Corrosion-resistant coating structures and steel members

Abstract

To provide an anticorrosive coating structure that has a metal substrate with an anticorrosive face, of which a part is coated with a corrosion-proof metal and another part is coated with a zinc-rich coating layer, wherein the corrosion-proof metal is protected from zinc embrittlement cracking even when the corrosion-proof metal is welded, and a steel member including the anticorrosive coating structure.SOLUTION: An anticorrosive coating structure 10 includes a corrosion-proof metal 16 that coats a part of an anticorrosive face 14 of a metal substrate 12, which requires corrosion protection, and a zinc-rich coating layer 18 that coats another part of the anticorrosive face 14. Between the corrosion-proof metal 16 and the zinc-rich coating layer 18 on the anticorrosive face 14, a separation region 14A is provided to separate them. A primer coating layer 20 is also provided to coat the separation region 14A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a corrosion-resistant coating structure and a steel member, and more particularly to a corrosion-resistant coating structure in which a portion of a surface to be protected from corrosion is coated with a corrosion-resistant metal and another portion is coated with a zinc-rich coating layer, and a steel member equipped with the corrosion-resistant coating structure. [Background technology]

[0002] Steel is inexpensive and has excellent mechanical properties, making it widely used in many fields. However, it suffers from a weakness: it is susceptible to corrosion. To address this weakness, steel structures (especially those located in marine areas) often use corrosion-resistant metals or heavy-duty coatings on their surfaces. Marine steel structures are subject to varying degrees of corrosion in different areas. Corrosion-resistant metal linings are often applied to the most corrosive environments, such as the splash zone and tidal zone, while heavy-duty coatings are applied to areas above those zones and cathodic protection is applied to the submarine zone. In these cases, a boundary between the heavy-duty coating and the corrosion-resistant metal lining is created. If a heavy-duty coating is applied directly on top of the corrosion-resistant metal lining at this boundary, the coating may peel off, potentially becoming a starting point for further peeling.

[0003] As a technique that may be useful for preventing peeling of the heavy-duty anticorrosion coating at the boundary, for example, there is a technique described in Patent Document 1.

[0004] According to the invention (corrosion-resistant coating structure) described in Patent Document 1, by providing a primer coating layer on the boundary between a corrosion-resistant thin metal plate and a zinc-rich coating with excellent corrosion resistance, it is possible to impart high corrosion resistance over a long period of time to port and marine steel structures that are exposed to severe corrosive environments, such as port structures such as piers, revetments, and breakwaters, oil drilling-related facilities, sea berths, offshore storage bases and other marine energy development-related structures, and transportation facilities such as immersed tunnels and offshore airports. In particular, Patent Document 1 states that by using a specific coating layer as the primer coating, it is possible to ensure excellent adhesion to all of the zinc-rich coating layer, corrosion-resistant metal layer, and epoxy resin coating layer (paragraph 0007 of Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-218699 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, other metal components may be attached to corrosion-resistant metals used in steel structures by welding. In this case, if a zinc-rich coating film is present near the welding point, the zinc in the zinc-rich coating film may melt under the influence of welding heat and diffuse into the grain boundaries of the corrosion-resistant metal, potentially causing zinc embrittlement cracking of the corrosion-resistant metal.

[0007] In paragraph 0004 of Patent Document 1, it is stated that "when stainless steel is exposed to a high-temperature environment such as welding or a fire while in contact with the zinc metal contained in the zinc-rich paint, it may cause solution metal embrittlement and reduce the strength of the structure, which is a problem." However, in the technology described in Patent Document 1, one end of the corrosion-resistant thin metal plate and one end of the zinc-rich coating layer are adjacent to each other, and when exposed to a high-temperature environment such as welding or a fire, the zinc in the zinc-rich coating layer may melt and come into contact with the corrosion-resistant thin metal plate.

[0008] The present invention has been made in view of the above points, and has an object to provide a corrosion-protective coating structure in which a part of a surface to be protected from corrosion of a metal substrate is coated with a corrosion-resistant metal and another part is coated with a zinc-rich coating layer, and in which the occurrence of zinc embrittlement cracking in the corrosion-resistant metal is suppressed even when welding is performed on the corrosion-resistant metal, and a steel member equipped with the corrosion-protective coating structure. [Means for solving the problem]

[0009] The present invention is an invention that solves the above-mentioned problems, and provides the following corrosion-resistant coating structure and steel member.

[0010] That is, a first aspect of the corrosion-protective coating structure according to the present invention is a corrosion-protective coating structure comprising a corrosion-resistant metal coating a part of a surface to be protected from corrosion of a metal substrate to be corrosion-protected, and a zinc-rich coating layer coating another part of the surface to be protected from corrosion, wherein a separation region is provided on the surface to be protected between the corrosion-resistant metal and the zinc-rich coating layer to separate them, and the corrosion-protective coating structure has a primer coating layer provided so as to cover the separation region.

[0011] Here, in the present application, the surface of a metal substrate to be protected from corrosion does not only include a surface extending in one two-dimensional direction, but also includes a surface formed by combining multiple surfaces extending in different two-dimensional directions, i.e., a curved, continuous surface. For example, if the metal substrate to be protected from corrosion is a cube, the curved, continuous surface formed by combining the six faces of this cube is also included in the surface to be protected from corrosion of the metal substrate. Furthermore, in the present application, the surface to be protected from corrosion of a metal substrate is not limited to a flat surface, but also includes a curved surface.

[0012] In addition, in this application, the word "above" may be used to describe the positional relationship regarding the arrangement position of components of a corrosion-resistant coating structure, but regardless of the actual up-down direction, "above" may mean the side farther from the corrosion-protected surface of the metal substrate to be corrosion-protected.

[0013] A second aspect of the corrosion-resistant coating structure according to the present invention is the first aspect, wherein the primer coating layer extends over at least a portion of the surface of the corrosion-resistant metal.

[0014] A third aspect of the corrosion-resistant coating structure according to the present invention is the first or second aspect, wherein the corrosion-resistant metal covering a portion of the surface to be protected is made of any one of austenitic stainless steel, duplex stainless steel, and nickel alloy.

[0015] A fourth aspect of the corrosion-resistant coating structure according to the present invention is any one of the first to third aspects, wherein the primer coating layer and the zinc-rich coating layer are coated with a corrosion-resistant layer.

