JP2511236B2 - Sealing method for thermal spray coating and coating composite - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a sprayed coating by forming a metal oxide coating, and a new coating composite comprising a metal sprayed coating and a metal oxide coating. .

[0002]

2. Description of the Related Art Since a thermal spray coating is generally porous, its pore structure changes physical properties such as heat and diffusion and permeation of a substance, and mechanical strength. It tends to have poor performance.
Therefore, it is necessary to close the pores, that is, perform a sealing treatment by some method.

As a conventional sealing treatment for a thermal spray coating, for example, an acrylic or epoxy resin paint is used.
Methods such as brush coating on the surface of the sprayed coating, inorganic sealing agent, for example, low temperature firing ceramics coating agent consisting of alumina and sodium silicate, brush coating or dip coating on the surface of the sprayed coating are known. There is. However, in the above method, the paint does not penetrate to the bottom of the pores, because the paint is only applied to the surface of the sprayed coating. Therefore, voids remained in the thermal spray coating, and the weather resistance of the thermal spray coating was poor.

[0004]

It is an object of the present invention to provide a method capable of performing a good sealing treatment on a metal spray coating formed on the surface of a base material made of ceramics or metal, with almost no voids left. It is an object of the present invention to provide and a new coating composite comprising a metal spray coating and a metal oxide coating.

[0005]

[Means for Achieving the Object] The method for sealing pores of a sprayed coating of the present invention comprises immersing a metal sprayed coating formed on the surface of a base material made of ceramics or metal in a solution of a polymer of metal alkoxide. As the anode, a current is passed between the cathode and the cathode soaked in the solution to cause the metal alkoxide polymer to adhere to the surface of the spray coating by electrophoresis, and the hydrolysis coating is further dried by air-drying the spray coating. It is characterized in that it is fired after being made.

The coating composite of the present invention comprises a metal spray coating formed on the surface of a base material made of ceramics or metal,
It is characterized by comprising a metal oxide film formed on this sprayed film.

Alumina, SiC, etc. can be used as the ceramics as the base material, and aluminum, iron, stainless steel, copper, etc. can be used as the metal as the base material. As the metal forming the sprayed coating, for example, aluminum, zinc, stainless steel, nickel, copper, alloys thereof, alloys such as stainless steel, or the like can be used.

As the metal alkoxide, Table 3 on page 20 of "Science of Sol-Gel Method" (author: Sakuka, published by Agne Chengfu Co., Ltd., published: July 5, 1988). 2 can be used. For example, Al (OC _{3
H 7) 3, Si (OC} 2 H 5) 4, Ti (OCH 3) is _4, and the like.

The metal alkoxide polymer solution is prepared by dissolving the metal alkoxide in a mixed solution of an alcohol containing water and an appropriate amount of acid.

Electrophoresis is carried out, for example, by a device as shown in FIG. In the figure, 10 is a power source, 11 is a metal spray coating that is an anode, 12 is a cathode, and 13 is a solution of a polymer of metal alkoxide in a container 14.

The time for air-drying, that is, the time of exposure to air, is until the hydrolysis and the polymerization of the adhered polymer of the metal alkoxide further proceed to the completion.

Firing is performed by a usual method.

[0013]

[Function] When a metal alkoxide is dissolved in a mixed solution of alcohol containing water and an appropriate amount of acid, the metal alkoxide is polymerized in a partially hydrolyzed state, and a polymer of the metal alkoxide is formed in the solution. To do. The polymer of the metal alkoxide has a structure in which the metals of several molecules of the metal alkoxide are bonded to each other via oxygen, and an alkoxy group is still bonded to the metal.

In FIG. 1, a metal spray coating 1 serving as an anode.
When a current is applied from the power source 10 between the cathode 1 and the cathode 12, the polymer of metal alkoxide moves toward the thermal spray coating 11,
It adheres to the surface of the thermal spray coating 11.

When the polymer of the metal alkoxide attached to the surface of the sprayed coating 11 is air-dried, the water content in the air causes further hydrolysis to proceed with the polymerization and the evaporation of the alcohol.

Upon firing, the polymer becomes a metal oxide.
In this way, a metal oxide film is obtained.

In the method of the present invention, since the metal alkoxide polymer migrates by electrophoresis, it spreads evenly on the surface of the sprayed coating, and of course reaches the bottom of the pores. Therefore, a metal oxide film having a uniform thickness is formed on the surface of the sprayed coating, and the pores are reliably filled. That is,
Almost no voids remain in the pores.

By changing the voltage for electrophoresis, a metal oxide film having an arbitrary thickness is formed, and the migration time is very short, within 5 minutes.

