JP2002180275A - Corrosion inhibition method for panel made of aluminum metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit corrosion in the contact parts between a panel member formed of a aluminum-based metal and an installation member and a joint member made of stainless steel in a panel made of aluminum metal having the above members. SOLUTION: This corrosion inhibition method is used for a panel made of aluminum metal having a panel member formed of aluminum based metal consisting of aluminum or an aluminum alloy and an installation member installed in contact with the panel member. In the method, the space between the contact faces between the panel member and the installation member is provided with a corrosion inhibition layer composed of a zinc-based metal consisting of zinc or a zinc alloy, or a magnesium-based metal consisting of magnesium or a magnesium alloy, or an aluminum-based metal, and having a potential baser by >=100 mV than the repassivation potential of the panel member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to corrosion prevention of an aluminum metal panel having a panel member made of an aluminum-based metal made of aluminum or an aluminum alloy, and a stainless steel member provided in contact with the panel member. About the method.

[0002]

2. Description of the Related Art In addition to the beauty of the surface, aluminum-based metals made of aluminum or aluminum alloy are lightweight, excellent in workability and formability, and have an oxide film or paint on the surface. Excellent corrosion resistance is imparted when formed, so when manufacturing indoor and outdoor facilities such as containers for land transportation and sea transportation, industrial refrigerators, temporary toilets, freezing and refrigeration rooms, aluminum It is often used as a metal panel.

In the case of such an aluminum metal panel, for example, when it is a container truck panel, a panel member in which a heat insulating material is sandwiched by using an aluminum sheet coated in advance with an oxide film or a coating is manufactured. After that, it is manufactured using a method of assembling into a box shape, and in the case of a panel member for a door located at the rear of the container, various additional members including door opening and closing members such as a steel door hinge and Various fastening members such as bolts and nuts and rivets for fastening between these attached members and the panel member are attached.

[0004] In such aluminum metal panels, conventionally, zinc-plated steel made of zinc-plated ordinary steel has been frequently used as a material of the attachment members and fastening members. However, these zinc-plated steel attachment members and fastening members have a disadvantage that they are susceptible to rust in a relatively short period of time, and furthermore, when rust occurs, the panel surface is contaminated and the rust is left unattended. In addition, cracks may occur in the panel members and other phenomena may occur, which in turn may affect the durability and adversely affect the life and function of the aluminum metal panel. It is being replaced.

However, in recent years, the amount of the deicing agent sprayed on the road has increased, and a part of the deicing agent has scattered during traveling and has adhered to the attachment members and fastening members of the aluminum metal panel.
Even if these attached members and fastening members are made of stainless steel, rust appears, and moreover, dissimilar metals are formed between the stainless steel attached members and the aluminum-based metal panel members that come into contact with such fastening members. The influence of contact corrosion is manifested, and corrosion starts, especially from scratches on coatings and defects on coatings, resulting in the appearance of aluminum metal panels being impaired.
Further, if corrosion progresses and cracks or through holes are generated, a functional problem such as penetration of rainwater or the like into the inside of the panel also occurs. Moreover, if the attachment members and the fastening members are made of stainless steel, the attachment members and the fastening members are not used because of the taste of the end user and because it is not possible to take advantage of the features using stainless steel such as metallic luster and material texture. In many cases, the members are used without any treatment, which is one of the causes that the problem of contact corrosion of dissimilar metals with the panel members becomes apparent.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present inventors have developed a panel member made of aluminum-based metal and a stainless steel attachment member in an aluminum metal panel having an attachment member and a fastening member made of stainless steel. As a result of earnestly studying a method for solving the problem of corrosion at the contact portion between the fastener and the fastening member and preventing the occurrence of corrosion over a long period of time, a zinc-based metal, a magnesium-based metal, or It has been found that this problem can be solved by providing an anticorrosion layer made of an aluminum-based metal and having a potential lower than the re-passivation potential of the panel member by 100 mV or more, and completed the present invention.

Accordingly, an object of the present invention is to provide an aluminum metal panel having an attachment member and a fastening member made of stainless steel, between the panel member formed of aluminum-based metal and the attachment member and the fastening member made of stainless steel. It is an object of the present invention to provide a method for preventing corrosion of an aluminum metal panel, which can solve the problem of corrosion at the contact portion of the aluminum metal panel.

