JP3035209B2 - Corrosion resistant material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant material applicable to facilities for treating aqueous solutions having acidic, basic, oxidizing, reducing, etc., seawater, sewage and the like, and a method for producing the same. It is effective when applied to materials used in molten salt processing equipment such as a plating tank for performing molten salt plating and a roll for transporting the material subjected to molten salt plating.

[0002]

2. Description of the Related Art In automobiles, structural members for civil engineering and construction, home electric appliances, and the like, demand for surface-treated steel sheets excellent in corrosion resistance, weldability, paintability and the like is rapidly expanding. Among such surface-treated steel sheets, those subjected to hot-dip galvanizing, electrogalvanizing, hot-dip aluminum plating, and the like have become mainstream. Recently, alloy plating using a molten salt having higher corrosion resistance than zinc and aluminum plating is being developed.

[0003] Molten salt plating is generally performed using a halide-containing electrolyte. For this reason, in equipment for performing such molten salt plating, a coating film or a sheet-like molded product made of a polyimide resin having corrosion resistance and heat resistance to halides is provided in a plating tank or an electrode portion. I have. In addition, members such as rolls for transporting steel sheets subjected to the molten salt plating are sprayed with alumina in consideration of abrasion resistance, and are further subjected to sealing treatment with a glass-based material for corrosion protection. Have been.

[0004] That is, in a facility for performing molten salt plating, for example, as shown in FIG. 2A, a sheet 12 made of a polyimide resin is adhered to the inner surface of the plating tank 11 to melt the inner surface of the plating tank 11. The sheet 12 prevents corrosion due to salt or the like, or as shown in FIG.
A coating 14 made of alumina is provided on the outer peripheral surface of the roll 13 by a plasma spraying method to improve the wear resistance of the roll 13, and a glass-based sealing material 15 is provided on the surface of the coating 14 by a vacuum sealing method or an atmospheric sealing method. The above coating 1
4 has improved corrosion resistance.

[0005]

The material of the molten salt treatment equipment which has been subjected to the above-described treatment has the following problems. (1) Coating film forming material When the base material is a welded structure or the like, it is difficult to uniformly apply the coating material, and a large variation occurs in the film thickness. Because the anchor effect to improve the adhesion between the substrate and the coating film does not work sufficiently, depending on the temperature during use,
The coating is easy to peel off. Since the film thickness is relatively thin, the surface of the base material is easily exposed when a flaw or the like is generated.

(2) Sheet sticking material If the base material is a complicated shape or the like, uniform sticking becomes difficult. The molten salt easily penetrates from the seam between the sheets, and it is difficult to maintain the corrosion resistance for a long time.

(3) Alumina coating and glass-based sealing material application material A sealing material is impregnated on the surface of the coating so as to seal fine pores which are necessarily formed in the coating by a thermal spraying method. Since only the pores near the surface of the coating penetrate and do not penetrate the pores (closed pores) inside the coating, only the pores near the surface of the coating are sealed. In addition, since the solvent used for the sealing material evaporates during drying, a slight gap is generated between the pores of the coating and the sealing material. For this reason, even if the coating film surface is slightly worn, the anticorrosion effect of the sealing material is remarkably reduced, so that the coating material is likely to become unusable in a short period of time.

[0008] Such a problem is not limited to materials applied to molten salt treatment equipment, but also in highly corrosive environments such as aqueous solutions having acidic, basic, oxidizing and reducing properties, seawater and sewage. As long as the material of the equipment to be used is the same as described above. Accordingly, an object of the present invention is to provide a corrosion-resistant material capable of maintaining corrosion resistance for a long period of time even in a highly corrosive environment and a method for producing the same.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, a corrosion-resistant material according to the present invention is provided on a substrate and has a high adhesion to the substrate and a high adhesion. Ni-base alloy or MCrAlX alloy with corrosion resistance
(However, M is Ni or Co, X is Y, Hf, Ce, L
a, Si, Ta, Pt)
An alloy layer made of a alumina layer provided on the alloy layer, characterized by comprising a glass layer provided on said alumina layer.