[0016] A fifth aspect of the corrosion-resistant coating structure according to the present invention is the fourth aspect, wherein the portion of the corrosion-resistant layer that is coated with the zinc-rich coating layer is made of at least one of epoxy resin paint, polyurethane resin paint, silicone acrylic resin paint, fluororesin paint, glass flake-containing paint, modified epoxy resin paint, and ultra-thick film epoxy resin paint.

[0017] A sixth aspect of the corrosion-resistant coating structure according to the present invention is the fourth or fifth aspect, wherein a weather-resistant layer is further provided on the corrosion-resistant layer.

[0018] A seventh aspect of the corrosion-resistant coating structure according to the present invention is any one of the first to sixth aspects, wherein the zinc-rich coating layer is replaced with a zinc-containing metal spray layer.

[0019] An eighth aspect of the corrosion-resistant coating structure according to the present invention is any one of the first to seventh aspects, in which the corrosion-resistant metal is composed of a clad steel composite with a main steel portion attached to the surface to be protected from corrosion.

[0020] A ninth aspect of the corrosion-resistant coating structure of the present invention is an aspect configured such that, in any of the first to seventh aspects, the corrosion-protected surface is the surface of the main steel part of a clad steel consisting of a main steel part and a clad material, the corrosion-resistant metal is the clad material of the clad steel, the zinc-rich coating layer coats the surface of the main steel part of the clad steel opposite the clad material, and the separation area is the surface of the main steel part of the thickness-wise surface of the clad steel formed by cutting or milling the clad steel in the thickness direction across both the main steel part and the clad material.

[0021] A tenth aspect of the corrosion-resistant coating structure according to the present invention is the ninth aspect, wherein the surface in the thickness direction is formed by an edge surface of the clad steel.

[0022] An eleventh aspect of the corrosion-resistant coating structure according to the present invention is the ninth aspect, wherein the thickness direction surface is formed by the inner surface of a through hole in the thickness direction of the clad steel.

[0023] A twelfth aspect of the corrosion-resistant coated structure according to the present invention is any one of the eighth to eleventh aspects, wherein the clad steel is made of rolled clad steel.

[0024] One aspect of the steel member according to the present invention is a steel member having the corrosion-resistant coating structure according to any one of the first to twelfth aspects. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a corrosion-protective coating structure in which a portion of a corrosion-protected surface of a metal substrate is coated with a corrosion-resistant metal and another portion is coated with a zinc-rich coating layer, and in which the occurrence of zinc embrittlement cracking in the corrosion-resistant metal is suppressed even when welding is performed to the corrosion-resistant metal, and a steel member equipped with the corrosion-protective coating structure. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating a corrosion-resistant coating structure 10 according to a first embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view schematically illustrating a corrosion-resistant coating structure 30 according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a cross-sectional view schematically illustrating a corrosion-resistant coating structure 40 according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view schematically illustrating a corrosion-resistant coating structure 50 according to a fourth embodiment of the present invention. [Figure 5] 10 is a vertical cross-sectional view schematically showing a box girder 62 of a box girder bridge 60 to which the corrosion-resistant coating structure 40 according to the third embodiment is applied. [Figure 6] A side view schematically showing the box girder bridge 60 as seen from the side (perpendicular to the bridge axis) [Figure 7] FIG. 10 is a half-sectional view schematically showing a support structure 70 to which the corrosion-resistant coating structure 40 according to the third embodiment is applied. [Figure 8] 10A and 10B are diagrams showing a schematic view of a plate-shaped clad steel 42 being lifted using a corrosion-resistant coating structure 40 according to the third embodiment, and a diagram showing a lifting piece 80 used for the lifting, where (A) is a front view showing a schematic view of the plate-shaped clad steel 42 being lifted, (B) is a side view showing a schematic view of the plate-shaped clad steel 42 being lifted, and (C) is an enlarged view showing a schematic view of the lifting piece 80 used for the lifting. [Figure 9] 10 is a vertical cross-sectional view showing a state in which a drainage pipe 90 is attached by fillet welding 92 to a bottom plate 62A of a box girder 62 of a box girder bridge 60 to which the corrosion-resistant coating structure 40 according to the third embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments (first to fourth embodiments) of the corrosion-resistant coating structure according to the present invention will be described in detail with reference to the drawings. Examples of application of the present invention to specific structures and components will also be described.

[0028] (1) First embodiment FIG. 1 is a cross-sectional view that schematically shows a corrosion-resistant coating structure 10 according to a first embodiment of the present invention.

[0029] 1, a corrosion-resistant coating structure 10 according to the first embodiment is provided on a surface 14 to be protected from corrosion of a metal substrate 12 to be protected from corrosion, and protects the metal substrate 12 from corrosion. The metal substrate 12 to be protected from corrosion may be any metal that does not produce liquid zinc even when affected by welding heat, and specific examples include carbon steel and low-alloy steel.

[0030] The corrosion-resistant coating structure 10 according to the first embodiment includes a corrosion-resistant metal 16 that coats a portion of a surface 14 to be protected of a metal substrate 12, a zinc-rich coating layer 18 that coats another portion of the surface 14 to be protected of the metal substrate 12, and a primer coating layer 20. A separation region 14A is provided on the surface 14 to be protected between the corrosion-resistant metal 16 and the zinc-rich coating layer 18 to separate them, and the primer coating layer 20 is provided to cover the entire surface of the separation region 14A. The primer coating layer 20 may not only cover the entire surface of the separation region 14A, but may also extend over at least a portion of the surface of the corrosion-resistant metal 16. In the corrosion-resistant coating structure 10 according to the first embodiment, the primer coating layer 20 is provided to extend over at least a portion of the surface of the corrosion-resistant metal 16, as shown in FIG. 1 .

[0031] On the corrosion-protected surface 14, a separation region 14A is provided between the corrosion-resistant metal 16 and the zinc-rich coating layer 18 to separate them. Therefore, even if welding is performed on the corrosion-resistant metal 16 to attach other components, the heat from the welding is not easily transmitted to the zinc-rich coating layer 18, and melting of the zinc in the zinc-rich coating layer 18 is suppressed. Even if the zinc in the zinc-rich coating layer 18 does melt, the provision of the separation region 14A prevents it from coming into contact with the corrosion-resistant metal 16. Therefore, in the corrosion-resistant coating structure 10 according to the first embodiment, even if welding is performed on the corrosion-resistant metal 16, zinc embrittlement cracking of the corrosion-resistant metal 16 is suppressed.

