JP2001335913A - Spray coated member excellent in corrosion resistance and environment improving characteristic, its producing method and thermal spraying composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member deposited with a sprayed coating excellent in environment improving activity and in corrosion resistance and adhesion by suppressing the change from anatase TiO2(a-TiO2) into rutile TiO2(r-TiO2). SOLUTION: This sprayed-coated member excellent in corrosion resistance and environmental purifying characteristics is obtained by thermally spraying a composite thermal spraying material containing a metal or an alloy having potential electrochemically baser than that of steel and anatase type TiO2 powder under the thermal spraying condition in which the flying speed in a thermal spraying heat source is controlled to >=200 m/sec, and providing the surface of a base material made of steel or the like with a sprayed coating in which anatase type TiO2 particles are dispersed into a metal or an alloy having potential electrochemically baser than that of steel, and the producing method uses the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member formed by coating a steel base material surface with a thermal spray coating, particularly to a surface of a steel structure including a galvanized steel sheet, etc.
Excellent environmental purification under sunlight irradiation 1
The present invention relates to a member having a plurality of sprayed coatings formed thereon, a method of manufacturing the same, and a composite sprayed material used in carrying out the method. The thermal spray coating technology of the present invention can be applied not only to existing structures, but also to, for example, surface-treated steel materials or other metal, concrete, or mortar surfaces.

[0002]

[Prior Art] Thermal power plants, municipal solid waste incineration plants,
Fossil fuel combustion gas emitted from vehicles
A small amount of sulfur oxide (SO_x) Ah
Or nitrogen oxides (NO_x) And other harmful environmental pollutants
include. In recent years, the technology for removing these pollutants has been
Research has progressed, with some success,
Is out of the question, but that's not enough. Toriwa
Ke, NO _xThe degree of improvement was low,
With suspended particulate matter contained in gin exhaust gas
This is a major research topic for the future.

In this regard, in recent years, titanium dioxide (TiO 2)
Technical decomposition harmless of the NO _x by the photocatalyst action of ₂₎ is spotlighted. This is because the photocatalytic action of TiO ₂ is effective for purifying contaminated water, removing bad odors, and the like.
(For example, JP-A-8-99041, JP-A-8-103631 and the like)

[0004] As those utilizing titanium oxide, other, intended porous TiO ₂ was developed _(Japanese Patent Laid-Open No. 8-196903) to improve TiO ₂ photocatalysis, the durability of the TiO ₂ photocatalysis There are proposals such as Japanese Patent Application Laid-Open No. 9-276706 for the purpose of improvement, and these technologies are expected to greatly improve the environmental purification action.

Conventionally, as a method of using TiO ₂ having a photocatalytic action, a method of applying it as a paint to the surface of a building exposed to sunlight has been widespread. It is common to use the lamp together with the electric lamp.

In addition, paints containing TiO ₂ , sols and gel-like T
Instead of applying iO ₂ , there has been proposed a method of coating a TiO ₂ film on the surface of a building by spraying. However, this technique has the following various problems.

[0007]

[Problems to be solved by the invention] (1) TiO₂Powder spraying
In the anatase type TiO excellent in photocatalysis₂ 
(Hereafter simply, `` a-TiO<sub>2</sub>Abbreviated as ``)
When flying through a hot spray heat source,
TiO₂ (Hereafter simply referred to as `` r-TiO₂)
To achieve the objectives (prevention of environmental pollution).
Disappears. (2) Lower the thermal spraying heat source temperature, or use a large amount of a-TiO₂powder
The powder is put into a thermal spraying device, and the exposure temperature per powder particle
Lowering the degree of r-TiO₂There is also a way to suppress the change to
However, the formed film has good adhesion to the substrate and
Because the mutual bonding force of the particles constituting
The film easily peels off even with a slight impact or contact
Become like (3) Also, a-TiO as in (2) above₂Thermal spray coating is porous
When used in a natural environment, its pores pass through
Rainwater infiltrates into the interior. As a result, a-TiO ₂The coating is
Electrochemically noble potential with respect to steel structural substrate
Promotes corrosion of the steel substrate and increases the amount of red rust (for example,
α, β, γ ・ FeOOH, Fe₂O₃・ X H₂O)
The volume expands and a-TiO₂Breaks and peels the film from the bottom
There is a fear. And some of the red rust of the generated steel base is
A-TiO in a healthy state flowing down with rainwater₂Table of coating
Because it covers the surface and blocks sunlight,
Expect its action even if it has a catalytic function
You will not be able to do it. (4) a-TiO with excellent photocatalytic action₂Coating (spraying method, painting method)
 Even if this film is used in urban and heavy industrial areas,
Used on main roads that emit a large amount of automobile exhaust gas
And particulate solids contained in dust and exhaust gas
(Unburned carbon particles, incompletely burned fuel particles), etc.₂
Covers the surface of the film and blocks sunlight,
Fruit (function) will be lost. (5) Currently, bridges using hot-dip galvanized steel members
Many beams, towers, steel frames, etc. have been constructed.
Provides corrosion resistance and environmental purification action that also serves as maintenance and inspection of buildings
Thermal spray coating technology has not been developed.