[0008]

That is, the present invention provides a panel member formed of an aluminum-based metal made of aluminum or an aluminum alloy, and a stainless steel member provided in contact with the panel member. Corrosion prevention method of an aluminum metal panel having, between the contact surface between the panel member and the additional member, zinc-based metal consisting of zinc or zinc alloy, magnesium-based metal consisting of magnesium or magnesium alloy, or from aluminum-based metal A corrosion prevention method for an aluminum metal panel, characterized in that a corrosion prevention layer having a potential lower than the passivation potential of the panel member by 100 mV or more is provided.

In the present invention, the panel members formed of aluminum-based metal include, for example, containers for land transportation, marine transportation, etc., as well as indoor and outdoor refrigerators such as industrial refrigerators, prefabricated refrigerators, temporary toilets, and refrigerators. Used when manufacturing facilities, etc., even if it is formed only of aluminum-based metal,
A pre-coated material of aluminum-based metal may be bonded to both sides of a plywood or a heat insulating material to form a sandwich structure, and any panel material using aluminum-based metal as a main material may be used.

As the stainless steel attachment member attached to such a panel member, typically, an opening / closing member such as a door hinge connecting the panel members to each other in a container truck panel, a locking member, and the like are given. be able to. The present invention can also be applied to fastening members such as bolts and nuts and rivets for attaching such an opening / closing member to a panel member, when they are made of stainless steel, in the same manner as the attached members.

Further, the stainless steel attachment member is not particularly limited in its cross-sectional shape as long as a corrosion prevention layer can be formed between the panel member and the attachment member. , Polygon, or circle.

In the method of the present invention, the panel member and the fastening member may be further provided, if necessary, between the contact surface between the panel member formed of the aluminum-based metal and the attached member made of stainless steel in contact with the panel member. Between a contact surface of the panel member and a zinc-based metal of zinc or a zinc alloy, a magnesium-based metal of magnesium or a magnesium alloy, or an aluminum-based metal.
An anti-corrosion layer having a lower potential than 00 mV is provided.

Here, the corrosion prevention layer provided between the contact surface between the panel member and the attachment member or the fastening member is basically formed of the aluminum-based metal of the panel member and the stainless steel of the attachment member or the fastening member. The shape and the forming method are not particularly limited as long as direct contact between them can be prevented, and the sacrificial anode interposed between the contact surfaces of these panel members and the attachment members and the fastening members is preferable. It is preferable that the surface treatment layer is a material that is provided by means such as plating treatment, chemical conversion treatment, or coating containing zinc powder (for example, zinc rich paint) on the surface of the attachment member or the fastening member.

When the corrosion prevention layer is a sacrificial anode material, the shape thereof can be interposed between the panel member and the additional member or the fastening member. Any shape may be used as long as it does not hinder the fastening between the panels, but it is preferably the same shape as the inner surface of the attachment member or the fastening member that is in contact with the panel member. It is possible to prevent water droplets from entering between the member and the attached member or the fastening member, and prevent water containing a large amount of electrolyte from staying.

Further, when the corrosion prevention layer is a surface treatment layer, when corrosion occurs in the attached member or the fastening member, for example, F
e ₂ O _3, FeOOH, etc. steel corrosion products well that is one that does not occur too much, either preferably galvanized, aluminum plating, zinc powder-based chemical conversion treatment, and selected from aluminum powder based chemical conversion treatment It may be a surface treatment layer formed by one or more methods.

In the method of the present invention, the zinc-based metal, the magnesium-based metal, or the aluminum-based metal forming the corrosion-preventing layer such as the sacrificial anode material or the surface treatment layer is 100 mV or more from the re-passivation potential of the panel member. Preferably 12
It must have a potential lower than 0 mV, and preferably has a potential lower than -770 mV, which is the corrosion protection potential of steel. If the potential of the anticorrosion layer is not lower than 100 mV than the re-passivation potential of the panel member, a sufficient anticorrosion effect may not be obtained due to potential fluctuations in the atmospheric environment, especially when the antifreezing agent is attached. It is difficult to reliably prevent corrosion in an environment where corrosion is likely to occur.