In the above-described corrosion-resistant material, the glass
The other layer is mainly composed of SiO ₂ and other acids except Na ₂ O.
Of a glass material containing a compound .

Further, in order to solve the above-mentioned problems, a method for producing a corrosion-resistant material according to the present invention provides a Ni-based alloy having high adhesion to a substrate and high corrosion resistance.
MCrAlX alloy (where M is Ni or Co, X is
Y, Hf, Ce, La, Si, Ta, Pt
At least one kind) is sprayed on the base material by a thermal plasma spraying method to form an alloy layer on the base material, and then the alumina is sprayed on the alloy layer by a thermal plasma spraying method. A layer is provided, and glass is sprayed on the alumina layer by a thermal plasma spraying method to provide a glass layer on the alumina layer.

In the method for producing a corrosion-resistant material described above, when the glass layer is provided on the alumina layer, the glass is sprayed on the alumina layer while heating the alumina layer to a temperature of 200 to 400 ° C. It is characterized by.

In the above-described method for producing a corrosion-resistant material, after the glass layer is provided on the alumina layer, the glass layer is heated to a temperature higher than the softening temperature of the glass.

In the above corrosion-resistant material, the glass
Other oxides containing SiO ₂ as the main component and excluding Na ₂ O
It is characterized by containing a substance .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a corrosion-resistant material and a method for manufacturing the same according to the present invention will be described with reference to FIG. In addition,
FIG. 1 is a schematic sectional view showing the configuration of the material.

As shown in FIG. 1, on a substrate 1 made of a steel material, an alloy layer 2 having high adhesion to the substrate 1 and high corrosion resistance is provided. An alumina layer 3 having excellent corrosion resistance and electrical insulation is provided on the alloy layer 2. On the alumina layer 3, a glass layer 4 having excellent corrosion resistance, electrical insulation and abrasion resistance is provided.

That is, by providing the alloy layer 2 as the first layer, the alumina layer 3 as the second layer, and the glass layer 4 as the third layer on the surface of the substrate 1, it has electrical insulation, corrosion resistance and wear resistance. The structure was made by laminating materials. The alloy layer 2 has excellent adhesion to the substrate 1. Alumina layer 3
Has excellent corrosion resistance against molten salts, halides and strong acids generated by hydrolysis of these salts,
Excellent electrical insulation. The glass layer 4 is composed of the alumina layer 3
It has excellent corrosion resistance against the penetration of a corrosive medium penetrating from very small or minute pores existing in the steel, and also has excellent electrical insulation properties.

Such a corrosion-resistant material is subjected to shot blasting in advance for the purpose of cleaning the surface of the base material 1 and improving the adhesion of the sprayed coating, and then to the alloy layer 2 by a thermal plasma spraying method.
Is formed by thermal spraying, then the alumina layer 3 is formed by thermal spraying, and the glass layer 4 is further formed by thermal spraying to form a multilayer coating structure.

Here, each layer will be described in more detail. The alloy layer 2 is for improving the adhesion to the substrate 1 and is made of a Ni-based alloy or a MCrAlX alloy (where M is Ni or Co, X is Y, Hf, Ce, La, Si, T
a, Pt). As the Ni-based alloy, NiCr (Ni: 20 to 80 wt%, C
(r: 80 to 20 wt%) is generally used. As this composition, there are many standard 80 wt% Ni-20 wt% Cr. To further improve adhesion and corrosion resistance,
MCrAlX alloy is suitable. The composition can be selected from many, but for the purpose of the present invention, Cr: 5 to 70
wt%, Al: 1 to 29 wt%, M component: Ni: 1 to 29 wt%
75 wt%, Co: 1 to 60 wt%, and 0.1% for the X component
Alloys in the range of ~ 3 wt% are preferred. Further, the thickness is practically 20 to 100 μm. 20 μm
Below, the stability of a film lacks. The purpose of this layer is to secure adhesion, and if the thickness is too large, it increases the cost and is uneconomical.
μm, but there is no particular limitation.

