JP2008001944A - Aluminum material and aluminum composite material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum material which is constituted such that an aluminum base material is not corroded by sacrificial anticorrosion effect and protected by a sacrificial metal superior in anticorrosion effect, and a composite material of the aluminum material and a metallic material nobler than aluminum. <P>SOLUTION: The aluminum material is composed of the aluminum base material comprising aluminum or an aluminum alloy and the sacrificial metal layer which is adhered to the surface of the aluminum base material through an insulative adhesive layer, wherein the sacrificial metal is a metal baser than aluminum or an alloy composed of the metal baser than aluminum and aluminum and containing 5 wt.% or less of aluminum. Further, a protective layer having a thickness of 2.0-30.0 nm is formed on the surface of the sacrificial metal layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is provided with a sacrificial metal layer composed of a base metal or alloy that sacrificially corrodes via an insulating adhesive layer on the surface of an aluminum substrate, and a protective layer of these metals or alloys, and has excellent corrosion resistance. The present invention relates to an aluminum material and an aluminum composite material obtained by joining such an aluminum material and a metal material nobler than aluminum.

  Currently, many aluminum materials are used as building materials and constituent materials for transport aircraft. In particular, in the field of transport aircraft, various regulations aimed at reducing the environmental load of fossil fuels are being improved, and fuel efficiency is being improved by reducing the weight of the aircraft. As a promising method, the movement to replace the constituent material with an aluminum material has become active.

  However, it is difficult to completely replace the aluminum material from the viewpoint of strength and the like, and the actual situation is that it is often used as a composite material combined with a steel material. In this composite material, since aluminum is relatively base electrochemically, there is a problem that corrosion preferentially proceeds. Therefore, as an anticorrosion of aluminum material, a method of covering the aluminum surface with an anodized film or a coating film to isolate it from a noble metal has been adopted.

  However, in an anodized film or a paint film, defects may occur in the film or film, and electrical continuity occurs between aluminum and a noble metal at the defective portion, and corrosion occurs. Moreover, since such a film or the coating itself has no effect of preventing the progress of corrosion, the generated corrosion easily proceeds.

  On the other hand, as a method for preventing the progress of corrosion of the body to be protected, a sacrificial metal such as zinc, which is more basic than aluminum, is used. For example, a sacrificial metal layer by electroplating or electroless plating is formed with an aluminum material and a noble metal material There is a method in which the sacrificial anodic action is exerted to prevent corrosion by providing a conductive state between them.

  However, in the anticorrosion method by plating, there is a problem that when aluminum is mixed in the zinc layer, the zinc layer is likely to cohesively break. Furthermore, since the anticorrosion effect is exhibited only during the period in which the sacrificial metal is present, the anticorrosion effect directly depends on the thickness of the plating layer. For this reason, there is a problem that the anticorrosion effect for a long period of time cannot be obtained unless the amount of sacrificial metal elution is suppressed or the plating layer is made considerably thick.

  A composite plating in which the elution rate of the plating layer is suppressed by controlling the composition of the plating metal layer has also been proposed. However, since it is difficult to provide a plating layer having a predetermined composition on the surface of the aluminum material, there are drawbacks such as instability in quality.

  Further, in order to increase the thickness of the plating layer in order to obtain the anticorrosion effect over a long period of time, it is necessary to extend the plating processing time. As a result, the impact on productivity reduction becomes very large, making it difficult to strike a balance between the anticorrosive effect and productivity. Further, in order to incorporate anticorrosion measures such as anodization and plating into the manufacturing process line, a large capital investment and a space for installing a large apparatus are required. Therefore, it is difficult to achieve the incorporation of such an apparatus into an existing processing apparatus line. Further, such anti-corrosion measures also have a problem of consuming a great amount of energy for maintaining the treatment liquid in an appropriate state and discarding the treatment liquid. Furthermore, countermeasures for preventing environmental pollution and the like are necessary, and there remains a problem that an increase in running cost cannot be avoided.