An object of the present invention is to overcome the above-mentioned problems of the TiO ₂ film forming technique by thermal spraying, and in particular, from anatase type TiO ₂ (a-TiO ₂ ) to rutile type TiO ₂ ( By suppressing the change to r-TiO ₂ )
It is an object of the present invention to provide a member having a thermal spraying film having excellent environmental purification action and excellent corrosion resistance and adhesion.

Another object of the present invention is to propose a method of manufacturing a thermal spray coated member for applying a TiO ₂ thermal spray coating having excellent corrosion resistance and environmental purification properties to a surface of a steel base material with strong adhesion. There. Still another object of the present invention, be exposed to high temperature thermal spraying heat source, r from a-TiO ₂
It is an object of the present invention to propose a composite material for forming a thermal spray coating which is effective for preventing a change to -TiO ₂ .

[0010]

SUMMARY OF THE INVENTION The present invention relates to the prior art.
In order to solve the above-mentioned problems,
We propose some means. (1) Use a-TiO2 on the surface of a substrate such as steel.₂Excessive powder
In order to suppress the rise in exposure temperature, electrochemical
Powders of metals and alloys, such as Al, which have a relatively low potential (low potential)
And a-TiO₂Formed by spraying composite thermal spray material consisting of powder
Low potential metal-a-TiO₂Thermal spray coatings (metals such as Al
A-TiO during tricks₂(Sprayed coating with dispersed state)
Excellent corrosion resistance and environmental purification characteristics
Sprayed coating member. (2) Apply an undercoat to the surface of a base material such as steel.
And a steel member, that is, a steel material,
Al, Zn, Al-Zn alloy, Al-Mg alloy, etc.
Spraying at least one metal or alloy selected from
The resulting anticorrosive undercoat (preferably
With good anti-corrosion action.
A-TiO₂Suppress excessive temperature rise of powder
Metal and alloys (hereinafter referred to as `` A
l) powder and a-TiO ₂Duplex consisting of powder
Has environmental purification properties formed by spraying the combined spray material
Al-a-TiO₂System with a top coat spray coating
Thermal spray coating with excellent corrosion resistance and environmental purification characteristics
Element. (3) The surface of a substrate such as steel
Any selected from Zn, Al-Zn alloy, Al-Mg alloy, etc.
Excellent corrosion protection obtained by spraying one or more metals and alloys
Undercoat (sprayed coating, etc.)
Above, a-TiO with environmental purification properties₂Spray powder and shape
Characterized by providing a sprayed top coat
Spray coated member with excellent corrosion resistance and environmental purification characteristics. (4) As the steel base material, hot-dip galvanized steel
Corrosion protection and environmental cleanliness are applied to the surface of a substrate
A-TiO containing Al etc. having both properties₂system
A-TiO that forms a thermal spray coating or has an environmental purification action₂
Form a thermal spray coating or a-TiO₂Thermal spray coating formation
Prior to the electrochemical
Undercoat thermal spray coating made of base metal and alloy
Excellent corrosion resistance and environmental purification characteristics
Spray coating member. (5) In each of the above members, the thermal spray coating is
In a metal / alloy matrix with a low electrochemical potential
At least 30wt% anatase TiO₂Particles dispersed
It is characterized in that it is a layer formed.

