JP6977986B2 - Coating liquid, composition for coating liquid and coating layer - Google Patents

Description

The present invention relates to a coating liquid, a composition for a coating liquid, and a coating layer.

Conventionally, in order to protect an inorganic member used in a thermal environment, a coating liquid is applied to the surface of the inorganic member, the coating film is dried, and then this is baked as necessary to form a coating layer. Is being done. For example, Patent Document 1 discloses that a coating liquid is applied to the surface of a refractory material and the coating film is dried to form a coating layer. The document describes a coating liquid containing water, an inorganic binder, a swellable clay mineral, an aggregate of ceramic fibers having a size of 2 μm or less, and a spherical ceramic powder having a median diameter of 40 μm or less.

Japanese Unexamined Patent Publication No. 2016-196387

In addition to refractories, metal members are important as inorganic members used in a thermal environment. However, since the conventional coating liquid is prepared for refractories, there is a limit to its application to metal members in the following points, and there is room for further improvement.

For example, metal members often have a smoother surface than refractories. Therefore, it is desired that the surface unevenness of the coating layer is small even after the coating layer is formed on the metal member. In order to reduce the surface unevenness of the coating layer, it is necessary to reduce the surface unevenness at the stage of the coating film formed by applying the coating liquid. This is because the surface unevenness of the coating film becomes the surface unevenness of the coating film almost as it is.

Further, the metal member has a higher degree of freedom in shape than the refractory material. Therefore, the application of the coating liquid to the metal member is not necessarily limited to the flat surface portion, but is also applied to the corner portion. However, when the conventional coating liquid is applied to the corners of the metal member, cracks are likely to occur when the coating film is dried by heating.

Further, the metal member having a coating layer is often rapidly heated and rapidly cooled when used in a thermal environment. However, the coating layer made of the conventional coating liquid tends to crack during rapid heating and rapid cooling due to the thermal stress generated by the difference in thermal expansion with the metal member.

The present invention has been made in view of the above background, and it is possible to form a coating film in which surface irregularities are suppressed, and it is possible to suppress cracking of the coating film at the corners of a metal member during drying by heating. It is an object of the present invention to provide a coating liquid capable of suppressing cracking due to rapid heating and rapid cooling of the formed coating layer, a composition for a coating liquid suitable for use thereof, and the above-mentioned coating layer.

One aspect of the present invention is a coating liquid for applying to an inorganic member.
It is in a coating liquid containing water, an inorganic binder, a first ceramic fiber having an average fiber length of 50 μm or less, and a second ceramic fiber having an average fiber length of 150 μm or more.

Another aspect of the present invention is a coating liquid composition used as a coating liquid for coating on an inorganic member.
A composition for a coating liquid containing an inorganic binder, a first ceramic fiber having an average fiber length of 50 μm or less, and a second ceramic fiber having an average fiber length of 150 μm or more.

Yet another aspect of the present invention is formed on the surface of an inorganic member.
The coating layer contains an inorganic binder, a first ceramic fiber having an average fiber length of 50 μm or less, and a second ceramic fiber having an average fiber length of 150 μm or more.

The coating liquid has the above structure. In particular, the coating liquid contains a short fiber first ceramic fiber having an average fiber length shorter than that of the second ceramic fiber and a long fiber second ceramic fiber having an average fiber length longer than that of the first ceramic fiber. ..

Therefore, according to the coating liquid, it is possible to form a coating film in which surface irregularities are suppressed. This includes not only the second ceramic fiber of the long fiber but also both the first ceramic fiber of the short fiber and the second ceramic fiber of the long fiber, so that the second ceramic fiber protrudes on the surface of the coating film. This is because it becomes possible to suppress.

Further, in addition to the above, according to the coating liquid, it is possible to suppress cracking of the coating film at the corners of the metal member during drying by heating. This is considered to be due to the following reasons. According to the coating liquid containing only the first ceramic fiber of the short fiber, it is possible to suppress the cracking of the coating film on the flat surface portion of the metal member during drying by heating. This is because the fibers are entangled with each other and the progress of cracks, which is the cause of cracks, can be suppressed in the flat surface portion. However, with a coating liquid containing only the first ceramic fibers of short fibers, it is not possible to suppress cracking of the coating film at the corners of the metal member during drying by heating. This is because the fiber length is short only with the first ceramic fiber, so that the fibers are not sufficiently entangled with each other at the corners of the metal member. On the other hand, according to the coating liquid, in addition to the short fiber first ceramic fiber, the long fiber second ceramic fiber is also arranged at the corner of the metal member. Therefore, according to the coating liquid, the fibers are sufficiently entangled with each other not only in the flat portion of the metal member but also in the corner portion of the metal member, and the growth of cracks that are the cause of cracks can be suppressed. Therefore, according to the coating liquid, it is possible to suppress cracking of the coating film at the corners of the metal member during drying by heating. Further, according to the coating liquid, it is possible to suppress cracking of the coating film on the flat surface portion of the metal member during drying by heating.

Further, in addition to the above, according to the coating liquid, it is possible to suppress cracking due to rapid heating and rapid cooling of the formed coating layer. This is considered to be due to the following reasons. A coating layer formed by using a coating liquid mainly composed of spherical ceramic particles cannot suppress cracks due to rapid heating and rapid cooling. This is because the spherical ceramic particles do not become entangled with each other, and therefore cracks are likely to develop due to the thermal stress generated by the difference in thermal expansion between the coating layer and the metal member. On the other hand, in the coating liquid, by using the first ceramic fiber having an average fiber length in a specific range, the fibers can be sufficiently entangled with each other as described above. Therefore, according to the coating liquid, it is possible to suppress the growth of cracks due to the thermal stress caused by the difference in thermal expansion between the formed coating layer and the metal member. Therefore, according to the coating liquid, it is possible to suppress cracking due to rapid heating and quenching of the formed coating layer. Further, since the coating liquid contains the second ceramic fiber having an average fiber length in a specific range, even if the coating layer is formed at the corners of the metal member, the coating layer is cracked due to rapid heating or quenching. Can be suppressed.

Therefore, according to the above coating liquid, it is possible to form a coating film in which surface irregularities are suppressed, and it is possible to suppress cracking of the coating film at the corners of the metal member during drying by heating, and the coating film is formed. It is possible to suppress cracking due to rapid heating and rapid cooling of the coating layer.

The coating liquid composition has the above composition. Therefore, the coating liquid can be easily prepared by adding water to the composition for the coating liquid. Therefore, the composition for the coating liquid can be suitably used for the coating liquid.

The coating layer has the above structure. Therefore, according to the above coating layer, even when an inorganic member such as a metal member is used in a thermal environment and is rapidly heated or rapidly cooled, cracking due to thermal stress caused by a difference in thermal expansion with the inorganic member can be suppressed. can. In addition, the coating layer is also advantageous for improving the adhesion to the inorganic member. Further, since the coating layer is also excellent in corrosion resistance in a thermal environment, it is possible to improve the corrosion resistance of inorganic members such as metal members used in a thermal environment.

First, the coating liquid will be described. The coating liquid contains water, an inorganic binder, a first ceramic fiber, and a second ceramic fiber.

