JP2010144223A - Surface treated metallic material having excellent anticorrosive performance to dissimilar metal contact corrosion and dissimilar material joint body provided with surface treated metallic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic material inexpensively and effectively preventing dissimilar metal contact corrosion even when it is not subjected to electric insulation or complete environmental isolation and to provide a dissimilar metal joint body provided with the metallic material. <P>SOLUTION: The surface treated metallic material 1 includes an anticorrosive layer 3 on the surface of a metallic mother material 2 formed from a pig iron material or an aluminum alloy material. The anticorrosive layer 3 contains 0.005-1 g/m<SP>2</SP>one or more selected from a group comprising tetraborate, vanadate, phosphate dihydrate, nitride and tungstate. The anticorrosive layer 3 is preferably one of potassium salt, sodium salt or ammonium salt. The dissimilar joint body is provided with at least the surface treated metallic material 1 as a material of one side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention uses, as a metal base material, an iron or steel material or an aluminum alloy material that is joined in contact with a dissimilar metal in the fields of transport equipment such as automobiles and railroad vehicles, machinery field, civil engineering plant field, and electronics field. The present invention relates to a surface-treated metal material and a dissimilar material joined body including the surface-treated metal material.

  In recent years, dissimilar metals such as a combination of steel materials and aluminum materials or aluminum alloy materials (hereinafter sometimes referred to as “aluminum materials”), including the transportation field of automobiles and railway vehicles, have been introduced. There is a growing demand for using parts and components that are partially joined and integrated in contact. However, it is known that when different types of metals are brought into contact with each other, there are many cases where different types of metal contact corrosion (galvanic corrosion) occurs. Dissimilar metal contact corrosion is a phenomenon in which a base metal with a corrosive potential serves as an anode and a noble metal serves as a cathode to constitute a battery, and corrosion of the base metal is promoted. For example, when a steel material and an aluminum material are brought into contact, corrosion of the aluminum material is promoted, and the corrosion rate in that case is much larger than when the aluminum material is used alone, so that holes are formed early. Cause damage. Therefore, when using members / parts in contact with different metals, it is necessary to prevent such different metal contact corrosion.

  As a method for preventing contact corrosion of dissimilar metals, it is effective to electrically insulate between dissimilar metals via an insulator. However, such a method is often difficult due to structural and manufacturing restrictions, and has a problem that it cannot be applied to welding by welding which is superior in terms of bonding strength between different metals.

  On the other hand, it is also effective as a method for preventing contact with different metals from blocking the environment so that moisture essential for the progress of corrosion does not enter the contact portion of different metals. For example, Japanese Patent Application Laid-Open No. 60-58272 (Patent Document 1) proposes a coating method such as a method in which a selective anion permeable membrane and a selective cation permeable membrane are overcoated. Also known is a method that utilizes both environmental interruption and insulation by painting. For example, Japanese Patent Laid-Open No. 6-136295 (Patent Document 2) proposes adding molybdenum disulfide to the paint. However, even if it is a coating film, it penetrates moisture somewhat, and when used outdoors, the coating film breaks down due to UV deterioration or scratches, etc., and moisture intrudes into the contact area of dissimilar metals. It is practically difficult to prevent completely over a long period of time.

  In addition, a technique for preventing contact corrosion of dissimilar metals from the structural aspect has been proposed. For example, Japanese Patent Application Laid-Open No. 2001-11665 (Patent Document 3) describes the effect of dissimilar metal contact corrosion between both materials by interposing a Zn—Al—Mg alloy between an aluminum-based composite material and a steel material. It has been proposed to prevent it.

  On the other hand, as a technique for preventing the corrosion of a metal material, an agent (referred to as an anticorrosive, a corrosion inhibitor, an inhibitor or the like) that reduces the corrosivity by adding a small amount or a trace amount to a corrosive environment to which the metal is exposed. Are known. As generally well-known inhibitors, as described in Non-Patent Document 1, sulfites and hydrazines that act as a deoxygenating agent to remove oxygen necessary for the corrosion reaction and reduce the corrosivity. Calcium ions that increase the protective property by forming a precipitated film of calcium carbonate on the metal surface, molybdate that contributes to corrosion resistance by passivating the iron surface, and elements such as N and O with high electronegativity Adsorption film-forming inhibitors (amines, anilines, etc.) that develop anti-corrosion effects by adsorbing polar groups to the metal surface, reacting with metal ions generated by metal dissolution to form stable chelate compounds on the surface Precipitation film formation type inhibitors (benzotriazole, thioglycolic acids, etc.) that exhibit anticorrosion effects, carboxylic acids that form an oxide film on the metal surface, etc. Rukoto can.