A sacrificial metal is affixed to an anticorrosive material through an adhesive or sticky substance having conductivity as a method of providing an anticorrosion effect equivalent to that of plating while improving the incorporation into an existing line and workability. A method is described in Patent Document 1. In this method, by using a thick film as the sacrificial metal to be attached, the anticorrosion period can be extended, and from the simplicity of simply attaching the anticorrosive material to the object to be protected, Easy to install.
: JP-A 62-234925

  However, in the method of attaching the sacrificial metal by plating or a conductive adhesive or sticky substance, when these laminates are made of a composite material with a noble metal rather than aluminum, the aluminum material, the sacrificial metal, Electrical continuity is always ensured between the noble metals. Therefore, an aluminum material that is normally difficult to corrode due to a highly corrosion-resistant oxide film that is normally present on the surface is corroded due to a sacrificial anticorrosive effect on a more precious metal, thereby preventing corrosion of the aluminum material. The achievement of the purpose will be reduced. Further, the sacrificial metal itself was easily corroded in an untreated state, and the anticorrosion effect could not be sufficiently exhibited.

  The present invention relates to an aluminum material configured to protect an aluminum base material from being sacrificed by a sacrificial anticorrosive effect and protected by a sacrificial metal having an excellent anticorrosive effect, and more excellent than such an aluminum material and aluminum. Provided is an aluminum composite material bonded to a metal material, which is manufactured by an apparatus that can be easily introduced into an existing production line, and is inexpensive and excellent in corrosion resistance.

  The present invention according to claim 1 is an aluminum base material made of aluminum or an aluminum alloy, and a sacrificial metal layer bonded to the surface of the aluminum base material via an insulating adhesive layer, wherein the sacrificial metal is aluminum. A sacrificial metal, or a sacrificial metal layer that is an alloy of the base metal and aluminum and containing 5 wt% or less of aluminum, and a thickness of 2.0 to 2.0 formed on the surface of the sacrificial metal layer An aluminum material provided with a 30.0 nm protective layer.

  According to a second aspect of the present invention, the base metal that is lower than aluminum contains at least one of zinc and magnesium. Furthermore, the present invention is the aluminum composite material according to claim 3, wherein the aluminum material according to claim 1 or 2 and a metal material nobler than aluminum are joined, wherein the aluminum material is interposed between the aluminum base material and the metal material. The aluminum composite material is configured to sandwich the adhesive layer, the sacrificial metal layer, and the protective layer.

  In the aluminum material according to the present invention, the surface of the aluminum base material is covered with an insulating adhesive layer so that the aluminum base material is isolated from corrosion inducing substances such as water. Is suppressed. An aluminum composite material according to the present invention is a composite of the above aluminum material and a metal material nobler than aluminum via an adhesive layer, a sacrificial metal layer, and a protective layer, and the continuity between the aluminum material and the metal material. Therefore, it is possible to easily and inexpensively construct a corrosion prevention mechanism that prevents the preferential corrosion of aluminum associated with aluminum and suppresses the occurrence and progression of corrosion of the aluminum itself over a long period of time even if conduction occurs. Furthermore, by providing a protective layer on the surface of the sacrificial metal layer, corrosion of the sacrificial metal itself can be suppressed.

  In the aluminum material according to the present invention, an insulating adhesive layer is provided on the surface of the aluminum base, and a sacrificial metal layer mainly composed of a base metal or an alloy thereof is bonded to the adhesive layer. By providing a protective layer having a thickness of 2.0 to 30.0 nm on the surface of the sacrificial metal layer. In the aluminum composite material according to the present invention, an adhesive layer, a sacrificial metal layer, and a protective layer are sandwiched between the aluminum base material and the metal material, and the aluminum material and a metal material (for example, a steel plate) more precious than aluminum. Thus, it can be obtained by bonding by bonding, hemming structure, rivets or the like.

A. Aluminum material
A-1. Aluminum base material As the aluminum base material used in the present invention, not only pure aluminum but also various aluminum alloys are used.