The above-mentioned spray-coated member is manufactured by applying the following manufacturing method. (6) On a surface of a base material such as steel, a metal / alloy having an electrochemically low potential with respect to a steel material, for example, a composite sprayed material mainly containing Al powder and a-TiO ₂ powder, flight speed in a spraying heat source is sprayed with spraying conditions to be 200 meters / sec or higher, obtained by suppressing the change of the r-TiO ₂ due to excessive temperature rise of a-TiO ₂ particles, the environmental purification characteristic A method for producing a thermal spray coated member having excellent corrosion resistance and environmental purification characteristics, characterized by forming an excellent a-TiO ₂ thermal spray coating. (7) First, on the surface of steel base material including hot-dip galvanized steel, Al, Zn, Al-Zn alloy, Al
-One or more metals selected from Mg alloys
By spraying the alloy, an anti-corrosive undercoat sprayed film is formed, on which a metal or alloy having an electrochemically lower potential than steel, such as Al powder and a-TiO
_The thermal spraying of a composite thermal spraying material mainly composed of powder ₂ and a thermal spraying source in a thermal spraying heat source at 200 m / sec or more causes r-TiO ₂ due to excessive temperature rise of a-TiO ₂ particles.
A-TiO ₂ top coat sprayed coating that suppresses the change to aluminum and has an environmental purification effect or does not contain Al powder
Production of a spray-coated member having excellent corrosion resistance and environmental purification characteristics, characterized in that a-TiO ₂ powder alone is sprayed under the above-mentioned flight speed of 300 m / sec or more to form an a-TiO ₂ top coat sprayed film. Method.

The present invention is also directed to a composite thermal spraying member according to the following gist for producing the above-mentioned thermal spray coated member, in order to exhibit corrosion resistance and to suppress an excessive rise in temperature of the a-TiO ₂ particles in the thermal spraying heat source. Propose the material. (8) That is, according to the present invention, powders of one or more metals and alloys selected from Al, Zn, Al-Zn alloy,
A composite thermal spraying material for forming a coating layer having excellent corrosion resistance and environmental purification characteristics, characterized in that it is a composite powder material containing 50 wt% and the balance consisting of a-TiO ₂ powder and unavoidable elements.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, anatase type TiO ₂ (a-TiO
₂ ) Powder of metal such as Al or Zn or their alloys, which shows a photocatalytic action of electric potential lower electrochemically than steel, and TiO
The characteristics of the composite thermal spray material composed of _two powders, the characteristics of the thermal spray coating (cross-sectional structure) obtained by thermal spraying the composite thermal spray material, and the environmental purification action (mechanism) of the applied thermal spray coating will be described.

[0014] (1) When the sunlight for the photocatalytic action of a-TiO ₂ to a-TiO ₂ is irradiated electrons are emitted, the emitted mark hole (holes) is left. The electron and hole portions are very active. In particular, the electron has a function of reducing a chemical substance in contact with the hole, while the hole has a property of accelerating the oxidation reaction. Moreover, this a-
TiO ₂ is well-excited for sunlight, especially those having a wavelength of 380 nm or less, and it is known that natural light is the driving force for the reaction. Incidentally, the TiO _2, in addition to a-TiO _2, but rutile type TiO _{2 (r-TiO 2)} is also present, the crystal form: almost no photocatalytic activity in r-TiO _2, for environmental clean The TiO ₂ that can be used for the above is exclusively the aforementioned a-TiO ₂ .

[0015] (2) low potential metal-containing a-TiO ₂ composite spray material powder for a-TiO _{2 (anatase)} and r-TiO _{2 (rutile} type), such as Al
Can easily be formed into a film by thermal spraying.
However, there were the following problems. Because the thermal spray material flies through a heat source during thermal spraying, it is heated and heated to a molten or semi-molten state. For this reason, a-
Even if only TiO ₂ is selected and sprayed, most of it is r
It changes to -TiO ₂ and loses the photocatalytic action.
Even if a-TiO ₂ or r-TiO ₂ is applied directly to the surface of the steel structure substrate, these films are electrochemically damaged.
There is a problem that the TiO ₂ film becomes a cathode and the substrate becomes an asode, and the corrosion of the substrate proceeds.

That is, a low-potential metal such as Al and a-TiO ₂
The composite sprayed material according to the present invention comprising a mixed powder with
O ₂ is one that was developed in order to solve the aforementioned problems have had. That is, this material is obtained by coating a surface of a-TiO ₂ powder with a metal such as Al having an electrochemically low potential with respect to a steel material such as Al by a granulation method. With the structure, a-TiO
_{2 It} is designed so that the powder does not come into direct contact with the high-temperature heat source.

(3) Method for Forming Thermal Sprayed Coating In the present invention, a thermal spraying method was studied in order to make the characteristics of the composite sprayed material more effective. That is, in the present invention, preferably, while using a combustion frame of a combustible gas having a lower temperature than the plasma heat source, the composite sprayed material powder is caused to fly at a high speed in the flame sprayed heat source. At the same time as minimizing (lowering) the opportunity for material exposure (temperature), as well as ensuring high flight speeds, it generates strong collision energy against the substrate. To improve the adhesion to the substrate surface.