[0032] The corrosion-resistant metal 16 can be any metal with excellent corrosion resistance, including, for example, austenitic, ferritic, or martensitic stainless steel, titanium or a titanium alloy, or a nickel alloy. Specific examples of suitable stainless steel include SUS410L, SUS410S, SUS430, SUS304, SUS304L, SUS316, SUS316L, SUS317, SUS317L, SUS321, SUS347, SUS310S, SUS329J1L, SUS329J3L, SUS329J4L, SUS312L, SUS836L, NAS354N, and JSL310Mo. Specific examples of suitable titanium or titanium alloys include TP270H and TP340H. Specific examples of suitable nickel alloys include NCF825, NW0276, NCF625, and NW6022.

[0033] The corrosion-resistant metal 16 can be attached to the corrosion-protected surface 14 of the metal substrate 12 by commonly used methods such as plasma welding, MAG (Metal Active Gas) welding, resistance welding, etc. Alternatively, explosive welding, friction diffusion welding, or build-up welding can also be used.

[0034] As described above, in the corrosion-resistant coating structure 10 according to the first embodiment, the separation region 14A is provided on the corrosion-protected surface 14 between the corrosion-resistant metal 16 and the zinc-rich coating layer 18, thereby preventing the corrosion-resistant metal 16 from suffering from zinc embrittlement cracking, even when the corrosion-resistant metal 16 is welded to, for example, attach another member. Therefore, the corrosion-resistant coating structure 10 according to the first embodiment is highly effective when the corrosion-resistant metal 16 is made of a corrosion-resistant metal that may suffer from zinc embrittlement cracking. Specific examples of corrosion-resistant metals that may suffer from zinc embrittlement cracking include austenitic stainless steel, duplex stainless steel, and nickel alloys.

[0035] In the corrosion-protective coating structure 10 according to the first embodiment, a separation region 14A is provided on the corrosion-protected surface 14, separating the corrosion-resistant metal 16 and the zinc-rich coating layer 18. This prevents the corrosion-resistant metal 16 from undergoing zinc embrittlement cracking, as described above. However, because neither the corrosion-resistant metal 16 nor the zinc-rich coating layer 18 is provided in this separation region 14A, corrosion of the metal substrate 12 in the separation region 14A is a concern. For this reason, in the corrosion-protective coating structure 10 according to the first embodiment, a primer coating layer 20 is provided to cover the entire surface of the separation region 14A. From the perspective of further improving corrosion protection, it is preferable to further provide a corrosion-protective layer 32 (see FIG. 2 ) on the primer coating layer 20 (second embodiment).

[0036] The primer coating layer 20 can be made of any material that has excellent corrosion resistance and good adhesion to the corrosion protection layer 32 to be applied thereon.Specific examples that can be used include epoxy resin paint, silicone acrylic resin paint, wash primer, polyurethane resin paint, and lacquer paint, but epoxy resin paint is most suitable from the standpoint of adhesion.

[0037] Prior to application of the primer coating layer 20, it is preferable to prepare the surface of the separation region 14A of the corrosion-protected surface 14 and the corrosion-resistant metal 16 in the area where the primer coating layer 20 will be applied, in order to improve adhesion of the primer coating layer 20. Specific methods for surface preparation include polishing and blasting with various abrasives. For large areas, blasting using at least one abrasive selected from silica sand, garnet, alumina, carborundum, stainless steel beads, stainless steel cut wire, copper slag, and nickel slag is recommended. Surface preparation for narrow areas, such as the sides of bolt holes, can be performed using a flap wheel, which rotates abrasive paper wrapped around a metal shaft. The surface preparation level is preferably ISO Sa 2.5 or higher.

[0038] In the corrosion-resistant coating structure 10 according to the first embodiment, the zinc-rich coating layer 18 is typically formed by painting to a dry film thickness of 10 μm or more, preferably 15 to 100 μm. The zinc-rich paint can be applied by commonly used methods, such as air spraying, airless spraying, or brushing. Suitable zinc-rich paints include organic zinc-rich paints containing an epoxy resin binder and zinc powder, and inorganic zinc-rich paints containing an inorganic binder and zinc powder. Zinc powder may be used in combination with other metal powders that have sacrificial corrosion protection, such as aluminum powder. Conventional extender pigments, rust-preventive pigments, and / or coloring pigments can be mixed into the zinc-rich paint to the extent that the denseness of the coating is not impaired. Examples of extender pigments that can be used include silica powder, barium sulfate, calcium carbonate, talc, kaolin, and clay. Examples of rust-preventive pigments and color pigments that can be used include titanium oxide, iron phosphide, MIO, lead cyanamide, zinc chromate, zinc phosphate, calcium phosphate, barium metaborate, zinc molybdate, aluminum molybdate, red iron oxide, cyanine color pigments, carbon black, rutile powder, and zircon powder.

[0039] When inorganic zinc-rich paint is used as the zinc-rich paint, if the coating film formed is thick, it will be porous, so if necessary, before forming the next step of the epoxy primer layer or anticorrosion layer, it is desirable to add a step of coating the zinc-rich coating film in advance with a paint diluted with a large amount of solvent, called a "mist coat," to seal the pores in the porous areas. As the mist coat, paints such as the epoxy primer mentioned above can usually be diluted to a sufficiently low viscosity and these are usually sprayed onto the thick zinc-rich coating film with a sprayer.

[0040] The corrosion-resistant metal 16 may be used in the corrosion-resistant coating structure 10 according to the first embodiment in a state where it is used as a clad steel clad material. In this case, a clad steel having the same metal as the metal substrate 12 as its base material (main steel portion) and the corrosion-resistant metal 16 as its clad material is used, and the base material portion of the clad steel is attached to the metal substrate 12 by butt welding to form the corrosion-resistant coating structure 10 according to the first embodiment shown in FIG. 1 . The thickness of the clad steel clad material used as a clad steel clad material is typically 1.5 mm or more. Alternatively, a clad steel having the same metal as the metal substrate 12 as its base material and the corrosion-resistant metal 16 as its clad material may be used, and the base material of the clad steel may be attached to the corrosion-protected surface 14 of the metal substrate 12 by fillet welding, thereby attaching the corrosion-resistant metal 16 to the metal substrate 12. In this case, however, the corrosion-resistant metal 16 is attached via the base material of the clad steel to the corrosion-protected surface 14 of the metal substrate 12. A primer coating layer 20 is also provided on the fillet welded portion.

