WO2003066934A1

WO2003066934A1 - Corrosion-resistant structure of metal material and method for surface treatment of metal material

Info

Publication number: WO2003066934A1
Application number: PCT/JP2003/001169
Authority: WO
Inventors: Tadashi Shinohara; Atsushi Ueda; Tamao HAYAKAWA
Original assignee: Center For Advanced Science And Technology Incubation, Ltd.
Priority date: 2002-02-08
Filing date: 2003-02-05
Publication date: 2003-08-14
Also published as: AU2003207220A1; JP2003231973A; JP4088078B2

Abstract

A corrosion-resistant structure of a metal material, characterized in that it comprises a metal material and, formed thereon, a coating layer comprising titanium oxide and an electroconductive metal oxide. In a preferred embodiment, said electroconductive metal oxide is an Sn oxide. A method for treating a surface of a metal material, wherein the surface of the metal material is coated with an SnOx · TiO2 sol and then is fired, for example, at 150˚C, to form a corrosion-resistant structure. The corrosion-resistant structure can be formed through a firing at a relatively low temperature, and has advantageous corrosion-resistance effect, and further exhibits the persistence of the corrosion-resistance effect even after a light is cut off.

Description

Description Corrosion protection structure for metal materials and surface treatment method for metal materials

The present invention relates to a corrosion prevention structure for a metal material and a surface treatment method for the metal material. The anticorrosion structure and the surface treatment method according to the present invention are preferably used for anticorrosion of an outer wall of a large structure such as a building or a bridge. Background art

When light is applied to the n-type semiconductor T i 0 ₂ , the anode current increases and the potential becomes lower accordingly. Moreover, since the anodic reaction on the surface is the oxidation of water, it does not dissolve or deteriorate itself. Therefore, research and development of a force-sword anticorrosion method using a TiO ₂ coating has been attempted by using this. However, the T i 0 ₂ only coatings, anticorrosion effect as capable of withstanding practical use can not be obtained. For example, in order to obtain the anticorrosive effect was sustained by T i O ₂ film layer is indispensable light irradiation, be formed much trouble T i 0 ₂ coating layer, progresses corrosion during the night light irradiation can not be obtained There is a problem of doing it.

Japanese Patent Application Laid-Open No. 117-16844 discloses that at least one metal element selected from the group consisting of Fe, V, and Cu is provided as a lower layer on the surface of a metal material in a titanium oxide film. A technique is described in which a first coating layer containing 5 to 20% is contained, and a second coating layer containing titanium oxide is provided thereon, even if light is blocked. The anticorrosion effect is maintained and high corrosion resistance is ensured. Further, as other techniques Una by expressing potential Takashika delay characteristic, T i 0 ₂ in the plus F e 2 0 _{3, 3-layer} coated between T i 0 ₂ coating layer and the underlying metal Some have a structure. Japanese Unexamined Patent Publication No. 2000-26239 describes an anticorrosion structure including a titanium oxide film and a conductive film laminated so as to be in contact with the main surface of the film. When electrons are generated in the coating when the coating is irradiated with light, the electrons are collected by the conductive coating and injected into the metal material through the conductive coating. Which are lower than the oxidation potential.

In each of these methods, two or more layers are formed on a substrate, and the number of film forming steps is increased accordingly. In addition, the baking temperature of the film provided on the base material is relatively high, and it is disadvantageous for practical use, considering that a film is formed on a large structure or the like on site.

The present invention provides an anticorrosion structure for a metal material and a surface treatment method for a metal material having a simple structure, yet having an advantageous anticorrosion effect and maintaining the anticorrosion effect even when light is blocked. The purpose is to do so.

Another object of the present invention is to carry out a baking treatment at a relatively low temperature, yet to provide an advantageous anticorrosion effect and to maintain the anticorrosion effect of a metal material even when light is blocked. And a method for surface treatment of a metal material. Disclosure of the invention

The technical means employed in the present invention is a corrosion prevention structure for a metal material, wherein a coating layer made of titanium oxide and a conductive metal oxide is formed on the surface of the metal material. By forming a coating layer composed of titanium oxide and a conductive metal oxide on the surface of a metal material, the anticorrosion effect of the metal is exhibited, and the anticorrosion effect is maintained even after light irradiation is blocked. I understand.

The conductive metal oxide employed in the present invention is preferably a Sn oxide Objects (e.g., tin oxide S n 0 ₂₎ is, in the present specification, the S n oxide, ITO (Indium Tin Oxide) are also included. As the conductive metal oxide other than the Sn oxide, an Fe oxide or another conductive metal oxide may be used.

