JP2002285314A - Thermal spraying wire, and thermal spraying method using the wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal spraying material capable of ensuring the corrosion resistance for a long time by employing a thermal spraying technology in the case of giving a corrosion protective function to a steel bridge, or the like, thereby forming a uniform and firm film on the surface thereof, and to provide a thermal spraying method using the thermal spraying material. SOLUTION: Aluminum alloy wire for thermal spraying contains, by weight, 5-15% zinc. Zinc alloy wire for thermal spraying contains 1-10% aluminum. Granular aluminum of 1-10% is diffused in zinc. Grain size of granular aluminum is 1-50 μm. An aluminum clad is formed around the zinc wire as a core. On the other hand, a zinc clad is formed around the aluminum wire as a core. In the thermal spraying method, a pair of electrodes are formed from the above thermal spraying wires, and a film is formed on a work by arc thermal spraying. In another method, one electrode is formed from the thermal spraying wire, the other electrode is formed from a metal having the melting point which is not melted in the arc thermal spraying, and the film is formed on the work by melting the thermal spraying wire by the arc thermal spraying. The other electrode is a fixed electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal spraying material for forming a thermal spray coating for imparting durability to a bridge wall or the like by arc thermal spraying, and a thermal spraying method using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating material having excellent corrosion resistance for prevention and a method for adapting the same.

[0002]

Heretofore, painting has been widely used as a means for protecting a structure which is easily exposed to a corrosive atmosphere such as a steel bridge. However, in order to maintain the corrosion resistance of these structures, repainting must be performed periodically. Even though the painting technology and the undercoating technology are improving, the repainting period is long, but the repainting is still indispensable from the viewpoint of corrosion resistance.

[0003] On the other hand, as an alternative to painting, a bridge may be constructed of weather-resistant steel, or hot-dip galvanizing may be applied to the surface of the steel. However, weather-resistant steel is expensive and galvanization is more expensive than painting. Although the life cycle is long, it also needs to be repaired regularly.

By the way, in order to improve the surface of a steel sheet or the like, a metal wire is sprayed by intersecting two metal wires and applying a large current to generate an arc, thereby melting the metal wire and fixing it to the steel sheet surface. Techniques are known. Specifically, two kinds of wire rods, zinc alloy and aluminum alloy, are brought into contact with each other and melted by applying an electric current, while the molten metal is adhered by a jet stream, and this film exerts a sacrificial anodic effect, and the inner steel material It is intended to prevent corrosion. Thus, a film in which zinc and aluminum are laminated irregularly is formed. Since this thermal spraying method sprays two types of thermal spraying materials simultaneously to form a coating, it is called composite thermal spraying. However, the melting point of zinc, 41
Since there is a gap between 9.47 ° C. and 660.2 ° C., which is the melting point of aluminum, there is a problem that aluminum is not sufficiently melted during arc spraying, sparks are generated, and workability is deteriorated. Further, the formed film is in an inhomogeneous state with a large porosity. In order to avoid this, an alloy wire in which the composition of zinc and aluminum is half each, and in the case of flame spraying, an alloy wire of 85% zinc and 15% aluminum are used. However, currently known thermal spray coatings using the above-mentioned wire are poor in adhesion to the base material surface and easily form porous. Further, the flame sprayed coating involves fine oxide particles and tends to reduce corrosion resistance. For these reasons, application to surface treatment of steel bridges, etc., has not been widely spread at present.

[0005] However, although the thermal spraying technique has the above-mentioned problems at present, if a uniform and high-adhesion thermal spray coating can be formed, problems such as corrosion resistance can be solved at once.

The present invention solves the above-mentioned conventional technical problems, and employs a thermal spraying technique for imparting an anti-corrosion function to a steel bridge or the like to form a uniform and firm coating on the surface, thereby providing a long-lasting coating. An object of the present invention is to disclose a thermal spray material capable of ensuring corrosion resistance and a thermal spray method using the thermal spray material.

[0007]

According to the present invention, in order to achieve the above-mentioned object, a material capable of forming a surface coating uniformly as a thermal spraying material while using zinc and aluminum as a wire material as in the prior art. Was determined. In the present invention, zinc as aluminum is used as such a material.
A material containing 15% by weight and aluminum in zinc
A material containing 10% by weight is disclosed. In these combinations, the aluminum alloy is in a completely molten state, almost no spark is generated, and workability is improved. Zinc alloys are not different from pure zinc in spraying work, but in terms of forming composite sprayed coatings, they are alloys, so familiarity is good and uniformity of the coating and small porosity are formed. Is done. The reason why the maximum aluminum content is specified to be 10% by weight is that the corrosion prevention of steel uses the sacrificial anodic action of the coating, and the zinc in the coating is sufficiently effective for the sacrificial anodic action. It is desirable that the amount is large, and at least 60% by weight or more is necessary, so that zinc in the formed film does not fall below 60% by weight in all the combinations of the alloys.

