferable to further include a resin film formed on the surface of the oxide film. By doing in this way, the said resin film protects an oxide film, and by reducing the quantity of a corrosion current etc., a corrosion prevention function and its sustainability can be improved more.

The method for producing the surface-treated metal material of the present invention is as follows.
A method for producing a surface-treated metal material comprising an aluminum base material made of aluminum or an aluminum alloy and used by being joined to a counterpart metal material having a metal base material having a corrosion potential nobler than that of the aluminum base material,
It has the process of making the acidic solution containing a Group 4 element contact the surface of the said aluminum base material.

  According to the manufacturing method, a surface-treated metal material excellent in contact corrosion resistance and durability can be manufactured relatively easily.

  The pH of the acidic solution is preferably 1 or more and 5 or less. By using an acidic solution having such a pH, the acidic solution can appropriately react with the surface portion of the aluminum base material and the like to effectively form the oxide film.

The bonded structure of the present invention is
The surface-treated metal material, and an opposing metal material adjacent to the surface side of the surface-treated metal material, the metal material having a metal base material having a corrosion potential more precious than the aluminum base material,
It is a joint structure in which the aluminum base material and the metal base material are joined in an electrically conductive state.

  Since the joint structure includes the surface-treated metal material, the occurrence of corrosion of the aluminum base material due to dissimilar metal contact can be suppressed for a long period of time.

  The metal base material may be a steel material. As described above, by using a steel material that has been frequently used as the metal base material of the counterpart metal material, the joint structure can be widely used as a member or a part of a transport machine or the like.

  More preferably, the steel material is a hot dip galvanized steel material. By using the hot dip galvanized steel material, the contact corrosion resistance can be further enhanced.

  It is preferable that the counterpart metal material further includes a resin film formed on the surface of the metal base material facing the surface-treated metal material. By forming a resin film on the surface of the metal base material in this way, the amount of corrosion current can be reduced and the occurrence of corrosion of the aluminum base material can be further reduced.

  The resin coating provided in the counterpart metal material may contain at least one selected from the group consisting of benzoic acid, glutamate, anisidine, glycine, glycine salt, quinolinol, phthalate, adipate, and acetate. By containing these compounds in the resin coating, the compounds function as inhibitors, and the occurrence of corrosion of the aluminum base material can be further reduced.

  As described above, the surface-treated metal material of the present invention has excellent contact corrosion resistance and is excellent in this sustainability. Moreover, the manufacturing method of the surface treatment metal material of this invention can manufacture such a surface treatment metal material comparatively easily. Therefore, the surface-treated metal material of the present invention and the joint structure including the same can be widely used for members and parts of transport machines such as automobiles and railway vehicles.

The typical sectional view showing the first embodiment of the surface treatment metal material of the present invention. The typical sectional view showing the second embodiment of the surface treatment metal material of the present invention. The typical sectional view showing one embodiment of the joined structure of the present invention. Schematic plan view showing a contact corrosion simulation test body used in the examples FIG. 5 is a schematic cross-sectional view taken along line AA showing the contact corrosion simulation test body of FIG. 4.

  Hereinafter, embodiments of the surface-treated metal material, the method for producing the surface-treated metal material, and the bonded structure according to the present invention will be described in detail with reference to the drawings as appropriate.

<Surface-treated metal material>
(First embodiment)
A surface-treated metal material 1 in FIG. 1 includes an aluminum base material 2 and an oxide film 3 formed on the surface of the aluminum base material 2.

  The aluminum base material 2 is made of aluminum or an aluminum alloy. The aluminum base material made of aluminum is a pure aluminum material. Examples of the aluminum alloy include JIS 5000 series Al-Mg series alloys, JIS 6000 series Al-Mg-Si series alloys, Al-Zn-Mg series alloys, Al-Si series alloys, Al-Cu series alloys, and the like. it can. Among these, magnesium-containing aluminum alloys are preferable. By using a magnesium-containing aluminum alloy as the aluminum base material 2, the surface treatment material 1 can be reduced in weight.

  The shape of the aluminum base material 2 is not particularly limited, and may be a plate shape, a rod shape, or any other shape.

  The oxide film 3 contains a Group 4 element. The surface-treated metal material 1 is provided with the surface-treated layer 3 containing a Group 4 element, thereby having excellent contact corrosion resistance and excellent durability.

  The Group 4 elements are Ti (titanium), Zr (zirconium), Hf (hafnium), and Rf (Razahodium). Among these, Ti, Zr and Hf are preferable from the viewpoint of productivity and the like, and Ti and Zr are more preferable. The oxide film 3 may contain a mixture of one or two or more Group 4 elements.

