JP7476712B2 - Method for manufacturing seal structure, and seal structure - Google Patents

Description

The present invention relates to a method for manufacturing a seal structure and a seal structure.

High-temperature equipment with an internal space that allows for atmospheric control, such as high-temperature atmospheric furnaces, are widely used in a variety of fields.

In such high-temperature equipment, the sealing ability of the sealing members that seal the internal space from the outside world may deteriorate during use of the high-temperature equipment. In such cases, it may often become necessary to carry out repairs to the sealing members while the high-temperature equipment is maintained at a high temperature.

Various methods have been proposed for so-called in-situ repair of such high-temperature equipment (e.g., Patent Document 1).

JP 2016-3313 A

One possible method for in-situ repair of high-temperature equipment is to apply a coating of a film component such as water glass to the deteriorated parts of the sealing material.

However, when a water glass coating is placed on a sealing member maintained at a high temperature, a problem occurs in that as the water evaporates from the water glass, through-holes form in the coating. In this case, the resulting coating becomes porous and is no longer able to provide a good sealing effect.

Thus, there is a demand for a method to produce a dense seal structure when performing in-situ repairs on high-temperature equipment.

The present invention has been made in consideration of this background, and aims to provide a manufacturing method for a seal structure that can be significantly applied to in-situ repair of high-temperature equipment. Another aim of the present invention is to provide such a seal structure.

The present invention provides a method for manufacturing a seal structure that isolates the internal space of a high-temperature device from the outside world, in which a raw material liquid containing a coating component is turned into a mist and sprayed onto a part to be coated at a temperature of 200°C or higher, and the coating component is deposited on the part to be coated to form a coating.

The present invention also provides a seal structure having a porous base member and a coating disposed on the base member, the coating being a non-organic film containing at least one of silica, alumina, and carbon, the surface roughness Ra of the base member being 1 mm or more, and the thickness of the coating being in the range of 1 μm to 20 μm.

The present invention can provide a method for manufacturing a seal structure that can be significantly applied to in-situ repair of high-temperature equipment. The present invention can also provide such a seal structure.

5A to 5C are diagrams illustrating a flow of a method for manufacturing a seal structure according to an embodiment of the present invention. 1 is a cross-sectional view showing a schematic diagram of a seal structure according to an embodiment of the present invention formed in a seal portion of a high-temperature device. FIG. 2 is a diagram illustrating a schematic configuration of a test device. FIG. 11 is a diagram showing a summary of evaluation test results at 200° C. for the seal structures according to the respective examples. FIG. 11 is a diagram showing a summary of evaluation test results at 300° C. for the seal structures according to the respective examples. FIG. 11 is a diagram showing a summary of evaluation test results at 400° C. for the seal structures according to the respective examples. FIG. 11 is a diagram showing a summary of evaluation test results at 500° C. for the seal structures according to the respective examples. 1 is a photograph showing an example of a cross section of a seal structure according to an embodiment of the present invention.

One embodiment of the present invention is described below.

In one embodiment of the present invention, a method for manufacturing a seal structure that isolates the internal space of a high-temperature device from the outside world is provided, in which a raw material liquid containing a coating component is turned into a mist and sprayed onto a part to be coated at a temperature of 200°C or higher, and the coating component is deposited on the part to be coated to form a coating.

In one embodiment of the present invention, the mist of the raw material liquid is sprayed onto the part to be coated, which is maintained at a high temperature of 200°C or higher.

The raw material liquid contains the coating components. Therefore, by turning this raw material liquid into mist, the coating components that are covered with the liquid are formed as a mist.

When such a mist is sprayed onto the part to be coated, the solvent contained in the mist evaporates when the mist comes into contact with the surface of the part to be coated. Therefore, coating components that do not contain the solvent are deposited on the surface of the part to be coated.

By repeatedly and continuously contacting the part to be coated with the mist and evaporating the solvent, the coating components are gradually deposited on the surface of the part to be coated.

For example, when the coating component contained in the raw material liquid is in the form of particles, the raw material liquid is misted to form particles containing the liquid (hereinafter, also referred to as "mist particles" in particular). When such mist particles are sprayed onto the part to be coated, the solvent is vaporized when the mist particles come into contact with the surface of the part to be coated. Therefore, particles of the coating component that do not contain the solvent are deposited on the surface of the part to be coated.

Alternatively, when the coating component contained in the raw material liquid is in the form of a pyrolyzed substance containing carbon, the raw material liquid is misted to form a pyrolyzed substance wrapped in liquid (hereinafter, also referred to as the "mist component" in particular). When this mist component comes into contact with the surface of the part to be coated, the solvent is vaporized and the pyrolyzed substance is decomposed at the same time. Therefore, carbon that does not contain the solvent is deposited on the surface of the part to be coated.