Water mainly has a role as a liquid dispersion medium for dispersing an inorganic binder, a first ceramic fiber, a second ceramic fiber and the like.

The inorganic binder is a coating film formed by applying and drying the above coating liquid, and a coating layer formed by heat-treating the coating film as necessary on the surface of an inorganic member such as a metal member by the binder effect. It is a necessary component for firmly fixing. As the inorganic binder, inorganic colloids such as colloidal silica, colloidal alumina, colloidal zirconia, and colloidal titania can be preferably used from the viewpoint of easily obtaining a binder effect. These can be used alone or in combination of two or more.

The first ceramic fiber is a ceramic fiber having an average fiber length of 50 μm or less. The second ceramic fiber is a ceramic fiber having an average fiber length of 150 μm or more . Both the first ceramic fiber and the second ceramic fiber can be made of an artificial ceramic fiber. According to this configuration, it is easy to select a ceramic fiber having high stability even in a thermal environment of 800 ° C. or higher, and it is easy to prepare a first ceramic fiber and a second ceramic fiber having a predetermined average fiber length.

The first ceramic fiber and the second ceramic fiber include, for example, a chemical composition _{containing SiO 2} , a chemical composition containing SiO ₂ and Al ₂ O _3, and a chemical composition containing SiO ₂ and an alkaline earth oxide. _{Those containing ZrO 2} in the chemical composition and the like can be used. These can be used alone or in combination of two or more. As the first ceramic fiber and the second ceramic fiber, specifically, alumina fiber, refractory ceramic fiber, silica fiber, zirconia fiber, biosoluble fiber and the like can be preferably used. These can be used alone or in combination of two or more. These ceramic fibers have high stability even in a thermal environment of 800 ° C. or higher. Therefore, according to this configuration, the stability of the coating layer in a thermal environment can be improved. In addition, in this specification, alumina fiber is used in a broad sense, and includes not only alumina fiber but also mullite fiber.

The average fiber lengths of the first ceramic fiber and the second ceramic fiber are both random, among the ceramic fibers appearing on the outermost surface in the SEM image of each ceramic fiber observed by a scanning electron microscope, those in which both ends can be confirmed. It is a value obtained by selecting 100 fibers and averaging the lengths of each of the selected ceramic fibers.

Since the first ceramic fiber and the second ceramic fiber are fibers, both have an aspect ratio of more than 1. This is because when the aspect ratio is 1, the particles become spherical particles. Specifically, the aspect ratio of the first ceramic fiber is preferably 1.2 or more, more preferably 1.4 or more, from the viewpoint of ensuring the above-mentioned action and effect and improving crack resistance. , More preferably, it can be 1.6 or more. The aspect ratio of the first ceramic fiber is preferably 12 or less, more preferably 10 or less, still more preferably, from the viewpoint of ensuring the above-mentioned action and effect and facilitating the suppression of surface irregularities of the coating film. Can be 8 or less, and even more preferably 6 or less. Further, the aspect ratio of the second ceramic fiber is such that the above-mentioned action and effect are ensured, the coatability to the surface of the inorganic member such as the metal member is improved, the adhesion to the inorganic member is improved, and the corner portion of the metal member is used. From the viewpoint of facilitating the suppression of cracking of the coating film, preferably more than 12, more preferably 15 or more, still more preferably 20 or more, still more preferably 24 or more, still more preferably 30 or more. Can be. The aspect ratio of the second ceramic fiber makes it easy to obtain the ceramic fiber as a raw material, suppress the surface unevenness of the coating film, improve the adhesion to the inorganic member, and easily suppress the cracking of the coating film at the corner of the metal member. From the viewpoint of The aspect ratio is a value calculated by (average fiber length of ceramic fibers) / (average fiber diameter of ceramic fibers). Further, the average fiber diameters of the first ceramic fiber and the second ceramic fiber are those in which the end face of each ceramic fiber reflected on the outermost surface can be confirmed in the SEM image of each ceramic fiber observed by a scanning electron microscope (SEM). Is a value obtained by randomly selecting 10 ceramic fibers and averaging the diameters of the end faces of the selected ceramic fibers.

The upper limit of the average fiber length of the first ceramic fibers, from the viewpoint of easily suppressing the surface roughness of the coating film, 5 0 .mu.m is below good Mashiku is 40 [mu] m or less, more preferably, be 30μm or less can. The lower limit of the average fiber length of the first ceramic fiber is, for example, 6 μm or more, preferably 7 μm or more, more preferably, from the viewpoints of easy adjustment of the fiber length by crushing, easy securing of the fiber shape, improvement of crack resistance and the like. Can be 8 μm or more. On the other hand, the upper limit of the average fiber length of the second ceramic fiber is to improve the coatability on the surface of an inorganic member such as a metal member, suppress the surface unevenness of the surface of the coating film, make the ceramic fiber as a raw material easily available, and the inorganic member. From the viewpoints of improving the adhesion, facilitating the suppression of cracking of the coating film at the corners of the metal member, and suppressing the viscosity of the coating liquid, for example, 2000 μm or less, preferably 1000 μm or less, more preferably 750 μm. Below, it can be further preferably 500 μm or less, even more preferably 400 μm or less, and even more preferably 300 μm or less. The lower limit of the average fiber length of the second ceramic fiber makes it easier to improve the coatability of the inorganic member such as the metal member on the surface, improve the adhesion to the inorganic member, and suppress the cracking of the coating film at the corner of the metal member. from the viewpoint of, Ru is a 1 50 [mu] m or more.

In the above coating liquid, the long second ceramic fiber is a component necessary for suppressing cracking of the coating film at the corner portion of the metal member during drying by heating. The second ceramic fiber is also a useful component for improving the coatability of the coating liquid on the metal member. It is considered that the reason why the applicability of the coating liquid to the metal member is improved by using the first ceramic fiber and the second ceramic fiber in combination is as follows.

Since the second ceramic fiber has a larger shape than the other components in the coating liquid, it has a property of being difficult to move in the coating liquid. Therefore, after the coating liquid containing the second ceramic fiber in addition to the first ceramic fiber is applied to the surface of the metal member, the second ceramic fiber is not easily dragged by the surface tension of water and is deposited on the surface of the metal member. It's easy to do. Further, coupled with the fact that the inorganic binder in the coating liquid has good compatibility with ceramics, other solids such as the first ceramic fiber can be easily placed on the second ceramic fiber of the long fiber deposited on the surface of the metal member. Minutes accumulate. Further, a capillary phenomenon occurs due to the gap formed between the second ceramic fibers of the long fibers deposited on the surface of the metal member, and the aggregation of water due to the surface tension during drying of the coating film is relaxed. The movement of solids in the coating liquid is suppressed. Therefore, according to the coating liquid, the applicability to the metal member can be improved.

Specifically, the coating liquid has an inorganic binder: 10 parts by mass or more, a first ceramic fiber: 10 parts by mass or more and 300 parts by mass or less, and a second ceramic fiber: 15 parts by mass or less with respect to 100 parts by mass of water. , Can be configured to contain.