Since it can be carried out by using a known apparatus for electrodeposition coating, the thermal spray coating 11 can be easily used even on a substrate having a large area, and a metal oxide coating having a uniform thickness is formed on the surface thereof. It Moreover, the device is simple, and the metal oxide film is inexpensively formed. Furthermore, unlike electrodeposition coating, a net is provided on the counter electrode (cathode 12) side of the thermal spray coating 11,
It is not necessary to provide equipment for flowing the liquid.
That is, in electrodeposition coating, since an aqueous solution is used, hydrogen gas or oxygen gas is generated on the counter electrode side of the object to be coated, and this gas is contained in the coating film and becomes a defect. It is necessary to provide a collecting net or to make the liquid flow, but since the solution 13 used in the method of the present invention is a solution of a metal alkoxide polymer, no gas is generated and a film defect due to the gas is not generated. It never happens.

[0020]

EXAMPLES Examples of the present invention will be specifically described below. (Example 1) As shown in FIG. 2, after blasting a base material 1 made of a pure aluminum material, copper (diameter 1.6 mm
Wire, purity 99.0%) was plasma sprayed at an output of 40 kW to form a sprayed coating 21 having a thickness of about 150 μm. The spray coating 21 has a surface with a height difference of 30 to 50 μm by adopting conditions such as increasing the spray distance.
It was formed in an uneven shape having m. Further, brass was plasma sprayed on the sprayed coating 21 to form a sprayed coating 22 having a film thickness of 30 to 70 μm. Then, the thermal sprayed coating 21 and the thermal sprayed coating 22 up to the interface between the two thermal sprayed coatings 21 and 22,
That is, the surface was polished up to the broken line A1. Thereby, as shown in FIG. 3, a thermal spray coating 11 having a two-layer structure was obtained in which the thermal spray coating 22 entered the recesses on the surface of the thermal spray coating 21. 30 is the surface of the thermal spray coating 11. Figure 4 is IV of Figure 3
It is an arrow view.

On the other hand, in a 300 ml beaker, 15 ml of zirconium tetrabutoxide (Zr (OC ₄ H ₉ ) ₄ ) (manufactured by Mitsuwa Chemical Industry Co., Ltd.) and 185 m of 1-butanol were placed.
l was added and mixed, and 3 ml of 35% hydrochloric acid was further added to prepare a polymer solution of zirconium tetrabutoxide.

Then, the thermal sprayed coating 1 was added to the above polymer solution.
1 was soaked as an anode, and a pure titanium plate was used as a cathode. Direct current voltages (50 V, 100 V, 150 V, 200 V) of four different values were applied between the electrodes for 3 minutes in an air atmosphere. The case where no DC voltage was applied was also examined. For the post-treatment, the sprayed coating 11 was immersed in a methanol solution, washed with water, air-dried for 30 minutes, and then dried in an electric furnace.
Heated at 00 ° C for 1 hour.

The following results were obtained. When a DC voltage of 50 V, 100 V, or 200 V was applied, a zirconium oxide coating having a uniform thickness of blue to light green was obtained on the surface of the thermal spray coating 11. The film thickness is 0.1
It was about 0.2 μm. The best is when a DC voltage of 150 V is applied,
On the surface of the sprayed coating 11, a blue-green zirconium oxide coating having a uniform thickness of 0.25 μm was obtained. When the direct current voltage was not applied, the zirconium oxide film was slightly formed in an uneven shape.

The spray coating 11 having the zirconium oxide coating formed thereon was subjected to a salt spray test according to JIS-H8502. As a result, RN 9.8 in 2000 hours
Met. This means that the pores are densely filled with zirconium oxide even in the two-layered thermal spray coating 11 as shown in FIG. 3, and almost no voids remain in the pores. ing. That is, the sealing treatment is performed well.

The thus obtained coating composite consisting of the two-layered thermal spray coating of copper and brass and the zirconium oxide coating has decorative properties and high fracture toughness, and is therefore effective as an exterior member. Can be used.

(Example 2) A base material made of mild steel was blasted by a direct pressure type blasting of # 24, and then aluminum (a wire having a diameter of 1.6 mm, a purity of 99.5%) was sprayed with Puma by an output of 40 kW, A sprayed coating having a thickness of 300 μm was formed.

On the other hand, barium alkoxide (Ba (OC
₃ H ₇ ) ₂ ) 5 ml and titanium alkoxide (Ti (OC ₅
H ₁₁ ) ₄ ) 7 ml and isopropyl alcohol 188 m
Further, 3 ml of 98% sulfuric acid was added to the mixed solution with 1 to prepare a polymer solution of barium alkoxide.

Then, the sprayed coating was dipped in the polymer solution to serve as an anode, and a pure titanium plate was used as a cathode. A direct current voltage of 50 V was applied for 2 minutes between both electrodes in a nitrogen stream, and then 150 V was applied. It was applied for 1 minute. Then, post-treatment was performed in the same manner as in Example 1. As a result, a film of barium metatitanate (BaTiO ₃ ) was formed on the surface of the sprayed film.