As another structure of the zinc alloy, a thermal spraying wire in which aluminum particles are uniformly dispersed is employed.
In addition, granular aluminum is put into zinc in a range of 1 to 10 in terms of weight%, dispersed in an insoluble state, and then cooled to obtain a thermal spraying wire. In this state, the aluminum particles are mechanically mixed and dispersed in the zinc, and the ductility of the zinc is hardly changed from that of the pure zinc, so that the plastic working into a wire or the like is easy. Thus, a wire can be easily manufactured by utilizing the difference in melting point between zinc and aluminum.
Further, considering the diameter of the wire rod, the granular aluminum particles are 1
Adopted in the range of ~ 50μ.

In the present invention, in order to further achieve the above object, a so-called composite composition is adopted as the sprayed wire. That is, a sprayed wire having a zinc wire as a core and an aluminum clad formed therearound, or a sprayed wire having an aluminum wire as a core and zinc clad formed therearound.

For example, in order to form an effective spray coating on an object whose surface has been appropriately roughened by blasting or the like in advance, how to melt a wire rod with good leveling and apply the molten metal to the object surface On the other hand, it is important to improve the adhesion. In the above configuration of the present invention, the relatively low melting point of zinc is melted first, followed by the melting of aluminum, so that the sprayed metal is not in a completely alloyed state, but is separately deposited and cooled, so that the coating is formed. Is stable in composition. Further, since it is not necessary to go through a process of uniformly melting two metals as a material of a wire to form an alloy, and forming a clad around a single metal wire, it is suitable for mass production. Will be.

Next, as the thermal spraying method, a method was adopted in which one of the above-mentioned thermal sprayed wires was used as a pair of electrodes, and a film was formed on an object by arc thermal spraying. There is no change.

Subsequently, a method of performing arc spraying by selectively using one of the above-mentioned sprayed wires as one electrode and using the other as an electrode having a melting point that is not melted by arc spraying is adopted. By performing the thermal spraying using the electrode that is not used as the reference coordinates, the thermal spray position on the target object can be made accurate. That is, if a wire that melts both is used as an electrode, the spraying position is slightly shifted due to variation of the wire, but if the other electrode is a metal that does not melt, the spraying can be performed based on this, and the spraying position can be determined. Can be easily defined. Further, by using the other electrode as a fixed electrode, the spraying position can be made more accurate. Further, in the configuration using an electrically conductive ceramic electrode as the electrode, this material has a very high melting point compared to the sprayed metal and maintains a stable state even when energized, so that it can be a fixed electrode with a long life. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In this embodiment, the aluminum alloy wire of claim 1 and the zinc alloy wire of claim 2 or 3 were paired, and a composite sprayed coating was obtained on the surface of the object by electric arc spraying. First, as a precautionary point in construction, it is necessary to adjust the base to be sprayed. This is to ensure the adhesion of the film to the object, but this adhesion is because mechanical engagement with the rough surface of the object is important. The rough surface can be obtained by applying a rough surface forming material or by appropriately roughening the surface by blasting. As an example of a rough surface forming material that can achieve an appropriate surface roughness, there is a material obtained by mixing ceramic particles with an epoxy resin.

Next, as another embodiment of the sprayed wire, there is a wire disclosed in claim 3 in which aluminum particles are mixed in a zinc wire. This means that granular aluminum
The mixture is charged into a continuous casting furnace at a ratio of 10% by weight, uniformly dispersed in an insoluble state, processed into a wire, and cooled. In this state, the aluminum particles are mechanically mixed and dispersed in the zinc, the ductility of the zinc is almost the same as that of pure zinc, and the plastic working such as rolling or elongating the zinc ingot is easy. Therefore, it is possible to appropriately select a method of processing the wire rod. In consideration of the diameter of the wire rod, the particle diameter of the aluminum particles is preferably about 1 to 50 μm.

FIG. 1 shows a sprayed wire according to still another embodiment of the present invention, in which 1 is a core, and 2 is a clad which covers the periphery of the core 1. The material of the core 1 is zinc or aluminum, and the material of the cladding 2 is aluminum or zinc. That is, when the core is zinc, the cladding is aluminum, and when the core is aluminum, the cladding is zinc. Since the melting point of zinc is considerably lower than the melting point of aluminum, aluminum cladding can be easily obtained by adopting an aluminum wire for the core and passing the aluminum wire through a molten zinc bath. Although the configuration of a zinc clad is preferable, the function as a spray wire is not different from the configuration of an aluminum clad in a zinc core.

The use of a pair of sprayed wires obtained as described above as electrodes for arc spraying is no different from known arc spraying techniques. Then, a composite thermal spray coating is obtained on the surface of the object by this thermal spraying.

For the thermal spraying, a known arc spraying machine is used as described above, but it is desirable to perform low-temperature thermal spraying so as to reduce the influence of thermal strain. The distance from the tip of the spray nozzle to the processing surface must be kept constant to keep the film thickness constant, but work within a range of about 10 to 30 cm and spray at an angle of 30 to 40 degrees. Is preferred.