The alumina layer 3 prevents corrosion from the environment of the substrate 1, has a good affinity with the glass layer 4, and has an electrical insulation property. The alumina layer 3 is preferably of high purity in terms of performance, and it is preferable to use the highest purity among those usually used for thermal spraying.
% Or more is preferable. A film thickness of 50 μm to several hundred μm is suitable for the purpose of electrical insulation and corrosion resistance.
If it is less than 50 μm, the stability of the film will be lacking. The upper limit is more preferably about 200 μm. This is because if the alumina layer 3 is too thick, there is a possibility that cracks and peeling problems may occur due to a difference in thermal expansion. Denseness is important for preventing the penetration of the molten salt during use and the penetration of the washing liquid during washing. Therefore, the thermal spray powder of the alumina layer 3 has an average particle diameter is small, though having a narrow particle size distribution range is preferred, depending on the spraying conditions, the restriction is no particular. In general, the thermal spraying method is carried out in the atmosphere, but when the denseness is to be further improved, the pressure is reduced (low pressure).
It is preferable to apply a thermal spraying method.

The glass layer 4 has the same electrical insulating properties as the alumina layer 3 and is nonporous and excellent in corrosion resistance. Further, it is a relatively hard film and has excellent wear resistance. The glass layer 4 is different from a conventionally used glass material in that a material having a thermal expansion coefficient close to that of the substrate 1 after thermal spraying is used. The heating of the alumina layer 3 and the like before thermal spraying is performed at a conventional temperature (600 to 750).
By maintaining the heating temperature at 200 ° C. to 400 ° C. without increasing the temperature to 200 ° C.), it is possible to improve the adhesion with the alumina layer 3 while performing thermal spraying in an environment with good workability, that is, at a low temperature. At the same time, a dense and smooth film without pores or cracks can be obtained. As a spraying method,
There are many processes to choose from, but thermal plasma spraying is the best. When the above-mentioned heating temperature is set to 200 ° C. to 400 ° C. and the thermal plasma spraying is performed, the glass layer 4 can be made almost void-free. By heating as described above, a completely non-porous film can be obtained.

It is essential that the glass layer 4 does not crack or peel during thermal spraying and use, and that the glass layer 4 be non-porous in order to prevent penetration of corrosive substances from the pores. You. For this reason, it is necessary to select a material for the glass layer 4 from materials that can be sprayed at a relatively low temperature and that do not cause cracking or peeling during spraying, cooling after spraying, or during use. Therefore, the following glass material was used. A material which is relatively resistant to acids and alkalis and has a thermal expansion coefficient close to that of steel as a base material, for example, 40 to 50 wt% SiO
A glass material containing ₂ as a main component, to which B ₂ O ₃ , LiO ₂ , Al ₂ O ₃ and a small amount of an oxide are added. To improve further the acid resistance, the alkali resistance than the glass material of SiO ₂ and 65～75Wt%, were the same as the other components. In order to improve the corrosion resistance, it is better not to contain Na ₂ O. Such a glass material has a melting point of about 560 ° C. and a coefficient of thermal expansion of 12.7 × 10 ⁻⁶ , and the above glass material has a melting point of 620 ° C. and a coefficient of thermal expansion of 1
It is 2.8 × 10 ^-6 .

The thickness of the glass layer 4 is several tens μm for the purpose of abrasion resistance and sealing of the pores of the alumina layer 3.
~ Several hundred µm is suitable. If the film thickness is too thin (several tens
m or less), causing problems such as generation of defects such as pores in the sprayed layer and a decrease in the smoothness of the surface after spraying. On the other hand, if it is too thick (several hundred μm or more), solidification during thermal spraying or cracking during cooling may occur. Conventional thermal spraying is performed by heating the base material 1 or the like to a temperature close to the melting point of the thermal sprayed material. However, the thermal spraying of the present invention employs a thermal plasma spraying process, so that a heating temperature of 200 to 400 ° C. is sufficient. . Therefore, a molten glass coating is formed at the same time as the sprayed glass droplet collides with the alumina layer 3. Further, by heating the glass layer 4 to a temperature higher than the softening temperature of the glass material using a hydrocarbon / oxygen combustion frame or an electric furnace, the pores disappear.

