KR20180074735A - Coating liquid, composition for coating liquid and refractory having coating layer - Google Patents

Abstract

A coating liquid for refractories which can be prepared by a simple operation and has excellent performance, a composition for producing a coating liquid, and a refractory having a coating layer having excellent heat insulating performance and wind speed resistance. The coating liquid contains 100 parts by mass of water, 10 to 20 parts by mass of an inorganic binder, 0.2 to 2 parts by mass of swelling clay mineral, and 10 to 200 parts by mass of radiation scattering material. The radiation scattering material may be a ceramic fiber and / or an alumina powder, an silica powder, a titania powder, a chromia powder, an yttria powder, a zirconia powder, or an alumina powder composed of fibrous particles containing Al ₂ O ₃ , , At least one ceramic powder having an intermediate diameter of 60 탆 or less selected from the group consisting of lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder .

Description

Coating liquid, composition for coating liquid and refractory having coating layer

The present invention relates to a refractory having a coating liquid for application to a refractory, a composition for making the coating liquid and a coating layer prepared using the coating liquid.

A heating furnace which is capable of heating at a high temperature, such as a crack furnace or a heat treatment furnace used for manufacturing a steel material or a furnace used for manufacturing ceramics or the like, has an outer wall and an inner wall disposed inside the outer wall. The inner walls are made of refractories.

The refractory constituting the inner wall is normally attached to the outer wall of the heating furnace through an attachment metal fitting. As the refractory of this kind, a block composed of ceramic fibers including silica, alumina, zirconia and the like is frequently used. Since this block has an excellent heat insulating performance, it can be easily controlled in temperature and temperature raising rate in the furnace by using it on the inner wall of the heating furnace. Further, the block includes a ceramic fiber having a small volume specific gravity, and thus is relatively light in weight. Therefore, the block can be easily attached to the outer wall of the heating furnace.

However, there is a problem that the block composed of ceramic fibers shrinks slowly when left for a long time under a high-temperature environment of, for example, 1000 캜 or more. Therefore, when the heating furnace is used over a long period of time, gaps are formed between adjacent blocks, resulting in deterioration of heat insulating performance.

Further, in addition to the block including the ceramic fiber, the refractory bricks including acidic oxide, neutral oxide and basic oxide as defined in JIS R2611, refractory plastic including chamotte, alumina and chromium as aggregates, Castable refractories containing alumina as an aggregate, and refractory materials such as refractory mortar may be used as the inner wall of the heating furnace. However, there is a problem that these refractories also shrink gradually when they are left for a long time under a high-temperature environment as described above. Further, there has been a problem that, when a refractory in a heating furnace for heating a metal is brought into contact with a byproduct generated during metal refining or metal refining, the refractory may be corroded. Especially when ferrous oxide (scale) containing an alkali substance was contacted.

Therefore, a technique of forming a coating layer on the surface of the refractory has been proposed in order to suppress shrinkage of the refractory due to temperature rise. For example, Patent Document 1 discloses a non-sedimentary fire resistant mortar containing a ceramic powder, a clay mineral, and a colloidal oxide solution and having thixotropic properties. Patent Document 2 discloses a coating material comprising inorganic fibers, inorganic particles, an inorganic binder, and an organic binder.

Patent Document 1: JP-A-2009-137809 Patent Document 2: Japanese Patent No. 4297204

Since the refractory mortar of Patent Document 1 has a high viscosity, it is difficult to apply the refractory mortar to deep irregularities such as refractory joints or portions having a complicated structure. Therefore, there is a problem that workability is low when the refractory mortar is applied. Further, since it is difficult to reduce the coating thickness of refractory mortar, there is a problem that the refractory coated with the refractory mortar tends to peel off from the outer wall of the heating furnace due to its own weight.

It is effective to use a coating liquid having a low viscosity in order to improve the coating property of the coating liquid applied to the refractory material and to thin the coating thickness. However, a coating liquid having a low viscosity generally contains a large amount of organic materials such as an organic binder and an organic solvent as in the case of the coating material of Patent Document 2. Therefore, when the coating liquid is heated and dried, the organic binder or the like is gasified, and cracks or the like may be generated in the obtained coating layer. Such a crack is not preferable because it causes deterioration in heat insulating performance and the like. Further, a coating liquid containing an organic binder or an organic solvent may be corrupted when stored for a long period of time.

As described above, from the viewpoints of coating property, coating thickness, performance and storage stability, it is preferable that the coating liquid for refractories has a low viscosity and does not contain an organic binder or the like. However, it is difficult to disperse a solid component in a solvent for a long period of time in a coating solution of low viscosity produced without using an organic binder or an organic solvent, and there is a problem that a solid component is precipitated relatively early after dispersing the solid component in the solvent. Therefore, it is necessary to perform operations such as mixing the solvent and the solid content each time the coating liquid is used, or sufficiently stirring it immediately before the application to the refractory material to disperse the solid content in the solvent again, and the preparation work before the application is troublesome .

SUMMARY OF THE INVENTION The present invention has been made in view of such background, and an object of the present invention is to provide a coating solution which can be prepared by a simple operation and which is applied to a refractory to exhibit excellent performance, a composition for producing the coating solution and a refractory having a coating layer will be.

One aspect of the present invention is a coating liquid for application to refractories,

100 parts by mass of water,

10 parts by mass or more of an inorganic binder,

0.2 to 2 parts by mass of the swellable clay mineral,

10 to 200 parts by mass of a radiation scattering material,

The radiation scattering material,

A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /

A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, And at least one kind of ceramics powder having an intermediate diameter of not more than 2 mu m.