Based on the above knowledge of inhibitors, the use of nitrite inhibitors and oxyanion inhibitors is disclosed in Japanese Patent Application Laid-Open No. 4-160169 (Patent Document 4) as a method for preventing contact corrosion of different metals using inhibitors. Are listed. However, such an inhibitor is effective in suppressing contact corrosion between a stainless steel material or a titanium material and a carbon-based steel material, which has a higher corrosion potential than that of the carbon-based steel material, but aluminum having a lower corrosion potential than that of the steel material. There is a problem that it cannot be applied to the suppression of contact corrosion between steel and steel.
JP 60-58272 A JP-A-6-136295 JP 2001-11665 A JP-A-4-160169 Edited by the Corrosion and Corrosion Association: Handbook of anticorrosion technology, 1986

  SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and a surface using a steel or aluminum alloy material as a metal base material that can effectively inhibit dissimilar metal contact corrosion at low cost without performing electrical insulation or complete environmental interruption. It aims at providing the dissimilar-material joined body provided with the process metal material and its surface treatment metal material.

  As mentioned above, contact corrosion of dissimilar metals is a phenomenon in which a base metal forms an anode and a noble metal serves as a cathode to form a battery, and corrosion of the base metal is promoted. Corrosion proceeds in a state of being polarized on the anode side. The present inventors have investigated the suppression of different metal contact corrosion, and since different metal contact corrosion proceeds at a different potential from that of a single metal, corrosion inhibitors for steel materials and aluminum materials that are generally known are not used. A sufficient anticorrosive effect could not be obtained. Therefore, as a result of diligent investigation of anticorrosives effective for contact corrosion of different metals, it was prominent by attaching tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate to the contact surface. As a result, it was found that a good anticorrosion effect was obtained, and the present invention was completed based on this finding.

That is, the surface-treated metal material according to the present invention includes a metal base material formed of a steel material or an aluminum alloy material, and an anticorrosion layer coated on the surface thereof, and the anticorrosion layer includes tetraborate and vanadate. , 0.005 to 1 g / m ^{2 of} one or more salts selected from the group consisting of dihydrogen phosphate, nitrite and tungstate.

According to the surface-treated metal material, the anticorrosion layer contains 0 or more salts selected from the group consisting of tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate. .005~1g / m including ^2. For this reason, the surface of the metal material of the surface-treated metal material and the counterpart metal material have a low corrosion potential, and the surface of the metal material polarized to the anode side, that is, the metal substrate of the surface-treated metal material is made of steel material. In the case where the corrosion potential is lower than that of the steel material, or the metal base material of the surface-treated metal material is an aluminum alloy material, and the corrosion potential of the counterpart metal material is higher than that of the aluminum alloy material. The salt acts on the surface of the aluminum alloy material to form either an oxide film, a precipitation film, or a mixed film thereof, thereby reducing the dissolution rate of the base metal material.

  In the surface-treated metal material, the salt forming the anticorrosion layer is preferably a potassium salt, a sodium salt or an ammonium salt. By forming the anticorrosion layer with any of these salts, the effect of reducing the dissolution rate of the base metal material can be further increased. This is because potassium salts, sodium salts, and ammonium salts are more easily dissolved in water than other salts such as calcium salts, so that a more uniform oxide film or precipitated film can be formed.

In the surface-treated metal material, as the steel material constituting the metal base material, a zinc-containing plated steel material in which at least one surface is coated with a zinc-containing plated layer can be used. In this case, the anticorrosion layer is formed on the zinc-containing plating layer. The zinc-containing plating layer preferably contains 50% or more of Zn, and the adhesion amount is preferably 1 to 150 g / m ² . By using a surface-treated metal material that uses the zinc-containing plated steel material as a metal base material, the potential difference when the base metal material comes into contact with the base material is smaller than the steel material that is not coated with the zinc-containing plated layer. Moreover, the corrosion rate by a dissimilar metal contact can be reduced more according to the synergistic effect of a zinc containing plating layer and the anticorrosion layer which concerns on this invention.