During normal operation, the molten salt treatment equipment does not contain moisture in the molten salt, so that its constituents hardly corrode. However, if cleaning after operation (mainly cleaning with water) is performed, At this time, the water reacts with the molten salt adhered to and solidified on the constituent members and the like to generate a large amount of hydrogen acid, for example, HCl, HF, HBr, HI, etc., and the corrosion of the constituent members proceeds. I will. However,
If the corrosion-resistant material according to the present invention is applied to the constituent members of the molten salt treatment facility, the stable operation can be performed for a long period of time without the permeation of the hydrogen acid into the substrate even in the above-described environment. The molten salt processing equipment is equipment that may come into contact with the molten salt, and its main constituent members include various rolls, processing containers, piping for circulating molten salt, pumps, and the like. Further, the present invention is not limited to such a molten salt treatment facility, and may be applied to a facility for treating an aqueous solution having acidic, basic, oxidizing, reducing, or the like, seawater, sewage, and the like.

[0025]

EXAMPLES Examples of the corrosion-resistant material and the method for producing the same according to the present invention will be described below. - Example 1 (1) thermal spray apparatus of 80% Ni-20% Cr alloy with SS400 to manufacture specimen A base material of the corrosion-resistant material (plasma gas: Ar, H ₂₎
After spraying about 75 μm with white alumina (purity 9
9.8%, average particle diameter of 20 μm) was sprayed by thermal plasma spraying to a thickness of 150 μm in the same manner as described above, and 45 wt% SiO _{2 was} sprayed.
With B ₂ O ₃ , LiO ₂ , CaO, SrO, A
A glass material containing another oxide such as l ₂ O ₃ , TiO ₂ , MgO was sprayed at 150 μm. The heating temperature of the alumina layer and the like during the glass spraying was set to about 300 ° C.

Specimen B 22% Cr-10% Al-1 using SS400 as a substrate
% Y-alloy consisting of the remaining Ni is sprayed by a thermal plasma spraying apparatus (plasma gas: Ar, H ₂ ) to about 100 μm, and then white alumina (purity 99.8%, average particle diameter 20 μm).
Is sprayed by thermal plasma spraying in the same manner as described above to a thickness of 100 μm, and B ₂ O ₃ , Li containing 66 wt% SiO ₂ as a main component.
A glass material containing another oxide such as O ₂ , CaO, SrO, Al ₂ O ₃ , TiO ₂ , and MgO was sprayed at 100 μm. The heating temperature of the alumina layer and the like during the glass thermal spraying was set to about 400 ° C., and after the thermal spraying, heating was performed at 720 ° C. for 1 hour.

Specimen C A bismaleimide resin was coated on the base material (SS400) to a thickness of 100 μm.
Coated. Specimen D 100 μm bismaleimide resin on the substrate (SS400)
After coating, white alumina (98% purity,
The average particle size of 25 μm) was 200
μm was sprayed. The shape of each specimen A to D is 20 mm in diameter and 2 mm in length.
It was made into a spherical shape with a radius of 10 mm and a tip of 00 mm.

(2) Test Method After immersion in a molten salt containing AlCl ₃ as a main component at 200 ° C. for 16 hours, immersion in boiling water for 8 hours was repeated, and the appearance of the surface of each specimen was observed. Table 1 shows the results.

[0029]

[Table 1]

(3) Results As can be seen from Table 1, the specimen C had the surface layer peeled off by about 70% in area ratio at the first time, and the specimen D had about 30% red rust by area at the second time. %, And a blistering phenomenon was observed in part of the coating. On the other hand, the test pieces A and B did not show any damage to the coating film even after repeated 20 times.