The deposit formed via such "mist particles" or "mist components" does not substantially contain solvent. Therefore, no through holes are formed in the deposit as a result of the solvent evaporating.

Therefore, in one embodiment of the present invention, a dense coating can be formed on the coated portion. This also makes it possible to manufacture a seal structure that exhibits good sealing performance in one embodiment of the present invention.

(Method of manufacturing a seal structure according to an embodiment of the present invention)
Next, the method for manufacturing a seal structure according to an embodiment of the present invention will be described in more detail with reference to the drawings.

Figure 1 shows a schematic flow of a method for manufacturing a seal structure according to one embodiment of the present invention.

As shown in FIG. 1, a method for manufacturing a seal structure according to an embodiment of the present invention (hereinafter referred to as a "first manufacturing method") includes the following steps:
(1) A step of preparing a raw material liquid (step S110);
(2) A step of misting the raw material liquid (step S120);
(3) A step of spraying the mist of the raw material liquid onto a part to be coated in a high-temperature device (step S130);
has.

Each step is explained below.

Here, as an example, each step of the first manufacturing method will be described assuming that the raw material liquid contains particles of the coating component, and therefore "mist particles" are formed by misting the raw material liquid.

(Step S110)
First, a raw material solution for the coating to be placed on the part to be coated in the high-temperature device is prepared.

The raw material liquid contains a solvent and particles dispersed in the solvent.

The solvent may include, but is not limited to, at least one of water, methanol, ethanol, n-propanol, and isopropanol. From a safety standpoint, it is particularly preferred that the solvent be water.

The particles are composed of the components of the coating that will be formed later. The particles may include, for example, alumina, or silica.

The raw material liquid may be, for example, an alkali silicate solution, a silica sol, or an alumina sol. The alkali silicate solution may be a sodium silicate solution (so-called water glass).

The concentration of solid particles contained in the raw material liquid is not particularly limited, but is, for example, in the range of 1% to 20% by mass. If the concentration of solid particles exceeds 20% by mass, the viscosity of the raw material liquid increases, and it may become difficult to maintain the specified mist state and to steadily supply the mist particles.

(Step S120)
Next, the raw material liquid prepared by the above-mentioned method is misted. That is, liquid particles containing solid particles, that is, "mist particles", are formed from the raw material liquid.

The method for turning the raw material liquid into a mist is not particularly limited. The raw material liquid may be turned into a mist using, for example, a spray gun, an airbrush, or an ultrasonic brush.

The diameter of the mist particles depends on the concentration and particle size of the solid particles contained, but is, for example, in the range of 2 μm to 50 μm. By making the diameter of the mist particles 50 μm or less, in the subsequent step S130, the mist particles come into contact with the surface of the part to be coated, and the solvent contained in the mist particles can be quickly vaporized before the next mist particles arrive. In addition, by making the diameter of the mist particles 2 μm or more, in the subsequent step S130, a coating can be formed on the part to be coated in a realistic amount of time.

In this application, the diameter of the mist particles is measured by laser diffraction particle analysis. In addition, in addition to air, argon, nitrogen, oxygen, etc. can be used as the carrier gas for the "mist particles."

(Step S130)
The mist of the raw material liquid is then supplied to a part to be coated. For example, the part to be coated may be a part of a seal member of a high-temperature device, for example, one surface of the seal member.

Examples of high-temperature equipment include, but are not limited to, various furnaces such as coal coke ovens, iron ore blast furnaces, glass melting furnaces, and glass forming furnaces. The temperature of the sealing members of these high-temperature equipment can range from 200°C to 500°C.

The supply rate of the raw material liquid varies depending on the composition of the raw material liquid, the concentration of the solid particles contained therein, the temperature of the installation target, etc. In general, the supply rate of the raw material liquid may be in the range of 0.0001 to 0.1 cc/(sec·cm ² ), for example.

However, if the supply speed is too high, the solvent may not evaporate quickly enough from the mist particles, resulting in the coating being contaminated with the solvent.

Therefore, in order to avoid or suppress such problems, the mist particles may be supplied intermittently. For example, the supply of the mist-formed raw material liquid may be periodically repeated on and off.

Because the part to be coated is maintained at a high temperature, when the mist particles reach the surface of the part to be coated, the solvent contained in the mist particles is vaporized and dispersed. Therefore, on the surface of the part to be coated, particles of the coating components that do not contain the solvent are deposited in a dense state without any air holes. In addition, the mist-formed raw material liquid is continuously supplied to the part to be coated. Therefore, in the part to be coated, the solvent of the mist particles is vaporized and the solid particles are deposited repeatedly. In addition, as a result, the solid particles of the coating components are deposited successively on the surface of the part to be coated.