  On the other hand, the dissimilar material joined body according to the present invention includes a surface-treated metal material and a counterpart metal material partially joined to the surface-treated metal material. As the surface-treated metal material, the surface-treated metal material according to the present invention is used. When the metal base material of the surface-treated metal material is a steel material, the counterpart metal material is a base metal material whose corrosion potential is lower than that of the steel material, and the metal base material of the surface-treated metal material is aluminum. In the case of an alloy material, it is a noble metal material that has a higher corrosion potential than the aluminum alloy material. And the said other metal material is arrange | positioned adjacent to the anti-corrosion layer side of the said surface treatment metal material, and the metal base material of the said surface treatment metal material and the said other metal material are joined in the electrically conductive state.

  According to this dissimilar material joined body, since one of the dissimilar material joined bodies is formed of the surface-treated metal material according to the present invention, the base metal material of the surface-treated metal material and the other metal material is a base metal material. Can prevent contact corrosion due to the anticorrosion layer of the surface-treated metal material, and can provide a structure excellent in corrosion resistance and durability.

  In the dissimilar material joined body, the metal material used as the base metal material is not particularly limited. For example, an aluminum alloy material, a magnesium alloy material, or a zinc alloy material can be used. Moreover, in the said dissimilar-material joined body, although the metal material used as said noble metal material is not specifically limited, For example, an aluminum alloy material or a steel material can be used.

  In addition, another dissimilar material joined body according to the present invention includes a first surface-treated metal material and a second surface-treated metal material partially joined to the first surface-treated metal material. The first surface-treated metal material is a steel-treated surface metal material, and the second surface-treated metal material is an aluminum alloy material according to the present invention. A surface-treated metal material is used. And it arrange | positions adjacent so that the anti-corrosion layer of a 2nd surface treatment metal material may come to the anti-corrosion layer side of the said 1st surface treatment metal material, The 1st metal base material and 2nd surface of the said 1st surface treatment metal material The second metal base material of the treated metal material is joined in an electrically conductive state.

  According to this other dissimilar material joined body, the aluminum constituting the metal base material of the second surface-treated metal material, which has a lower corrosion potential than the steel material constituting the metal base material of the first surface-treated metal material. Since the alloy material is prevented from contact corrosion by the double anticorrosion layer of the first and second surface-treated metal materials, excellent corrosion resistance and durability can be obtained.

  Since the surface-treated metal material and the dissimilar material joint according to the present invention are excellent in corrosion resistance and durability against contact corrosion, they can be suitably used as materials for automobile members.

According to the surface-treated metal material according to the present invention, tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate are formed on the surface of a metal base material formed of a steel material or an aluminum alloy material. Since the anticorrosive layer containing 0.005 to 1 g / m ^{2 of} one or more kinds of salts selected from the group consisting of is formed, the salt forming the anticorrosive layer is a metal material having a corrosion potential on the base side, that is, By acting on the surface of the counterpart metal material or metal base material polarized on the anode side, either an oxide film or a precipitation film can be formed to reduce the dissolution rate of the metal. In addition, since the dissimilar material joined body according to the present invention includes the surface-treated metal material, contact corrosion of the base metal material among the metal base material and the counterpart metal material of the surface-treated metal material is caused by the surface-treated metal material. It is suitably prevented by the anticorrosion layer. For this reason, according to the present invention, it is possible to provide a surface-treated metal material and a dissimilar material joined body excellent in corrosion resistance and durability against contact corrosion.

  Hereinafter, a surface-treated metal material according to an embodiment of the present invention will be described with reference to the drawings. In the surface-treated metal material 1 according to the embodiment, as shown in FIG. In the illustrated example, the anticorrosion layer 3 is formed so as to cover only one side of the metal base material 2, but it may be formed on both sides.

  The anticorrosion layer 3 is formed of one or more salts selected from the group consisting of tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate. Moreover, it is preferable that the salt which forms the said anticorrosion layer 3 is either potassium salt, sodium salt, or ammonium salt, respectively. Since these salts are more easily dissolved in water than other salts such as calcium salts, a more uniform oxide film or precipitated film can be formed, and the metal base material 2 of the surface-treated metal material 1 and the surface The effect of reducing the dissolution rate of the base metal material among the counterpart metal materials arranged adjacent to the anticorrosion layer 3 side of the treated metal material 1 can be increased.