When the corrosion prevention layer is a sacrificial anode material, the thickness thereof is usually 0.1 mm or more and 5 mm or less.
Preferably, the thickness is in the range of not less than 0.2 mm and not more than 4 mm. If the thickness is less than 0.1 mm, a relatively large amount of electrolyte or moisture is supplied between the panel member and the contact surface between the attachment member and the fastening member. In an environment that is easily eroded and corroded, the sacrificial anode material is greatly consumed and may not be able to exhibit its intended durability (lifetime). Conversely, when the wall thickness exceeds 5 mm, the corrosion resistance effect is saturated. As a result, only an increase in the cost of the sacrificial anode material becomes apparent, and the attachment of the additional member to the panel member may be adversely affected.

In the present invention, the corrosion prevention layer provided between the panel member and the contact surface between the attachment member and the fastening member is as follows.
The sacrificial anode material and the surface treatment layer may be provided independently, respectively, or these sacrificial anode materials and the surface treatment layer may be used in combination. Can be improved.

[0019]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show the basic structure of an aluminum metal container truck door panel to which the anticorrosion method of the present invention is applied. And this container truck door panel is made of aluminum pre-coated door panel material 1a and aluminum pre-coated side wall forming panel material 1b.
An aluminum metal panel member 1 comprising: a stainless steel door opening / closing hinge (attached member) 2 attached to the aluminum precoated door panel member 1a; an aluminum precoated door panel member 1a and a door opening / closing hinge 2; Stainless steel bolt and nut (fastening member) 3
It is composed of

Further, in this embodiment, the aluminum precoated door panel material 1a has a sandwich structure in which a plywood is used as a core material and precoated panels are bonded to both sides thereof.
A thickness of 0.1 to 100 mV or more which is lower than the re-passivation potential of the aluminum pre-coated door panel material 1a so as to insulate the direct contact between the two and the door opening / closing hinge 2 from each other. 5mm sacrificial anode material (anti-corrosion layer) 4
Is interposed.

Further, in this embodiment, the surface of the bolt and nut 3 is zinc-plated, aluminum-plated,
A non-illustrated surface treatment layer (corrosion prevention layer) formed by zinc powder-based chemical conversion treatment or aluminum powder-based chemical conversion treatment is provided.

Therefore, the container door panel made of aluminum metal of this embodiment comprises a door opening / closing hinge 2 and a bolt made of stainless steel, the aluminum pre-coated door panel member 1a and the aluminum pre-coated side wall constituting panel member 1b made of aluminum-based metal. An aluminum metal panel that does not come into direct contact with the nut 3 and that has a sacrificial anode material 4 and a surface treatment layer provided between the nut 3 and a corrosion-preventing effect, and has an attached member and a fastening member made of stainless steel. Corrosion problem can be solved.

[0023]

The present invention will now be described more specifically based on examples and comparative examples.

Examples 1 to 9 and Comparative Example 1 In the basic structure shown in FIGS. 1 and 2, the surface of an aluminum precoated door panel material 1a constituting the panel member 1 is subjected to a chemical conversion treatment in a chromate tank, and then a roll coater. Undercoat is applied, and a polyester, acrylic, epoxy, silicon or fluorine-based paint is further applied thereon to provide a coating layer having a thickness of 8 μm or more and 25 μm or less. Is untreated or has a coating of about 5 μm.

The door opening / closing hinge 2 and the bolt / nut 3 are made of stainless steel SUS304. Between the aluminum precoated door panel member 1a and the door opening / closing hinge 2, 3% by weight of Zn and 0.02% by weight are used. % In containing aluminum alloy (Al-3wt% Zn-0.02wt% In alloy), commercially available zinc plate (99.9wt% Zn), or magnesium alloy containing 9wt% Al and 1wt% Zn (Mg A sacrificial anode material 4 formed by casting -9 wt% Al-1 wt% Zn) in a plate shape is interposed.

The aluminum metal panel thus obtained was subjected to a salt spray test (JIS Z237) for 3,000 hours.
1), and the state of corrosion of the surface of the aluminum metal panel was observed. The evaluation was as follows: no: good without coating film defects, and good: remarkable coating film defects. After performing the salt water spray test for 3,000 hours, the self potential was measured using a saturated calomel electrode and a digital voltmeter at a position 30 cm away from the door opening / closing hinge 2 through a filter paper soaked in salt water. went. Table 1 shows the results.