Another aspect of the present invention is a coating liquid composition for application to a refractory,

10 parts by mass or more of an inorganic binder,

0.2 to 2 parts by mass of the swellable clay mineral,

10 to 200 parts by mass of a radiation scattering material,

The radiation scattering material,

A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /

A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, And at least one kind of ceramics powder having an intermediate diameter of not more than 1 mu m.

According to still another aspect of the present invention, there is provided a refuse-

A coating layer formed on the substrate,

The coating layer comprises,

10 parts by mass or more of an inorganic binder,

0.2 to 2 parts by mass of the swellable clay mineral,

10 to 200 parts by mass of a radiation scattering material,

The radiation scattering material,

A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /

A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, And at least one kind of ceramics powder having an intermediate diameter of not more than 10 mu m.

The coating liquid contains the inorganic binder, the swellable clay mineral (hereinafter referred to as " clay mineral ") and the radiation scattering material in the specified ratio with respect to 100 parts by mass of water. The radiation scattering material is composed of a ceramic fiber and / or a ceramic powder whose particle diameter distribution is controlled as described above.

The solvent and the binder of the coating liquid are composed of an inorganic material. Therefore, the above-mentioned coating liquid has excellent storage stability and can suppress the occurrence of cracks in the coating layer after drying.

In addition, the above-mentioned coating liquid can form the coating layer having excellent performance by having the above specific composition. Further, since the coating liquid has a low viscosity, the coating liquid has excellent coating properties and can be thinned.

Further, the coating liquid can stably disperse the solid content in the solvent over a long period of time. Therefore, the coating liquid can be mixed with water and solid beforehand, further, the stirring operation before coating with the refractory material can be shortened, and in some cases, it is not necessary to carry out the stirring operation. As a result, preparation work before coating can be greatly simplified.

As described above, the coating liquid can be prepared by a simple operation, is excellent in coating property, and can be thinned.

Further, since the refractory has the coating layer including the inorganic binder, the clay mineral, and the radiation scattering material in the specified ratio, it has an excellent heat insulating performance and an effect of improving wind speed resistance or refractory corrosion resistance. The refractory having the coating layer can maintain excellent performance over a long period of time in a high-temperature environment of, for example, 1000 占 폚 or higher.

Further, the composition for a coating liquid contains the inorganic binder, the clay mineral, and the radiation scattering material at the specified ratios. Therefore, by adding water to the composition, the coating liquid can be easily produced.

The composition of the coating liquid will be described below.

· Inorganic binder: 10 parts by mass or more

The coating liquid contains 10 parts by mass or more of an inorganic binder with respect to 100 parts by mass of water. The inorganic binder has an action of firmly bonding the dried coating layer to a base made of a refractory material. When the content of the inorganic binder in the coating liquid is within the above specified range, it is possible to suppress problems such as occurrence of cracks or the like in the coating layer after drying or peeling of the coating layer from the gas.

As the inorganic binder, fine particles capable of forming an inorganic colloid solution such as colloidal silica by dispersing in water can be used. That is, the coating liquid can be produced, for example, by mixing colloidal silica or the like into the coating liquid so that the content of the colloid particles is in the above specific range. Usually, the median diameter of the colloidal particles contained in the inorganic colloid solution is 100 nm or less. As the inorganic colloid solution, colloidal silica, colloidal alumina and colloidal zirconia can be used.

When the content of the inorganic binder is less than 10 parts by mass, the adhesion between the coating layer and the substrate is lowered, and cracking or peeling may occur in the coating layer. As a result, the performance of the refractory may be deteriorated.

In order to improve the adhesion between the coating layer and the substrate, it is preferable that the content of the inorganic binder is large. However, if the content of the inorganic binder is excessively large, it may be difficult to obtain a cost-effective effect, and the problem of lowering the melting point of the coating layer may occur.

In addition, since the inorganic binder has high reactivity, if the content of the inorganic binder is excessively large, there is a possibility that the coating layer may be deteriorated due to reaction with a gas, a radiant scattering material or the like under a high temperature environment, and further, the performance may deteriorate. The reaction with a gas or a radiant scattering material or the like can occur even when any of fine particles derived from colloidal silica, fine particles derived from colloidal alumina, and fine particles derived from colloidal zirconia are used. Particularly, It is likely to occur when used as a < / RTI > In order to avoid such a problem, the content of the inorganic binder is preferably 20 parts by mass or less.

Therefore, the content of the inorganic binder is more preferably 10 to 20 parts by mass from the viewpoints of improving the adhesion between the coating layer and the substrate and suppressing the deterioration of the coating layer at a high temperature.

Swellable clay minerals: 0.2 to 2 parts by mass

The coating liquid contains 0.2 to 2 parts by mass of the clay mineral with respect to 100 parts by mass of water. The clay minerals have an action of improving the dispersibility of the solid content into water. By setting the content of the clay mineral within the above-specified range, the coating liquid can stably disperse clay minerals, inorganic binders and radiation scattering materials in water over a long period of time. As a result, preparation work before coating can be greatly simplified.

As the clay mineral, swellable clay minerals such as kaolinite, halosite, smectite, mica, vermiculite, chlorite, imoglitol, allopan, sepiolite, valylilate and gibbsite can be used .

When the content of the clay mineral is less than 0.2 part by mass, it is difficult to disperse the solid component in water, and there is a fear that the solid component is precipitated relatively early after dispersing the solid component in water. On the other hand, if the content of the clay mineral exceeds 2 parts by mass, the viscosity of the coating solution may increase, resulting in a problem of lowering the coating property or lowering the heat resistance of the coating layer.

Radiation scattering material: 10 to 200 parts by mass

The coating liquid contains 10 to 200 parts by mass of radiant scattering material per 100 parts by mass of water. The radiation scattering material has an action of reflecting or scattering electromagnetic waves such as infrared rays radiated in the furnace.