[0041] (2) Second embodiment FIG. 2 is a cross-sectional view that schematically shows a corrosion-resistant coating structure 30 according to a second embodiment of the present invention.

[0042] As described above in "(1) First Embodiment," from the viewpoint of further improving corrosion resistance, it is preferable to further provide a corrosion-resistant layer 32 on the primer coating layer 20. The corrosion-resistant coating structure 30 according to the second embodiment of the present invention is an embodiment in which a corrosion-resistant layer 32 is further provided on the primer coating layer 20 of the corrosion-resistant coating structure 10 according to the first embodiment. In the corrosion-resistant coating structure 30 according to the second embodiment, a corrosion-resistant layer 32 is also provided on the zinc-rich coating layer 18 of the corrosion-resistant coating structure 10 according to the first embodiment. In other respects, the corrosion-resistant coating structure 30 according to the second embodiment is similar to the corrosion-resistant coating structure 10 according to the first embodiment. Therefore, in the corrosion-resistant coating structure 30 according to the second embodiment, the same components as those in the corrosion-resistant coating structure 10 according to the first embodiment are designated by the same reference numerals, and a description of these same components will generally be omitted.

[0043] The corrosion-resistant coating structure 30 according to the second embodiment includes a corrosion-resistant metal 16 that coats a portion of the corrosion-protected surface 14 of the metal substrate 12, a zinc-rich coating layer 18 that coats another portion of the corrosion-protected surface 14 of the metal substrate 12, a primer coating layer 20, and a corrosion-resistant layer 32. A separation region 14A is provided on the corrosion-protected surface 14 between the corrosion-resistant metal 16 and the zinc-rich coating layer 18 to separate them, and the primer coating layer 20 is provided to cover the entire surface of the separation region 14A. The primer coating layer 20 may not only cover the entire surface of the separation region 14A, but may also extend over at least a portion of the surface of the corrosion-resistant metal 16. In the corrosion-resistant coating structure 30 according to the second embodiment, the primer coating layer 20 is provided to extend over at least a portion of the surface of the corrosion-resistant metal 16, as shown in FIG. 2 .

[0044] In the corrosion-protective coating structure 30 according to the second embodiment, a corrosion-protective layer 32 is further provided on the primer coating layer 20 and the zinc-rich coating layer 18 that are provided on the surface 14 to be protected from corrosion of the metal substrate 12. Therefore, the corrosion-protective coating structure 30 according to the second embodiment has improved corrosion protection performance compared to the corrosion-protective coating structure 10 according to the first embodiment.

[0045] The corrosion-resistant layer 32 is typically coated with epoxy resin paint, thick-film epoxy resin coating, epoxy glass flake paint, ultra-thick epoxy resin coating, ultra-thick polyurethane resin coating, mortar, or corrosion-resistant tape combining plastic film, rubber, or metal foil with a pressure-sensitive adhesive layer, typically at a thickness of 200 μm or more, preferably 300 μm or more. Pinholes can occur in paint, but to ensure a thickness that is less susceptible to pinholes, the thickness is typically 200 μm or more. To further reduce pinhole resistance, applying the same thickness in two or more coats is effective, reducing the likelihood of pinholes penetrating the film thickness. A thickness of 300 μm or more further reduces moisture penetration and improves corrosion resistance.

[0046] The portion of the corrosion-resistant layer 32 that is coated with the zinc-rich coating layer 18 may be made to have specifications consisting of at least one of epoxy resin paint, polyurethane resin paint, silicone acrylic resin paint, fluororesin paint, glass flake-containing epoxy resin paint, modified epoxy resin paint, and ultra-thick film epoxy resin paint, and the corrosion-resistant specification that combines the above specifications for the corrosion-resistant layer 32 with the zinc-rich coating layer 18 is a corrosion-resistant specification called heavy-duty corrosion-resistant paint.

[0047] A weather-resistant layer may be further provided on the anticorrosion layer 32, and as this weather-resistant layer, for example, at least one of polyurethane resin paint, silicone acrylic resin paint, and fluororesin paint can be used.

[0048] (3) Third embodiment FIG. 3 is a cross-sectional view schematically showing a corrosion-resistant coating structure 40 according to a third embodiment of the present invention.

[0049] A corrosion-resistant coating structure 40 according to the third embodiment is a corrosion-resistant coating structure that protects a clad steel base material 44 of clad steel 42 from corrosion. The clad steel base material 44 is the main steel portion of the clad steel 42. A corrosion-protected surface 48 of the clad steel base material 44 is divided into a corrosion-protected surface 48B that is covered with a clad steel cladding material 46 that is a corrosion-resistant metal, a corrosion-protected surface 48C that is the corrosion-protected surface 48 on the opposite side of the corrosion-protected surface 48B, and a corrosion-protected surface 48D that is the corrosion-protected surface 48 at an edge surface 42X that is a cut surface in the thickness direction of an end of the clad steel 42.

[0050] The primer coating layer 20a used in the corrosion-resistant coating structure 40 of this third embodiment is made of the same material as the primer coating layer 20 used in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments, the zinc-rich coating layer 18a used in the corrosion-resistant coating structure 40 of this third embodiment is made of the same material as the zinc-rich coating layer 18 used in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments, and the corrosion-resistant layer 32a used in the corrosion-resistant coating structure 40 of this third embodiment is made of the same material as the corrosion-resistant layer 32 used in the corrosion-resistant coating structure 30 of the second embodiment, so as a general rule, explanations of these will be omitted.

[0051] Clad steel 42 is a component formed by metallurgically joining clad steel clad steel clad material 46 to clad steel base material 44, and clad steel clad steel 46, which is a corrosion-resistant metal, is joined so as to cover the entire surface of corrosion-protected surface 48B, which is one surface of clad steel base material 44, which is the metal substrate to be protected from corrosion, and corrosion-protected surface 48B is protected from corrosion by clad steel clad steel 46, which is a corrosion-resistant metal.

[0052] The material of the clad steel base material 44 of the clad steel 42 can be the same as the material of the metal substrate 12 to be protected from corrosion in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments, and the material of the clad steel clad material 46 of the clad steel 42 can be the same as the material of the corrosion-resistant metal 16 in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments.