According to this configuration, the action and effect of the above-mentioned coating liquid can be ensured. In addition, according to the above configuration, the coating property of the coating liquid on the metal member is improved, cracks of the coating film are suppressed on the flat surface portion of the metal member during drying by heating, and the flat surface of the metal member is dried by forced heating. It is also possible to obtain effects such as suppressing cracks in the coating film at the portion and suppressing cracks in the coating layer on the flat surface portion of the metal member during baking (during firing). Further, according to the above configuration, it is easy to form a coating layer having high adhesion to the metal member.

In the above coating liquid, the content of the inorganic binder is preferably 10 parts by mass or more, more preferably 12 with respect to 100 parts by mass of water, from the viewpoint of ensuring the binder effect and improving the adhesion to the inorganic member. It can be by mass or more, more preferably 15 parts by mass or more. The content of the inorganic binder is preferably 67 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of water, from the viewpoint of facilitating the maintenance of the stability of the inorganic binder such as an inorganic colloid. It can be more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less.

As will be described later, the content of the first ceramic fiber in the coating liquid is such that the surface unevenness of the coating film makes it easy to secure the above-mentioned action and effect even when spherical particles are added as other components to the coating liquid. It can be preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass or more with respect to 100 parts by mass of water from the viewpoint of facilitating suppression. The content of the first ceramic fiber suppresses the formation of surface irregularities on the surface of the coating film by the first ceramic fiber, and makes it easier to form the coating film in which the surface irregularities are suppressed, thereby increasing the viscosity of the coating liquid. From the viewpoint of easy suppression and easy improvement of coatability, it is preferably 275 parts by mass or less, more preferably 250 parts by mass or less, and further preferably 225 parts by mass or less with respect to 100 parts by mass of water. , Even more preferably, it can be 200 parts by mass or less.

In the above coating liquid, the content of the second ceramic fiber is the coating film formed on the corner portion having a strict conditionally an angle of about 0.1R, which ensures the effect of the addition of the second ceramic fiber. From the viewpoint of ensuring the crack suppressing effect and improving the adhesion to the inorganic member, it is preferably 0.15 part by mass or more, more preferably 0.2 part by mass or more with respect to 100 parts by mass of water. , More preferably, it can be 0.25 parts by mass or more. The content of the second ceramic fiber suppresses the formation of surface irregularities on the surface of the coating film by the second ceramic fiber, and makes it easier to form the coating film in which the surface irregularities are suppressed, thereby increasing the viscosity of the coating liquid. From the viewpoint of easy suppression and easy improvement of coatability, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, still more preferably less than 10 parts by mass with respect to 100 parts by mass of water. It can be even more preferably 8 parts by mass or less, even more preferably 5 parts by mass or less, and most preferably 3 parts by mass or less.

In the coating liquid, the content of the second ceramic fiber may be smaller than the content of the first ceramic fiber. According to this configuration, the effect of improving the coatability on the metal member can be ensured. Further, according to the above configuration, it is easy to secure fluidity suitable for coating without causing an excessive increase in viscosity of the coating liquid. Further, according to the above configuration, the number of the second ceramic fibers protruding on the surface of the coating film is reduced, which is advantageous for forming the coating film in which the surface unevenness is suppressed. The above configuration can be realized by reducing the content of the second ceramic fiber with respect to water to be smaller than the content of the first ceramic fiber with respect to water.

The coating liquid can further contain a swellable clay mineral. According to this configuration, the dispersibility of each component in the coating liquid can be improved. Further, according to this configuration, the adhesion of the coating film and the coating layer to the inorganic member can be improved.

Examples of the swelling clay mineral include smectite, kaolinite, halloysite, mica, vermiculite, chlorite, imogolite, allophane, sepiolite, varigylskite, and gibbsite. These may be contained alone or in combination of two or more.

When the coating liquid contains a swellable clay mineral, the content of the swellable clay mineral can be 4 parts by mass or less with respect to 100 parts by mass of water. According to this configuration, it is possible to improve the adhesion of the coating film and the coating layer to the inorganic member while suppressing the gelation of the coating liquid.

In the coating liquid, the content of the swellable clay mineral is preferably 3.5 parts by mass or less, more preferably 3 parts by mass with respect to 100 parts by mass of water, from the viewpoint of ensuring the above effect. It can be less than or equal to parts by mass, more preferably less than or equal to 2.5 parts by mass. In addition, the content of the swellable clay mineral ensures the effect of the addition of the swellable clay mineral, improves the dispersibility of each component in the coating liquid, and improves the adhesion of the coating layer to the inorganic member. It can be preferably 0.1 part by mass or more, more preferably 0.15 part by mass or more, and further preferably 0.2 part by mass or more with respect to 100 parts by mass of water.

In addition to the above components, the coating liquid may contain, for example, one or more of various heat-resistant spherical particles. According to this configuration, it is advantageous to suppress deterioration of the coating layer due to the heat of the inorganic member. Various ceramics and the like can be used as the material constituting the spherical particles. Specific examples of the materials constituting the spherical particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), mullite (Al ₆ O ₁₃ Si ₂ ), silicon carbide (SiC), and silicon nitride (Si). ₃ N ₄ ), Aluminum Silicon Carbide _{(Al 4 SiC 4} ), Titania (TIO ₂ ), Aluminum Titanium (Al ₂ TIO ₅ ), Chromia (Cr ₂ O ₃ ), Itria (Y ₂ O ₃ ), Zirconia (ZrO) _2), zircon (ZrSiO _4), lanthanum oxide _{(La 2 O} 3), ceria _(CeO 2), and the like can be exemplified boron nitride (BN). Since the alkaline earth metal oxide tends to gel the coating liquid, it is not preferable as a material constituting the spherical particles. Further, the median diameter of the spherical particles is preferably 60 μm or less from the viewpoint of ensuring dispersibility in the coating liquid and suppressing surface irregularities of the coating film. The median diameter is the particle diameter (diameter) when the volume-based cumulative frequency distribution is 50%, which is measured by a laser diffraction / scattering type particle diameter distribution measuring device.

In the above coating liquid, the content of spherical particles is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 15 parts by mass or more with respect to 100 parts by mass of water from the viewpoint of improving the denseness of the coating layer. Can be 20 parts by mass or more. The content of the spherical particles suppresses the formation of surface irregularities on the surface of the coating film due to the spherical particles, facilitates the formation of a coating film having suppressed surface irregularities, and facilitates the suppression of an increase in the viscosity of the coating liquid. From the viewpoint of facilitating improvement of coatability, the amount is preferably 290 parts by mass or less, more preferably 275 parts by mass or less, still more preferably 250 parts by mass or less, still more preferably, with respect to 100 parts by mass of water. Can be 200 parts by mass or less. However, when the total amount of the first ceramic fiber and the spherical particles exceeds 300 parts by mass with respect to 100 parts by mass of water, the viscosity of the coating liquid increases, the coatability deteriorates, and the surface unevenness of the coating film is generated. There is a risk. Therefore, the total amount of the first ceramic fiber and the spherical particles is preferably 300 parts by mass or less with respect to 100 parts by mass of water.