As a result of this phenomenon being repeated, a film is formed on the coated part. The thickness of the film is not particularly limited, but is, for example, in the range of 1 μm to 20 μm.

The coating obtained by the first manufacturing method does not contain any through holes and has a dense morphology.

Therefore, the first manufacturing method can form a dense coating with good sealing properties in-situ.

In addition, in the first manufacturing method, the mist particles are desolvated and only the particle components are deposited sequentially, thereby forming a coating. With this type of film formation method, a dense coating can be formed even if the surface of the part to be coated has relatively large irregularities.

For example, the first manufacturing method can form a dense, continuous coating even when the surface roughness Ra of the coated portion is 1 mm or more.

The first manufacturing method has been described above using an example in which the raw material liquid contains solid particles of the coating component.

However, this is merely one example, and the first manufacturing method may have a different configuration. For example, the raw material liquid may contain a pyrolysis substance containing carbon instead of particles of the coating component. In this case, the pyrolysis substance containing carbon may be dissolved in the raw material liquid.

When such a raw material liquid is used, in step S120, a "mist-forming component" is formed instead of "mist-forming particles." Therefore, in the subsequent step S130, when the "mist-forming component" comes into contact with the surface of the part to be coated, the decomposition of the pyrolysis substance and the evaporation of the solvent occur simultaneously. As a result, a carbon coating is formed on the part to be coated.

Those skilled in the art will easily understand that various other modifications are possible.

(Seal structure according to one embodiment of the present invention)
Next, a seal structure according to one embodiment of the present invention will be described with reference to FIG.

Figure 2 is a cross-sectional view showing a schematic of a seal structure according to one embodiment of the present invention formed in a seal portion of a high-temperature device.

As shown in FIG. 2, a seal structure 100 according to one embodiment of the present invention (hereinafter referred to as the "first seal structure") is installed in a seal section 20 that seals a gap 15 in a high-temperature device 10.

More specifically, the high-temperature device 10 has a first wall member 30 and a second wall member 31, and the first and second wall members 30, 31 form an internal space 40 inside the high-temperature device 10. However, a gap 15 exists between the first wall member 30 and the second wall member 31, and in order to seal this gap 15, a sealing member 42 (base member) is filled into the gap 15. This forms a sealing portion 20, and the internal space 40 is isolated from the outside world.

However, if the high-temperature device 10 is used for a long period of time, the sealing member 42 deteriorates and its sealing performance decreases. In such a case, it may become necessary to repair the sealing member 42 while the high-temperature device 10 is in use, i.e., while the sealing portion 20 is at a high temperature.

The first seal structure 100 is formed by such an in-situ repair.

The first seal structure 100 has a (deteriorated) seal member 42 and a coating 120.

The coating 120 is manufactured by a manufacturing method according to one embodiment of the present invention, such as the first manufacturing method, as described above. Therefore, the coating 120 has a dense structure in which through holes are significantly suppressed.

The coating 120 is made of a non-organic material and contains at least one of silica, alumina, and carbon.

The sealing member 42 may also have large irregularities on the surface 44. The surface roughness Ra of the surface 44 is, for example, 1 mm or more. Normally, it is not easy to form a uniform continuous coating in situ on a surface 44 having such large irregularities. Therefore, even if a coating can be formed on the surface 44 by a conventional method, such a coating will be discontinuous and/or will not have good adhesion. In other words, it is difficult to form a coating that exhibits good sealing properties over a long period of time.

However, in the first seal structure 100, the coating 120 is formed by the manufacturing method according to one embodiment of the present invention as described above. That is, when the coating 120 contains alumina and/or silica, the coating 120 is formed by utilizing the phenomenon in which the mist particles are desolvated and the particles are successively deposited on the surface. Also, when the coating 120 contains carbon, the coating 120 is formed by utilizing the phenomenon in which the carbon is successively deposited on the surface due to the desolvation and thermal decomposition of the mist components. Therefore, the coating 120 can be applied uniformly with appropriate adhesion even on a surface 44 having large irregularities.

Therefore, the first seal structure 100 can place a coating 120 that provides good sealing properties over a long period of time on the uneven surface 44 of the seal member 42. This also allows the first seal structure 100 to ensure good sealing properties for the high-temperature device 10 over a long period of time.

The first wall member 30 and the second wall member 31 that form the seal portion 20 in which the seal structure 100 is installed may be made of any heat-resistant material, such as metal (e.g., heat-resistant metal) and ceramics (e.g., fire-resistant bricks).