[0053] A corrosion-protected surface 48C, which is the surface of the clad steel base material 44 opposite to the corrosion-protected surface 48B of the clad steel base material 44 protected from corrosion by the clad steel clad material 46, which is a corrosion-resistant metal, is provided with a zinc-rich coating layer 18a to protect it from corrosion.

[0054] 3, a separation region 48A is provided between the clad steel cladding material 46, which is a corrosion-resistant metal, and the zinc-rich coating layer 18a to spatially separate them. The separation region 48A coincides with the corrosion-protected surface 48D, which is the corrosion-protected surface 48 on the edge surface 42X, which is a cut surface in the thickness direction of the end of the clad steel 42. Since a separation region 48A is provided to separate the clad steel clad material 46, which is a corrosion-resistant metal, from the zinc-rich coating layer 18a, even if welding is performed on the clad steel clad material 46 to attach other components, etc., the heat from the welding is not easily transmitted to the zinc-rich coating layer 18a, and melting of the zinc in the zinc-rich coating layer 18a is suppressed.Furthermore, even if the zinc in the zinc-rich coating layer 18a melts, the provision of the separation region 48A prevents it from coming into contact with the clad steel clad material 46, which is a corrosion-resistant metal.Therefore, in the corrosion-resistant coating structure 40 of this third embodiment, even if welding is performed on the clad steel clad material 46, zinc embrittlement cracking of the clad steel clad material 46, which is a corrosion-resistant metal, is suppressed.

[0055] However, because neither the corrosion-resistant clad steel cladding material 46 nor the zinc-rich coating layer 18a is provided in this separation region 48A, there is concern about corrosion of the clad steel base material 44 in the separation region 48A (corrosion-protected surface 48D). For this reason, in the corrosion-protective coating structure 40 according to the third embodiment, a primer coating layer 20a is provided to cover the entire surface of the separation region 48A (corrosion-protected surface 48D). In addition, to further improve corrosion resistance, a corrosion-protective layer 32a is further provided on the primer coating layer 20a.

[0056] Specifically, the primer coating layer 20a is provided over the entire edge surface 42X, which is a cut surface in the thickness direction of the end of the clad steel 42. The primer coating layer 20a is provided not only in the separation region 48A of the edge surface 42X but also in the portion of the edge surface 42X where the clad steel clad material 46 is located, ensuring that the primer coating layer 20a covers the entire separation region 48A of the edge surface 42X. The corrosion-resistant layer 32a covers the entire surface of the primer coating layer 20a and also the entire surface of the zinc-rich coating layer 18a, further improving corrosion resistance. In addition, the clad steel clad material 46 is a corrosion-resistant metal and often has an inactive surface, but by applying a primer coating layer 20a to the entire edge surface 42X and covering the portion of the clad steel clad material 46 on the edge surface 42X with the primer coating layer 20a, the corrosion protection layer 32a applied to the edge surface 42X will not come into direct contact with the clad steel clad material 46, and the adhesion of the corrosion protection layer 32a will also be improved.

[0057] Of the portions of the corrosion-resistant layer 32a, the portion covering the entire surface of the zinc-rich coating layer 18a may be made of at least one of epoxy resin paint, polyurethane resin paint, silicone acrylic resin paint, fluororesin paint, glass flake-containing epoxy resin paint, modified epoxy resin paint, and ultra-thick film epoxy resin paint.In this case, the portion of the corrosion-resistant layer 32a covering the entire surface of the zinc-rich coating layer 18a will have a corrosion-resistant specification called heavy-duty corrosion-resistant paint.

[0058] (4) Fourth embodiment FIG. 4 is a cross-sectional view that schematically shows a corrosion-resistant coating structure 50 according to a fourth embodiment of the present invention.

[0059] Similar to the corrosion-resistant coating structure 40 according to the third embodiment, the corrosion-resistant coating structure 50 according to the fourth embodiment is a corrosion-resistant coating structure that protects a clad steel base material 44 of clad steel 42 from corrosion. Similar to the corrosion-resistant coating structure 40 according to the third embodiment, the corrosion-protected surface 48 of the clad steel base material 44 is divided into a corrosion-protected surface 48B covered with a clad steel cladding material 46 that is a corrosion-resistant metal, a corrosion-protected surface 48C that is the corrosion-protected surface 48 opposite to the corrosion-protected surface 48B, and a corrosion-protected surface 48D that is the corrosion-protected surface 48 at an edge surface 42X that is a cut surface in the thickness direction of an end of the clad steel 42. However, the corrosion-protective coating structure 50 according to the fourth embodiment is a corrosion-protective structure that further stabilizes the corrosion protection structure, particularly at the edge surface 42X.

[0060] The primer coating layer 20b used in the corrosion-resistant coating structure 50 of this fourth embodiment is made of the same material as the primer coating layer 20 used in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments, the zinc-rich coating layer 18b used in the corrosion-resistant coating structure 50 of this fourth embodiment is made of the same material as the zinc-rich coating layer 18 used in the corrosion-resistant coating structures 10 and 30 of the first and second embodiments, and the corrosion-resistant layer 32b used in the corrosion-resistant coating structure 50 of this fourth embodiment is made of the same material as the corrosion-resistant layer 32 used in the corrosion-resistant coating structure 30 of the second embodiment, so as a general rule, explanations of these will be omitted.

[0061] Furthermore, since the clad steel 42 that is the target of the corrosion-resistant coating structure 50 of this fourth embodiment is the same as the clad steel 42 that is the target of the corrosion-resistant coating structure 40 of the third embodiment, as a general rule, an explanation of the clad steel 42 itself will be omitted.

[0062] In the corrosion-resistant coating structure 50 according to the fourth embodiment, as shown in FIG. 4, the corrosion-protected surface 48B of the clad steel base material 44 is covered with the clad steel cladding material 46 and protected from corrosion, and the corrosion-protected surface 48C of the clad steel base material 44 opposite the corrosion-protected surface 48B is covered with the heavy-duty corrosion-protective coating 52 and protected from corrosion.

[0063] The heavy-duty corrosion-resistant coating 52 is a corrosion-resistant specification in which a corrosion-resistant layer 54 made of at least one of epoxy resin paint, polyurethane resin paint, silicone acrylic resin paint, fluororesin paint, glass flake-containing epoxy resin paint, modified epoxy resin paint, and ultra-thick film epoxy resin paint is applied to cover the entire surface of the zinc-rich coating layer 18b provided on the corrosion-protected surface 48C.