In the heating furnace where the temperature in the furnace is higher than 1000 占 폚, the heat transfer from the furnace to the furnace outside the furnace becomes dominant as compared with the heat transfer by convection or conduction. On the other hand, since the coating layer formed by drying the coating liquid includes a radiation scattering material, electromagnetic waves such as infrared rays radiated in the furnace can be effectively reflected or scattered. Further, since the refractory can reflect or scatter electromagnetic waves radiated in the furnace by the coating layer on the surface, the heat transfer to the furnace can be effectively reduced. As a result, the refractory has excellent heat insulating performance and the like.

Further, since the refractory can reduce the electromagnetic wave reaching the gas by the presence of the coating layer, it is possible to suppress the temperature rise of the gas. As a result, the refractory can suppress the shrinkage of the gas by heating, and further, the shrinkage of the refractory as a whole can be suppressed.

When the content of the radiant scattering material is less than 10 parts by mass, the function of reflecting or scattering electromagnetic waves becomes insufficient, so that it is difficult to improve the heat insulating performance. On the other hand, when the content of the radiant scattering material exceeds 200 parts by mass, the viscosity of the coating liquid becomes high and the coating property may be deteriorated. Therefore, in order to achieve both adiabatic performance and coatability, the content of the radiation scattering material is set to 10 to 200 parts by mass. From the same viewpoint, the content of the radiation scattering material is preferably 10 to 120 parts by mass, more preferably 10 to 80 parts by mass.

As the radiant scattering material, ceramic fibers and / or one or more kinds of ceramics powders having an intermediate diameter of 60 탆 or less can be used. The intermediate diameter of the ceramics powder can be calculated based on the particle diameter distribution measured by the laser diffraction scattering method.

The ceramic fiber is composed of fibrous particles containing Al ₂ O ₃ . The ceramics fibers are usually composed of Al ₂ O ₃ and SiO ₂ , but may contain other components.

The higher the content of Al ₂ O ₃ is, the more effectively the reflected or scattered electromagnetic waves can be radiated from the ceramic fibers. Therefore, the ceramics fiber having a high content of Al ₂ O ₃ can improve the performance of the finally obtained refractory. The content of Al ₂ O _{3 in} the ceramic fiber is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 65 mass% or more, and most preferably 70 mass% or more Is particularly preferable.

The individual fibrous particles constituting the ceramic fiber usually have a length at least one times the diameter. The average diameter of the fibrous particles can be set to 60 탆 or less. In this case, the dispersibility of the ceramic fiber can be improved and the coating thickness of the coating liquid can be reduced. From the viewpoint of industrial availability, the average diameter of the fibrous particles is preferably 12 占 퐉 or less.

The average fiber length of the ceramic fibers is 100 탆 or less. When the average fiber length exceeds 100 mu m, the content of the excessively long fibrous particles becomes large, so that the ceramic fiber tends to precipitate during storage. Further, when the content of the excessively long fibrous particles is increased, it is difficult to reduce the coating thickness of the coating liquid, and furthermore, it becomes difficult to reduce the thickness of the coating layer after drying.

Therefore, in order to improve the dispersibility of the ceramic fibers and to thin the coating thickness of the coating liquid, the average fiber length of the ceramic fibers is set to 100 m or less. From the same viewpoint, the average fiber length of the ceramic fibers is preferably 60 탆 or less, more preferably 40 탆 or less.

As the ceramic powder, specifically, alumina (Al ₂ O _3), silica (SiO _2), titania (TiO _2), chromia (Cr ₂ O _3), yttria (Y ₂ O _3), zirconia (ZrO ₂ ), Lanthanum oxide (La ₂ O ₃ ), ceria (CeO ₂ ), silicon carbide (SiC), aluminum silicon carbide (Al ₄ SiC ₄ ), silicon nitride (Si ₃ N ₄ ) and boron nitride Any one kind or two or more types of powders to be selected may be used. These ceramics powders may be used singly or in combination with ceramics fibers.

The ceramics powder has a particle diameter distribution in which the median diameter is 60 占 퐉 or less. By setting the median diameter of the ceramic powder to 60 mu m or less, the content of particles having a large particle diameter can be reduced. As a result, the dispersibility of the ceramic powder into water can be improved, and the coating thickness of the coating liquid can be easily reduced. From the same viewpoint, it is preferable that the median diameter of the ceramics powder is 40 占 퐉 or less, more preferably 20 占 퐉 or less, and further preferably 10 占 퐉 or less. From the viewpoint of avoiding an increase in the viscosity of the coating liquid, it is preferable that the median diameter of the ceramic powder is 1 占 퐉 or more.

When the coating liquid contains either the ceramic fiber or the alumina powder as a radiation scattering material, it is preferable that the content of Al ₂ O ₃ to the total solid content of the coating liquid is 50 mass% or more. In this case, the coating liquid can form a coating layer capable of more effectively reflecting or scattering the radiated electromagnetic waves. By using the coating liquid, the heat insulation performance of the refractory can be further improved.

When the coating liquid contains two or more kinds of radiation scattering materials, it is preferable that the radiation scattering materials include at least a ceramic fiber. That is, it is preferable that the coating liquid contains two or more radiation scattering materials including a ceramic fiber.

The above ceramic powder has excellent performance as a radiation scattering material. However, when two or more types of ceramic powders are used in combination, the viscosity of the coating liquid tends to increase, which may cause problems such as deterioration of coating property or thickening of coating. On the other hand, when the ceramics fiber is used together with the ceramics powder, it is difficult to increase the viscosity of the coating liquid. Therefore, the coating liquid containing two or more kinds of radiation scattering materials including the ceramic fibers can further improve the performance of the refractory while suppressing the viscosity increase.