The metal serving as the base material of the anticorrosion structure according to the present invention is not particularly limited, but preferred examples include stainless steel, iron, and aluminum. Further, the metal surface serving as the base material may be plated. For example, the base material may be a zinc-plated steel plate.

In a preferred example, the coating layer comprising the titanium oxide and the conductive metal oxide according to the present invention is produced by applying the metal oxide / titanium oxide sol to the surface of a metal material and firing the surface. You.

The method of applying the metal oxide / titanium oxide sol is not particularly limited, and dip coating, spray coating, spin coating, brush coating, or the like can be employed. However, considering the provision of anti-corrosion structures on relatively large structures such as buildings and bridges, the coating method using an airbrush or the like is advantageous. It is difficult to employ dip coating, which is commonly used in the conventional sol-gel method, for coating structures. In addition, the ordinary sol-gel method generally has a baking temperature of 200 ° C. to 400 ° C. or higher, which is a relatively high temperature. Not suitable for doing.

It is believed that the firing temperature may range from 100 ° C. to 350 ° C., but in one preferred range, the firing temperature is 100 ° C. (: to 200 ° C.). As is evident from the experimental examples described below, it was found that the coating formed by the low-temperature baking treatment exhibited an advantageous anticorrosion effect. Work can be performed relatively easily.

Formation of a coating layer comprising the titanium oxide and the conductive metal oxide according to the present invention. The film method is not limited to a method in which a sol solution is applied and baked, but may be a method such as a thermal spraying method, a CVD method, or a PVD method (including sputtering).

A titanium oxide film may be further formed on the film layer made of titanium oxide and the conductive metal oxide. The method of forming the titanium oxide film constituting the surface layer is not limited, and includes a method of applying a titanium oxide sol solution (spray coat or dip coating), a thermal spray method, a CVD method, a PVD method (including sputtering). And so on. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a change in a natural potential and a photopotential, and FIG. 2 is a diagram showing a change in a potential after holding a constant voltage (after holding at 600 mV for 30 minutes). BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described. A substrate coated with a film composed of titanium oxide and a conductive metal oxide is ITO glass having a size of 2 × 3 cm, a thickness of about 1 mm, and a surface having a particle size of 0.05 μππι. Polished stainless steel 304, which was puffed and finished with aluminum, was used. ITO glass was chosen as a comparison for stainless steel. Tin chloride _{(S n C l 2) 0.} 0 1 mo 1 in an electric furnace in air atmosphere, and baked for 30 minutes at 3 5 0 ° C, was ground in a mortar. To this was added 40 ml of H ₂ O, and 4 ml of solids 4 wt% Ti 0 ₂ sol 20 m 1 (Ti 0 ₂ content about 0.01 mo 1) was added. in stirring S n a mixture of oxides and T i O ₂ (hereinafter, referred to as S η θ χ · T i 0 2 sol) was prepared, which was used as a coating material.

Hot plate substrate on I TO glass, stainless 3 04 steel and heat, S n OX · T i 0 ₂ sol on the respective substrate using an airbrush Coated. Thereafter, a baking treatment was performed for 20 minutes in an air atmosphere at a predetermined temperature (150 ° C. to 250 ° C.). The prepared sample was left for 24 hours or more.

Electrochemical measurements were performed as follows: (1) To measure the polarization curve of the prepared sample in the dark and under light irradiation (sweep rate: 10 mV / 10 sec) and to confirm the reproducibility Then, it was reciprocated three times in the 喑 state (100 mV to 500 mV vs. SCE-10 mVZ 10 sec). (2) Potential nobleness To confirm the delay characteristics, after holding the constant potential in the 喑 state (60 OmV · 30 min), apply a constant current (1 μA / cm ² ) to the sample and measure the potential over time. The change was measured.

Figure 1 shows the zeta potential and photopotential of the prepared sample. The 喑 potential was about 1 374 024 mV for ITO glass and about 1 360 280 mV for stainless 304 steel. On the other hand, the photopotential dropped to about 182,733 mV for ITO glass and to 1,680,550 mV for stainless steel 304. This is well below the 400 mV required for stainless steel corrosion protection. The light potential when coated with only T i 0 ₂ sol stainless steel is about a 2 0 about 0 mV, for industrial sol was found to be advantageous added addition of S n OX. In addition, when going back and forth three times in the 喑 state, there was almost no change in the orbit, and the method of reproducing the orbit was also confirmed. As is clear from FIG. 1, in this experiment, the best results were obtained when the firing temperature was 200 ° C.