A-2. Adhesive Layer The adhesive layer used in the present invention is composed of an adhesive or adhesive (hereinafter simply referred to as “adhesive”) or adhesive (hereinafter simply referred to as “adhesive”) to an aluminum material. Is done. As such an adhesive, an organic adhesive, an inorganic adhesive or a mixture thereof is used, but is not particularly limited. Organic adhesives include organic adhesive components dissolved in organic solvents (toluene, ethyl acetate, etc.); emulsion dispersed in water; aqueous solution dissolved in water; hot in film, sheet or powder form Solventless type such as melt; etc. are included. The organic adhesive component is not particularly limited, but a resin system such as thermosetting urea resin, phenol resin, epoxy resin, unsaturated polyester resin, melamine resin, acrylic resin, alkyd resin; EPDM of synthetic rubber component , Rubber systems such as acrylic rubber, butyl rubber, butadiene rubber, styrene butadiene rubber, nitrile rubber, and polyisobutylene; metal-containing systems such as metal alkoxides; or a mixture thereof. Inorganic adhesives include alkali metal silicates, low melting glass and the like.

  Such an adhesive bonding method is also not particularly limited. For example, adhesion by applying pressure to an aluminum substrate and a sacrificial metal layer (with an oxide layer or hydrated oxide layer formed) sandwiching the adhesive layer, or melting, modification or polymerization of the adhesive layer by heat treatment, etc. Adhesion is available. For the purpose of ensuring sufficient insulation between the aluminum substrate and the sacrificial metal layer, the adhesive layer is preferably thick so as to increase the electrical resistance between the sacrificial metal layer and the aluminum substrate. The thickness is determined in consideration of the use of the material, productivity, and economy. The thickness of the adhesive layer is usually preferably around 100 μm.

  Since the adhesive does not erode the aluminum base material and the sacrificial metal and needs to be non-reactive with them, one having a low acid value shown in JIS K 5601 and 2 or less are preferable. Some adhesives require treatments such as adding a regulator to achieve an acid value in this range. In addition to adhesive components, solvents, etc., organic or inorganic preservatives and other additives may be added to the adhesive for the purpose of enhancing the shielding from the environment that generates and accelerates corrosion. .

A-3. The sacrificial metal layer provided on the sacrificial metal layer adhesive layer plays a role of preventing the corrosion of a metal material (such as steel) that is nobler than aluminum combined with the aluminum substrate through the sacrificial metal layer. Even in the case where electrical connection is made between the aluminum base material and the noble metal material, the sacrificial metal sandwiched between them is preferentially corroded instead of aluminum, Corrosion of the aluminum substrate is also suppressed. Such electrical continuity is caused by the presence of a conductive medium such as water between the aluminum base material and a noble metal material. This is caused by electrical conduction or by passing through this metal material from an aluminum substrate with conductive screws or rivets used for bonding.

  As the sacrificial metal, a base metal such as zinc or magnesium having a natural electrode potential lower than that of aluminum and an alloy of these base metals are used. Moreover, you may use the alloy which made one or more types of these base metals a main component, and added the noble metal (for example, aluminum) arbitrarily from this. In such an alloy with a noble metal, an alloy having a higher noble metal component ratio than these base metals and a higher natural electrode potential than the corrosion-protected body cannot be used as a sacrificial metal.

  In general, it may be necessary to perform chemical conversion treatment on an aluminum composite material in which a metal nobler than aluminum such as a steel plate is joined. In the case where an alloy of zinc and aluminum is used as the sacrificial metal layer, if the aluminum content is large, the chemical conversion property on the surface of the sacrificial metal layer may be lowered and become insufficient. In such a portion where the chemical conversion treatment is insufficient, there arises a problem that adhesion of the coating applied thereon is impaired, and a problem that cohesive failure easily occurs in the zinc portion of the sacrificial metal layer. Therefore, the aluminum content optionally contained in the sacrificial metal layer needs to be 5% by weight or less.