The form of inclusion in the oxide film 3 of the Group 4 element is not particularly limited. The form contained as single metal particles, the form present as a metal oxide (for example, TiO ₂ or the like), and other compounds. The form etc. which are contained as particle | grains can be mentioned. Among these, it is preferable to exist as a metal oxide. Furthermore, it is preferable that the oxide film 3 is substantially formed of an oxide of a Group 4 element. In this case, the oxide film 3 and the Group 4 element contained therein can be firmly fixed to the surface of the aluminum base material 2, and the durability of the contact corrosion resistance can be increased.

The adhesion amount of the Group 4 element may be a total of Group 4 elements of 3 atomic% or more as the atomic ratio of the metal elements in the oxide film. The adhesion amount may be ² mg / m ² or more in total for the Group 4 elements. The upper limit of the adhesion amount is not particularly limited, but may be 100 mg / m ² or less from the viewpoint of cost and manufacturability.

  Components other than the Group 4 element in the oxide film 3 include aluminum and oxygen. The oxide film 3 may contain components other than these.

  Although it does not specifically limit as a minimum of the film thickness (average film thickness) of the said oxide film 3, 5 nm is preferable, 10 nm is more preferable, 20 nm is further more preferable, 40 nm is especially preferable. On the other hand, the upper limit of the film thickness is not particularly limited, but is preferably 200 nm, and more preferably 150 nm. When this film thickness is less than the above lower limit, the durability of contact corrosion resistance may not be sufficiently increased. On the contrary, when the film thickness exceeds the upper limit, the effect of improving the sustainability reaches its peak, and the manufacturing cost increases.

  The film thickness of the oxide film 3 is an elemental analysis along the depth direction at any five points, and the average value of the depth from the surface until the oxygen content falls below 15 atomic%. The elemental analysis can be performed by glow discharge emission spectroscopic analysis. In addition, when another film exists on the surface of the oxide film, the value measured according to the above method is used.

  The method for forming the oxide film 3 is not particularly limited, and includes, for example, (1) a method of bringing the acidic solution containing the Group 4 element into contact with the surface of the aluminum base material 2 and (2) a Group 4 element. Examples include a method of oxidizing the surface of the base material 2 using the aluminum base material 2, and a method of stacking the oxide film 3 on the surface of the aluminum base material 2 using (3) a vapor phase film forming method. Among these, the method (1) is preferable. By using the method (1), the oxide film 3 having excellent long-term stability can be formed relatively easily. Moreover, the film thickness of the oxide film 3 can be easily adjusted by adjusting the contact time or the pH of the solution.

  Examples of the contact method in the method (1) include a method of immersing the aluminum base material 2 in the acidic solution and a method of applying the acidic solution to the surface of the aluminum base material 2. . Before bringing the acidic solution into contact with the surface of the aluminum base material 2, for example, the base material 2 is immersed in a mixed acid aqueous solution composed of hydrofluoric acid and nitric acid and then subjected to a pretreatment such as washing with ion exchange water. May be.

  In the acidic solution, the Group 4 element is usually present as an ion. The ion may be a single metal ion or a complex ion coordinated with fluorine or the like.

  The concentration of the Group 4 element in the acidic solution is not particularly limited, but is preferably 0.005% or more and 5% or less. By setting the concentration within the above range, it is possible to effectively form the oxide film 3 having sufficient durability and excellent contact corrosion resistance.

  The acidic solution includes, for example, a soluble group 4 element salt: nitrate, sulfate, halide complex salt (hexafluoro complex salt, hexachloro complex salt, etc.), etc., and an acid for adjusting pH (nitric acid, sulfuric acid, It can be prepared with hydrofluoric acid, hydrochloric acid, etc.), alkali (sodium hydroxide, potassium hydroxide, ammonia, etc.) and the like.

  The pH of the acidic solution is preferably 1 or more and 5 or less, more preferably 2 or more and 4 or less. By using an acidic solution having such a pH, the acidic solution can react with the surface portion of the aluminum base material 2 and the like to form the oxide film 3 effectively. When the pH of the acidic solution is less than 1, the oxide film 3 to be formed is easily dissolved by the acidic solution, and film formation may be insufficient. Conversely, when the pH of the acidic solution exceeds 5, the aluminum base material 2 or the oxide film originally formed on the surface region of the aluminum base material 2 is difficult to dissolve, and the oxide film 3 containing a Group 4 element is not easily dissolved. It takes time to form. The pH can be adjusted by using an alkali such as sodium hydroxide or aqueous ammonia, or an acid such as nitric acid or hydrofluoric acid.