According to such a thermal spraying method, when the above-mentioned composite thermal spraying material according to the present invention is used, a low-melting point Al or the like (the melting point of which is coated on the surface of the a-TiO ₂ particles) is used.
(660 ° C) metal melts early in the heat source,
For a-TiO ₂ particles, the temperature rise is suppressed,
The change to -TiO ₂ is significantly reduced. Besides, molten Al
Such metals and alloys greatly contribute to the improvement of the bonding force between the particles and the adhesion to the base material during the formation of the coating, so that the sprayed coating is dense and has good adhesion. In addition, since Al and the like exhibit a lower potential (lower potential) than the steel structure base material, an effect of electrochemically exhibiting a sacrificial anode effect to prevent corrosion of the base material occurs.

FIG. 1 shows a-TiO₂Carbonization using powder material
Combustion of hydrogen (ethylene, propylene, kerosene) and oxygen
Fly through the heat source by spraying using the flame as the heat source
a-TiO ₂X-ray of film formed by changing the speed of powder
From the result of the diffraction peak intensity ratio, r-TiO₂Shows the rate of change to
Things. According to the results, a-TiO₂Dissolve powder only
If the material is a shooting material, the flight speed in the heat source should be 250m / sec or less.
At lower speeds, mostly r-TiO₂To increase flight speed
R-TiO₂Changes to Its critical
Flight speed is more than 300 m / sec.
A-TiO₂Is about 30% (r-T
iO₂To 70%)
It is possible. However, in this case, a-TiO₂Thermal spray layer (top
Underneath the aluminum, Zn or their alloys.
It is preferable to use a composite coating having a dark coat.
Then, at least the expected effect of the corrosion resistance of the substrate
can get. In contrast, metals such as Al and Zn and their alloys
A-TiO by granulation, for example. ₂Coated on the surface of the powder
In the case of the preferred thermal spray material of the present invention, the flight speed in the heat source is
 R-TiO even at 200m / sec₂Rate of change to less than 50%
In other words, at 300 m / sec or more, around 30-40% changes
Not just.

The composite sprayed material according to the present invention comprises:
The use of particles obtained by coating the surface of a-TiO ₂ powder with a low-melting metal such as Al by a granulation method is effective for forming a film which is preferable in the present invention. Even when the powder and a-TiO ₂ powder are mechanically mixed in an inert gas atmosphere, the rate of change to r-TiO ₂ is 250 m / sec compared to the sprayed powder material of a-TiO ₂ alone. It has been experimentally found that the speed can be suppressed to about 60 to 65% under the speed condition. Therefore, although the performance is slightly lowered, it is economical as a method for producing a thermal sprayed powder material and can be sufficiently used. In the composite sprayed material according to the present invention, a-TiO ₂
The proportion of the Al powder that covers the surface of the powder or is mechanically mixed and added is preferably in the range of 1 to 50% by weight, particularly 5% by weight.
~ 20 wt% is preferred. If the Al content is 1 wt% or less, the effect of addition is small, while if it is more than 50 wt%, its performance is not particularly improved and the effect is saturated.

In the present invention, as the metal to be added to the a-TiO ₂ powder, Zn, Al—Zn alloy, Al—Mg
Any metal or alloy can be used as long as it is a powder of a metal or alloy, such as an alloy, which has a low melting point, exhibits a base potential against a steel structure base material, and exhibits an anticorrosive action. . Specifically, zinc and aluminum specified in JIS H 8300-1999 and their alloys, Zn metal specified in JIS H 2107,
Aluminum and its alloys specified in JIS H 4000 are suitable.

A-TiO thus formed₂And Al
Sprayed coating consisting of
At least 30wt% anatase TiO₂ (a-TiO₂)
 , Preferably 50 wt%, more preferably 60 wt% remains
And the rest is rutile TiO ₂ (r-TiO₂) Containing
Are preferred. The basis is also based on the results shown in Fig. 1.
But a-TiO₂But at least 30wt% Al matrix
NO if not dispersed inside_xA-Ti in contact with air containing
O₂The area of the soil becomes smaller and the effect of environmental purification decreases
It is.

(4) Structure of Thermal Sprayed Coating and Its Mechanism of Operation FIG. 2 shows an example of a cross-sectional structure of a sprayed coating formed by using the composite sprayed material according to the present invention and employing a method conforming to the present invention. a) to (d) are shown. Here, 1 is a substrate, 2 is Al matrix, 3 is a-TiO ₂ particles, 4 is very small in a-TiO ₂ layer or Al addition amount, for example at 1wt% Al-99wt% a- TiO 2 . 5 is a hot-dip galvanized layer.