  The shape of the sacrificial metal layer is not particularly limited, and various shapes are used. The thickness of the sacrificial metal layer can also be selected variously according to the use of the aluminum composite material and the desired anticorrosion period. When a sacrificial metal layer coated with an adhesive layer is affixed to an aluminum substrate having a complicated shape, wrinkles are generated when the sacrificial metal layer is made of a thin piece with a slit rather than an integral foil. Less preferred. The thickness (amount) of the sacrificial metal is determined electrochemically based on the sacrificial anode effect, but is usually preferably about 100 μm.

A-4. In the sacrificial metal layer in which the protective layer is not formed on the surface of the protective layer, corrosion of the sacrificial metal layer itself cannot be sufficiently suppressed, and the period during which the anticorrosion effect is maintained is shortened. Therefore, it is necessary to provide a protective layer having a thickness of 2.0 to 30.0 nm on the surface of the sacrificial metal layer. Such a protective layer is provided on either or both of the surface of the sacrificial metal layer on the pressure-sensitive adhesive layer side and the surface on the opposite side. The protective layer may be formed on the surface of the sacrificial metal layer separately from the sacrificial metal layer. However, the sacrificial metal layer may be formed on the surface of the sacrificial metal layer by heat treatment or the like. It is preferred to form a layer. For example, the sacrificial metal oxide layer is formed on the surface as a protective layer by heat-treating the sacrificial metal layer in air at a temperature equal to or lower than the melting point of the sacrificial metal. Alternatively, a sacrificial metal hydrated oxide layer is formed on the surface as a protective layer by immersing the sacrificial metal layer in hot water or spraying superheated steam on it. In order for such an oxide layer or hydrated oxide layer to exhibit a sufficient protective function as a protective layer for the sacrificial metal layer, a thickness of 2 nm or more is required. On the other hand, if the thickness is greater than 30 nm, cohesive failure occurs easily in the protective layer, and the adhesiveness between the adhesive layer and the sacrificial metal layer is impaired, and the structure as a composite material cannot be maintained.

A-5. Manufacturing process of aluminum material In order to manufacture and manufacture the aluminum material according to the present invention in an actual process, a process using a large-scale apparatus is not required. That is, a step of applying or coating an adhesive on the aluminum base and a step of attaching a sacrificial metal layer having a protective layer formed on the surface in advance to the adhesive layer may be provided. Instead, an adhesive is applied in advance to the sacrificial metal layer having the protective layer formed on the surface, or the sacrificial metal layer is formed on the adhesive layer by a method such as vapor deposition, and then the protective layer is formed (this In this case, the protective layer is formed only on the surface opposite to the adhesive layer), and the tape is wound up with a release paper or the like interposed between such a band consisting of a sacrificial metal layer and an adhesive layer. A method of simultaneously providing a sacrificial metal layer (having a protective layer) and an adhesive layer on the aluminum substrate by sticking the tape on the aluminum substrate is also used.

  As described above, the production of the aluminum material according to the present invention does not require the cost for maintaining and discarding the treatment liquid and does not require a large-sized device, as compared with the corrosion prevention by anodic oxidation or plating. Therefore, the aluminum material manufacturing process can be easily and inexpensively introduced into the existing process line.

B. Aluminum composite
B-1. Metal Material to be Joined In the aluminum composite material according to the present invention, a steel material, SUS, copper or the like is used as a metal material nobler than aluminum to be joined to the aluminum base material.

B-2. Joining Form of Aluminum Composite Material In the aluminum composite material according to the present invention , the joining form of the aluminum base material and the metal material is not particularly limited. The adhesive layer, the sacrificial metal layer and the protective layer of the sacrificial metal layer are sandwiched between the aluminum base material and the metal material, for example, by bonding using an adhesive or by mechanical bonding such as rivet or hemming Can do. In the case of using an adhesive for bonding, the sacrificial material including the metal material to be bonded and the protective layer, for example, by mixing metal particles in the adhesive, in order to obtain the benefit of the anticorrosive effect due to the sacrificial anodic action of the sacrificial metal It is preferable to ensure electrical conductivity with the metal.