In the above case, it is more preferable that the content of the alumina powder in the coating liquid is 30 parts by mass or less. When the alumina powder is used together with the ceramics fiber, the viscosity of the coating liquid is easily increased as compared with the silicon carbide powder, silicon nitride powder and boron nitride powder. Therefore, by controlling the content of the alumina powder to 30 parts by mass or less, increase in viscosity of the coating liquid can be suppressed.

Further, in the above case, it is more preferable that the content of Al ₂ O ₃ in the coating liquid is 50% by mass or more with respect to the total solid content. In this case, the coating liquid can form a coating layer capable of more effectively reflecting or scattering the radiated electromagnetic waves. By using the coating liquid, the heat insulation performance of the refractory can be further improved.

The coating liquid preferably has a viscosity of 20 Pa · s or less. In this case, the coating liquid can be applied to the base by spraying. In this case, gas may be immersed in the coating liquid. As a result, the workability in the coating operation of the coating liquid can be further improved. From the viewpoint of more easily carrying out application by spray coating or immersion, it is more preferable that the coating liquid has a viscosity of 5 Pa · s or less.

In addition, it is preferable that the coating liquid is configured so as to maintain the solid content dispersed in water for more than one day. In this case, by preliminarily mixing water with solid content, it is possible to shorten the stirring work before coating with the refractory material, and in some cases, it is not necessary to carry out the stirring work. As a result, preparation work before coating can be greatly simplified.

The coating liquid may contain an organic substance as long as the coating property and the preservability are not impaired. Examples of organic substances that can be contained in the coating liquid include colorants, preservatives, and thickeners.

Colorant: not more than 0.5 part by mass

The coating liquid may contain 0.5 parts by mass or less of a coloring agent based on 100 parts by mass of water. In this case, the color tone of the coating liquid can be adjusted to a color tone different from that of the base body. This makes it possible to easily distinguish between a portion coated with the coating liquid and a portion not coated. As a result, coating unevenness of the coating liquid can be reduced.

Preservative: 0.5 parts by mass or less

The coating liquid may contain 0.5 parts by mass or less of preservative based on 100 parts by mass of water. In this case, the decay of the coating liquid can be prevented over a longer period of time.

· Thickening agent: 0.5 parts by mass or less

The coating liquid may contain 0.5 parts by mass or less of a thickening agent relative to 100 parts by mass of water. The thickener is used to finely adjust the viscosity of the coating liquid.

The content of the colorant, preservative and thickener is preferably 0.5 part by mass or less. By limiting the content of the organic substance to the above specific range, the amount of gas generated upon drying of the coating liquid can be sufficiently reduced. As a result, occurrence of cracks in the coating layer after drying can be avoided.

The refractory material can be produced, for example, by applying the coating liquid to a substrate made of a refractory material, and then drying the coating liquid to form a coating layer. By using the coating liquid for forming the coating layer, the thickness of the coat layer that can be obtained can be reduced. Further, since the viscosity of the coating liquid can be lowered than that of the conventional coating liquid as described above, it can be applied to the substrate by spraying. Also, the coating liquid may be applied to the surface of the substrate by using a brush, a spatula or the like as in the prior art.

The substrate to which the coating liquid is applied is made of a conventionally known refractory. Concretely, as the refractory constituting the base body, a block and a molded product including a ceramic fiber can be employed. As the ceramic fiber constituting the base body, for example, a refractory ceramics fiber, an alumina fiber and a biodegradable fiber can be used.

The refractory ceramics fiber contains, for example, 30 to 60% by mass of Al ₂ O _{3 and} 40 to 60% by mass of SiO ₂ , and a chemical component composed of ZrO ₂ and / or Cr ₂ O ₃ Of fibrous particles. The fibrous particles constituting the refractory ceramics fiber are amorphous.

The alumina fiber is composed of fibrous particles containing, for example, 60% by mass or more of Al ₂ O ₃ and having a chemical component composed of SiO ₂ . Further, the fibrous particles constituting the alumina fiber include both the water-light crystal and the alumina crystal.

The biodegradable fiber comprises, for example, 40 to 60% by mass of SiO ₂ , and the remainder is composed of fibrous particles having a chemical component composed of MgO and / or CaO. Further, the fibrous particles constituting the biodegradable fiber are amorphous.

As the refractory, a plastic refractory material including heat-resistant refractory bricks, chamotte, alumina and chromium as specified in JIS R2611 as an aggregate, a castable refractory including calcia and alumina as an aggregate, and a refractory mortar It is also possible.

The above-described heat-resistant refractory bricks, plastic refractories, castable refractories and refractory mortars have smooth surfaces as compared with blocks including ceramic fibers and the like. Therefore, when a coating layer is formed using a conventional coating liquid, it is difficult to suppress problems such as low adhesiveness between the substrate and the coating layer, cracks or the like in the coating layer, or peeling of the coating layer.

On the other hand, the coating liquid can reduce the coating thickness on the surface of the base body as compared with the conventional coating liquid, and consequently the thickness of the coating layer can be reduced. Therefore, it is possible to improve the adhesion of the coating layer to the base made of heat-resistant refractory bricks or the like, and to suppress the occurrence of peeling or cracking of the coating layer.

Example

Examples of the coating liquid will be described below. In this example, a coating liquid was prepared using the following materials.