  The surface-treated metal material 1 is used by being joined to a mating metal material including a metal base material having a corrosion potential nobler than that of the aluminum base material 2. As described above, the surface-treated metal material 1 includes the surface-treated layer 3 containing a Group 4 element, thereby having excellent contact corrosion resistance and excellent durability. Therefore, the surface-treated metal material 1 can be suitably used as a transport machine such as an automobile or a railway vehicle, or a member or part such as a structure.

(Second embodiment)
The surface-treated metal material 4 in FIG. 2 includes an aluminum base material 2, an oxide film 3 formed on the surface of the aluminum base material 2, and a resin film 5 formed on the surface of the oxide film 3. Since the aluminum base material 2 and the oxide film 3 provided in the surface-treated metal material 4 are the same as those provided in the surface-treated metal material 1 shown in FIG.

  The resin film 5 is laminated on the surface of the oxide film 3. By doing in this way, the said resin film 5 protects the oxide film 3, and reduces the amount of corrosion current etc., and can improve the anticorrosion function of the said surface treatment metal material 4, its sustainability, etc. more. it can.

  Although it does not restrict | limit especially as a film thickness (average film thickness) of the said resin film 5, 0.1 micrometer or more and 5 micrometers or less are preferable. When this film thickness is less than 0.1 μm, the effect of the coating of the resin coating 5 may not be sufficiently exhibited, such as insufficient coating and easy pinholes. Conversely, if this film thickness exceeds 5 μm, resistance spot welding or the like may be difficult.

  The resin for forming the resin film 5 is not particularly limited, but polyolefin-based, polyurethane-based, and epoxy-based resins are preferable. By using these resins, contact corrosion resistance and the like can be more effectively exhibited. Resin can be used 1 type or in mixture of 2 or more types. Although it does not specifically limit as content rate of the resin in the said resin film 5, 20 mass% or more and 100 mass% or less are preferable. When the resin content is less than 20% by mass, a sufficient film may not be formed, and pinholes may occur.

  The resin film 5 preferably contains silica. When the resin coating contains silica, contact corrosion resistance and the like can be further improved. Although it does not restrict | limit especially as a content rate of the silica in the said resin film 5, For example, 5 mass% or more and 80 mass% or less are preferable. The type of the silica is not particularly limited, and known dry silica, colloidal silica, and the like can be used.

  It is also preferable that the resin coating 5 contains an inhibitor that suppresses corrosion of the metal material. Examples of the inhibitor include, but are not limited to, benzoic acid, glutamate, anisidine, glycine, glycine salt, quinolinol, phthalate, adipate, and acetate. These compounds dissolve in the corrosive environment from the resin coating and adhere to the surface of the surface-treated metal material 4 or the counterpart metal material to reduce the corrosion rate, or the aluminum base material 2 and the metal base material of the counterpart metal material Has a function of reducing the potential difference between the two. The content of the inhibitor in the resin coating 5 can be, for example, 0.1% by mass or more and 20% by mass or less.

  The method for forming the resin coating 5 is not particularly limited. For example, the resin film 5 can be formed by applying a coating liquid containing a component such as a resin to the surface of the oxide film 3 and drying it.

<Method for producing surface-treated metal material>
The method for producing the surface-treated metal material of the present invention is as follows.
A method for producing a surface-treated metal material comprising an aluminum base material made of aluminum or an aluminum alloy and used by being joined to a counterpart metal material having a metal base material having a corrosion potential nobler than that of the aluminum base material,
It has the process of making the acidic solution containing a Group 4 element contact the surface of the said aluminum base material.

  According to the manufacturing method, a surface-treated metal material excellent in contact corrosion resistance and durability can be manufactured relatively easily. The details of the manufacturing method are as described above as the method for forming the oxide film 3 in the surface-treated metal material 1.

<Joint structure>
The bonding structure 11 of FIG. 3 includes a surface-treated metal material 1 and a counterpart metal material 6 that is disposed adjacent to the surface side of the surface-treated metal material 1. The surface-treated metal material 1 is the same as the surface-treated metal material 1 in FIG.

  The counterpart metal material 6 includes a metal base material 7 and a resin coating 8.