The temperature of the seal portion 20 to which the seal structure 100 is applied varies depending on the high-temperature device 10. In one example, the temperature of the seal portion 20 to which the seal structure 100 is applied is in the range of 200°C to 500°C.

Next, examples of the present invention will be described. In the following description, Examples 1 to 5 are examples, and Example 11 is a comparative example.

(Example 1)
The sealing performance of the seal structure was evaluated by the following method.

(Preparation of coating solution)
The raw material liquid for the coating was a solution in which water glass No. 3 (manufactured by Fuji Chemical Co., Ltd.) was diluted with water (water glass:water = 2:1 (mass ratio)). The concentration of silicon dioxide particles contained in the raw material liquid was 5 mass %. The average diameter of the silicon dioxide mist particles was 2.5 μm. The diameters of the mist particles in Examples 1 to 4 were measured using a laser diffraction particle size distribution analyzer (HELOS) manufactured by Sympatex Co., Ltd.

Hereinafter, the prepared raw material liquid will be referred to as "Liquid A."

(Evaluation using test equipment)
The configuration of the test apparatus is shown in Fig. 3. As shown in Fig. 3, the test apparatus 210 includes a metal tube 220 and an electric furnace 230 that houses the metal tube 220.

The metal tube 220 is made of stainless steel and has a generally cylindrical shape. One surface of the metal tube 220 is an opening 226, which has a diameter of 25 mm. The internal volume of the metal tube 220 is approximately 1 L.

The metal tube 220 is placed in the electric furnace 230 so that the opening 226 coincides with the tip of the electric furnace 230. In addition, another opening is provided in a part of the metal tube 220, and this opening is connected to a buffer tank 240 for a stable supply of nitrogen gas.

A seal member 228 is already installed inside the opening 226 of the metal tube 220.

The sealing member 228 has a two-layer structure consisting of a base layer (first layer) made of silica sand and a second layer made of mortar on top of that. The sealing member 228 was formed as follows.

First, a cylindrical silica sand base layer (diameter 25 mm × length 30 mm) was prepared using a binder (water glass) and placed in the opening 226. Next, after raising the temperature to the test temperature, a second layer of mortar was formed on the surface.

The resulting sealing member 228 had many air holes. In addition, the surface of the sealing member 228 was very uneven, with a surface roughness Ra of approximately 0.1 mm.

When using the test device, the electric furnace 230 was heated and the opening 226 of the metal tube 220 was maintained at a predetermined temperature. After the temperature of each component of the test device was sufficiently stabilized, the aforementioned liquid A was sprayed toward the opening 226 of the metal tube 220 using an airbrush (Custom Micron Series CM-CP2; manufactured by Anest Iwata Corporation).

The distance between the airbrush and the opening 226 was about 100 mm. Liquid A was sprayed for 3 cycles, with one cycle consisting of a supply of 0.0005 cc/(sec·cm ² ) for 10 seconds and a 10-second pause.

Three minutes after spraying of Liquid A was completed, nitrogen gas was supplied from the buffer tank 240 into the metal tube 220. When the nitrogen gas pressure reached 0.7 kPa, the supply of nitrogen gas was stopped. The time when the nitrogen gas supply was stopped was set as the 0 (zero) point, and the change in pressure over time in the metal tube 220 was measured.

(Example 2)
The sealing performance of the seal structure was evaluated in the same manner as in Example 1.

However, in this Example 2, a solution of silica sol (Cataloid S-20L; manufactured by JGC Catalysts and Chemicals) diluted with water was used as the raw material liquid for the coating. The concentration of silicon dioxide particles contained in the raw material liquid was 5% by mass. The average diameter of the silicon dioxide mist particles was 2.5 μm.

Hereinafter, the prepared raw material liquid will be referred to as "Liquid B."

(Example 3)
The sealing performance of the seal structure was evaluated in the same manner as in Example 1.

However, in this Example 3, a solution of silica sol (Snowtex C; manufactured by Nissan Chemical Industries, Ltd.) diluted with water was used as the raw material liquid for the coating. The concentration of silicon dioxide particles contained in the raw material liquid was 5 mass %. The average diameter of the silicon dioxide mist particles was 2.5 μm.

Hereinafter, the prepared raw material liquid will be referred to as "Liquid C."

(Example 4)
The sealing performance of the seal structure was evaluated in the same manner as in Example 1.

However, in this Example 4, a solution of alumina sol (Cataloid Specialty Product; manufactured by JGC Catalysts and Chemicals) diluted with water was used as the raw material liquid for the coating. The concentration of alumina sol contained in the raw material liquid was 5 mass %. The average diameter of the mist particles of alumina sol was 2.5 μm.