[0027]

[Table 1]

Embodiments 10 to 17 Unlike the embodiments 1 to 9, the sacrificial anode material 4 is not used in the basic structure shown in FIGS.
The door opening / closing hinge 2 and the bolt / nut 3 are immersed in a zinc dust-based chemical conversion bath having a composition of 80 to 95% by weight of zinc powder, 5 to 20% by weight of Al powder, chromic anhydride, and glycol at 300 ° C. For 10 minutes, and a zinc powder-based chemical conversion treatment is performed to reduce the basis weight to 10 g / m ² , 20 g / m ² , or 30 g / m ² , or similarly, the composition of Al powder, chromic anhydride and glycol Using an aluminum powder-based chemical conversion bath consisting of 10 g / m ² and 20 g / m ²
m ^2, or performs aluminum powder based chemical conversion treatment to 30 g / m ^2, or, the door hinge 2 and the bolt nut 3 45
It is immersed in a molten zinc at 0 ° C. and subjected to a hot-dip galvanizing treatment with a basis weight of 350 g / m ² , or, similarly, 700 ° C.
The aluminum plating was performed to a basis weight of 350 g / m ² using the molten aluminum of Example 1, and then Examples 1 to 9 were performed.
As in the case of the above, an aluminum metal panel was prepared and
A 00 hour salt spray test (based on JIS Z2371) and self potential measurement were performed. Table 2 shows the results.

[0029]

[Table 2]

As is clear from the results shown in Tables 1 and 2, in each of the examples of the present invention, no rusting was observed on the surface of the aluminum metal panel, and the test was conducted. The surface potential of the later aluminum metal panel was found to maintain a potential that was 100 mV or more lower than the re-passivation potential of the panel member (aluminum pre-coated door panel material 1a), and excellent corrosion resistance was observed. Has been found to be maintenance-free.

[0031]

According to the present invention, corrosion resistance is excellent,
As a result, it is possible to provide an aluminum metal panel which has excellent durability and can be used for a long period without maintenance.

[Brief description of the drawings]

FIG. 1 is an explanatory front view showing an aluminum metal container truck door panel according to a preferred embodiment of the present invention.

FIG. 2 is an enlarged sectional explanatory view taken along line II-II of FIG. 1;

[Explanation of symbols]

1: Panel member, 1a: Aluminum pre-coated door panel material,
1b: Aluminum precoated side wall panel material, 2: Door opening / closing hinge (attached member), 3: Bolt / nut (fastening member), 4: Sacrificial anode material (corrosion prevention layer).

Claims (5)

[Claims] An anticorrosion method for an aluminum metal panel having a panel member formed of an aluminum-based metal made of aluminum or an aluminum alloy, and a stainless steel member provided in contact with the panel member. Yes, between the contact surface between the panel member and the additional member, zinc-based metal consisting of zinc or zinc alloy, magnesium-based metal consisting of magnesium or magnesium alloy, or aluminum-based metal, from the re-passivation potential of the panel member 10
A corrosion prevention method for an aluminum metal panel, comprising providing a corrosion prevention layer having a potential lower than 0 mV. 2. The corrosion prevention of an aluminum metal panel according to claim 1, wherein the corrosion prevention layer is a sacrificial anode material having a thickness of 0.1 to 5 mm interposed between contact surfaces of the panel member and the attached member. Method. 3. A corrosion prevention layer is provided on the surface of the attached member by one or more methods selected from a galvanizing treatment, an aluminum plating treatment, a zinc powder-based chemical conversion treatment, and an aluminum powder-based chemical conversion treatment. The method for preventing corrosion of an aluminum metal panel according to claim 1, which is a surface treatment layer. 4. The panel member and the attached member are fastened with a stainless steel fastening member, and the surface of the fastening member is subjected to galvanizing, aluminum plating, zinc dust-based chemical conversion, and aluminum dust. The method for preventing corrosion of an aluminum metal panel according to any one of claims 1 to 3, wherein the surface treatment layer is provided by any one or more methods selected from system conversion treatment. 5. The method according to claim 1, wherein the attached member is a door hinge for opening and closing the door, and the fastening member is a bolt and a nut and / or a rivet.