The coating liquid may contain an organic component or the like in addition to the above components as long as the coating property, storage stability, crack resistance and the like are not impaired. Examples of the organic component that can be contained in the coating liquid include surfactants, colorants, preservatives, thickeners and the like. These may be contained alone or in combination of two or more.

The coating liquid is applied to an inorganic member. Examples of the inorganic member include a metal member and a ceramic member. Specific examples of the metal (including alloy) constituting the metal member include cast iron, steel, stainless steel, aluminum, aluminum alloy, copper, copper alloy, and brass. Examples of the ceramic member include refractory materials (ceramic fiber molded products, heat-resistant refractory bricks described in JIS R2611, plastic refractory materials, castable refractory materials, refractory mortars, etc.), non-oxide molded products such as carbides and nitrides. A graphite molded body and the like can be exemplified. However, the metal member has a larger thermal expansion in a thermal environment than the ceramic member. Therefore, when the inorganic member to which the coating liquid is applied is a metal member, the above-mentioned action and effect can be sufficiently exerted. Further, the inorganic member is preferably used in a thermal environment from the viewpoint of sufficiently exerting the above-mentioned action and effect. The temperature under the thermal environment can be, for example, 300 ° C. or higher. This is because the coating film made of the coating liquid is baked at a temperature of 300 ° C. or higher, which makes it easier to secure the adhesion of the coating film to the inorganic member, particularly the metal member.

In addition, the said coating liquid can be adopted by appropriately referring to the description described in the composition for coating liquid and the coating layer described later.

Next, the composition for the coating liquid will be described. The coating liquid composition is a composition that can be suitably used for preparing the coating liquid. Specifically, the composition for the coating liquid is added with an inorganic binder: 10 parts by mass or more, a first ceramic fiber: 10 parts by mass or more and 300 parts by mass or less, and a second ceramic fiber: 15 parts by mass or less, if necessary. Swellable clay mineral to be formed: It can be configured to contain 4 parts by mass or less. The preferable range of the content of each component can be the same as the range shown in the above coating liquid (however, the wording "relative to 100 parts by mass of water" is unnecessary). According to the above configuration, the coating liquid can be easily prepared by adding water. In addition, the above-mentioned composition for a coating liquid can be adopted by appropriately referring to the description described in the above-mentioned coating liquid and the description described in the coating layer described later.

Next, the coating layer will be described. Specifically, the coating layer can be formed on the surface of the inorganic member described in the description of the coating liquid. The coating layer can be formed, for example, by applying the coating liquid to the surface of an inorganic member, drying the coating film, and then baking the coating film, if necessary. As a method for applying the coating liquid, for example, a known application method such as dipping, brush coating, or spraying can be applied. It is also possible to omit the baking step performed in advance and to bake the coating film onto the inorganic member to form a coating layer when used in an actual thermal environment. Further, when the inorganic member is a ceramic member such as a refractory material, the coating film formed by the coating liquid can be used as it is as a coating layer without being baked. However, even when the inorganic member is a ceramic member, it is easy to secure the adhesion of the coating layer by baking in the same manner as when the inorganic member is a metal member. The coating layer formed by baking can be used at a temperature lower than the baking temperature.

The coating layer can be suitably used in, for example, a casting field, a forging field, a heat treatment / surface treatment field, various fields in which a furnace is used, and the like.

Specifically, the coating layer can be used in the casting field as follows. In the casting field, there are metal members that come into contact with molten metal, such as ladles, holding tanks, and ladle. When the metal member comes into contact with the molten metal, the molten metal reacts with the metal member, causing melting damage of the metal member. In particular, when the metal member is steel, stainless steel, or the like, melting damage due to molten aluminum is significant. Therefore, in the field of casting, in order to protect the surface of a metal member such as a metal ladle, the current situation is that a coating material made of oxide powder or the like is adhered to the surface of the metal member like a powder. However, such a coating material easily falls off due to convection of molten metal or the like. In addition, the ladle and the like are often hit by other objects during handling, which also makes it easy for the coating material to fall off. Therefore, the conventional coating material needs to be reapplied many times, and it is difficult to suppress the melting damage of the metal member due to the molten metal. On the other hand, once the coating layer is formed on the surface of the metal member, it can exhibit high crack resistance, so that it is not necessary to reapply the coating liquid many times. Further, since the coating layer can suppress the melting damage of the metal member due to the molten metal, the life of the metal member in contact with the molten metal such as a ruddle can be improved.

In addition, in the casting field, salt cores and the like are manufactured using a furnace having a metal member in the furnace. In this case, in the furnace, the metal member that comes into contact with the salt is corroded by rust. Therefore, in such a furnace, a metal member such as stainless steel, which is generally considered to have relatively good corrosion resistance, is used. However, in a harsh thermal environment for metals such as heat and salt, even a corrosion-resistant metal such as stainless steel tends to deteriorate. On the other hand, since the coating layer is excellent in corrosion resistance to salt in a thermal environment, it is possible to improve the life of the metal member that comes into contact with the salt in a thermal environment.

Further, the coating layer can be used in the forging field as follows. In the forging field, for example, there are metal members such as dies used for forging. The coating layer can be formed on the surface of a die or the like in order to prevent the metals from seizing with each other during forging such as hot forging.

Further, the coating layer can be used as follows in the field of heat treatment / surface treatment. In the field of heat treatment and surface treatment, for example, a metal member is used in a treatment tank during salt bath treatment. Also in this case, as described above, the metal member comes into contact with the molten salt in a thermal environment. Since the coating layer is excellent in corrosion resistance to molten salt in a thermal environment, it can be formed on the surface of a metal member used in a salt bath treatment tank. This makes it possible to improve the life of the metal member that comes into contact with the molten salt in a thermal environment.

In addition, the coating layer can be used as follows in various fields in which a furnace is used. For example, if the metal member is exposed inside the furnace, the metal member is likely to be oxidized due to the high temperature oxidizing atmosphere. Further, depending on the case, the metal member may be used in a high temperature atmosphere containing a compound gas containing Cl, F, etc. such as a chlorine-based gas or a fluorine-based gas. Even in such a case, the metal member is likely to be deteriorated by the atmospheric gas. The coating layer can suppress oxidation of metal members and deterioration due to atmospheric gas in a thermal environment.

As described above, the coating layer is a metal member in contact with molten metal, a metal member in contact with salt or molten salt in a thermal environment, a metal member in contact with metal in a thermal environment, or an oxidizing atmosphere in a thermal environment. By forming on the surface of a metal member exposed to an atmosphere containing a compound gas or a compound gas, the corrosion resistance of the metal member used in a thermal environment can be improved. Ceramics are generally excellent in corrosion resistance, but due to the above-mentioned effects, corrosion occurs to some extent. Since the coating layer can improve the corrosion resistance even when used for a metal member whose corrosion resistance is inferior to that of the ceramic member, it can naturally exhibit a high protective effect even when used for the ceramic member. Further, when the coating layer is applied to a ceramic member such as a refractory material, heat shrinkage of the ceramic member can be suppressed.