· Fine particles derived from inorganic binder colloidal silica

· Swelling clay mineral smectite

· Al ₂ O ₃ ceramic fiber A content: 65 mass%, SiO ₂ content: 35% by mass, average particle diameter of the fiber: 6㎛, average fiber length: 10㎛

Ceramic fiber B Al ₂ O ₃ content: 65% by mass, SiO ₂ content: 35% by mass, average diameter of fibrous particles: 6 μm, average fiber length: 20 μm

Ceramic fiber C Al ₂ O ₃ content: 65 mass%, SiO ₂ content: 35 mass%, average diameter of fibrous particles: 6 탆, average fiber length: 40 탆

Ceramic fiber D Al ₂ O ₃ content: 65% by mass, SiO ₂ content: 35% by mass, average diameter of fibrous particles: 6 μm, average fiber length: 60 μm

Ceramic fiber E Al ₂ O ₃ content: 65 mass%, SiO ₂ content: 35 mass%, average diameter of fibrous particles: 6 탆, average fiber length: 80 탆

Ceramic fiber F Al ₂ O ₃ content: 65 mass%, SiO ₂ content: 35 mass%, average diameter of fibrous particles: 6 탆, average fiber length: 100 탆

Ceramic fiber G Al ₂ O ₃ content: 70 mass%, SiO ₂ content: 30 mass%, average diameter of fibrous particles: 6 탆, average fiber length: 20 탆

Ceramic fiber H Al ₂ O ₃ content: 50 mass%, SiO ₂ content: 50 mass%, average diameter of fibrous particles: 6 탆, average fiber length: 20 탆

· Silicon carbide powder A Medium diameter: 1 μm

· Silicon carbide powder B Medium diameter: 5 μm

· Silicon carbide powder C Medium diameter: 40 μm

Alumina powder A Medium diameter: 1 탆

Alumina powder B Medium diameter: 20 占 퐉

Alumina powder C Medium diameter: 40 탆

· Silica powder middle diameter: 40 탆

Medium diameter of chromia powder: 40 탆

· Zirconia powder middle diameter: 40 ㎛

The average fiber length of the ceramic fibers was calculated by the following method. First, an SEM (scanning electron microscope) image of a ceramic fiber before mixing was obtained. Among the fibrous particles embedded in the SEM, 100 fibrous particles capable of identifying both ends were randomly selected. The average fiber length was obtained by averaging the lengths of these fibrous particles.

The average diameter of the fibrous particles was calculated by the following method. First, an SEM (scanning electron microscope) image of a ceramic fiber before mixing was obtained. Ten randomly selected fibrous particles were observed from the fibrous particles on the SEM. The average value of the cross-sectional diameters of these fibrous particles was defined as the average diameter of the fibrous particles.

The median diameter of the ceramic powder was measured using a laser diffraction / scattering particle diameter distribution measuring apparatus ("LA-500" manufactured by Horiba Seisakusho Co., Ltd.).

(Experimental Example 1)

This example is an example of a coating liquid containing one type of ceramic fiber as a radiation scattering material. In this example, as shown in Table 1, 14 types of coating liquids (Tests 1 to 14) were prepared by changing the kind and content of the ceramics fiber. Thereafter, evaluation was made on the properties of the obtained coating liquid.

≪ Preparation method of test agent >

First, swellable clay minerals were added in several portions while stirring with water to disperse the swellable clay minerals in water. An inorganic binder, a radiation scattering material, a coloring agent, an antiseptic agent and a thickening agent were sequentially added while stirring the solution, to thereby prepare Test Examples 1 to 14. Further, the inorganic binder was mixed into the solution in the state of a colloidal silica solution.

≪ Characteristic evaluation of test agent &

·Viscosity

Viscosity of each test agent at 20 占 폚 was measured using a viscometer ("Biscot Tester VT-04E" manufactured by Leion Chemical Co., Ltd.). The results are shown in Table 1. The meanings of the symbols of " viscosity " in Table 1 are as follows.

A +: The viscosity of the test agent was 1 Pa · s or less.

A: The viscosity of the test agent was more than 1 Pa · s and not more than 5 Pa · s.

B: The viscosity of the test agent was more than 5 Pa · s and not more than 20 Pa · s.

C: The viscosity of the test agent exceeded 20 Pa · s.

D: The viscosity was insufficient due to lack of water.

<Dispersion stability>

Each test agent was thoroughly stirred to disperse the solid components, and then the test agent was allowed to stand at room temperature. Then, the time until the solid content completely settled was measured. The results are shown in Table 1. The meanings of the symbols shown in the column of &quot; dispersion stability &quot; in Table 1 are as follows. The term &quot; completely precipitated solid matter &quot; refers to a state in which a boundary between a precipitated solid matter and a supernatant liquid is clearly observed.

A +: During the evaluation period, the solids did not settle.

A: Solids precipitated for several days.

B: Solids precipitated for several tens of minutes.

C: The solid content settled immediately after standing.

-: The viscosity of the test agent was too high to be evaluated.

&Lt; Coatability >

As a test piece, a lattice having a plurality of holes each having a square shape of 3 mm in length and 3 mm in width was prepared. In this test piece, application of each test agent was tried by using a spray and a spatula to evaluate the applicability of the spray application. The coated test piece was visually observed to evaluate the presence or absence of clogging of the hole by the test agent. Table 1 shows the evaluation results. The meanings of the symbols shown in the &quot; applicability &quot; column in Table 1 are as follows.

A +: Spray application of the test agent could be performed. No clogging of the hole portion occurred in the test piece after spray application, and all the hole portions were opened.

A: Spray application of the test agent could be performed. The clogging of the test agent occurred in a part of the hole in the test piece after spray application.

B: Spraying of the test agent could not be performed, and application with a spatula was performed. In the test piece after application, clogging of the test agent occurred in almost all of the holes.

-: Since the viscosity of the test agent was very high, it was impossible to apply the test agent.

&Lt; Crack after drying >

As a test piece, a glass plate, an alumina plate, a refractory brick and a ceramic fiber block were prepared. The glass plate and the alumina plate have a smooth surface and show a square shape of 5 cm in length and 5 cm in width. The refractory brick has a rough surface and has a cubic shape with a side of 5 cm. The ceramic fiber block has a large number of gaps on its surface and a cubic shape with a side of 5 cm.