  In the hemming structure as shown in FIG. 1, an adhesive layer 3, a sacrificial metal layer 4, and a sacrificial metal layer protective layer 5 are formed between a curved aluminum base 1 and a noble metal material 2 such as a steel plate. It is joined so as to sandwich the anticorrosive material. As a result, the aluminum base material 1 having the insulating adhesive layer 3 sandwiched between the metal material 2 is free from corrosion due to the sacrificial action on the noble metal, and the noble metal is protected by the sacrificial action of the sacrificial metal. .

  A conductive structural adhesive layer is provided between the sacrificial metal layer and the noble metal material for the purpose of increasing the strength of the aluminum composite material as a structure, or the joint end of the aluminum base material and the noble metal material, etc. The anticorrosion effect may be further enhanced by filling a sealable substance called a sealer in a portion where corrosion promoting substances such as water are likely to accumulate. The conductivity of the structural adhesive is preferably imparted by the same material as the sacrificial metal or a powder having a natural electrode potential of the same level so as not to hinder the sacrificial effect of the sacrificial metal on the noble metal material.

  As another example of the mechanical joining, an adhesive layer 3, a sacrificial metal layer 4, and a protective layer 5 for the sacrificial metal layer are sandwiched between an aluminum base material 1 and a noble metal material 2, and rivets pass through these layers. The method of joining by 6 is mentioned (FIG. 2). In this joining method, since the rivet is generally made of metal, electrical continuity occurs between the aluminum base 1 and the noble metal 2 around the portion where the rivet 6 penetrates. As a result, due to the sacrificial action of aluminum on the noble metal material, corrosion of the aluminum substrate cannot be completely prevented.

  However, the sacrificial metal layer 4 has priority over the aluminum base material 1 because the metal constituting the sacrificial metal layer 4 that is electrically connected to the noble metal material 2 is baser than aluminum. It will corrode. Therefore, compared with the case where the aluminum base material 1 and the noble metal material 2 are in direct contact without inclusions, the corrosion resistance of the aluminum base material 1 can be kept high. Similar to the rivet, the same high corrosion resistance as that of the aluminum base material can be obtained by joining with screws.

Examples 1 and 2 and Comparative Examples 1 to 3
A 6022 series alloy plate (thickness: 1.0 mm) used as a body sheet for automobiles as an aluminum base material, which is a body to be protected, is a steel plate (thickness 0) as a noble metal material joined to the aluminum base material. .6 mm) as the sacrificial metal layer, zinc foil having a thickness of 200 μm and a purity of 99% was used. The zinc foil was heat-treated at 100 ° C. in air to form a protective layer made of zinc oxide on both surfaces, and the thickness of the protective layer was adjusted by changing the heat treatment time. The thickness of the protective layer was measured by observing the cross section of the zinc foil cut by a microtome with a TEM.

For the adhesive forming the adhesive layer, A: neutral butyl rubber adhesive, B: zinc powder having a particle size of about 100 μm for the purpose of imparting conductivity to A, 70 wt. Two types were prepared, mixed at%. Each of A and B was applied to one of the protective layers of the zinc foil, and then a silicone-treated release paper was attached to the adhesive layer, and the release paper was wound outward to form a tape. Next, the release paper was peeled off, and the tape was attached to the aluminum substrate so that the adhesive layer was in contact with the aluminum substrate surface. Finally, the steel sheet was joined to the aluminum base material with a hemming structure with a tape sandwiched therebetween to produce an aluminum composite material of the aluminum base material and the metal material. In Comparative Example 3, a sample of an aluminum composite material was prepared in the same manner as in Comparative Example 1 except that a steel plate that had been galvanized (Zn: 0.06 g / cm ² ) was used instead of the sacrificial metal layer.