The thickness of the coating layer is preferably 0.1 mm or more, more preferably 0.2 mm or more, still more preferably 0.3 mm or more, from the viewpoint of ensuring the protective effect of the inorganic member. be able to. The thickness of the coating layer can be preferably 2 mm or less, more preferably 1.5 mm or less, still more preferably 1 mm or less, from the viewpoint of suppressing cracks due to rapid heating and rapid cooling.

Specifically, the coating layer has an inorganic binder: 10 parts by mass or more, a first ceramic fiber: 10 parts by mass or more and 300 parts by mass or less, a second ceramic fiber: 15 parts by mass or less, and swelling added as needed. Sexual clay mineral: It can be configured to contain 4 parts by mass or less. The preferable range of the content of each component can be the same as the range shown in the above coating liquid (however, the wording "relative to 100 parts by mass of water" is unnecessary). Further, the coating layer having the above structure can be formed by applying the coating liquid adjusted to the above-mentioned composition to the surface of the inorganic member and drying the coating film, or by further baking the coating film. can. In addition, the coating layer can be adopted by appropriately referring to the description described in the coating liquid and the composition for the coating liquid.

Hereinafter, the coating liquid, the composition for the coating liquid, and the coating layer will be described more specifically with reference to Examples.

(Example 1)
<Preparation of raw materials>
-Inorganic binder (coloidal silica) (manufactured by JGC Catalysts and Chemicals, "Cataloid SI-40")
・ Swellable clay mineral (Smectite) (manufactured by Kunimine Kogyo Co., Ltd., "Kunipia F")
-Ceramic fiber Alumina fiber ("FMX bulk fiber" manufactured by ITM Co., Ltd.) as a raw material was put into a ball mill containing alumina balls as a crushing medium, and crushed by a dry crushing method. At this time, by adjusting the crushing time, ceramic fibers having the following average fiber length and average fiber diameter were produced.
-First ceramic fiber-
Alumina fiber with an average fiber length of 10 μm and an average fiber diameter of 5 μm Alumina fiber with an average fiber diameter of 15 μm, an alumina fiber with an average fiber diameter of 5 μm, an alumina fiber with an average fiber diameter of 5 μm, and an alumina fiber with an average fiber diameter of 5 μm. 2 Ceramic fiber-
Alumina fiber with an average fiber length of 120 μm and an average fiber diameter of 5 μm Alumina fiber with an average fiber diameter of 170 μm, an alumina fiber with an average fiber diameter of 5 μm Denko Co., Ltd., "A-172")
Alumina particles (median diameter 0.55 μm) (Showa Denko KK, “AL-160SG-4”)
Alumina particles (median diameter 3.8 μm) (manufactured by Sumitomo Chemical Co., Ltd., “AM-21”)
Alumina particles (median diameter 50 μm) (manufactured by Sumitomo Chemical Co., Ltd., “A-21”)
Mullite particles (median diameter 60 μm or less) (Marusu Glazed Joint Stock Co., Ltd., “FCM-4”)
Aluminum titanate particles (median diameter 60 μm or less) (Marusu Glazed Joint Stock Co., Ltd., “TM-19”)
Zircon particles (median diameter 60 μm or less) (Marusu Glazed Joint Stock Co., Ltd., “SCZ-101”)
Other particles (median diameter 60 μm or less) (general reagent)
Silica particles, mulite particles, silicon carbide particles, silicon nitride particles, silicon carbide particles, titania particles, aluminum titanate particles, chromia particles, ittoria particles, zirconia particles, zircon particles, lanthanum oxide particles, ceria particles.

<Preparation of coating liquid>
The swellable clay mineral was added at the blending ratios shown in Tables 1 to 8 while stirring 100 parts by mass of water, and the swellable clay mineral was dispersed in water (however, in the sample 16, the swellable clay mineral was added. Not done.). Next, while stirring the dispersion, an inorganic binder, predetermined ceramic fibers, and if necessary, predetermined spherical particles were sequentially added at the blending ratios shown in Tables 1 to 8 to sufficiently disperse the dispersion. As a result, the coating liquids for each sample shown in Tables 1 to 8 were obtained.

<Applicability>
A 2 cm × 5 cm stainless steel plate (SUS304) having a surface roughness Ra of about 0.02 to 0.07 μm was prepared. Next, the coating liquid was applied onto the flat surface of the stainless steel plate using a brush. "◎" indicates that the coating liquid can be applied without recoating or after reapplying several times, and "◎" indicates that the coating liquid needs to be reapplied about 10 times, but the coating liquid can be reapplied. ○ ”, if it cannot be applied without taking time, or if a special application method (such as heating a stainless steel plate and applying it while evaporating water instantly) is required,“ × ”, high viscosity, application When it was difficult, it was set as "-".

<Crack resistance when the coating film is dried by heating-Forming the coating film on the flat surface of the metal plate->
A 2 cm × 5 cm metal plate (stainless steel plate: SUS304, copper plate, aluminum plate) having a surface roughness Ra of about 0.02 to 0.07 μm was prepared. Next, the coating liquid was applied onto the flat surface of the metal plate using a brush. Next, the coating film (thickness 0.1 to 0.5 mm) was dried at 110 ° C. for 1 hour, and the state of cracks in the coating film after heating and drying was visually confirmed. If there were no cracks in the coating film, it was marked as "○", if some cracks were found in the coating film, it was marked as "△", and if the cracking progressed significantly and the coating film was peeled off, it was marked as "×". ..

<Crack resistance when the coating film is dried by heating-Formation of the coating film on the corners of metal square bars->
A stainless steel square bar (SUS302) having a corner portion of about 0.1R was prepared. Next, the coating liquid was applied to the surface including the corners of the stainless steel square bar using a brush. Next, the coating film (thickness 0.1 to 0.5 mm) was dried at 110 ° C. for 1 hour, and the state of cracks in the coating film after heating and drying was visually confirmed. "○" when the coating film at the corners was not cracked, "△" when the coating film at the corners was partially peeled off, and "△" when the coating film was peeled off at the entire corners. × ”.

<Crack resistance when the coating film is dried by forced heating-Forming the coating film on the flat surface of the metal plate->
A 2 cm × 5 cm stainless steel plate (SUS304) having a surface roughness Ra of about 0.02 to 0.07 μm was prepared. Next, the coating liquid was applied onto the flat surface of the stainless steel plate using a brush. Next, the coating film (thickness 0.1 to 0.5 mm) was forcibly dried by burning with a burner flame at 1200 ° C., and the state of cracks in the coating film after the burner was dried was visually confirmed. If there were no cracks in the coating film, it was marked as "○", if some cracks were found in the coating film, it was marked as "△", and if the cracking progressed significantly and the coating film was peeled off, it was marked as "×". ..

<Surface unevenness of the coating film-Formation of the coating film on the flat surface of the metal plate->
A 2 cm × 5 cm metal plate (stainless steel plate: SUS304, copper plate, aluminum plate) having a surface roughness Ra of about 0.02 to 0.07 μm was prepared. Next, the coating liquid was applied onto the flat surface of the metal plate using a brush. Then, the coating film (thickness 0.1 to 0.5 mm) was dried at 100 ° C. for 1 hour. The unevenness of the surface of the coating film after drying was visually observed. "○" when the entire surface of the coating film is smooth and no noticeable unevenness is seen, "△" when unevenness is seen on a part of the surface of the coating film, unevenness on the entire surface of the coating film The case where was seen was regarded as "x".