  The metal base material 7 has a higher corrosion potential than the aluminum base material 2. The metal base material 7 is not particularly limited as long as the metal base material 7 has a corrosion potential nobler than that of the aluminum base material 2 as described above, and has a corrosion potential nobler than the steel base material, titanium material, and the aluminum base material 2 described above. A certain aluminum material etc. can be used. Among these, the metal base material 7 is preferably a steel material. As described above, by using a steel material that has been widely used as the metal base material 7 of the counterpart metal material 6, the joint structure 11 can be widely used as a member or a part of a transport machine or the like.

  It does not specifically limit as said steel material, The steel material for steel plates, the steel material for machine structures, etc. can be used. As said steel material, what has a zinc containing plating layer formed in at least one surface (surface of the side facing the surface treatment metal material 1) is preferable. By providing the zinc-containing plating layer in this manner, the contact corrosion resistance is improved. The zinc-containing plating layer contains Zn such as hot dip galvanizing, alloyed hot dip galvanizing, electrogalvanizing, Zn-Al plating, Zn-Fe plating, Zn-Ni plating, Zn-Cr plating, Zn-Mg plating. It can be formed using binary or higher alloy plating. Further, dispersion plating in which a metal oxide, a polymer, or the like is dispersed in a zinc-containing plating layer, for example, Zn plating in which silica is dispersed can be used. Moreover, you may apply the multilayer plating which laminated | stacked two or more types of different zinc containing plating layers.

  Among these, a so-called hot dip galvanized steel material in which the zinc-containing plating layer is formed by hot dip galvanizing is preferable. By using the hot dip galvanized steel material, the contact corrosion resistance can be further enhanced.

  The shape of the metal base material 7 is not particularly limited, and may be a plate shape, a rod shape, or any other shape.

  The resin coating 8 is formed on the surface of the metal base material 7 on the side facing the surface-treated metal material 1. By forming the resin coating 8 on the surface of the metal base material 7 in this way, the amount of corrosion current can be reduced and the occurrence of corrosion of the aluminum base material 2 can be further reduced.

  The film thickness (average film thickness) of the resin film 8 is not particularly limited, but is preferably 0.1 μm or more and 5 μm or less. When this film thickness is less than 0.1 μm, the effect of coating with the resin coating 8 may not be sufficiently exhibited, such as insufficient coating and easy pinholes. Conversely, when this film thickness exceeds 5 μm, resistance spot welding or the like becomes difficult.

  The resin for forming the resin film 8 is not particularly limited, but polyolefin-based, polyurethane-based, and epoxy-based resins are preferable. By using these resins, contact corrosion resistance and the like can be more effectively exhibited. Resin can be used 1 type or in mixture of 2 or more types. Although it does not specifically limit as a resin content rate in the said resin film 8, 20 mass% or more and 100 mass% or less are preferable. When the resin content is less than 20% by mass, a sufficient film may not be formed, and pinholes may occur.

  The resin film 8 preferably contains silica. When the resin coating contains silica, contact corrosion resistance and the like can be further improved. Although it does not restrict | limit especially as a content rate of the silica in the said resin film 8, For example, 5 mass% or more and 80 mass% or less are preferable. The type of the silica is not particularly limited, and known dry silica, colloidal silica, and the like can be used.

  It is also preferable that the resin film 8 contains an inhibitor that suppresses corrosion of the metal material. The inhibitor is not particularly limited, but for example, benzoic acid, glutamate, anisidine, glycine, glycine salt, quinolinol, phthalate, adipate and acetate are preferable. These compounds dissolve in the corrosive environment from the resin coating and adhere to the surface of the surface treatment material 1 or the counterpart metal material 6 to reduce the corrosion rate, or cause a potential difference between the aluminum base material 2 and the metal base material 7. It has a function of reducing.

  Among the inhibitors, compounds as salts (glutamate, glycine salt, phthalate, adipate and acetate) are preferable, and glycine salt and phthalate are more preferable. These salts are excellent in water solubility and have high uniform dispersibility when the resin film is formed with an aqueous coating solution. Therefore, by using these salts, the ability to prevent contact corrosion can be exhibited uniformly throughout the resin coating 8.

  As said salt, potassium salt, sodium salt, ammonium salt etc. can be mentioned, for example. These inhibitors (compounds) can be used alone or in combination of two or more.

  The content of the inhibitor in the resin coating 8 can be, for example, 0.1% by mass or more and 20% by mass or less.

  The method for forming the resin film 8 is not particularly limited. For example, the resin coating 8 can be formed by applying a coating liquid containing a component such as a resin to the surface of the metal base material 7 and drying it.