FIG. 2- (a) shows the surface directly on the SS400 substrate.
A coating (a-TiO ₂ dispersed layer) is formed by spraying a composite spraying material consisting of a-TiO ₂ powder coated with Al, and the sprayed coating has a photocatalytic effect in the Al matrix.
It has a structure in which TiO ₂ particles are dispersed. In this thermal spray coating, only the a-TiO ₂ particles exposed on the surface decompose NO _{x in} the air by irradiation of sunlight.
Since recent rainwater is acidic, it becomes Al
Elutes, the outermost a-TiO ₂ particles fall off,
At the same time, new a-TiO ₂ particles are sequentially exposed from the lower part, so that the NO _x decomposing effect is again exerted. Accordingly, in such a film, it is possible to maintain the decomposition of the NO _x until the entire thermal spray coating is lost. Moreover, in this case, the surplus Al exerts an anticorrosion effect on the SS400 substrate, so that no red rust or the like is generated from the substrate.

FIG. 2- (b) shows the surface on the film shown in FIG. 2- (a).
In addition, 300 m / sec as the top layer (top coat)
A-TiO at higher flight speeds₂Thermal spray coating 4 consisting only of
(a-TiO₂(Residual rate of 35 to 38%). FIG.
-(c) is Al-containing a-TiO₂A-TiO obtained by spraying powder₂
Dispersion layer and a-TiO ₂Film consisting of only
Very little a-TiO₂Multiple sprayed coatings with extremely high content
This is an example of a multi-layer thermal spray coating formed by stacking several layers.
When the film disappears at the beginning of use or over time, a-TiO₂
Due to the rich layer, NO_xMore strongly decomposes
A structure suitable for volatilization can be provided. Fig. 2- (d)
As an undercoat on the surface of substrate 1
Metals and alloys with electrochemically low potentials such as Al,
Metals and alloys such as Zn, Al-Zn alloy and Al-Mg alloy
Undercoat, for example, for thermal spraying, plating, CVD, etc.
Steel structure coated with a film (in the example shown, hot-dip galvanized)
On the surface of the structure, Al and a-TiO described above₂Topcon consisting of
It shows a structural example in which a heat sprayed coating is formed,
The undercoat is provided to provide anticorrosion properties.
Fig. 2- (e) shows hot-dip galvanizing as an undercoat.
Table of the plating layer (undercoat) of a damaged steel structure
A-TiO2 on the surface under spraying conditions with a flight speed of 300 m / sec or more₂
It is sectional drawing of what formed the film by spraying only a powder.

(5) NO of thermal sprayed coating formed on the member of the present invention
_x Decomposition performance A thermal spray coating conforming to the present invention, that is, a-
For TiO ₂ confirms NO _x decomposition performance of the thermal spray coating having a dispersed structure, utilizing the test apparatus shown in FIG. The apparatus of sprayed coating and set under the irradiation of artificial sunlight, the reactor (31) contacting the NO _x gases, this NO
_{x A} gas cylinder (32) and a humidity controller (33) that gives humidity to the air are equipped with a flow meter (34) for adjusting and measuring the amount of gas circulating, and at the top of the reactor (1) Arrange a lamp (35) (wavelength 370 nm) simulating sunlight,
Sunlight and has a configuration which guides the contact reaction of the irradiated while the thermal spray coating and NO _x, and the exiting the reactor gas was analyzed by gas analyzer (36), the decomposition rate (or NO _x Survival rate)
Is to be asked.

[0027] Using this device was tested for NO _x resolution compatible thermal spray coating of the present invention. Test, NO _x content: 0.5 ppm, humidity: 50% air at a rate of 1 minute 50 ml, was fed into the reactor being irradiated by the lamp,
The thermal spray coating according to the present invention, in which 5 wt% Al-95 wt% a-TiO ₂ was formed at a flight speed of 300 m / sec, showed a decomposition rate of 60 to 70%. In contrast, in the film according to the prior art forming only a-TiO ₂ at a flying speed of 250 m / sec, it was only shows the 1-2% of the decomposition rate. From the experimental results, NO _x decomposition reaction compatible thermal spray coating in the present invention, as shown in FIG. 1, a-TiO ₂ by exposure temperature history during spraying heat source
It was found that the ratio was almost proportional to the survival rate.