Figure 2 shows the change over time in the potential when a constant current is applied after holding the 喑 state constant potential. The substrate is stainless 304 steel. From this result, it was found that the coating of the Ti O ₂ sol to which SnO x was added (especially in the case of firing at 150 ° C.) also had the potential noble delay property. About 1 for 5 hours did not substantially change from the potential one 5 0 0 mV around, accumulated electrostatic load volume that is obtained by accumulating this result was approximately ^{5. 6 X 1 0- 2 CZ c} m2. This order is extremely large It is a thing. For example, the plus F e ₂ O ₃ to T i 0 ₂ described in the prior art, T i 0 In ₂ as was coated with three-layer structure between the coating layer and the underlying metal, also accumulated charge amount at the maximum was ^{1 · 2 X 1 0- 2 CZc} πι2. However even in sol 'gel method, 1. To obtain a 2 X 1 0- ² Bruno c m @ 2 is 1 0 coats - it is necessary for (Deitsubingu repeated firing 1 0 times). In the present invention, only one layer is applied, and the number of times of application is one, the amount of accumulated electric charge is large, and an advantageous effect is obtained as compared with the conventional one.

On the film coated with S n OX · T i O ₂ sol, further coated with T i O ₂ sol may be formed a three-layer structure. _{S ηθ X · T i 0 2} / T i 0 2 made of film, compared to S n O x · T i 0 2 alone film, the optical characteristics can be considered high.

As for the manufacturing method of the S n OX · T i 0 ₂ sols, such is limited to the above-les. For example, the S n C 1 _2, was dissolved in a small amount water added to HC 1, there was sufficiently dried the precipitate obtained was left by adding T i 0 ₂ sol solution, which in a ball mill May be crushed and suspended in water. Alternatively, S n (OH) ₂ may be used as a starting material.

The formation of S n OX · T i 0 ₂ alone film is not limited to by airbrush, for example, may be coated with a S n OX · T i 0 ₂ sol on a substrate using a brush, It does not exclude the sol-gel method. However, considering the provision of anticorrosion structures on relatively large structures such as buildings and bridges, the coating method using an airbrush is advantageous. In contrast, the conventional sol-gel method mainly employs dip coating, and it is difficult to employ this for structures. In addition, the sol-gel method generally has a baking temperature of 200 ° C. to 400 ° C. or higher, which is a relatively high temperature, and is not suitable for on-site coating work. It is. On the other hand, in the application using the air brush performed in this experiment, it is advantageous even if the firing temperature is 200 ° C or less. Effect was obtained.

ADVANTAGE OF THE INVENTION According to this invention, while having a simple structure and performing a baking process at a relatively low temperature, it has an advantageous anticorrosion effect, and the anticorrosion effect is maintained even in a state where light is blocked. The anticorrosion structure of the metal material and the method of surface treatment of the metal material can be obtained. Industrial applicability

INDUSTRIAL APPLICATION This invention can be used for corrosion prevention of the outer wall of large structures, such as a building and a bridge.

Claims

The scope of the claims

1. An anticorrosion structure for a metal material, wherein a coating layer made of titanium oxide and a conductive metal oxide is formed on the surface of the metal material.

2. The corrosion prevention structure for a metal material according to claim 1, wherein the conductive metal oxide contains a Sn oxide.

3. The anticorrosion structure for a metal material according to claim 1, wherein a titanium oxide film is further formed on the film layer made of the titanium oxide and the conductive metal oxide.

4. A method for treating a surface of a metal material, comprising forming a film layer made of titanium oxide and a conductive metal oxide on the surface of the metal material.

5. The metal according to claim 4, wherein the coating layer is produced by applying the conductive metal oxide / titanium oxide sol to a surface of a metal material and firing the surface. Material surface treatment method.

6. The surface treatment method for a metal material according to claim 4, wherein the conductive metal oxide contains a Sn oxide.

7. The method according to claim 4, wherein the firing temperature is from 100 ° C. to 350 ° C.

8. The surface treatment method for a metal material according to claim 7, wherein the firing temperature is from 100 ° C to 250 ° C.

9. The method of claim 8, wherein the firing temperature is from 150 ° C to 250 ° C.

10. The method according to claim 8, wherein the firing temperature is from 100 ° C to 200 ° C.

11. The method according to any one of claims 4 to 10, wherein a titanium oxide film is further formed on the film layer comprising the titanium oxide and the conductive metal oxide.