As said anti-corrosion layer 3, it is good for the adhesion amount of various salt to be 0.005-1 g / m < ² > in total. In the case of less than 0.005 g / m ² , since the salt concentration in the solution formed by the intrusion of moisture is low at the contact portion between the surface-treated metal material and the counterpart metal material, the metal mother of the surface-treated metal material Oxide film or precipitation film formed on the surface of the base metal material determined by the relationship between the material and the counterpart metal material, or a mixed film thereof is insufficient, and sufficient anticorrosion properties cannot be obtained. Further, when the adhesion amount exceeds 1 g / m ² , the anticorrosion properties are saturated, and there is a possibility that the weldability when the mating metal material is welded in contact with the surface-treated metal material may be adversely affected. Accordingly, the adhesion amount is good to the 0.005~1g / m ^2, and more preferred lower limit is 0.01 g / m ^2, and more preferable upper limit is 0.9 g / m ^2.

  The anticorrosion layer 3 can be formed by attaching the various salts to a metal base material. The method for attaching the various salts is not particularly limited, and may be applied by an appropriate application method using a solution obtained by mixing various salts with an appropriate solvent. For example, application methods such as dip coating, spray coating, shower coating, roll coating, and brush coating can be employed.

  As the metal base material 2, a steel material or an aluminum alloy material is used. As the steel material, various steel materials such as a zinc-containing plated steel material to be described later can be used in addition to a normal steel material such as a steel material for steel plate and a steel material for machine structure. Moreover, the form can also take various forms, such as plate shape, C shape, H shape, and I shape. As the aluminum alloy material, various aluminum alloy materials such as an Al—Mn alloy material, an Al—Mg alloy material, an Al—Zn—Mg alloy material, and an Al—Si alloy material can be used. The steel material and aluminum alloy material constituting the metal base material 2 may be a solid metal material, or may be one that has been subjected to appropriate surface treatment on at least the side where the anticorrosion layer is formed.

  In the case where a zinc-containing plated steel material, that is, a steel material coated with a zinc-containing plated layer on at least one surface (the surface on which the anticorrosion layer is coated) is used as the metal base material 2, Zn in the zinc-containing plated layer is used. The content of is preferably 50% by mass or more. By using a surface-treated metal material having the zinc-containing plated steel material as a metal base material, the potential difference when a base metal material is in contact with the steel material is made smaller, and the zinc-containing plated layer and the anticorrosion layer By this synergistic effect, the corrosion rate due to contact with different metals can be further reduced. When Zn in the zinc-containing plating layer is less than 50% by mass, the effect of reducing the potential difference is reduced, and the effect of reducing the corrosion rate is reduced.

Moreover, it is good for the adhesion amount of the said zinc containing plating to be 1-150 g / m < ² >. When the zinc-containing plating adhesion amount is less than 1 g / m ² on one side, the effect of reducing the potential difference is small, so that the corrosion rate is not sufficiently reduced. Moreover, when the zinc-containing plating adhesion amount exceeds 150 g / m ² on one side, the effect of improving the corrosion resistance against dissimilar metal contact corrosion is saturated. For these reasons, the zinc-containing plating adhesion amount is preferably 1 to 150 g / m ^{2 on} one side. The more preferable lower limit of the zinc-containing plating adhesion amount is 3 g / m ^{2 on} one side, and the more preferable upper limit is 70 g / m ² .

In addition to hot dip galvanizing, alloyed hot dip galvanizing, electrogalvanizing, etc., the zinc-containing plating layer includes Zn-Al plating, Zn-Fe plating, Zn-Ni plating, Zn-Cr plating, Zn-Mg plating, etc. First, it can be formed using a binary alloy plating or more containing Zn. Also, dispersion plating in which metal oxides or polymers are dispersed in a zinc-containing plating layer, such as Zn plating in which SiO ₂ is dispersed, can be used, and two or more different zinc-containing plating layers are laminated. Multilayer plating that has been performed may be applied.

  Next, a first embodiment of the dissimilar material joined body of the present invention will be described with reference to FIG. In the dissimilar material joined body 6 of the first embodiment, the same members as those of the surface-treated metal material 1 shown in FIG.