<Crack resistance during baking of the coating film-Forming the coating film on the flat surface of the metal plate->
A 2 cm × 5 cm stainless steel plate (SUS304) having a surface roughness Ra of about 0.02 to 0.07 μm was prepared. Next, the coating liquid was applied onto the flat surface of the stainless steel plate using a brush. Then, the coating film (thickness 0.1 to 0.5 mm) was dried at 110 ° C. for 1 hour. Next, the coating film was heated at 600 ° C. for 1 hour, and the coating film was baked on the surface of the stainless steel plate to form a coating layer (thickness 0.1 to 0.5 mm). Then, the state of cracks in the coating layer was visually confirmed. If there were no cracks in the coating layer, it was marked as "○", if some cracks were found in the coating layer, it was marked as "△", and if the cracks progressed significantly and the coating layer was peeled off, it was marked as "x". ..

<Crack resistance of the coating layer during rapid heating and cooling-Forming a coating layer on the flat surface of the metal plate->
In the same manner as described above, a coating layer (thickness 0.1 to 0.5 mm) was formed on the flat surface portion of the stainless steel plate. Next, the test piece was placed directly in a furnace whose temperature was adjusted to 1000 ° C., and after 20 minutes, it was taken out and air-cooled. After that, the state of cracking property of the coating layer due to rapid heating / cooling was visually confirmed. If there were no cracks in the coating layer, it was marked as "○", if some cracks were found in the coating layer, it was marked as "△", and if the cracks progressed significantly and the coating layer was peeled off, it was marked as "x". ..

<Pencil hardness of coating layer-Formation of coating layer on the flat surface of a metal plate->
In the same manner as described above, a coating layer (thickness 0.1 to 0.5 mm) was formed on the flat surface portion of the stainless steel plate. Next, the surface of the coating layer was scraped with a pencil (B-9H), and the adhesion of the coating layer was investigated by the pencil hardness. Specifically, the surface of the coding layer was scraped with a pencil, and the hardness immediately before the scratch was measured was measured.

Tables 1 to 8 summarize the mixing ratio of each component in the coating liquid of each sample, and the evaluation results of the coating liquid and the coating layer. As for the sample 2, the coating liquid was repeatedly applied 5 times to separately prepare a sample 2-2 having a coating film thickness of about 1 mm.

Table 1 shows an example in which a coating liquid was prepared using a single ceramic fiber. According to Table 1, the following can be seen. It is difficult to suppress cracking of the coating film at the corners of the metal member during drying by heating only by using the first ceramic fiber, which is a short fiber having an average fiber length of 60 μm or less. The coatability of the coating liquid is also poor. On the other hand, by using a long second ceramic fiber having an average fiber length of more than 60 μm, it becomes easier to suppress cracking of the coating film at the corners of the metal member during drying by heating, and the metal member The applicability of the coating liquid to the coating liquid is also improved. However, only the second ceramic fiber, which is a long fiber having an average fiber length of more than 60 μm, tends to have surface irregularities on the surface of the coating film. When the coating layer is formed on the flat surface portion of the metal member, cracking of the coating layer due to rapid heating and quenching can be suppressed regardless of the average fiber length of the ceramic fibers. As described above, the coating liquid using a single ceramic fiber cannot solve the above-mentioned problems at the same time. Further, as shown in Table 1, the effect of suppressing cracks in the coating film at the corners of the metal member during drying by heating occurs with the average fiber length of the ceramic fibers as a boundary of 60 μm. From the results in Table 1, it was found that the above-mentioned problems can be solved at the same time by combining a short ceramic fiber having an average fiber length of 60 μm or less and a long ceramic fiber having an average fiber length of more than 60 μm. ..

Table 2 shows an example in which a coating liquid was produced without combining the first ceramic fiber of the short fiber and the second ceramic fiber of the long fiber. According to Table 2, the following can be seen. It is difficult to suppress cracking of the coating film at the corners of the metal member during drying by heating only by using spherical particles, and the coating property of the coating liquid on the metal member also has a high content of spherical particles. When it decreases, it deteriorates sharply. When the spherical particles and the long-fiber second ceramic fiber were combined, the coatability of the coating liquid could be improved, but the cracking of the coating film at the corners of the metal member during drying by heating was suppressed. That was still difficult. Further, it is difficult to suppress the cracking of the coating film at the corners of the metal member during drying by heating only by using the first ceramic fiber of the short fiber, and the coating property of the coating liquid on the metal member is also good. It was easy to get worse. Further, when the spherical particles and the first ceramic fiber of the short fiber were combined, the cracking in the flat surface portion could be suppressed, but the cracking of the coating film in the corner portion could not be suppressed. As described above, the above-mentioned problems are solved in the combination of only the spherical particles, the combination of the spherical particles and the second ceramic fiber of the long fiber, the combination of only the first ceramic fiber of the short fiber, and the combination of the spherical particle and the first ceramic fiber of the short fiber. It cannot be solved at the same time.

Table 3 shows an example of producing a coating liquid by combining the first ceramic fiber of the short fiber and the second ceramic fiber of the long fiber. According to Table 3, the following can be seen. By using the short fiber 1st ceramic fiber and the long fiber 2nd ceramic fiber together, it is possible to form a coating film with suppressed surface irregularities, and the coating film at the corners of the metal member during drying by heating. It was confirmed that the cracking of the ceramic fiber could be suppressed, and the cracking due to rapid heating and quenching of the formed coating layer could be suppressed. It can also be seen that the effect can be easily obtained when the average fiber lengths of the first ceramic fiber of the short fiber and the second ceramic fiber of the long fiber are separated from each other with a boundary of 60 μm. In addition, when the second ceramic fiber, which is a long fiber, is added, the content of the second ceramic fiber is made smaller than the content of the first ceramic fiber, thereby improving the coatability on the metal member. I was able to make sure. Further, it was confirmed that the above-mentioned effect can be obtained even when spherical particles are used in addition to the first ceramic fiber and the second ceramic fiber. In this case, by setting the content of the first ceramic fiber to 10 parts by mass or more with respect to 100 parts by mass of water, it was easy to secure the above-mentioned action and effect even when spherical particles were added to the coating liquid. When the content of the first ceramic fiber in the coating liquid exceeds 300 parts by mass with respect to 100 parts by mass of water, the surface unevenness tends to be formed on the surface of the coating film by the first ceramic fiber. Therefore, the content of the first ceramic fiber is 300 mass from the viewpoint of suppressing the formation of surface irregularities on the surface of the coating film by the first ceramic fibers and facilitating the formation of the coating film in which the surface irregularities are suppressed. It is preferable that the amount is less than or equal to the part. Further, although not shown in Table 3, when the total content of the first ceramic fiber and the spherical particles in the coating liquid exceeds 300 parts by mass with respect to 100 parts by mass of water, the spherical particles are applied to the surface of the coating film. There was a tendency for surface irregularities to be formed. Therefore, the content of the spherical particles is set to 290 parts by mass or less from the viewpoint of suppressing the formation of surface irregularities on the surface of the coating film by the spherical particles and facilitating the formation of the coating film in which the surface irregularities are suppressed. Is preferable. Although not shown in Table 3, Sample 2-2 in which the film thickness of the coating film was increased showed that the pencil hardness of the coating layer decreased to 2H due to the increase in the film thickness of the coating film, but each resistance was reduced. Similar results to Sample 2 were obtained for other properties including crackability. From this, it can be said that the above-mentioned problems can be solved at the same time even when the coating liquid is reapplied many times.