  The characteristics of each sample were evaluated by the SST test and the exposure test shown below. Table 1 shows the adhesive used, the thickness of the protective layer of the sacrificial metal layer, the noble metal material, and the evaluation results. The thickness of the protective layer was the average value of those formed on both surfaces of the sacrificial metal layer.

SST test conditions: 1 cycle of 5% by weight aqueous sodium chloride solution sprayed on the sample surface at 35 ° C. for 24 hours and then stored in a constant temperature and humidity chamber at 40 ° C. and 80% humidity for 6 days. This was repeated 4 cycles and the corrosion site was observed.
Evaluation results: The case where corrosion occurred in less than 1% of the total area of the aluminum base material was evaluated as ◯, the case where corrosion occurred in 1 to 30% was evaluated as △, and the case where corrosion exceeding 30% occurred was evaluated as x. . ○ was accepted and Δ and × were rejected.

Exposure test conditions: Exposure was conducted for one year in an outdoor environment in an industrial area.
Evaluation results: The case where corrosion occurred in less than 1% of the total area of the aluminum base material was evaluated as ◯, the case where corrosion occurred in 1 to 30% was evaluated as △, and the case where corrosion exceeding 30% occurred was evaluated as x. . ○ was accepted and Δ and × were rejected.

In Examples 1 and 2, the evaluation results of the SST test and the exposure test were both good.
In Comparative Example 1, since the thickness of the protective layer was insufficient, the corrosion rate of zinc in the sacrificial metal layer was increased and the anticorrosion period was short.
In Comparative Example 2, since the conductive zinc powder is contained in the adhesive layer, the aluminum base material and the steel plate are electrically connected to each other, and thereby the aluminum base material exhibits a sacrificial anode effect and is corroded. Was promoted.
In Comparative Example 3, since the insulating adhesive layer is not used, the aluminum base material and the galvanized steel plate are electrically connected to each other, and thereby the aluminum base material exhibits a sacrificial anode effect and is not corroded. Was promoted.
Further, in Example 2, the amount of zinc in the sacrificial metal layer corresponding to the unit area of the steel sheet is about 0.14 g / cm ² , whereas in Comparative Example 3, it corresponds to the unit area of the galvanized steel sheet. The amount of zinc in the sacrificial metal layer to be produced was 0.06 g / cm ² , and this difference in the amount of zinc appeared as a difference in the anticorrosion period.

Examples 3 and 4 and Comparative Examples 4 and 5
Except for using a zinc-aluminum alloy foil having a thickness of 200 μm as the sacrificial metal layer and having a different aluminum content, and bonding the zinc-aluminum alloy foil and the aluminum base material without using a tape using an epoxy resin as an adhesive. Produced an aluminum composite in the same manner as in Example 1. This aluminum composite material was degreased (FC-L4460: manufactured by Nihon Parkerizing Co., Ltd., 43 ° C., 2 minutes immersion), and then subjected to surface adjustment (titanium colloid system, room temperature, immersion for 30 seconds). Furthermore, the zinc phosphate chemical conversion treatment is performed by immersion for 2 minutes at 43 ° C. using PB-L3020, and the amount of chemical conversion film per unit area formed on the zinc-aluminum alloy foil not covered with the steel plate is determined. Measurement was performed as follows.
Table 2 shows the aluminum content in the sacrificial metal layer of the aluminum composite and the amount of chemical conversion film formed.

Measurement of formation amount of chemical coating The chemical coating amount is obtained by immersing the test piece subjected to the zinc phosphate chemical conversion treatment in a 5% CrO ₃ solution at 25 ° C. for 5 minutes to dissolve the chemical conversion film in the solution. It calculated | required from the weight difference of the test piece before and behind a process. And the amount of the produced chemical conversion film is 1.0 g / cm ² or more, ○, 0.7 g / cm ² or more and less than 1.0 g / cm ^{2, and} less than 0.7 g / cm ² × , ◯ was accepted, and Δ and x were rejected.