  In the dissimilar material joined body 6 according to the first embodiment, the mating metal material 4 is adjacently disposed so as to contact the surface-treated metal material 1 and the surface of the anticorrosion layer 3 of the surface-treated metal material 1. The metal base material 2 and the mating metal material 3 of the surface-treated metal material 1 are partially joined by a welded portion 7, and both are electrically connected through the welded portion 7. In the illustrated example, the metal base material 2 and the counterpart metal material 3 of the surface-treated metal material 1 are partially joined by welding, but the partial joining method may be spot welding, brazing or diffusion joining, As shown by a two-dot chain line in the drawing, a metal mechanical connecting member such as a rivet 8 or a bolt may be used. However, welding such as arc welding or spot welding is recommended from the viewpoint of securing bonding strength and reliability.

  When a steel material is used as the metal base material 2 of the surface-treated metal material 1, a base metal material having a lower corrosion potential than the steel material forming the metal base material 2 is used as the counterpart metal material 4. . As the base metal material, for example, an aluminum alloy material, a magnesium alloy material, or a zinc alloy material can be used.

  Further, when an aluminum alloy material is used as the metal base material 2 of the surface-treated metal material 1, the noble metal whose corrosion potential is nobler than the aluminum alloy material forming the metal base material 2 as the counterpart metal material 4. A material is used. As the noble metal material, for example, a noble aluminum alloy material and various steel materials can be used rather than a metal base material.

  According to this dissimilar material joined body 6, the metal base material 2 and the mating metal material 4 of one surface-treated metal material 1 are joined in an electrically conductive state, and between the surface-treated metal material 1 and the mating metal material 4. Even if moisture enters the metal, the anticorrosion layer 3 is formed on the surface of the metal base material 2 and the counterpart metal material 4 on the side where the corrosion potential is low, that is, the metal material polarized on the anode side. Since the salt acts to form an oxide film or a precipitate film or a mixed film thereof on the surface of the base metal material, dissolution of the metal material is suppressed, and contact corrosion is less likely to occur. The anti-corrosion property and durability of the material are improved.

  Next, the dissimilar material joined body 6A according to the second embodiment will be described with reference to FIG. In addition, the dissimilar-material joined body 6 and the same member which concern on 1st Embodiment shown in FIG. 2 attaches | subjects the same code | symbol, abbreviate | omits description and demonstrates centering on difference.

  In the dissimilar material joined body 6A according to the second embodiment, the mating metal material 4 is disposed adjacent to the surface-treated metal material 1, and the outer metal material 5 is disposed adjacent thereto, and these are illustrated by rivets 8 in the illustrated example. Are connected to each other. The counterpart metal material 4 can be said to be an intermediate metal material provided between the surface-treated metal material 1 and the outer metal material 5, and is in contact with the anticorrosion layer 3 and the outer metal material 5 of the surface-treated metal material 1. The metal base material 2 of the surface-treated metal material 1 is electrically connected to the mating metal material 4 and the outer metal material 5 through the rivets 8. In the illustrated example, a rivet is used as a joining method, but a connecting member such as a bolt may be used, or metal members may be partially joined using welding or the like.

  Also in the case of the second embodiment, contact corrosion between the metal base material 2 of the surface-treated metal material 1 and the counterpart metal material 4 can be effectively prevented. However, as the outer metal material 5, it is preferable to use materials having the same or similar corrosion potential so that contact corrosion does not occur with the counterpart metal material 4.

  Next, the dissimilar material joined body 6B according to the third embodiment will be described with reference to FIG. In this dissimilar material joined body 6B, another surface-treated metal material (similar to the embodiment of FIG. 1) is used as the mating metal material 4 of the dissimilar material joined body 6 of the first embodiment. 1 A of surface treatment metal materials and the 2nd surface treatment metal material 1B arrange | positioned adjacent to this are provided. The anti-corrosion layer 3A of the first surface-treated metal material 1A and the anti-corrosion layer 3B of the second surface-treated metal material 1B are arranged adjacent to each other, the metal base material 2A of the first surface-treated metal material 1A and the second surface treatment In the illustrated example, the metal member 2B of the metal material 1B is partially joined by a rivet 8, and the first metal base material 2A and the second metal base material 2B are in an electrically conductive state. In the illustrated example, a rivet is used as a joining method, but a connecting member such as a bolt may be used, or partial joining may be performed using welding or the like.