As described above, in the case of known arc spraying, a pair of sprayed wires according to the embodiment is used, and the two electrodes are used to perform arc discharge. However, in order to keep the film thickness constant, the tip of the nozzle is required. It has been stated that it is preferable to keep the distance to the treatment surface constant. However, the individual sprayed wires have variations on the product, and even if the distance and the spraying position are managed, the coordinates of the spraying point may gradually shift due to the variation in the product. In order to avoid this, in the present invention, as another embodiment of the thermal spraying method, one electrode uses the thermal sprayed wire of the present invention, and the other electrode has a melting point considerably higher than the melting point of the thermal sprayed wire and has stable electric conductivity. A ceramic electrode was used. With the electrodes provided in this way, a reliable spraying position can be obtained only by unitary control of giving reference coordinates to the ceramic electrode and moving the electrode on the spraying wire side according to wear without changing this coordinate position. . The conductive ceramic electrode is an example, and if the material has a melting point considerably higher than the melting point of aluminum and does not easily break or oxidize even when a large current flows, another material is used as the other electrode. It does not deny adoption.

The sprayed coating thus obtained is porous with flat particles deposited thereon, but the particles are in close contact with each other due to the mechanical anchoring effect. If the temperature of the surface of the object is too low, the internal strain increases due to rapid cooling, and it is desirable that the open-air temperature is plus 3 ° C. or higher to avoid condensation on the surface of the object.

The coating obtained by the above-mentioned process is subjected to a sealing treatment when pores are found in the final inspection. For the sealing treatment, a material that impregnates the pores is used.

The reason for providing the thermal spray coating is to make the thermal spray coating perform a sacrificial anodic action by utilizing the difference in ionization tendency between the object and the coating, and zinc is very suitable as a sacrificial anode. In order to extend the life of the coating, it is preferable that the distribution of zinc and aluminum in the thermal spray wire is increased by zinc. However, if the distribution of aluminum is too small, the hardness of the film becomes low and the film becomes weak against a physical external force. In this embodiment, the content of zinc is at least 60% by weight or more. Therefore, when manufacturing a sprayed wire with zinc as the core and aluminum as the clad,
Since the distribution amount of aluminum is small, even when the zinc wire is passed through the molten aluminum, by appropriately adjusting the passing speed, the zinc wire is not instantaneously melted, and the aluminum coating can be formed. .
In this embodiment, the content of zinc is set to 60% by weight or more. However, the zinc content is not limited to this value depending on the conditions required for the film and the installation location.

[0022]

According to the present invention, a zinc or aluminum alloy wire is used as a spray wire, but when a film is formed on an object by a normal arc spraying method, a dense and uniform film is formed. Was completed. The sprayed coating thus obtained is porous with zinc-rich and aluminum-rich flat particles deposited, but compared to pure zinc and pure aluminum, the flat particles are zinc-aluminum alloys with different concentrations. For this reason, the compatibility between the particles was good, the whole was homogeneous, the porosity was small, and a film extremely ideal for corrosion protection could be formed.

In addition, since the sprayed wire employs a structure in which zinc or aluminum is used as a core and the other is a clad, it can be easily manufactured by merely passing the core wire through a molten bath of a metal to be a clad. It was possible to make a configuration suitable for mass production.

Furthermore, when an electrode having a melting point that is not melted by arc spraying on the other electrode, that is, an electrode having a melting point considerably higher than the melting point of aluminum, is employed as a thermal spraying method, there may be variations in the manufacturing of the thermal sprayed wire. However, since the other electrode functions as a stable coordinate, the sprayed position can be reliably captured, and the accuracy of the sprayed coating is significantly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a sprayed wire of the present invention.

[Explanation of symbols]

 1 core 2 clad

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yuyasu Kurimoto 2-11-11-1110 Higashi Mikuni, Yodogawa-ku, Osaka F-term (reference) 4K031 AA05 AB09 CA03 CA04 CB31 CB37 DA03 EA08

Claims (10)

[Claims] An alloy wire for thermal spraying aluminum containing 5 to 15% by weight of zinc. 2. An alloy wire for zinc spraying containing 1 to 10% by weight of aluminum. 3. A thermal spraying wire in which 1 to 10% by weight of granular aluminum is dispersed in zinc. 4. The sprayed wire according to claim 3, wherein the granular aluminum diameter is 1 to 50 μm. 5. A sprayed wire having a zinc wire as a core and an aluminum clad formed around the core. 6. A sprayed wire having an aluminum wire as a core and a zinc clad formed around the core. 7. A spraying method in which the sprayed wire according to claim 1 is used as a pair of electrodes, and a film is formed on an object by arc spraying. 8. The sprayed wire according to claim 1 is used as one electrode, and the other is used as an electrode having a melting point that is not melted by arc spraying, and the sprayed wire is melted by arc spraying to form a coating on an object. The spraying method to be formed. 9. The thermal spraying method according to claim 8, wherein the other electrode is a fixed electrode. 10. The thermal spraying method according to claim 8, wherein the other electrode is a conductive ceramic electrode.