[0064] 4, in the corrosion-resistant coating structure 50 according to the fourth embodiment, a primer coating layer 20b is provided centered on the edge surface 42X of the clad steel 42, with a portion of the primer coating layer 20b extending over the heavy-duty corrosion-resistant coating 52 and the edge region of the clad steel clad material 46, and a corrosion-resistant layer 32b is provided on the primer coating layer 20b. As a result, the primer coating layer 20b and the corrosion-resistant layer 32b are provided not only on the edge surface 42X but also on the corrosion-protected surfaces 48B and 48C, making it difficult for moisture and corrosion-accelerating substances to penetrate the edge surface 42X and also preventing the heavy-duty corrosion-resistant coating 52 from peeling off from the edge (edge ​​surface 42X), resulting in a more stable corrosion-resistant structure for the corrosion-resistant coating structure 50 according to the fourth embodiment.

[0065] Furthermore, in the corrosion-resistant coating structure 50 according to the fourth embodiment, the corrosion-resistant layer 32b is provided on the primer coating layer 20b, so that the corrosion-resistant layer 32b does not come into direct contact with the clad steel clad material 46, which is a corrosion-resistant metal and often has an inactive surface, and the adhesion of the corrosion-resistant layer 32b is also good.

[0066] (5) Examples of application of the present invention to specific structures and components Examples of application of the present invention to specific structures and components will be described below, but the examples shown here are merely examples to which the present invention can be applied, and the application of the present invention is not limited to the examples shown here.

[0067] Fig. 5 is a vertical cross-sectional view showing a box girder 62 of a box girder bridge 60 to which a corrosion-resistant coating structure 40 according to a third embodiment is applied, and Fig. 6 is a side view showing the box girder bridge 60 as viewed from the side (perpendicular to the bridge axis). Although Fig. 5 and Fig. 6 do not clearly show the corrosion-resistant coating structure 40, the corrosion-resistant coating structure 40 (see Fig. 3) is provided on a portion including the edge surface 42X of the clad steel 42 that constitutes the bottom plate 62A and the web 62B. In Fig. 5, reference numeral 210 denotes a precast PC deck slab, and reference numeral 212 denotes an asphalt pavement.

[0068] As shown in Figure 6, a bearing 300 is placed on the top of a pier 200, the end of a box girder 62 rests on the bearing 300, and a precast PC deck 210 is placed on the box girder 62, thereby forming a box girder bridge 60. An expansion joint 220 is placed between the precast PC decks 210 above the pier 200 (above the space between the ends of adjacent box girders 62 in the bridge axis direction). If the water-stopping components of the expansion joint 220 are damaged or deteriorated, or if the expansion joint 220 is a drainage type expansion joint, corrosion-promoting substances such as moisture and salt will flow from above to below through the expansion joint 220, placing the edge surface of the box girder 62 (edge ​​surface 42X of the clad steel 42) in a severely corrosive environment.

[0069] As described above, the box girder 62 of the box girder bridge 60 uses clad steel 42 for the bottom plate 62A and web 62B, and within the clad steel 42, the clad steel clad material 46, which is a corrosion-resistant metal, faces outward and the clad steel base material 44 faces inward. A zinc-rich coating layer 18a is provided on the inner surface of the clad steel base material 44 (the surface facing the inside of the box girder 62), a primer coating layer 20a is provided on the entire edge surface 42X, and a corrosion-resistant layer 32a is provided on the zinc-rich coating layer 18a and the primer coating layer 20a. The corrosion-resistant coating structure 40 of the third embodiment (see Figure 3) is applied to the portion of the clad steel 42, including the edge surface 42X.

[0070] In addition, although not shown, a zinc-rich coating layer 18a is provided on the surfaces (surfaces facing the inside of the box girder 62) of the components provided inside the box girder 62, namely the bottom plate vertical rib 62A1, horizontal rib 62C, upper flange 62D, upper flange tip vertical rib 62D1, and vertical stiffener 62E, and a corrosion-resistant layer 32a is provided on top of that.

[0071] 7 is a half-sectional view schematically showing a support structure 70 to which the corrosion-resistant coating structure 40 according to the third embodiment is applied, with the left side of the center line being a side view seen from a direction perpendicular to the bridge axis, and the right side of the center line being a vertical section seen from a direction perpendicular to the bridge axis. Although the corrosion-resistant coating structure 40 is not clearly shown in FIG. 7, the corrosion-resistant coating structure 40 (see FIG. 3) is applied to a portion of the support structure 70, including the edge surfaces that are the inner circumferential surfaces of the bolt through holes 62A2 and 62A3 provided in the bottom plate 62A (bottom plate made of clad steel 42) of the box girder 62.

[0072] The bearing structure 70 comprises a bearing portion 300 provided at the top of the pier 200 and a bottom joint portion 62X of the bottom plate 62A (bottom plate made of clad steel 42) of the box girder 62 of the box girder bridge 60, which comes into contact with the bearing portion 300. The bearing portion 300 comprises members that transmit the load transmitted from the box girder 62, which is the superstructure of the box girder bridge 60, to the pier 200, which is the substructure of the box girder bridge 60, and is located between the box girder 62 and the pier 200. The bearing portion 300 comprises, in order from the side closest to the top of the pier 200, a base plate 302, a bearing body 304, and a sole plate 306. The base plate 302, which is the lowest of the members constituting the bearing portion 300, is fixed to the top of the pier 200 by anchors 302A.

[0073] The sole plate 306 of the bearing portion 300 is in direct contact with the underside joint portion 62X of the bottom plate 62A (bottom plate made of clad steel 42) of the box girder 62, but the sole plate 306 is also formed of clad steel 42a, and the clad steel clad material 46a of the sole plate 306 is in direct contact with the clad steel clad material 46 of the clad steel 42 that forms the bottom plate 62A of the box girder 62. The clad steel 42a that forms the sole plate 306 is made of a clad steel base material 44a and a clad steel clad material 46a, but is made of the same material as the clad steel 42 in the third embodiment (the clad steel made of the clad steel base material 44 and the clad steel clad material 46), and the clad steel clad material 46a of the clad steel 42a that forms the sole plate 306 is a corrosion-resistant metal made of the same material as the clad steel clad material 46 of the clad steel 42 that forms the bottom plate 62A of the box girder 62. From the viewpoint of preventing galvanic corrosion, it is preferable that the material of the clad steel clad material 46a of the clad steel 42a that forms the sole plate 306 be the same as the material of the clad steel clad material 46 of the clad steel 42 that forms the bottom plate 62A of the box girder 62, as in this example (the example shown in Figure 7).