  In the dissimilar material joined body 6B, the metal base material 2A of the first surface-treated metal material 1A is formed of a steel material (including a zinc-containing plated steel material), and the metal base material of the other second surface-treated metal material 1B. 2B is formed of an aluminum alloy material.

  In the dissimilar material joined body 6B according to the third embodiment, among the first metal base material 2A and the second metal base material 2B, the aluminum alloy material of the second metal base material 2B whose corrosion potential is the base side is the first surface. Contact corrosion is prevented by the double anticorrosion layer of the anticorrosion layer 2A of the treated metal material 1A and the anticorrosion layer 2B of the second surface-treated metal material 1B, so that excellent anticorrosion properties and durability are obtained.

  In the dissimilar material joined body 6B according to the third embodiment, an intermediate metal material can be adjacently disposed between the first and second surface-treated metal materials 1A and 1B. The intermediate metal material may be either a noble or base material for the corrosion potential of the metal base materials 2A and 2B of the surface-treated metal materials 1A and 1B. In this case, the first surface-treated metal material 1A and the intermediate metal material, and the intermediate metal material and the second surface-treated metal material 1B can be regarded as the dissimilar material joined body 6 according to the first embodiment.

  Next, the surface-treated metal material and the dissimilar material joined body according to the present invention will be described with specific examples. However, the present invention is not limited to the examples.

[Production of test materials]
As shown in Table 1 and Table 2 below, as a raw material of the metal base material, using a cold-rolled steel sheet, various plated steel sheets, various aluminum alloys (plate materials, the same applies hereinafter), magnesium alloy, zinc alloy, except for a part, As will be described later, a surface-treated metal material was prepared by coating the anticorrosion layer made of various salts shown in the same table by the dipping method. In Table 2, numbers of aluminum alloy, magnesium alloy, and zinc alloy are alloy numbers defined in JISH4000: 1999, JISH4201: 2005, and JISH5301: 1990, respectively.

  The anticorrosion layer is obtained by cutting a metal base material (thickness 1.2 to 2.0 mm) into 300 × 300 mm, washing the original plate with acetone, and then mixing it with a mixture of various salts and ion-exchanged water at room temperature. It was formed by dipping for an appropriate period of time, lifting and drying. At the time of immersion in the mixed solution, the mixed solution was stirred with a magnetic stirrer so that the salt uniformly adhered to the original plate. The amount of weight increase before and after the immersion was defined as the amount of various salts attached. Tables 1 and 2 also show the amount of adhesion per unit area. In this way, a 50 × 30 mm small piece was cut out from the original plate of the test material to which a predetermined salt adhered, and used as a test piece for galvanic current measurement described below. Similarly, a test piece for galvanic current measurement was prepared from the original plate of the metal base material on which the anticorrosion layer was not formed.

[Measurement method of galvanic current]
In order to simulate the contact corrosion of dissimilar materials joints made of these combinations by selecting two kinds of test pieces of surface-treated metal materials or metal base materials (those not formed with anti-corrosion layer) shown in Table 1 and Table 2. Further, as shown in Table 3, these test pieces were used as electrodes A and B, and the galvanic current flowing between both electrodes was measured.

  As shown in FIGS. 5 and 6, the galvanic current was measured by placing the electrode B horizontally and dropping 0.2 mL of 3% saline as the test solution 12 in the center. At this time, a Teflon sheet 11 (“Teflon” is a registered trademark) having a thickness of 0.3 mm and 10 × 30 mm is disposed at both ends of the electrode B, and the plane space occupied by the test solution 12 is 30 × 30 mm. It was. The electrode A was placed on the Teflon sheet 11. When a surface-treated metal material was used as the test piece used for the electrodes A and B, the anticorrosion layer was disposed on the inner side (test solution side). In addition, among the metal base materials of the test pieces used for the electrodes A and B, the test piece having a low corrosion potential was used as the anode-side electrode B. Thereafter, a lead wire was connected to the electrode A and the electrode B, connected to the non-resistance ammeter 13 and allowed to stand at room temperature for 60 minutes, and then the current value between the electrodes was read. This galvanic current is a current generated due to the electrochemical reaction of corrosion and is proportional to the corrosion rate. Therefore, the degree of contact corrosion of dissimilar metals can be evaluated based on the magnitude of the galvanic current.