Table 4 shows an example in which the content of the second ceramic fiber of the long fiber in the coating liquid was changed. According to Table 4, the following can be seen. When the content of the second ceramic fiber in the coating liquid exceeds 15 parts by mass with respect to 100 parts by mass of water, the surface unevenness tends to be formed on the surface of the coating film by the second ceramic fiber. Therefore, the content of the second ceramic fiber is 15 mass from the viewpoint of suppressing the formation of surface irregularities on the surface of the coating film by the second ceramic fiber and facilitating the formation of the coating film in which the surface irregularities are suppressed. It is preferable that the amount is less than or equal to the part. When the coating liquid is applied including the corners of the metal member having corners of about 0.1R, the content of the second ceramic fiber is 0.15 parts by mass or more with respect to 100 parts by mass of water. This makes it easier to ensure that the coating film is prevented from cracking at the corners of the metal member during drying by heating. When the metal member has corners looser than 0.1R, it is considered that the effect of suppressing cracks at the corners can be exhibited even if the addition amount is less than 0.15 parts by mass.

Table 5 shows an example in which the content of the swellable clay mineral in the coating liquid was changed. According to Table 5, the following can be seen. When the coating liquid contained swellable clay minerals, the adhesion of the coating film and the coating layer to the inorganic member could be improved. Although not shown in Table 5, when the content of the swellable clay mineral in the coating liquid exceeds 4 parts by mass with respect to 100 parts by mass of water, the coating liquid tends to start to gel. Therefore, the content of the swellable clay mineral in the coating liquid is preferably 3.5 parts by mass or less with respect to 100 parts by mass of water from the viewpoint of ensuring the above effect.

Table 6 shows an example in which the particle size of the spherical particles in the coating liquid is changed. According to Table 6, the following can be seen. As long as the median diameter of the spherical particles that can be arbitrarily added to the coating liquid was 60 μm or less, no significant change in characteristics was observed even when the particle size was changed. Although not shown in Table 6, when the median diameter of the spherical particles exceeds 60 μm, the dispersibility of the coating liquid tends to decrease. It is also possible that the smoothness of the coating film may be reduced. Therefore, the median diameter of the spherical particles is preferably 60 μm or less.

Tables 7 and 8 show examples in which particles other than alumina particles are added as spherical particles in the coating liquid. As shown in Tables 7 and 8, no particular problem occurred when any of the spherical particles was added to the coating liquid.

(Example 2)
The following confirmation test was performed using a part of the coating liquid prepared in Example 1 described above.

<Confirmation of the effect of molten metal on suppressing melting damage of metal members>
The coating liquids of Sample 2 and Sample 6 were applied to steel bars (columnar), respectively, and each coating film was dried and then baked at 600 ° C. to obtain a test piece having each coating layer. Next, the test piece and the steel bar to which the coating liquid was not applied were immersed in molten aluminum (ADC12) at 800 ° C., and stirred with the driving force of a motor for 8 hours. Then, after taking out the test piece and the steel bar from the molten aluminum, the attached aluminum was removed using a sodium hydroxide solution. Then, visually, the presence or absence of melting damage due to molten aluminum was investigated.

As a result of the above investigation, melting marks were found on the steel bars that did not form the coating layer. On the other hand, no trace of erosion was observed on the steel bar of the test piece on which the coating layer was formed. From the above, it was confirmed that the coating layer is effective in suppressing the melting damage of the metal member due to the molten metal.

<Confirmation of the effect of molten salt on suppressing erosion of metal parts (1)>
The coating liquid of sample 6 is applied to a stainless steel plate (SUS304), the coating film is dried, and then the coating film is baked using preheating from a molten salt obtained by melting a mixture of sodium chloride and barium chloride to form a coating layer. A test piece having was obtained. Next, the test piece and the stainless steel plate to which the coating liquid was not applied were immersed in the molten salt for 1 hour. Then, after taking out the test piece and the stainless steel plate from the molten salt, the attached molten salt was removed. Then, the presence or absence of erosion by the molten salt was visually investigated.

As a result of the above investigation, erosion marks such as rust were found on the stainless steel plate that did not form the coating layer. On the other hand, no erosion trace was observed on the stainless steel plate of the test piece on which the coating layer was formed. From the above, it was confirmed that the coating layer is effective in suppressing the erosion of the metal member by the molten salt.

<Confirmation of the effect of molten salt on suppressing erosion of metal parts (2)>
The coating liquid of Sample 6 was applied to a stainless steel plate (SUS304), the coating film was dried, and then the coating film was baked at 600 ° C. to obtain a test piece having a coating layer. Next, sodium chloride and sodium fluoride were placed on the surfaces of the test piece and the stainless steel plate to which the coating liquid was not applied, and the mixture was heated at 600 ° C. for 1 hour as it was. Then, the attached salt was removed. Then, the presence or absence of erosion by the molten salt was visually investigated.

As a result of the above investigation, erosion marks such as rust were found on the stainless steel plate that did not form the coating layer. On the other hand, no erosion trace was observed on the stainless steel plate of the test piece on which the coating layer was formed. From the above, it was confirmed that the coating layer is effective in suppressing the erosion of the metal member by the molten salt.

<Confirmation of oxidation suppression effect of metal parts in thermal environment>
The coating liquid of Sample 6 was applied to the copper plate, and the coating film was dried. After the above drying, the copper plate on which the coating film was formed was heated at 400 ° C. for 1 hour to obtain a test piece having a coating layer. Next, the weight change due to oxidation was investigated for the test piece and the copper plate to which the coating liquid was not applied.

As a result of the above investigation, an increase in weight due to oxidation was observed in the copper plate that did not form the coating layer. On the other hand, no increase in weight due to oxidation was observed in the copper plate of the test piece on which the coating layer was formed. From the above, it was confirmed that the coating layer is effective in suppressing oxidation of the metal member in a thermal environment.

<Confirmation of heat shrinkage suppression effect of ceramic members (1)>
The coating liquid of Sample 2 was applied to a molded product (5 cm × 5 cm × 10 cm) made of refractory ceramic fibers, and the coating film was dried. Next, the molded product on which the coating film was formed was fired at 1500 ° C. for 24 hours to obtain a refractory material having a coating layer. Next, for the refractory material on which the coating layer was formed and the refractory material on which the coating layer was not formed, the heating line shrinkage rate was calculated from the dimensions before and after firing, and the state of heat shrinkage was investigated.