On the surfaces of the four test pieces, the test agent was applied so that the entire surface of the test piece was as thin as possible. Thereafter, the test piece was heated at 110 캜 for 12 hours and dried.

The surface of the test piece after drying was visually observed to evaluate the presence or absence of cracks in the coating layer. The results are shown in Table 1. The symbols shown in the column "Crack after drying" in Table 1 have the following meanings.

A +: No crack occurred in the coating layer after drying.

A: Cracks occurred in a part of the coating layer after drying, but no deterioration in heat insulating performance due to cracks was observed.

B: Cracks occurred on almost the entire surface of the coating layer after drying.

-: Since the viscosity of the test agent was very high, it was impossible to apply the test agent.

<Roughness of Coating Layer>

Of the test pieces thus obtained, the surface of the test piece having the coating layer formed on the alumina plate was visually observed in the diagonal direction to evaluate the roughness of the surface of the coating layer. The results are shown in Table 1. The meanings of the symbols in the &quot; surface roughness &quot; column in Table 1 are as follows.

A: The entire surface of the coating layer was smooth.

B: Unevenness was observed in a part of the coating layer.

C: Unevenness was observed on the entire surface of the coating layer.

-: Since the viscosity of the test agent was very high, it was impossible to apply the test agent.

&Lt; Thickness of coating layer &

Of the test pieces obtained by the above, the thickness of the coating layer formed on the alumina plate was measured. The results are shown in Table 1. The symbols used in the &quot; thickness of coating layer &quot; column in Table 1 mean the following. The thickness of the coating layer was measured by the following method.

The thickness of five randomly selected alumina plates before application of the coating layer was measured in advance using a vernier caliper. The average value of the thicknesses obtained at the five places was taken as the average thickness of the alumina plate. Thereafter, a coating layer was formed on the alumina plate by the above-mentioned method, and a test piece was produced. In the test piece, the thicknesses of the thickest portion and the thinnest portion judged by the naked eye were measured using a vernier caliper. In addition, three portions were randomly selected from the portions excluding the two portions, and the thickness of the test pieces was measured using a vernier caliper. The average value of the thicknesses obtained at the above five points was defined as the average thickness of the test pieces. The thickness of the coating layer was determined by subtracting the average thickness of the alumina plate from the average thickness of the test piece.

A +: The thickness of the coating layer was 0.1 mm or less.

A: The thickness of the coating layer was more than 0.1 mm but not more than 0.3 mm.

B: The thickness of the coating layer was more than 0.3 mm but not more than 1 mm.

C: The thickness of the coating layer was more than 1 mm and less than 3 mm.

D: The thickness of the coating layer exceeded 3 mm.

-: Since the viscosity of the test agent was very high, it was impossible to apply the test agent.

&Lt; Crack after firing >

Of the four test pieces having the coating layer formed thereon, three kinds of alumina plate, refractory brick and ceramic fiber block were heated at 1500 DEG C for 3 hours to fuse the coating layer.

The surface of the test piece after firing was visually observed to evaluate the presence or absence of cracks in the coating layer. The results are shown in Table 1. In Table 1, the symbols shown in the column "Crack after firing" have the following meanings.

A +: No crack occurred in the coating layer after firing.

A: Cracks occurred in a part of the coating layer after firing, but no deterioration in heat insulating performance due to cracking was found.

B: Cracks occurred on almost the entire surface of the coating layer after firing.

-: Since the viscosity of the test agent was very high, it was impossible to apply the test agent.

&Lt; Evaluation of adiabatic performance &

The test agent was applied to the surface of the substrate made of refractory material so that the entire surface of the substrate was covered as thin as possible. Thereafter, the gas was heated at 110 DEG C for 12 hours to dry the test agent to form a coating layer. Thus, a refractory having a coating layer was prepared. As the base, ceramics fiber blocks having a maximum use temperature of 1260 占 폚 and castable refractories having a maximum use temperature of 1300 占 폚 were used.

Next, a high-temperature endurance test was performed to heat the refractory for a long time by the following method. In the refractory using the ceramic fiber block, after the refractory was charged into the heating apparatus, the temperature in the apparatus was raised to 1500 ° C at a heating rate of 150 ° C / hour, and then the temperature was maintained at 1500 ° C for 24 hours. After holding for 24 hours, the heating was stopped and the refractory was allowed to naturally cool in the apparatus to complete the high-temperature durability test. In the refractory using a castable refractory, a high-temperature endurance test was carried out in the same manner as above except that the heating rate was 100 ° C / hour and the holding time at 1500 ° C was 3 hours.

Next, the dimensions of the refractory after the high-temperature endurance test were measured, and the pre-shrinkage ratio with respect to the dimensions of the refractory before the high-temperature endurance test was calculated. The results are shown in the column of &quot; line contraction ratio &quot; The symbol &quot; - &quot; in Table 1 indicates that the measurement of the line shrinkage ratio is not performed. For comparison with the refractory having a coating layer, a high-temperature endurance test was performed using a ceramic fiber block and a castable refractory in a state in which no coating layer was formed. The linear shrinkage of the ceramic fiber block was 5.4%, and the linear shrinkage of the castable refractory was 4.8%.

(Experimental Example 2)

This example is an example of a coating liquid in which the content of the inorganic binder and the swelling clay mineral is changed. As shown in Table 2, in this example, eight kinds of coating liquids (Test Examples 15 to 22) in which the content of the inorganic binder and the swellable clay mineral were changed were prepared in the same manner as in Experimental Example 1. Then, evaluation of various properties was carried out by the same method as in Experimental Example 1. The results are shown in Table 2.