[Test results]
The measurement results of the galvanic current are also shown in Table 3. In Table 3, sample Nos. 1 to 5 are measurement samples corresponding to the dissimilar material joined bodies according to the comparative examples, and sample Nos. 6 to 58 are measurement samples corresponding to the dissimilar material joined bodies according to the invention examples.

  Sample No. according to the comparative example. 1 is a combination of a test piece (N1) of a cold-rolled steel sheet and an Al-Mg-Si alloy test piece (L5) both having no anticorrosion layer, but in this combination, a galvanic current exceeding 500 μA flows, Corrosion of the Al—Mg—Si alloy was greatly accelerated. Sample No. 3 is a combination of a test piece (N7) of a cold-rolled steel sheet coated with benzotriazole, which is a generally known anticorrosive agent, and a test piece (L5) of an Al—Mg—Si alloy sheet having no anticorrosion layer. Yes, and sample no. 4 and no. No. 5 is a combination using test pieces in which the amount of salt adhesion of the present invention is less than the specified value. 3 to 5 are sample Nos. It was almost the same level as the current value of 1. Sample No. 2 is a combination of test pieces of aluminum alloy plates having no anticorrosion layer, but a galvanic current exceeding 100 μA flowed, and corrosion of the base Al—Zn—Mg alloy plate test pieces was promoted.

  On the other hand, in the samples according to the invention examples (No. 6 to No. 58), the galvanic current is the sample No. Compared to the current value indicated by 1, the value decreased to 1/10 or less. This means that in the surface-treated metal material according to the present invention, the rate of dissimilar metal contact corrosion is suppressed to 1/10 or less, and it was confirmed that an excellent anticorrosive effect was obtained. In particular, by using the surface-treated metal material according to the present invention as the two members constituting the dissimilar material joined body from the sample Nos. 42 to 58 in which both test pieces were collected from the surface-treated metal material according to the present invention, different metal contacts It was confirmed that the effect of inhibiting corrosion was significant.

  Moreover, when the adhesion salt in an anticorrosion layer differs, sample No. which made calcium tetraborate adhere is attached. No. 6 to which the same sodium was adhered. No. 12 or No. 1 with magnesium dihydrogen phosphate attached. No. 8 with the same sodium attached. Comparison with 14 shows that the current value is lower when the anticorrosion layer is formed with sodium salt than with calcium salt or magnesium salt, and the progress of corrosion can be further suppressed. Similarly, the sample No. to which vanadate was adhered was used. 7 (calcium salt) and no. Compared with 13 (potassium salt), the current value is lower when the anticorrosion layer is formed with potassium salt than with calcium salt. 9 (lithium salt) and no. Comparison with 15 (ammonium salt) shows that the formation of the anticorrosion layer with an ammonium salt rather than a lithium salt has a lower current value and is excellent in anticorrosion properties. This confirmed that potassium salt, sodium salt, and ammonium salt are preferable as the salt forming the anticorrosion layer. In addition, as a result of attaching various salts to the cold-rolled steel sheet, the sample No. It can be seen that sodium tungstate indicated by 16 is particularly preferable as a salt forming the anticorrosion layer.

  In addition, in the case of a surface-treated metal material using a steel plate coated with a plating layer containing a different metal as a metal base material, the sample No. 1 to which the same lithium nitrite is adhered is used. 9 (hot-dip aluminized steel sheet) and no. No. 22 (hot dip galvanized steel sheet) or No. 22 with potassium vanadate adhered. 13 (hot-dip aluminized steel sheet) and No. Comparison with No. 26 (hot Zn-Al plated steel sheet) shows that when using a plated steel sheet, the plated steel sheet containing zinc has a lower current value and is excellent in corrosion resistance.

  As described above, all of the surface-treated metal materials according to the present invention have excellent anticorrosion properties against contact corrosion, and are suitable as iron-based and aluminum-based surface-treated metal materials used in contact with different metals, Moreover, the dissimilar-material joined body using them is excellent also in the anti-corrosion characteristic with respect to contact corrosion.