As a result of the above investigation, the heat ray shrinkage rate of the refractory material that did not form the coating layer was 5.4%. On the other hand, the heat ray shrinkage rate of the refractory material on which the coating layer was formed was 1.9%. From the above, it was confirmed that the coating layer is effective in suppressing heat shrinkage of the ceramic member.

<Confirmation of heat shrinkage suppression effect of ceramic members (2)>
The coating solution of Sample 2 was applied to a molded product (5 cm × 5 cm × 10 cm) made of biosoluble fiber, and the coating film was dried. Next, the molded product on which the coating film was formed was fired at 1100 ° C. for 24 hours to obtain a refractory material having a coating layer. Next, for the refractory material on which the coating layer was formed and the refractory material on which the coating layer was not formed, the heating line shrinkage rate was calculated from the dimensions before and after firing, and the state of heat shrinkage was investigated.

As a result of the above investigation, the heat ray shrinkage rate of the refractory material that did not form the coating layer was 2.8%. On the other hand, the heat ray shrinkage rate of the refractory of the test piece on which the coating layer was formed was 1.8%. From the above, it was confirmed that the coating layer is effective in suppressing heat shrinkage of the ceramic member.

<Confirmation of corrosion resistance improvement effect of ceramic members>
The coating liquid of Sample 2 was applied to a molded product (10 cm × 10 cm × 2 cm) made of refractory ceramic fibers, and the coating film was dried. Next, a metal scale (FeO) was spread thinly on the surface of the molded product on which the coating film was formed and the molded product on which the coating film was not formed so as to have a diameter of 2 to 3 cm, and placed as it was at 1400 ° C. for 3 hours. It was heated. Next, the presence or absence of erosion by the metal scale was investigated for the refractory on which the coating layer was formed and the refractory on which the coating layer was not formed.

As a result of the above investigation, erosion marks due to the metal scale were observed in the refractory material that did not form the coating layer. On the other hand, no erosion trace was observed in the refractory material on which the coating layer was formed. From the above, it was confirmed that the coating layer is effective in improving the corrosion resistance of the ceramic member.

Although the examples of the present invention have been described in detail above, the present invention is not limited to the above examples, and various modifications can be made without impairing the gist of the present invention.
Hereinafter, an example of the reference form will be added.
Item 1.
A coating liquid for applying to inorganic members,
water and,
With an inorganic binder,
The first ceramic fiber with an average fiber length of 60 μm or less and
Second ceramic fibers with an average fiber length of over 60 μm and
Containing, coating liquid.
Item 2.
Water: 100 parts by mass
The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
Item 1. The coating liquid according to Item 1.
Item 3.
Item 2. The coating liquid according to Item 1 or Item 2, further comprising a swellable clay mineral.
Item 4.
Water: 100 parts by mass
Item 3. The coating liquid according to Item 3, which contains 4 parts by mass or less of the swellable clay mineral.
Item 5.
Item 2. The coating liquid according to any one of Items 1 to 4, wherein the first ceramic fiber and the second ceramic fiber are both composed of artificial ceramic fibers.
Item 6.
The first ceramic fiber and the second ceramic fiber are composed of one or more selected from the group consisting of alumina fiber, refractory ceramic fiber, silica fiber, zirconia fiber, and biosoluble fiber. Item 5. The coating liquid according to any one of Items 1 to 5.
Item 7.
Item 2. The coating liquid according to any one of Items 1 to 6, wherein the inorganic member is a metal member.
Item 8.
A composition for a coating liquid used as a coating liquid for coating on an inorganic member.
With an inorganic binder,
The first ceramic fiber with an average fiber length of 60 μm or less and
Second ceramic fibers with an average fiber length of over 60 μm and
A composition for a coating liquid containing.
Item 9.
The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
Item 8. The composition for a coating liquid according to Item 8.
Item 10.
It is formed on the surface of the inorganic member and
With an inorganic binder,
The first ceramic fiber with an average fiber length of 60 μm or less and
Second ceramic fibers with an average fiber length of over 60 μm and
Containing, coating layer.
Item 11.
The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
Item 10. The coating layer according to Item 10.
In Items 1 to 10,
The upper limit of the average fiber length of the first ceramic fiber is preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, from the viewpoint of facilitating the suppression of surface irregularities of the coating film. can. The lower limit of the average fiber length of the first ceramic fiber is, for example, 6 μm or more, preferably 7 μm or more, more preferably, from the viewpoints of easy adjustment of the fiber length by crushing, easy securing of the fiber shape, improvement of crack resistance and the like. Can be 8 μm or more. On the other hand, the upper limit of the average fiber length of the second ceramic fiber is to improve the coatability on the surface of an inorganic member such as a metal member, suppress the surface unevenness of the surface of the coating film, make the ceramic fiber as a raw material easily available, and the inorganic member. From the viewpoints of improving the adhesion, facilitating the suppression of cracking of the coating film at the corners of the metal member, and suppressing the viscosity of the coating liquid, for example, 2000 μm or less, preferably 1000 μm or less, more preferably 750 μm. Below, it can be further preferably 500 μm or less, even more preferably 400 μm or less, and even more preferably 300 μm or less. The lower limit of the average fiber length of the second ceramic fiber makes it easier to improve the coatability of the inorganic member such as the metal member on the surface, improve the adhesion to the inorganic member, and suppress the cracking of the coating film at the corner of the metal member. From such a viewpoint, it can be preferably 75 μm or more, more preferably 100 μm or more, still more preferably 120 μm or more, and even more preferably 150 μm or more.

Claims (11)

A coating liquid for applying to inorganic members,
water and,
With an inorganic binder,
The first ceramic fiber with an average fiber length of 50 μm or less and
A second ceramic fiber with an average fiber length of 150 μm or more,
Containing, coating liquid. Water: 100 parts by mass
The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
The coating liquid according to claim 1. The coating liquid according to claim 1 or 2, further comprising a swellable clay mineral. Water: 100 parts by mass
The coating liquid according to claim 3, which contains 4 parts by mass or less of the swellable clay mineral. The coating liquid according to any one of claims 1 to 4, wherein the first ceramic fiber and the second ceramic fiber are both composed of artificial ceramic fibers. The first ceramic fiber and the second ceramic fiber are composed of one or more selected from the group consisting of alumina fiber, refractory ceramic fiber, silica fiber, zirconia fiber, and biosoluble fiber. The coating liquid according to any one of claims 1 to 5. The coating liquid according to any one of claims 1 to 6, wherein the inorganic member is a metal member. A composition for a coating liquid used as a coating liquid for coating on an inorganic member.
With an inorganic binder,
The first ceramic fiber with an average fiber length of 50 μm or less and
A second ceramic fiber with an average fiber length of 150 μm or more,
A composition for a coating liquid containing. The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
8. The composition for a coating liquid according to claim 8. It is formed on the surface of the inorganic member and
With an inorganic binder,
The first ceramic fiber with an average fiber length of 50 μm or less and
A second ceramic fiber with an average fiber length of 150 μm or more,
Containing, coating layer. The above inorganic binder: 10 parts by mass or more,
First ceramic fiber: 10 parts by mass or more and 300 parts by mass or less,
Second ceramic fiber: 15 parts by mass or less,
10. The coating layer according to claim 10.