JP2023101295A - Inorganic fiber molded body - Google Patents

Abstract

To provide an inorganic fiber molded body excellent in heat insulation and scale resistance.SOLUTION: An inorganic fiber molded body according to the present invention comprises an inorganic fiber filler and an inorganic porous filler. The inorganic porous filler contains CA6 particles containing CaO 6Al2O3 in a crystalline phase, and alkali resistance index measured based on a specified alkali gas exposure test is -1,800 μm or more and +1,800 μm or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to inorganic fiber moldings.

Various developments have been made in the field of inorganic fiber moldings. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes an inorganic fiber molded body formed by vacuum forming a slurry containing alumina fiber, alumina powder, silica sol, and starch as a refractory heat insulating material for high temperatures (Table 1 of Patent Document 1).

JP-A-10-194863

However, as a result of investigation by the present inventors, it has been found that the inorganic fiber molded article described in Patent Document 1 has room for improvement in terms of scale resistance and heat insulation.

As a result of further investigation by the present inventors, it was found that by using the surface erosion state of the inorganic fiber molded article when exposed to high-temperature alkaline gas as an index, it is possible to stably evaluate the scale resistance and heat insulating properties of the inorganic fiber molded article. I found out.

In general, when materials containing alkali metals are fired in a firing furnace, high-temperature alkaline gases such as lithium gas and sodium gas may be generated, which may deteriorate the components of the firing furnace. be. The inventor of the present invention thought that scale resistance and heat insulating properties could be improved if the inorganic fiber molded article was such that deterioration such as erosion due to such high-temperature gas was suppressed.
As a result of further studies based on such findings, it was found that the alkali resistance index obtained by quantifying the surface erosion state was controlled within an appropriate range using an inorganic fiber molded body containing an inorganic fiber filler and an inorganic porous filler. The inventors have found that scale resistance and heat insulation can be improved by the method, and have completed the present invention.

According to the invention,
An inorganic fiber molded body containing an inorganic fiber filler and an inorganic porous filler,
The inorganic porous filler comprises CA ₆ particles containing CaO 6Al ₂ O ₃ in the crystal phase,
Provided is an inorganic fiber molded article configured to have an alkali resistance index of −1800 μm or more and +1800 μm or less, which is determined based on the alkali gas exposure test described below.
(Alkaline gas exposure test)
A test plate having a thickness of 25 mmt is prepared using the inorganic fiber molded body.
Subsequently, 4.8 g of an alkaline gas source obtained by mixing lithium carbonate and cobalt oxide so that the molar ratio of lithium element and cobalt element is 1:1 is put into an alumina crucible having an opening of φ32 mm. The opening of the alumina crucible is covered with the test plate, these are heated in a furnace at 1100 ° C. for 8 hours, and the alkali gas generated from the alkali gas source is introduced into the test plate located in the opening. The process of contacting the surface of the plate is regarded as one cycle, and this process is repeated for 5 cycles.
After that, on the surface of the test plate, a three-dimensional shape measuring machine is used to measure the distance between the center point in the area exposed to the alkaline gas and the reference surface in the area not exposed to the alkaline gas. This distance is defined as the alkali resistance index (μm).

INDUSTRIAL APPLICABILITY According to the present invention, an inorganic fiber molded article having excellent scale resistance and heat insulation is provided.

It is a schematic diagram for demonstrating an alkali gas exposure test. It is a reference diagram for calculating an alkali resistance index.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Also, the drawings are schematic diagrams and do not correspond to actual dimensional ratios.

An outline of the inorganic fiber molded article of the present embodiment will be described.

The inorganic fiber molded body of the present embodiment contains an inorganic fiber filler and an inorganic porous filler, the inorganic porous filler contains CA ₆ particles containing CaO 6Al ₂ O ₃ in the crystal phase, and the following alkaline gas The alkali resistance index obtained based on the exposure test is configured to be −1800 μm or more and +1800 μm or less.

(Alkaline gas exposure test)
A test plate having a thickness of 25 mmt is prepared using an inorganic fiber molding.
Subsequently, 4.8 g of an alkaline gas source obtained by mixing lithium carbonate and cobalt oxide so that the molar ratio of lithium element and cobalt element is 1:1 is put into an alumina crucible having an opening of φ32 mm.
Subsequently, the opening of the alumina crucible is covered with the test plate, and these are heated in a furnace at 1100° C. for 8 hours, and the alkali gas generated from the alkali gas source is applied to the test plate positioned at the opening. The process of contacting the surface is regarded as one cycle, and this process is repeated for 5 cycles.
After that, on the surface of the test plate, a three-dimensional shape measuring machine is used to measure the distance between the center point in the area exposed to the alkaline gas and the reference surface in the area not exposed to the alkaline gas. This distance is defined as the alkali resistance index (μm).