Hereinafter, the prepared raw material liquid will be referred to as "Liquid D."

(Example 5)
The sealing performance of the seal structure was evaluated in the same manner as in Example 1.

However, in this Example 5, a sucrose (sucrose manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) solution was used as the raw material solution for the coating. The concentration of sucrose contained in the raw material solution was 5% by mass.

Hereinafter, the prepared raw material liquid will be referred to as "Liquid E."

(Example 11)
The sealing performance of the seal structure was evaluated in the same manner as in Example 1.

However, in this Example 11, no coating was placed on the sealing member 228. That is, in Example 11, the change in pressure over time inside the metal tube 220 was measured with only the sealing member 228 placed in the opening 226.

(result)
The results obtained by the evaluation tests for each example are shown in Figures 4 to 7. Figure 4 shows the test results when the opening 226 is at 200°C, Figure 5 shows the test results when the opening 226 is at 300°C, Figure 6 shows the test results when the opening 226 is at 400°C, and Figure 7 shows the test results when the opening 226 is at 500°C.

These test results show that at all temperatures, pressure drop is suppressed in Examples 1 to 5 compared to Example 11. The temperature of the spray area affects the evaporation rate of the solvent and the degree of particle bonding, so the sealing performance of each coating changes with each temperature.

Figure 8 shows an example of a cross section near the surface of the seal member 228 in Example 1 after testing.

From Figure 8, it can be seen that in Example 1, a thin and uniform coating is formed on the sealing member 228. It can also be seen that this coating has almost no through holes. Analysis using SEM-EDX revealed that this coating is composed of silica.

Although not shown in the figure, a similar morphology was observed in the coating portions of the seal structures in Examples 2 to 5.

The coating of the seal structure in Examples 2 and 3 was found to be made of silica. The coating of the seal structure in Example 4 was found to be made of alumina. Furthermore, the coating of the seal structure in Example 5 was found to be made of carbon.

In this way, it was confirmed that a seal structure with good sealing properties could be obtained by misting the raw material liquid prepared in Examples 1 to 5 and spraying it onto the target part.

(summary)
As described above, it is possible to provide a method for manufacturing a seal structure that can be effectively applied to in-situ repair of high-temperature equipment by misting the raw material liquids prepared in Examples 1 to 5 and spraying the mist onto a portion to be coated at a temperature of 200° C. or higher. Also, it is possible to provide such a seal structure.

REFERENCE SIGNS LIST 10 High temperature device 15 Gap 20 Seal portion 30 First wall member 31 Second wall member 40 Internal space 42 Seal member 44 Surface 100 First seal structure 120 Coating 210 Test device 220 Metal tube 226 Opening 228 Seal member 230 Electric furnace 240 Buffer tank

Claims (7)

A method for manufacturing a seal structure that isolates an internal space of a high-temperature device from the outside world, comprising the steps of:
The raw material liquid containing the coating components is turned into a mist and sprayed onto the part to be coated at a temperature of 200°C or higher.
A step of depositing the coating component on the coated part to form a coating,
the raw material liquid contains a solvent and particles of the coating component, and the concentration of the particles of the coating component is in the range of 1% by mass to 20% by mass (excluding 20% by mass);
The diameter of the mist particles, which are particles containing the liquid and are formed by misting the raw material liquid, is in the range of 2 μm to 50 μm . The method according to claim 1 , wherein the solvent comprises at least one of water, methanol, ethanol, n-propanol, and isopropanol. The method according to claim 1 or 2 , wherein the raw material liquid is an alkali silicate solution, a silica sol, or an alumina sol. The method according to any one of claims 1 to 3 , wherein the coating has a thickness in the range of 1 µm to 20 µm. The manufacturing method according to any one of claims 1 to 4 , wherein the portion to be coated is a part of a seal member. A seal structure,
A porous base material;
a coating disposed on the base member;
having
The coating is a non-organic film and contains at least one of silica, alumina, and carbon;
The surface roughness Ra of the base member is 1 mm or more,
The seal structure, wherein the coating has a thickness in the range of 1 μm to 20 μm. A method for manufacturing a seal structure that isolates an internal space of a high-temperature device from the outside world, comprising the steps of:
The raw material liquid containing the coating components is turned into a mist and sprayed onto the part to be coated at a temperature of 200°C or higher.
A step of depositing the coating component on the coated part to form a coating,
The method of claim 1, wherein the coating components are in the form of pyrolyzed materials that include carbon, and the coating is comprised of carbon.

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