  In the joint structure 11, the surface-treated metal material 1 and the counterpart metal material 6 are joined by rivets 9 penetrating through holes formed in the respective surfaces. The rivet 9 is made of metal, and the aluminum base material 2 and the metal base material 7 are electrically connected by the rivet 9.

  Since the joint structure 11 includes the surface-treated metal material 1, the occurrence of corrosion of the aluminum base material 2 due to the contact with different metals can be suppressed for a long period of time. Therefore, the joint structure 11 can be suitably used as a transport machine such as an automobile or a railway vehicle, or a member or part such as a structure.

(Other embodiments)
In addition, the surface treatment metal material of this invention, the manufacturing method of a surface treatment metal material, and a joining structure are not limited to the said embodiment. For example, in the surface-treated metal material of the present invention, an oxide film may be formed on the entire surface of the aluminum base material. Further, the surface-treated metal material and the mating metal material in the bonded structure of the present invention may further have another layer. Furthermore, in the joint structure of the present invention, the surface-treated metal material and the counterpart metal material may be joined by bolts, welding, or the like in addition to the rivets. In any case, the effect of the present invention that the contact corrosion resistance can be exhibited for a long time can be exhibited.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

<Example 1: Preparation of contact corrosion simulation test body (joint structure)>
(Preparation of acidic solution)
By adding sodium hydroxide to an aqueous solution containing hexafluorozirconium, an acidic solution having a pH of 2 to 4 and a concentration of 0.01 to 0.05% was obtained.
(Production of surface-treated metal material)
The above acidic solution was applied to the surface of an aluminum plate (JIS6000-based magnesium-containing aluminum alloy, width 70 mm × length 150 mm × thickness 1.2 mm) as an aluminum base material, and dried to form an oxide film. Further, a polyurethane resin solution was applied to the surface of the oxide film and dried to form a resin film on the surface of the oxide film, thereby obtaining a surface-treated metal material.
(Production of mating metal material)
A polyurethane-based resin solution was applied to the surface of a zinc-containing plated steel sheet (width 70 mm × length 80 mm × thickness 1.0 mm) as a metal base material, and a resin film was formed by drying to obtain a counterpart metal material .

  Using the surface-treated metal material and the counterpart metal material, a contact corrosion simulation test body 20 (joined structure) shown in FIGS. 4 and 5 was produced. In order to accurately evaluate the contact corrosion, the contact corrosion simulation test body 20 is provided on the surface (position shown in FIG. 4) of the surface-treated metal material 21 (aluminum plate) with a spacer 22 on the surface. A metal material 23 (steel plate) was laminated. The surface-treated metal material 21 and the counterpart metal material 23 were laminated so that the surfaces subjected to the above-described treatments face each other. As the spacer 22, a polytetrafluoroethylene plate having a thickness of 0.1 mm was used. A conductive tape 24 (model number 1170, width 10 mm × length 80 mm × thickness 0.1 mm, manufactured by Sumitomo 3M Limited) is attached so that the outer surfaces of the surface-treated metal material 21 and the counterpart metal material 23 are electrically connected to each other. I let you. In a joined structure joined by resistance spot welding, self-piercing rivets, or the like, the steel plate and the aluminum plate are distorted, and the distance between the steel plate and the aluminum plate is not uniform. Therefore, in the contact corrosion simulation test body 20, in order to prevent such a non-uniform spacing, the uniformity of the spacing is ensured by joining using the conductive tape 24 as described above. Further, a seal 25 (shown only in FIG. 5) was applied to the outer surface side of the counterpart metal material 23. The surface-treated metal material 21 (aluminum plate) and the mating metal material 23 (steel plate) were fixed with four clips 26 to complete the contact corrosion simulation test body 20.

<Examples 2-7 and Comparative Examples 1-3>
Presence or absence of application (coating treatment) of acidic solution in aluminum base material (aluminum plate), presence or absence of oxide film thickness and resin coating, presence or absence of resin coating on metal base material (steel plate), and application to this resin coating Except having changed the presence or absence and kind of additive as Table 1, it carried out similarly to Example 1, and each contact corrosion simulation test body (joining structure) of Examples 2-7 and Comparative Examples 1-3. Obtained. The film thickness of the oxide film was adjusted by changing the concentration, pH, temperature, and treatment time of the acidic solution. As the acidic solution, an aqueous solution containing hexafluorozirconium and / or hexafluorotitanium and adjusted to a pH of 2 to 4 and a concentration of 0.01 to 0.05% by adding sodium hydroxide is appropriately used. Using. In Examples 6 and 7, 1% by mass of ammonium phthalate or sodium glycine was contained in the polyurethane resin solution in terms of solid content.