Example 2 The surface of the seal roll (SS400) of the molten salt processing equipment was subjected to the same treatment as the above-described specimens A and B of Example 1. That is, a seal roll treated in the same manner as the specimen A and a seal roll treated in the same manner as the specimen B were attached to an actual machine and actually used for about one month. During the period, washing was performed 5 times. As a result, the surface of the roll was not damaged at all, and there was no problem such as abrasion caused by contact with a steel plate.

[0032]

According to the corrosion resistant material of the present invention, the corrosion resistance can be maintained for a long period of time even in a highly corrosive environment. Therefore, for example, if it is applied to components of equipment that is exposed to highly corrosive substances, such as molten salt treatment equipment, stable operation can be performed over a long period of time. And the cost can be reduced.

Further, according to the method for producing a corrosion-resistant material of the present invention, a corrosion-resistant material having the above-described effects can be easily produced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a configuration of a corrosion-resistant material according to the present invention.

FIG. 2 is a schematic sectional view illustrating a configuration of a conventional corrosion resistant material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Alloy layer 3 Alumina layer 4 Glass layer

Continued on the front page (72) Inventor Sadato Shigemura 4-6-22 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Toyoaki Yasui 4-6-1 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima No. 22 Mitsubishi Heavy Industries, Ltd.Hiroshima Research Institute (72) Inventor Shizuaki Ueno 4-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd.Hiroshima Works (72) Inventor Yasuhiro Yamamoto Chuo-ku, Osaka-shi, Osaka 4-5-33 Kitahama Sumitomo Metal Industries, Ltd. (72) Inventor Takeshi Hattori 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Junichi Uchida Osaka-shi, Osaka Sumitomo Metal Industries Co., Ltd. 4-5-33 Kitahama, Chuo-ku Sumitomo Metal Industries Co., Ltd. (72) Inventor Yoshio Harada 4-3-1-4 Fukae-Kitacho, Higashinada-ku, Kobe-shi, Hyogo Prefecture Inside Talkaro Co., Ltd. 4-1-4 Fukae-Kitacho, Higashinada-ku, Yokohama-shi The inner (56) Reference Patent flat 7-268594 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) C23C 4/06 - 4/10 C23C 28/00

Claims (6)

(57) [Claims] 1. A base material, a Ni-based alloy or MCrA provided on the base material and having high adhesion to the base material and high corrosion resistance.
1X alloy (where M is Ni or Co, X is Y, Hf,
At least one of Ce, La, Si, Ta, and Pt
A corrosion-resistant material comprising: an alloy layer made of the above-described (1 ) , an alumina layer provided on the alloy layer, and a glass layer provided on the alumina layer. 2. The method according to claim 1, wherein the glass layer contains SiO ₂ as a main component,
_2. The corrosion-resistant material according to claim 1, comprising a glass material containing another oxide except for Na2O . 3. A Ni-based alloy or an MCrAlX alloy having high adhesion to a substrate and high corrosion resistance (however,
M is Ni or Co, X is Y, Hf, Ce, La,
At least one of Si, Ta, and Pt) is sprayed on the base material by a thermal plasma spraying method to form an alloy layer on the base material, and then the alloy layer is sprayed with alumina by a thermal plasma spraying method. Forming an alumina layer on the alloy layer and spraying glass on the alumina layer by a thermal plasma spraying method to provide a glass layer on the alumina layer. 4. The method according to claim 3, wherein, when the glass layer is provided on the alumina layer, the glass is sprayed on the alumina layer while heating the alumina layer to a temperature of 200 to 400 ° C. A method for producing the corrosion-resistant material described above. 5. The method for producing a corrosion-resistant material according to claim 3, wherein after the glass layer is provided on the alumina layer, the glass layer is heated to a temperature higher than a softening temperature of the glass. 6. The glass according to claim 1, wherein said glass is mainly composed of SiO ₂ ,
method for producing a corrosion-resistant material according to claims 3 to one of the 5, characterized by containing other oxides excluding a ₂ O.