  In Examples 3 and 4 in which the aluminum content was 5% by weight or less, a sufficient amount of chemical conversion film was formed. On the other hand, in Comparative Examples 4 and 5 in which the aluminum content exceeds 5% by weight, the amount of chemical conversion film formed was not sufficient.

Examples 5-8 and Comparative Examples 6-8
As shown in FIG. 3, two 2022 × 150 mm alloy plates of 20 mm × 150 mm were used as the aluminum bases 1, 1, and the zinc-aluminum alloy foil used in Examples 3 and 4 and Comparative Examples 4 and 5 as the sacrificial metal layer. 4 was used. A protective layer 5 is provided on each side of the zinc-aluminum alloy foil 4. An epoxy adhesive was applied to a long side end 20 mm × 20 mm of each aluminum base material with a thickness of 0.5 mm to form an adhesive layer 3, and bonded with a zinc-aluminum alloy foil 4 interposed therebetween. At this time, in each aluminum base material piece 1, 1, it adhered mutually shifted in the short side direction (left-right direction in the figure) so that the area which the adhesion part may face may be decreased. Apply tensile load to both ends of the non-bonded part, measure the shear strength, which is the load when the bonded part peels off, and measure the cohesive failure rate of the adhesive on the peeled surface, as follows: Adhesion was evaluated. The results are shown in Table 3.

Evaluation of shear strength: A sample having a shear strength of 12 MPa or more was evaluated as ◯, a sample having a shear strength of less than 12 MPa, and a sample having a shear strength of less than 10 MPa as x. ○ was accepted and △ and × were rejected.
Evaluation of cohesive failure rate The ratio of the area where the adhesive remains on the peeled surface to the total area is defined as the cohesive failure rate, ○ for 90% or more, Δ for 80% or more and less than 90%, or less than 80% X. ○ was accepted and △ and × were rejected.

  In Examples 5 to 8, both the shear strength and the cohesive failure rate were acceptable. In Comparative Example 6, since the oxide layer serving as the protective layer for the sacrificial metal layer was too thick, the shear strength and the cohesive failure rate were reduced. In Comparative Examples 7 and 8, since the aluminum content in the sacrificial metal layer was too much, the shear strength and the cohesive failure rate were significantly reduced.

  As described above, the aluminum material according to the present invention can prevent the corrosion caused by the sacrificial anode effect generally caused by the establishment of electrical conduction in the joining of a noble metal and a composite material, and is a substance that causes corrosion. The anticorrosive action due to the removal of can be effectively exhibited. In addition, the production of aluminum composite material according to the present invention can be easily introduced into an existing production line without requiring a large-scale investment or equipment modification, so that it is inexpensive and has excellent corrosion resistance. An aluminum composite can be provided.

It is sectional drawing which shows the aluminum composite material of the hemming structure which concerns on this invention. It is sectional drawing which shows the aluminum composite material by the rivet joining which concerns on this invention. It is sectional drawing which shows the aluminum composite material which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Aluminum base material 2 ... Metal material 3 ... Adhesive layer 4 ... Sacrificial metal layer 5 ... Protective layer 6 ... Rivet

Claims (3)

An aluminum substrate made of aluminum or an aluminum alloy;
A sacrificial metal layer bonded to the surface of the aluminum base material via an insulating adhesive layer, wherein the sacrificial metal is a base metal that is lower than aluminum or an alloy of the base metal and aluminum. A sacrificial metal layer that is an alloy containing no more than wt% aluminum;
An aluminum material comprising: a protective layer having a thickness of 2.0 to 30.0 nm formed on a surface of the sacrificial metal layer.   The aluminum material according to claim 1, wherein the base metal is aluminum or zinc alloy.   An aluminum composite material obtained by joining the aluminum material according to claim 1 and a metal material nobler than aluminum, wherein the adhesive layer, the sacrificial metal layer, and the protection are provided between the aluminum base material and the metal material. Aluminum composite configured to sandwich layers.

Images