A cast test was carried out on the thermal spray coating having the barium metatitanate coating formed thereon.
The RN was 9.8 in 8 hours. With the thermal spray coating as it was, it was RN5 in 1 hour. This indicates that the pores of the thermal spray coating are densely filled with barium metatitanate, and that almost no voids remain in the pores. That is, the sealing treatment is performed well.

Further, the film composite comprising the aluminum sprayed film and the barium metatitanate film thus obtained has ferroelectricity and therefore can be effectively used as an electronic member such as a capacitor.

(Example 3) Zinc (1.6 mm diameter wire, purity 99.0%) was applied to a ceramic board for outer wall.
Was plasma sprayed at an output of 40 kW to form a sprayed coating having a thickness of 250 μm. The thermal spray coating was smoothed by grinding with a grinder.

On the other hand, ethanol 119 ml, water 59 m
1, a mixed solution of 0.2 ml of sulfuric acid was sufficiently stirred, and 59 ml of silica alkoxide (Si (OC ₂ H ₅ ) ₄ ) was slowly added thereto to prepare a polymer solution.

Then, the sprayed coating was dipped in the polymer solution and left for 1 minute, then used as an anode, a pure titanium plate was used as a cathode, and a DC voltage of 10 V was applied between both electrodes for 3 minutes. Immediately thereafter, the thermal spray coating was taken out of the solution, washed with tap water and then with distilled water, and air dried at room temperature for 30 minutes. Then, the temperature was raised to 150 ° C. in the furnace for about 7 hours, and the firing was performed for about 3 hours. It was left overnight, returned to room temperature, and then taken out of the furnace. As a result, a silicon dioxide (SiO ₂ ) film was formed on the surface of the sprayed film.

An accelerated weather resistance test was carried out on the above-mentioned sprayed coating having the silicon dioxide coating formed thereon.
There was no change at 0 hours. With the thermal spray coating as it is,
Whitening occurred in 250 hours, and zinc was dissolved. This indicates that the pores of the thermal spray coating are densely filled with silicon dioxide, and almost no voids remain in the pores. That is, the sealing treatment is performed well.

Further, the film composite comprising the zinc sprayed film and the silicon dioxide film thus obtained has decorative properties and acid resistance, and therefore can be effectively used as an exterior member.

(Other Embodiments) In the above embodiments, other metals (for example, iron, copper) and other ceramics may be used as the base material. Further, as the metal constituting the sprayed coating, other metals such as nickel, stainless steel, nickel-chromium alloy, etc. may be used. Further, as the form of the sprayed coating, various two-layered structures and multilayered structures may be adopted. In these cases as well, the sealing treatment is satisfactorily performed as in the above-mentioned embodiment.

As the solution of the metal alkoxide polymer, for example, the following may be used. That is, a mixed solution of 119 ml of ethanol, 59 ml of water, and 0.2 ml of sulfuric acid was sufficiently stirred, and aluminum alkoxide (A
It was prepared by slowly adding 59 ml of 1 (OC ₃ H ₇ ) ₃ ).

[0038]

As described above, according to the present invention, the polymer of the metal alkoxide is electrophoresed, so that the metal sprayed coating formed on the surface of the base material made of ceramics or metal is voided in the pores. It is possible to perform a good sealing treatment with almost no remaining.

Further, it is possible to provide a new coating composite comprising a metal spray coating and a metal oxide coating.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for performing a sealing treatment method of the present invention.

FIG. 2 is a cross-sectional view showing a process of forming a target sprayed coating in Example 1 of the present invention.

FIG. 3 is a cross-sectional view showing a target thermal spray coating in Example 1 of the present invention.

FIG. 4 is a view taken in the direction of arrow IV in FIG. 3;

[Explanation of symbols]

 11 Metal Sprayed Coating 12 Cathode 13 Solution (of Polymer of Metal Alkoxide)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C25D 13/00 307 C25D 13/00 307D 13/06 13/06 Z (56) References 60-42287 (JP, A) JP-A 52-58722 (JP, A) JP-A 54-14127 (JP, A) JP-A 1-219006 (JP, A) JP-A 59-209462 (JP, A) A) JP 64-62453 (JP, A) JP 4-187532 (JP, A) JP 5-246701 (JP, A) JP 1-247598 (JP, A)

Claims (2)

(57) [Claims] 1. A metal spray coating formed on the surface of a base material made of ceramics or metal is immersed in a solution of a polymer of metal alkoxide to form an anode, and a current is applied between the cathode and the solution. A polymer of the metal alkoxide is attached to the surface of the thermal spray coating by flow electrophoresis, and further hydrolysis and polymerization are allowed to proceed by air-drying the thermal spray coating, followed by firing. Sealing of the thermal spray coating. Processing method. 2. A coating composite comprising a metal spray coating formed on the surface of a base material made of ceramics or a metal, and a metal oxide coating formed on the spray coating.