(Experimental Example 3)

This example is an example of a coating liquid containing only a ceramic powder as a radiation scattering material. As shown in Table 3, in this example, 18 kinds of coating liquids (Tests 23 to 39, 41) in which the type and content of the ceramics powder were changed were produced by the same method as in Experimental Example 1. Then, evaluation of various properties was carried out by the same method as in Experimental Example 1. The results are shown in Table 3.

(Experimental Example 4)

This example is an example of a coating liquid containing both a ceramic fiber and a ceramics powder as a radiation scattering material. As shown in Tables 4 and 5, in this example, 26 kinds of coating liquids (Test Nos. 43 to 68) in which the kind and content of the ceramics powder were changed were produced by the same method as in Experimental Example 1. Then, various characteristics were evaluated by the same method as in Experimental Example 1. The results are shown in Tables 4 and 5.

As can be seen from the above Experimental Examples 1 to 4, the test agent having the content of the inorganic binder, the swellable clay mineral and the radiation scattering agent within the specific range is low in viscosity, has excellent dispersion stability, I could. In addition, such a test agent can form a coating layer exhibiting excellent adhesion to various test pieces such as glass and brick, and can suppress cracking of the coating layer after drying and firing.

The test agent having the content of the swelling clay mineral and the radiation scattering material within the above specific range is superior to the refractory having no coating layer or the test article 4 containing no radiant scattering material in terms of the line shrinkage rate after the high- It was possible to make it small.

From the above results, it can be understood that the test agent having the content of the inorganic binder, the swellable clay mineral and the radiation scattering agent within the above specific range can be prepared by a simple operation and a coating layer having excellent performance can be formed .

(Experimental Example 5)

This example is an example of evaluating the wind resistance of the refractory. The test specimens used for the evaluation were produced by the following methods. First, as a base, a ceramic fiber block showing a flat plate-like shape having a length of 10 cm, a width of 10 cm, and a thickness of 1 cm was prepared. The test piece 2 (see Table 1) was coated on the surface of the base material so that the entire surface of the base material was as thin as possible. Thereafter, the substrate was heated at 110 DEG C for 12 hours to dry the test piece 2 to form a coating layer. Thus, a refractory material (test piece A) was produced.

For comparison with the test piece A, a test piece B consisting solely of the gas and the test pieces C through F shown in Table 6 were prepared. Test pieces C to F were refractory materials produced by the same method as in Test piece A except that the components of the coating solution were changed as shown in Table 6. [

Evaluation of wind speed resistance was carried out by the following method. First, the masses of the test bodies A to F obtained by the above method were measured. Next, the compressed air supplied from the compressor was ejected for 20 seconds to the center of the plate surface of the test body. The pressure of the compressed air was 9 kg / cm 2. The outlet of the compressed air was disposed at a position 3 cm away from the surface of the test piece in the thickness direction. The diameter of the outlet was 3 mm. Thereafter, the mass of the test piece after the compressed air was blown out was measured.

Based on the mass of the test sample before and after the ejection obtained by the above, the mass reduction rate based on the mass of the test sample before ejecting the compressed air was calculated. That is, the mass reduction rate R (%) is a value calculated by the following equation.

R = (Wi-Wf) / Wi x 100

In the above equation, Wi is the mass (g) of the test piece before ejecting the compressed air, and Wf is the mass (g) of the test piece after ejecting the compressed air.

Table 6 shows the mass reduction rate of each specimen.

As can be seen from Table 6, the refractory (test piece A) produced using the test piece 2 having the contents of the inorganic binder, the swellable clay mineral and the radiation scattering material within the above-mentioned specific range is the test piece B made of only the ceramic fiber block, The mass reduction rate can be reduced as compared with the test bodies C, D and F which do not have at least one of inorganic binder and clay mineral.

In the test piece E, the mass reduction rate was lower than that of the test piece A. However, since the test piece D does not contain the radiation scattering material (ceramic fiber B), it is estimated that the heat insulating performance is lower than that of the test piece A.

(Experimental Example 6)

This example shows the effect of improving the corrosion resistance by using a part of the coating liquid (Test Nos. 1, 2, 14, 33, 34, 36, 54, 60, 61, 62, 23, 24, 38, 39 and 41) The results are shown in Fig.

<Production of Refractory Test Specimen>

As the refractory to be a gas, two kinds of 10-cm square ceramic fiber blocks were prepared. The first ceramic fiber block used in the present example is one having a composition containing 50 mass% of Al ₂ O ₃ and SiO ₂ , respectively, and having an upper limit operating temperature of 1260 ° C (manufactured by ITM Corporation). The second ceramic fiber block is a commercially available product (manufactured by ITM Corporation) having an Al ₂ O ₃ content of 70% by mass, a SiO ₂ content of 30% by mass, and an upper limit operating temperature of 1600 ° C.

On the surfaces of these ceramic fiber blocks, a coating solution (test agent) was applied so as to be as thin as possible and to cover the entire surface of the surface. Thereafter, the coating solution was dried at 110 DEG C for 12 hours to obtain a refractory test piece having a coating layer having a thickness of 0.3 mm or less on the surface of the ceramic fiber block as a base. The refractory test specimen using the second ceramics fiber block was used for Test No. 2 and Test No. 544 as shown in Table 7 to be described later.

<Corrosion test>

Two kinds of scales were prepared as materials that cause corrosion of refractories. Scale 1 is a mass ratio of FeO powder: carbon powder = 10: 0.5, and scale 2 is a FeO powder: sodium carbonate: carbon powder = 9: 1: 0.45 in mass ratio. Corrosivity is stronger on scale 2 than on scale 1.