The inorganic fiber molding has an alkali resistance index of −1800 μm or more and +1800 μm or less, preferably −1600 μm or more and +1600 μm or less, more preferably −1300 μm or more and +1300 μm or less. As a result, the scale resistance of the inorganic fiber molded article can be improved. In addition, deterioration in durability as a furnace member can be suppressed in a high-temperature alkaline atmosphere.
A convex state in which the center point is higher than the reference plane indicates a positive value, and a concave state in which the central point is lower than the reference plane indicates a negative value.

In the present embodiment, it is possible to control the alkali resistance index by appropriately selecting the type and amount of each component contained in the inorganic fiber molded body, the method for producing the inorganic fiber molded body, and the like. . Among these factors, for example, increasing the content of CaO.6Al ₂ O ₃ , keeping the content of silica low, increasing the bulk density, etc. are factors for setting the alkali resistance index within the desired numerical range. It is mentioned as.

In addition, according to the findings of the present inventors, the combined use of an inorganic fiber filler and an inorganic porous filler containing _CA6 particles reduces the thermal conductivity at high temperatures compared to the case where the inorganic porous filler is not included. It has been found that the heat resistance can be suppressed and the heat insulation can be improved.
Although the detailed mechanism is not clear, the following assumptions can be made.
First, when the inorganic fiber filler is used alone, even if heat insulation is obtained at low temperatures, the heat insulation deteriorates due to radiant heat transfer at high temperatures.
Next, when an inorganic fiber filler and a non-porous inorganic filler are used together, the addition of the inorganic filler suppresses radiant heat transfer at high temperatures, but the heat insulation at high temperatures is not sufficient.
On the other hand, when inorganic fiber filler and inorganic porous filler are used together, the filler occupies a larger area than the non-porous inorganic filler with the same content because the inorganic porous filler has a small bulk density. The thermal conductivity of the inorganic fiber molded body can be kept low at high temperatures, and the heat insulation can be enhanced. In addition, since the inorganic porous filler is appropriately filled in the gaps between the inorganic fibers inside the inorganic fiber molded body, it is thought that erosion by a high heat source such as scale can be suppressed. In addition, since the non-porous inorganic filler has a large bulk density, the filler is separated during molding of the inorganic fiber molded body, and the moldability of the inorganic fiber molded body is deteriorated. The content can be increased because it has little effect on moldability.
Moreover, the CA ₆ particles themselves have the property of being difficult to conduct heat, and are lightweight, so they can be suppressed from peeling off from the inorganic fiber molding.

The inorganic fiber molded body can be applied without particular limitation as long as it is a member that requires heat insulation. can.
Specifically, the inorganic fiber molded body may be used as part of a furnace for forming alkali metal-containing materials such as battery materials.

Examples of firing furnaces include industrial furnaces such as iron-making furnaces, non-iron-making furnaces, ceramic furnaces, and chemical industry furnaces. Among these, it may be used in a firing furnace (heating furnace) that requires heat insulation at 1400° C. or higher.
Inorganic fiber moldings may also be used as refractory heat insulating materials for high temperatures in a wide range of fields such as steel, metals, ceramics, and automobiles.

Each configuration of the inorganic fiber molded article of the present embodiment will be described in detail.

The inorganic fiber molded body contains an inorganic porous filler.
The inorganic porous filler includes CA ₆ particles, which consist of calcium aluminate porous particles containing CaO.6Al ₂ O ₃ in the crystalline phase.

The CA ₆ grains may contain other crystalline phases, if desired. Other crystal phases include 3CaO.Al ₂ O ₃ , 12CaO.7Al ₂ O ₃ , CaO.Al ₂ O ₃ , CaO.2Al ₂ O ₃ and the like. These may be used alone or in combination of two or more.

In the volume frequency particle size distribution of _CA6 particles measured by a laser diffraction scattering method, the particle diameter at which the cumulative value is 50% is defined as D50.
The lower limit of D50 for _CA6 particles is, for example, 10 μm or more, preferably 13 μm or more, and more preferably 15 μm or more. As a result, clogging during papermaking is less likely to occur, and a fibrous molded product with a homogeneous structure can be obtained. In addition, the papermaking time can be shortened, resulting in the effect of improving the production amount.
The upper limit of D50 for _CA6 particles is, for example, 40 μm or less, preferably 30 μm or less, more preferably 25 μm or less. This makes it possible to improve the adhesion between the inorganic porous filler and the inorganic fiber through the organic binder and the inorganic binder, or the adhesion between the inorganic porous fillers. Therefore, separation of the raw material during slurry production can be suppressed by making it difficult to separate from the fibers and filler. In addition, it is possible to prevent the inorganic porous filler from easily peeling off when the organic binder is burned off and the adhesive strength is lost when used at a high temperature.