The thickness of the thermal spray coating conforming to the present invention is a-Ti
Mixed film of O ₂ and Al, with a-TiO ₂ alone film, 20 m to
A range of 800 µm is practical, and a range of 50 to 300 µm is particularly preferable. If the thermal spray coating is thinner than 20 μm, it is difficult to form a uniform film. Thickness greater than 800 μm is a good measure to extend the corrosion protection period of the steel structure, but is not economical.

As an undercoat, Al, Zn, Al
When applying (sprayed) coatings such as -Zn alloy, Al-Mg alloy, etc., the thickness should be 30 to 500 µm, especially 50 to 200 µm.
m is preferred. This is because the case where the undercoat is applied is a case where the corrosiveness in the use environment of the member is further severe, and in this case, sufficient anticorrosion performance is required. In such a case, if the thickness of the undercoat is less than 30 μm, it is difficult to meet the above-mentioned requirements. On the other hand, if the thickness is more than 500 μm, a special effect cannot be expected.

[0030] Regarding the mechanism of action compatible thermal spray coating of the present invention described above, has been mainly described intended for removal of the NO _x contained in the atmosphere, the action of a-TiO ₂ is sterilized,
It is known that it is effective in decomposing and deodorizing odorous gas, removing water pollutants, and the like, and the present invention can be sufficiently applied as a countermeasure technique.

[0031]

Example 1 In this example, considering that a thermal sprayed coating formed under conditions compatible with the present invention is used in a natural environment,
The atmospheric corrosion property was evaluated by a salt spray test. (1) Specimen sprayed coating specimen SS400 Carbon steel specimen (width 50mm x length 100mm x thickness 5mm)
After roughened only by the blasting one surface, as sprayed coating compatible with the present invention, Al powder 1 to 50 wt%, the balance using mainly a-TiO ₂ powder, the spray particles in the high-velocity flame spraying heat source Thermal spraying was performed at a flying particle velocity of 300 to 350 m / sec to form a film with a thickness of 100 μm. Then, some of the test pieces were further used as top coats under the same spraying conditions as those containing only a-TiO ₂ and those containing 1 wt% Al.
-TiO ₂ was applied to a thickness of 50 μm each, and a composite sprayed coating was formed by forming 100 μm of 100% Al as an undercoat, and a 5 wt% Al-a-TiO ₂ coating as a top coat thereon. On the other hand, for the spray coating for comparison, SS
On one side of the 400 substrate, directly spraying material a-TiO ₂ alone, by changing the flying speed in the heat source as well as prepare the one formed on the 100μm thickness, air plasma spray for some specimens Was also prepared. (2) Corrosion test method In order to accelerate the corrosion reaction in the natural environment, a salt spray test specified in JIS Z 2371 was performed for 500 hours. However, the test was interrupted every 100 hours, and the occurrence of red rust from the sprayed coating was observed. Prior to the test, the back surface (bare surface) and the end surface of the test piece were coated so that there was no exposed surface of the substrate. (3) Corrosion test results Table 1 summarizes the results of the salt spray test. As apparent from the results, obtained by directly forming a-TiO ₂ sprayed coating on SS400 substrate of Comparative Example (No.7~9) is generating a large amount of red rust after 100 hours, the carbon steel base It was found that the anticorrosion performance of the material was poor. In contrast, compatible coating to the invention, either construction the a-TiO ₂ containing Al as an undercoat (No.1~5), because of the construction of the 100% Al, 50
No red rust was observed even after 0 hours, and Al
It was found that the SS400 base material was protected by the components. In place of test piece No. 6, pure Zn, 15 wt% Zn-85 wt% Al, 95 wt% Al-5 wt% were used as undercoats.
After applying Mg to each 100μm thickness, a-TiO
Was also investigated composite thermal spray coating was formed ₂ to 50μm thick at a flying speed of 300 to 350 m / sec, but the occurrence of red rust after 500 hours was observed.

[0032]

[Table 1]