It is a partial cross section schematic diagram of the surface treatment metal material concerning an embodiment. It is a partial cross-section schematic diagram of the dissimilar-materials joined body which concerns on 1st Embodiment. It is a partial cross section schematic diagram of the dissimilar-materials joined body which concerns on 2nd Embodiment. It is a partial cross-section schematic diagram of the dissimilar material conjugate | zygote which concerns on 3rd Embodiment. It is sectional explanatory drawing which shows the galvanic current measurement point. FIG. 6 is a cross-sectional view taken along line C in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface treatment metal material, 1A 1st surface treatment metal material, 1B 2nd surface treatment metal material 2, 2A, 2B Metal base material 3, 3A, 3B Anticorrosion layer 4 Counter metal material 6, 6A, 6B Dissimilar material joined body

Claims (13)

It is a surface-treated metal material for joining with a counterpart metal material whose corrosion potential is lower than that of a steel material,
A metal base material formed of the steel material, and a corrosion protection layer formed on the surface of the metal base material,
The anticorrosion layer contains 0.005 to 1 g / m ^{2 of} one or more salts selected from the group consisting of tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate. A surface-treated metal material with excellent corrosion resistance against contact corrosion of dissimilar metals.   The surface-treated metal material according to claim 1, wherein the salt forming the anticorrosion layer is each a potassium salt, a sodium salt, or an ammonium salt. The metal base material is a zinc-containing plated steel material in which a zinc-containing plating layer containing 50% by mass or more of Zn is coated on at least one surface, and the adhesion amount of the zinc-containing plating layer is 1 to 150 g / m. ^The surface-treated metal material according to claim 1, wherein the anticorrosion layer is formed on the zinc-containing plating layer.   The surface-treated metal material according to any one of claims 1 to 3, which is used as a material for an automobile member. It is a surface-treated metal material for joining with a counterpart metal material that has a higher corrosion potential than an aluminum alloy material,
A metal base material formed of the aluminum alloy material, and a corrosion protection layer formed on the surface of the metal base material,
The anticorrosion layer contains 0.005 to 1 g / m ^{2 of} one or more salts selected from the group consisting of tetraborate, vanadate, dihydrogen phosphate, nitrite, and tungstate. A surface-treated metal material with excellent corrosion resistance against contact corrosion of dissimilar metals.   The surface-treated metal material according to claim 5, wherein the salt forming the anticorrosion layer is each a potassium salt, a sodium salt, or an ammonium salt.   The surface-treated metal material according to claim 5 or 6, which is used as a material for an automobile member. A surface-treated metal material, and a counterpart metal material partially joined to the surface-treated metal material,
The surface-treated metal material is the surface-treated metal material according to any one of claims 1 to 3, wherein the counterpart metal material has a corrosion potential higher than a steel material forming a metal base material of the surface-treated metal material. Is a base metal material that is base,
Dissimilar material joining, wherein the mating metal material is disposed adjacent to the anticorrosion layer side of the surface-treated metal material, and the metal base material of the surface-treated metal material and the mating metal material are joined in an electrically conductive state. body.   The dissimilar material joined body according to claim 8, wherein the base metal material is any one of an aluminum alloy material, a magnesium alloy material, and a zinc alloy material. A surface-treated metal material, and a counterpart metal material partially joined to the surface-treated metal material,
The surface-treated metal material is the surface-treated metal material according to claim 5 or 6, and the counterpart metal material is a noble metal material having a corrosion potential nobler than an aluminum alloy material forming the surface-treated metal material. And
Dissimilar material joining, wherein the mating metal material is disposed adjacent to the anticorrosion layer side of the surface-treated metal material, and the metal base material of the surface-treated metal material and the mating metal material are joined in an electrically conductive state. body.   The dissimilar material joined body according to claim 10, wherein the noble metal material is either an aluminum alloy material or a steel material. A first surface-treated metal material, and a second surface-treated metal material partially joined to the first surface-treated metal material,
The first surface-treated metal material is the surface-treated metal material according to any one of claims 1 to 3, and the second surface-treated metal material is the surface-treated metal material according to claim 5 or 6. And
The first surface-treated metal material is disposed adjacent to the anti-corrosion layer side so that the anti-corrosion layer of the second surface-treated metal material is in contact with the metal base material of the first surface-treated metal material and the second surface treatment. The dissimilar material joined body joined in a state where the metal base material of the metal material is electrically conducted.   The dissimilar material joined body according to any one of claims 8 to 12, which is used as a material for an automobile member.

Images