This scale is spread thinly on the surface of the above-described refractory test body so as to have a circular shape with a diameter of 2 to 3 cm. For comparison, a specimen was also prepared in which the scale was placed directly on the surface of the two kinds of ceramic fiber blocks having no coating layer. After inserting the scale-mounted refractory test body into the heating apparatus, the temperature in the apparatus was raised to 1400 占 폚 at a heating rate of 150 占 폚 / hour, and then the temperature of 1500 占 폚 was maintained for 3 hours. Thereafter, the refractory test body was removed from the heating apparatus, and the state of erosion was evaluated by visual observation and cross-sectional observation. The results are shown in Table 7. The meanings of symbols shown in the &quot; corrosion resistance &quot; column in Table 7 are as follows.

A: In the visual and cross-sectional observations, no erosion was observed in the gas.

B: Although it can not be judged by the naked eye, erosion of the gas was seen by cross-section observation.

C: There was a depression in the scale portion, and it was found that there was erosion in the gas with the naked eye, without observing the cross section.

As shown in Table 7, it is found that the effect of improving the corrosion resistance of the refractory is obtained when the coating solution of this example is coated on the surface of the refractory as the base to form the coating layer. At least in the case of the ceramic fiber block having the upper limit of the use temperature of 1260 DEG C, the coating layer formed by all of the tested coating solutions showed an excellent corrosion resistance improving effect on the scale 1. From the results of Scale 2, a higher corrosion resistance improving effect tends to be obtained at least when the content of alumina (Al ₂ O ₃ ) as the solid content in the coating liquid is 50 mass% or more.

(Experimental Example 7)

This example shows the results of performing an experiment for evaluating another corrosion resistance improving effect using a part of the coating liquid (Tests 2, 14, 36, 38, 39, and 41).

<Production of Refractory Test Specimen>

As a refractory material to be a gas, a 10-cm square ceramic fiber block having an upper limit of the use temperature of 1260 DEG C was prepared as in Experimental Example 6, and a pit for receiving the molten aluminum described later was provided on the surface. On the surface of the ceramic fiber block, a coating solution (test agent) was applied as thin as possible and in such a manner that the entire surface of the ceramic block was covered. Thereafter, the coating solution was dried at 110 DEG C for 12 hours to obtain a refractory test piece having a coating layer having a thickness of 0.3 mm or less on the surface of the ceramic fiber block as a base.

<Corrosion test>

An aluminum alloy ingot (10 g) of ADC12 was prepared assuming an aluminum alloy melt as a material causing corrosion of the refractory. After the aluminum alloy ingot was placed in a cavity of a ceramic fiber block and inserted into a heating device, the aluminum alloy was melted by raising the temperature in the device to 800 캜 at a temperature raising rate of 150 캜 / hour, And maintained for 10 hours. Thereafter, the refractory test body was removed from the heating apparatus, and the state of corrosion was evaluated by visual observation and cross-sectional observation. For the sake of comparison, the same test was carried out on a specimen in which an aluminum alloy ingot was placed directly on a pit of a ceramic fiber block having no coating layer. The results are shown in Table 8. The symbols shown in the &quot; corrosion resistance &quot; column in Table 8 have the following meanings.

A: In the visual and cross-sectional observations, no erosion was observed in the gas.

B: Although it can not be confirmed by the naked eye, gas erosion was observed by cross-sectional observation.

As shown in Table 8, it is understood that the coating layer can be formed by coating the surface of the refractory material as a base with the coating liquid of the present invention, thereby improving the corrosion resistance of the refractory.

Claims (10)

As a coating liquid for application to refractories,
100 parts by mass of water,
10 parts by mass or more of an inorganic binder,
0.2 to 2 parts by mass of the swellable clay mineral,
10 to 200 parts by mass of a radiation scattering material,
The radiation scattering material,
A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /
A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, And one or more kinds of ceramic powders having an intermediate diameter of not more than 2 mu m. The coating liquid according to claim 1, wherein the coating liquid contains only one of the group consisting of the ceramic fiber and the ceramic powder as the radiation scattering material. The coating liquid according to claim 2, wherein the coating liquid contains only either the ceramic fiber or the alumina powder as the radiation scattering material, and the content of Al ₂ O _{3 in} the coating liquid is 50% by mass or more with respect to the total solid content, . The coating liquid according to claim 1, wherein the coating liquid comprises at least two kinds of radiation scattering materials including the ceramic fibers. The coating liquid according to claim 4, wherein the coating liquid has a content of the alumina powder of 30 parts by mass or less. The coating liquid according to claim 4 or 5, wherein the coating liquid has a content of Al ₂ O ₃ of 50 mass% or more with respect to the total solid content. The coating liquid according to any one of claims 1 to 6, wherein the coating liquid has a viscosity of 20 Pa · s or less. The coating liquid according to any one of claims 1 to 7, wherein the coating liquid is configured so as to maintain the solid content dispersed in water for at least one day. As a composition of a coating liquid for application to refractories,
10 parts by mass or more of an inorganic binder,
0.2 to 2 parts by mass of the swellable clay mineral,
10 to 200 parts by mass of a radiation scattering material,
The radiation scattering material,
A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /
A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, And at least one kind of ceramics powder having an intermediate diameter of not more than 1 mu m. A gas composed of a refractory material,
A coating layer formed on the substrate,
The coating layer comprises,
10 parts by mass or more of an inorganic binder,
0.2 to 2 parts by mass of the swellable clay mineral,
10 to 200 parts by mass of a radiation scattering material,
The radiation scattering material,
A ceramic fiber composed of fibrous particles containing Al ₂ O ₃ and having an average fiber length of 100 μm or less and /
A powder selected from the group consisting of alumina powder, silica powder, titania powder, chromia powder, yttria powder, zirconia powder, lanthanum oxide powder, ceria powder, silicon carbide powder, silicon carbide aluminum powder, silicon nitride powder and boron nitride powder, A refractory having a coating layer comprising one or more kinds of ceramics powder having an intermediate diameter of 탆 or less.