Example 2 In this example, a sprayed coating of an example conforming to the present invention was compared.
Example of thermal spray coating NO_xThe removal rate was measured immediately after thermal spraying and outdoors.
To investigate the durability and evaluate its durability.
Was. (1) Coating test specimen
Spray coating as a compatible example of the present invention with the flame spraying method
A-TiO of Comparative Example₂A film was formed. Incidentally, the a-TiO of the comparative example
₂Atmospheric plasma spray coating is also added to part of the coating
did. (2) Film evaluation test method The film was evaluated using the NO shown in Fig. 3 above._xDecomposition test equipment
Exposure to fresh surface immediately after thermal spray deposition and outdoors for 6 months
NO about the film after exposure_xWas measured. What
The test gas is humidity 50%, NO_xContent 0.5
100 ml per minute was distributed in ppm. (3) Test results The test results are shown in Table 2. As is clear from this result
A-TiO₂Film formed directly on SS400 substrate (No.6)
 Is r-TiO because of short exposure time by thermal spray heat source ₂Change to
(A-TiO₂Is high), but immediately after film formation
High NO_xThe decomposition rate was shown. However, exposed outdoors for 6 months
Then, the test piece generates red rust over the entire surface and sprays
Contamination progresses to the surface of the film, NO_xDegradation rate is almost recognized
I can no longer do it. Also, in this film specimen, sunlight
The occurrence of red rust on the unreachable back surface was remarkable. Praz
Ma-a-TiO₂In the test piece (No. 7) on which
NO after 6 months of exposure_xThe decomposition performance of
Was. A large amount of red rust was also observed on this film.
In contrast, those with a thermal spray coating conforming to the present invention
(No. 1 to 5) are high NO immediately after thermal spraying_xDemonstrates decomposition performance
To prevent Al and Al-Mg alloy forming the film even when exposed outdoors
Because phagocytosis suppressed the generation of red rust,
NO high over_xDegradation performance was maintained. In addition, the present invention
In the test piece according to the example,
No red rust was observed.

[0034]

[Table 2]

Example 3 In this example, as a substrate to be sprayed, carbon steel which had already been subjected to hot-dip galvanizing or hot-dip zinc-aluminum alloy plating was used, and a sprayed film conforming to the present invention was formed thereon. Thereafter, its corrosion resistance was evaluated by a salt spray test. For the purpose of comparison, a hot-dip coated steel sheet and an untreated carbon steel test piece were used. (1) Test film test Hot-dip galvanized steel test piece (width 50 mm x length 100 mm x thickness 5 mm) Hot-dip zinc-aluminum alloy test piece (55 wt% Al-45
The wt% Zn alloy was melted plating, only on one side of width 50 mm × length 100 mm × thickness 5mm) above the substrate, Al, Zn, Al-Zn alloy, Al-Mg alloy, respectively 40wt%, a-TiO ₂ A sprayed coating having a thickness of 150 μm was formed using the sprayed material of the present invention which was added to the present invention. In addition, as an example conforming to the present invention, a substrate in which only a-TiO ₂ was formed to a thickness of 80 μm on a hot-dip zinc-aluminum alloy plating substrate was also prepared. The above coatings were formed by a high-speed flame spraying method at a flight speed of sprayed particles in a heat source of 200 to 350 m / sec. (2) Corrosion test method The same test method was used as in Example 1, but the test time was up to 20 minutes.
00 hours. (3) Corrosion test result Table 3 shows the corrosion test result. As is clear from the results, the untreated steel sheet (No. 10) of the comparative example already had red rust generated over the entire surface in a 100-hour test. In contrast, the hot-dip galvanized steel sheet (No. 8) was 1,500 hours later, and the hot-dip zinc-aluminum alloy-plated steel sheet (No. 9) was 16 hours later.
After 00 hours, considerable corrosion resistance was exhibited, such as the occurrence of red rust for the first time. On the other hand, the thermal spray coatings (Nos. 1 to 6) of the examples conforming to the present invention exhibited more excellent corrosion resistance. In other words, no red rust was observed even after 2,000 hours, and it was confirmed that the effect of the existing anticorrosive film was not impaired but rather extended.
Also in the steel plate (No.7) which was formed only a-TiO _2, molten zinc base - it was not observed to promote the corrosion of the aluminum alloy layer, extending the time to rather red rust A trend was seen.

[0036]

[Table 3]

[0037]

As described in detail above, Al, Zn, Al-Zn,
Or a material consisting of electrochemically metal or alloy and a-TiO ₂ powder showing the lower potential relative to the steel base material such as Al-Mg deposited by spraying method, or the lower potential of the on the film, such as a metal showing, a-TiO ₂ or Al, Zn, Al-Zn, Al-M
thermal spray coating one or more composite thermal spray material comprising a metal-alloy and a-TiO ₂ Metropolitan formed as a top coat selected from among the g are air pollutants with anticorrosive action of steel structures
Also it includes a NO _x removal capability, yet is characterized in that the corrosion resistance and environmental purification characteristic can be maintained for a long period of time. Therefore, by applying the coating of the present invention to a steel structure such as an urban area, a heavy industrial area, or a highway, a great effect can be expected on corrosion prevention and environmental purification of the steel structure.