[0074] In the support structure 70, through holes 62A2 and 62A3 for bolts are provided in the bottom plate 62A (a bottom plate made of clad steel 42) of the box girder 62, and through holes 306A and 306B are also provided in the sole plate 306 provided directly below the bottom plate 62A of the box girder 62 at positions corresponding to the through holes 62A2 and 62A3 in the bottom plate of the box girder 62. The shank of the sole plate mounting bolt 308 is inserted through the through hole 62A2, and the head of the sole plate mounting bolt 308 engages with the upper surface of the part of the through hole 306A with a larger diameter, and the shank of the set bolt 310 is inserted through and screwed into the through holes 62A3 and 306B, connecting the box girder 62 and the support part 300.

[0075] In the support structure 70, the corrosion-resistant coating structure 40 (see FIG. 3) is applied to the area including the edge surface, which is the inner circumferential surface of the bolt through holes 62A2, 62A3 provided in the bottom plate 62A (bottom plate made of clad steel 42) of the box girder 62. Specifically, the main part of the box girder 62 of the box girder bridge 60, including the outer surface portion, is made of clad steel 42. Of the clad steel 42, the clad steel clad material 46, which is a corrosion-resistant metal, faces outward, and the clad steel base material 44 faces inward. The inner surface of the clad steel base material 44 ( A zinc-rich coating layer 18a is provided on the box girder 62 (the surface facing the inside), a primer coating layer 20a is provided on the entire edge surface, which is the inner surface of the bolt through holes 62A2 and 62A3 of the bottom plate 62A (a bottom plate made of clad steel 42), and a corrosion-resistant layer 32a is provided on the zinc-rich coating layer 18a and the primer coating layer 20a, and the corrosion-resistant coating structure 40 of the third embodiment (see Figure 3) is applied to the area including the edge surface, which is the inner surface of the bolt through holes 62A2 and 62A3.

[0076] 8A and 8B are diagrams showing a state in which plate-shaped clad steel 42 to which corrosion-resistant coating structure 40 according to the third embodiment is applied being lifted, and a diagram showing a lifting piece 80 used for the lifting, where (A) is a front view showing a state in which plate-shaped clad steel 42 is being lifted, (B) is a side view showing a state in which plate-shaped clad steel 42 is being lifted, and (C) is an enlarged view showing a state in which lifting piece 80 is used for the lifting. In Fig. 8, corrosion-resistant coating structure 40 (see Fig. 3) is applied to a portion of plate-shaped clad steel 42 to which lifting piece 80 is attached, including edge surface 42X.

[0077] The plate-shaped clad steel 42 is the same as the clad steel 42 used in the corrosion-resistant coating structure 40 of the third embodiment, and consists of a clad steel base material 44 and a clad steel clad material 46, with the clad steel clad material 46 being a corrosion-resistant metal.

[0078] 8(A) and (B), the plate-shaped clad steel 42 is a substantially square clad steel plate, and two hanging pieces 80 are attached by welding, spaced apart, near the end of one side (near the edge surface 42X) to the surface of the clad steel clad material 46 of the clad steel 42. A wire 82 is inserted into the through holes 80A of the two attached hanging pieces 80 to connect them, and the clad steel 42 is lifted up by a crane (not shown).

[0079] A zinc-rich coating layer 18a is provided on the surface of the clad steel base material 44 of the plate-shaped clad steel 42, a primer coating layer 20a is provided on the entire edge surface 42X of the plate-shaped clad steel 42, and a corrosion-resistant layer 32a is provided on the zinc-rich coating layer 18a and the primer coating layer 20a, and a corrosion-resistant coating structure 40 (see Figure 3) related to the third embodiment is applied to the area including the edge surface 42X of the plate-shaped clad steel 42.

[0080] Two hanging pieces 80 are attached by welding to the surface of the clad steel clad material 46 of the plate-shaped clad steel 42, but a separation area 48A (see Figure 3) is provided to separate the clad steel clad material 46, which is a corrosion-resistant metal, from the zinc-rich coating layer 18a.Therefore, even if welding is performed to attach the two hanging pieces 80 to the surface of the clad steel clad material 46, the heat from the welding is not easily transmitted to the zinc-rich coating layer 18a, and the melting of the zinc in the zinc-rich coating layer 18a is suppressed.Furthermore, even if the zinc in the zinc-rich coating layer 18a melts, the separation area 48A (see Figure 3) is provided to prevent it from coming into contact with the clad steel clad material 46, which is a corrosion-resistant metal, and thus the clad steel clad material 46, which is a corrosion-resistant metal, is suppressed from experiencing zinc embrittlement cracking.

[0081] 9 is a vertical cross-sectional view schematically showing a state in which a drainage pipe 90 is attached by fillet welding 92 to a bottom plate 62A of a box girder 62 of a box girder bridge 60 to which the corrosion-resistant coating structure 40 according to the third embodiment is applied. In FIG. 9, the corrosion-resistant coating structure 40 (see FIG. 3) is applied to a region including the edge surface, which is the inner circumferential surface of a through hole 62A4 for drainage provided in the bottom plate 62A of the box girder 62 (a bottom plate made of clad steel 42).

[0082] The drain pipe 90 is made of, for example, stainless steel, a corrosion-resistant metal, and is attached to the clad steel clad material 46 of the clad steel 42, which is the bottom plate 62A of the box girder 62, by fillet welding 92. When the materials of the drain pipe 90 and the clad steel clad material 46 of the clad steel 42 are stainless steel, from the viewpoint of preventing bimetallic corrosion, it is preferable that the difference in pitting corrosion index of these stainless steels be 6 or less. Also, from the viewpoint of preventing bimetallic corrosion, it is more preferable that the material of the drain pipe 90 be the same as the clad steel clad material 46 to which it is welded.