<Evaluation: Corrosion test>
The obtained contact corrosion simulation test specimen was subjected to a composite cycle test (JIS-H8502 neutral salt spray cycle test) for 30 cycles (10 days) (8 hr / cycle) and a salt spray test for 3000 hours as corrosion tests. (125 days). The dismantling and removal of the corrosion products were performed on the specimen after the corrosion test, and then the erosion depth due to the corrosion of the aluminum plate (surface-treated metal material) was measured.
The corrosion product was removed under the following conditions.
-Removal of corrosion product on the aluminum plate side Immersion in 30% nitric acid aqueous solution at 60 ° C for 10 minutes The erosion depth was measured using a dial gauge having a sharp tip. The maximum value of the erosion depth of the portion where the steel plate and the aluminum plate were overlapped was measured. The corrosion test was performed with n = 3, and the average value of the maximum values was defined as the erosion depth. When the erosion depth of Comparative Example 1 is 1, 0.6 or more is xx, 0.6 or more and less than 0.4 is x, 0.2 or more and less than 0.4 is Δ, 0.1 or more and 0.2 Less than 0 was evaluated as ○, and less than 0.1 was evaluated as ◎. The results are shown in Table 1.

  As Table 1 shows, it turns out that the joining structure of Examples 1-7 has high contact corrosion resistance sustainable for a long period of time.

  As described above, the surface-treated metal material of the present invention of the present invention has excellent contact corrosion resistance and is excellent in this sustainability. Therefore, the surface-treated metal material of the present invention and the joint structure including the same can be widely used for members and parts such as transportation machines and structures such as automobiles and railway vehicles.

DESCRIPTION OF SYMBOLS 1, 4 Surface treatment metal material 2 Aluminum base material 3 Oxide film 5 Resin film 6 Partner metal material 7 Metal base material 8 Resin film 9 Rivet 11 Joint structure 20 Contact corrosion simulation test body 21 Surface treatment metal material (aluminum plate)
22 Spacer 23 Counter metal material (steel plate)
24 conductive tape 25 seal 26 clip

Claims (7)

An aluminum base material made of aluminum or an aluminum alloy, and an oxide film formed on the surface of the aluminum base material, a metal base material having a corrosion potential nobler than that of the aluminum base material, and a surface of the aluminum base material It is the above oxide film and the side facing the metal matrix Ru provided with a resin film is joined to the mating metallic material surface-treated metal material used to be formed on the surface of which is formed,
Further comprising a resin film formed on the surface of the oxide film,
The oxide film substantially consists of a metal oxide of a Group 4 element,
An average film thickness of the oxide film is 5 nm or more and 200 nm or less, and an average film thickness of the resin film is 0.1 μm or more and 5 μm or less. An aluminum base material made of aluminum or an aluminum alloy, a metal base material having a corrosion potential nobler than that of the aluminum base material, and the metal base on the side facing the oxide film formed on the surface of the aluminum base material a method of manufacturing a surface treated metal material used is joined to the mating metallic material Ru comprising a resin film formed on the surface of the wood,
Contacting an acidic solution containing an element of Group 4 on the surface of the aluminum base material, the step of forming the oxide film made of a metal oxide essentially the Group 4 element,
Forming a resin film on the surface of the oxide film,
An average film thickness of the oxide film is 5 nm to 200 nm, and an average film thickness of the resin film is 0.1 μm to 5 μm.   The method for producing a surface-treated metal material according to claim 2, wherein the acidic solution has a pH of 1 or more and 5 or less. The surface-treated metal material according to claim 1, and a metal base material that is disposed adjacent to the surface side of the surface-treated metal material and has a corrosion potential nobler than that of the aluminum base material, and the aluminum base material It includes a mating metal material formed on the surface of the Ru with a resin coating formed on the surface of the metal base material of the oxide coating and the opposite side,
A joined structure in which the aluminum base material and the metal base material are joined in an electrically conductive state.   The joint structure according to claim 4, wherein the metal base material is a steel material.   The joined structure according to claim 5, wherein the steel material is a hot-dip galvanized steel material. The resin coating provided in the counterpart metal material contains at least one selected from the group consisting of benzoic acid, glutamate, anisidine, glycine, glycine salt, quinolinol, phthalate, adipate and acetate. The joined structure according to claim 5 or claim 6 .

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