[Brief description of the drawings]

Fig. 1 Flight speed and r-TiO _{2 of} a-TiO ₂ particles in thermal spraying heat source
It shows the relationship of the rate of change to.

FIG. 2 shows an example of a cross-sectional structure of a thermal spray coating of the present invention.

[3] in circulation air containing NO _x, is the NO _x decomposition performance of the thermal spray coating shows a configuration of a test apparatus for evaluating.

[Explanation of symbols]

 1 Carbon steel base material 2 Al matrix 3 a-TiO₂Particle 4 a-TiO₂Or a-TiO with small amount of Al added₂  5 Hot-dip galvanizing applied to the surface of carbon steel members
layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 37/02 301 C23F 13/00 P 4K062 C23C 28/00 15/00 C23F 13/00 17/00 15 / 00 B01D 53/36 ZABJ 17/00 102D F-term (Reference) 4D048 AA06 AB03 BA07X BA39X BA41X BB03 EA01 4G069 AA03 AA08 BA04A BA04B BA17 BA48A BB02A BB02B BC10A BC10B BC16A BC16 EC03 CA03 EA034 AA01 AA05 AB02 AB03 AB05 AB09 AB11 CA02 CB12 CB37 CB39 CB42 DA01 DA03 DA07 4K044 AA02 AB02 BA10 BA12 BB01 BB03 BB04 BB05 BB11 BC02 BC05 CA11 CA14 CA18 4K060 AA02 BA13 BA39 DA01 EA08 EB01 FA03A02

Claims (10)

[Claims] Claims 1. An anti-corrosion coating comprising an anatase type TiO ₂ particle dispersed in a metal or alloy having a potential electrochemically lower than that of a steel material on the surface of a base material such as steel. Thermal spray coating with excellent environmental purification properties. 2. A steel base material is provided with an undercoat made of a metal or an alloy having an electrochemically lower potential with respect to the steel material on the surface of the steel base material. A spray-coated member that is excellent in corrosion resistance and environmental purification properties by providing a top-coat sprayed coating in which anatase TiO ₂ particles are dispersed in a metal or alloy having a potential. 3. An electric machine for a steel material on a surface of a steel base material.
Undercoat made of metal or alloy with chemically low potential
Anatase-type TiO ₂System top
Corrosion resistance and environmental purification properties with coated thermal spray coating
Excellent thermal spray coating. 4. The thermal spray coating according to claim 1, wherein at least 30% by weight of anatase TiO ₂ particles are dispersed in a metal / alloy matrix having a potential electrochemically lower than that of steel. The thermal spray coating member according to claim 1. 5. A metal having an electric potential which is electrochemically lower than that of a steel material, which is selected from Al, Zn, an Al-Zn alloy and an Al-Mg alloy. The thermal spray coating member according to any one of claims 1 to 4, characterized in that: 6. An anatase type TiO ₂ and a metal / alloy having an electrochemically lower potential with respect to a steel material on a surface of a steel base material.
A method for producing a thermal spray coated member having excellent corrosion resistance and environmental purification characteristics, characterized by spraying a composite thermal spray material containing powder under thermal spraying conditions in which a flight speed in a thermal spray heat source is 200 m / sec or more. 7. An undercoat is formed by spraying a metal or alloy having an electrochemically low potential on a steel material on the surface of a steel base material, and then forming an undercoat on the steel material. Metal / alloy and anatase type TiO ₂
It is characterized by forming a top coat sprayed film by spraying a composite sprayed material containing a powder under a spraying condition in which the flight speed in a spraying heat source is 200 m / sec or more. An excellent method for producing a thermal spray coated member. 8. An undercoat is formed on a surface of a steel substrate by spraying a metal or alloy having a potential which is electrochemically low with respect to a steel material, and then forming an undercoat thereon.
The thermal spraying of the composite thermal spray material mainly composed of O ₂ powder is performed under the thermal spraying condition in which the flight speed in the thermal spraying heat source is 300 m / sec or more.
A method for producing a thermal spray coating member having excellent corrosion resistance and environmental purification properties, characterized by forming a thermal spray coating on a top coat. 9. A metal or alloy selected from the group consisting of Al, Zn, an Al-Zn alloy and an Al-Mg alloy as a metal having an electrochemically lower potential than steel. The method according to any one of claims 5 to 8, wherein: 10. An Al, Zn, Al-Zn alloy and Al-Mg alloy.
Powder of one or more metals or alloys selected from
1-50wt%, balance is anatase TiO ₂Powder and non
Corrosion resistance and environment characterized by unavoidable impurities
Composite spray material for coating layer formation with excellent purification properties.