[0083] As shown in FIG. 9, the corrosion-resistant coating structure 40 (see FIG. 3) is applied to a portion including the edge surface, which is the inner peripheral surface of the through-hole 62A4 for drainage provided in the bottom plate 62A (bottom plate made of clad steel 42) of the box girder 62. Specifically, the main portion of the box girder 62 of the box girder bridge 60, including the outer surface portion, is made of clad steel 42. Of the portions of the clad steel 42, the clad steel clad material 46, which is a corrosion-resistant metal, faces outward, and the clad steel base material 44 faces inward. A zinc-rich coating layer 18a is provided on the surface (the surface facing the inside of the box girder 62), a primer coating layer 20a is provided on the entire edge surface, which is the inner surface of the drainage through hole 62A4 of the bottom plate 62A (a bottom plate made of clad steel 42), and a corrosion-resistant layer 32a is provided on the zinc-rich coating layer 18a and the primer coating layer 20a, and the corrosion-resistant coating structure 40 of the third embodiment (see Figure 3) is applied to the area including the edge surface, which is the inner surface of the drainage through hole 62A4.

[0084] As shown in Figure 9, a drain pipe 90 is attached to the surface of the clad steel clad material 46 of the clad steel 42 by fillet weld 92 so as to communicate with the drainage through hole 62A4. However, a separation area 48A is provided to separate the clad steel clad material 46, which is a corrosion-resistant metal, from the zinc-rich coating layer 18a. Therefore, even if welding is performed to attach the drain pipe 90 to the surface of the clad steel clad material 46, the heat from the welding is not easily transmitted to the zinc-rich coating layer 18a, and melting of the zinc in the zinc-rich coating layer 18a is suppressed. Furthermore, even if the zinc in the zinc-rich coating layer 18a melts, the separation area 48A prevents it from coming into contact with the clad steel clad material 46, which is a corrosion-resistant metal. This prevents the clad steel clad material 46, which is a corrosion-resistant metal, from developing zinc embrittlement cracking.

[0085] (6) Supplementary information In the corrosion-resistant coating structures according to the first to fourth embodiments, a metal spray layer containing zinc may be used in place of the zinc-rich coating layers 18, 18a, 18b.

[0086] Furthermore, when using clad steel (clad steel using a corrosion-resistant metal as a cladding material) in implementing the present invention, it is preferable to use rolled clad steel because it is easy to manufacture large plates and is cheaper than explosively bonded clad steel or build-up clad steel. [Explanation of symbols]

[0087] 10, 30, 40, 50...Corrosion-resistant coating structure 12...Metal base material 14...Surface to be protected from corrosion 14A…Separation area 16...Corrosion-resistant metal 18, 18a, 18b...Zinc-rich coating layer 20, 20a, 20b...Primer coating layer 32, 32a, 32b, 54...Corrosion protection layer 42, 42a...Clad steel 42X...Edge 44, 44a... Clad steel base material 46, 46a...Clad steel clad material 48, 48B, 48C, 48D…corrosion-protected surface 48A…Separation area 52...Heavy-duty anti-corrosion coating 60…Box girder bridge 62...Box girder 62A…Bottom plate 62A1...Bottom plate vertical rib 62A2, 62A3, 62A4...Through hole 62B…Web 62C...Horizontal rib 62D...Top flange 62D1...Vertical rib at the tip of the upper flange 62E…Vertical stiffener 62X…Bottom surface joint part 70...Support structure 80...Hanging piece 80A...Through hole 82...Wire 90...Drain pipe 92...Fill weld 200...Bridge pier 210...Precast PC deck 212...Asphalt pavement 220…Expansion device 300...Support part 302...Base plate 302A...Anchor 304…Support body 306...sole plate 306A, 306B...Through hole 308...Sole plate mounting bolt 310...Set bolt

Claims

1. On the surface of the metal substrate to be protected from corrosion, a corrosion-resistant metal covering a first region that is a part of the surface to be protected from corrosion; a zinc-rich coating layer containing zinc dust that covers a second region that is a part of the surface to be protected that is different from the first region; a third region between the first region and the second region, the third region being free from the corrosion-resistant metal and the zinc-rich coating layer; A corrosion-resistant coating structure comprising: A corrosion-resistant coating structure comprising a primer coating layer not containing zinc dust, the primer coating layer being provided so as to cover the third region.

2. 2. The corrosion-resistant coating structure according to claim 1, wherein the primer coating layer also extends over at least a portion of the surface of the corrosion-resistant metal.

3. 2. The corrosion-resistant coating structure according to claim 1, wherein the corrosion-resistant metal that coats a portion of the surface to be protected from corrosion is any one of austenitic stainless steel, duplex stainless steel, and nickel alloy.

4. 2. The corrosion-resistant coating structure according to claim 1, wherein the primer coating layer and the zinc-rich coating layer are coated with a corrosion-resistant layer, and the corrosion-resistant layer is coated with any one of epoxy resin paint, thick-film epoxy resin paint, epoxy glass flake paint, ultra-thick-film epoxy resin coating, ultra-thick-film polyurethane resin coating, mortar, plastic film, rubber, and corrosion-resistant tape combining metal foil with a pressure-sensitive adhesive layer, to a film thickness of 200 μm or more.

5. 5. The corrosion-resistant coating structure according to claim 4, further comprising a weather-resistant layer provided on the corrosion-resistant layer, the weather-resistant layer being made of at least one of polyurethane resin paint, silicone acrylic resin paint, and fluororesin paint.

6. 2. The corrosion-resistant coating structure according to claim 1, wherein a metal spray layer containing zinc is used instead of the zinc-rich coating layer.

7. 7. The corrosion-resistant coating structure according to claim 1, wherein the corrosion-resistant metal is a clad steel clad material formed by metallurgically joining a clad steel clad material to cover the entire surface of one surface of the clad steel base material, the first region is the one surface of the clad steel base material, the zinc-rich coating layer covers the other surface of the clad steel base material opposite to the clad steel clad material, the second region is the other surface of the clad steel base material, and the third region is the surface of the clad steel base material in the thickness direction formed by cutting or milling in the thickness direction across both the clad steel base material and the clad steel clad material.

8. 8. The corrosion-resistant coating structure according to claim 7, wherein the surface in the thickness direction is an edge surface of the clad steel consisting of the clad steel base material and the clad material.

9. 8. The corrosion-resistant coating structure according to claim 7, wherein the thickness-wise surface is an inner surface of a through hole in the thickness direction of the clad steel, which is made up of the clad steel base material and the clad material.

10. A structure comprising the corrosion-resistant coating structure according to any one of claims 1 to 6.

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