The upper limit of the bulk density of _CA6 particles is, for example, 0.9 g/cm ³ or less, preferably 0.89 g/cm ³ or less. Thereby, the heat insulating property of the fiber molding can be improved.
The lower limit of the bulk density of _CA6 particles is, for example, 0.6 g/cm ³ or more, preferably 0.61 g/cm ³ or more. Thereby, the strength of the fiber molding can be increased.

The CA ₆ particles are produced by, for example, mixing raw materials such as a calcia raw material and an alumina raw material, or by mixing and pulverizing raw materials _such as calcium _aluminate . After adding an organic binder as appropriate, kneading with water and molding, firing at a temperature of 1000 ° C to 1700 ° C and pulverizing with a pulverizer can.

The upper limit of the content of CA ₆ particles is, for example, 79% by mass or less, preferably 75% by mass or less in 100% by mass of the inorganic fiber molding. As a result, aggregation of the raw material slurry and clogging during suction molding can be suppressed to improve moldability, and the bulk density of the inorganic molded body can be reduced to improve heat insulation. In addition, this makes it possible to reduce the weight and reduce the heat capacity. By setting the content to 75% by mass or less, it becomes possible to reduce the weight of the inorganic fiber molded article, and it is possible to suppress an increase in thermal conductivity in a low temperature range lower than 1000°C. In addition, the heat insulating properties are improved, and it is possible to suppress the destruction of the structure and the occurrence of cracks due to the thermal stress that occurs with the heat cycle.
The lower limit of the content of CA ₆ particles is, for example, 25% by mass or more, preferably 28% by mass or more, more preferably 30% by mass or more in 100% by mass of the inorganic fiber molding. As a result, it is possible to reduce the thermal conductivity at high temperatures, improve the heat insulating property, and improve the scale resistance while providing a predetermined strength.

The lower limit of the content of CA ₆ particles is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more in 100% by mass of the inorganic porous filler. This makes it possible to improve lightness and heat insulation.
In addition, the upper limit of the content of _CA6 particles may be, for example, 100% by mass or less in 100% by mass of the inorganic porous filler.

The inorganic fiber molding contains an inorganic fiber filler.
From the viewpoint of thermal conductivity, the inorganic fiber filler preferably contains alumina fibers.

Other inorganic fiber fillers include oxide fibers such as titania and silica, alkaline earth silicate wool (AES), and refractory ceramic fibers (RCF). These may be used alone or in combination of two or more.

The lower limit of the true specific gravity of alumina fibers is, for example, 2.8 or more, preferably 2.9 or more, and more preferably 3.0 or more. Thereby, the mechanical strength of the inorganic fiber molding can be improved.
Although the upper limit of the true specific gravity of the alumina fiber is not particularly limited, it is, for example, 3.8 or less, preferably 3.7 or less, and more preferably 3.6 or less. Thereby, weight reduction can be achieved.

The alumina/silica mass ratio of the alumina fibers may be, for example, 80/20 to 99/1, preferably 97/3 to 90/10. As a result, durability against reducing substances or alkaline substances can be enhanced.

Alumina fibers may include mullite (3Al ₂ O ₃ .2SiO ₂ ). The mineral composition of alumina fibers can be identified and quantified by powder X-ray diffraction.

The upper limit of the mullite content in the alumina fibers is, for example, 80% by mass or less, preferably 20% by mass or less, and more preferably 12% by mass or less. Thereby, fiber strength can be improved.
The lower limit of the mullite content in the alumina fibers may be, for example, 1% by mass or more.

The upper limit of the content of alumina fiber shots (unfibrous particles) having a length of 50 μm or more, measured in accordance with ISO 10635, is, for example, 10% or less, preferably 5% or less, more preferably 3% or less. be. Production variation can be reduced by using alumina fibers with reduced shots.
Although the lower limit of the shot content is not particularly limited, it may be 0.1% or more.

The upper limit of the alumina fiber content is, for example, 70% by mass or less, preferably 65% by mass or less, more preferably 60% by mass or less in 100% by mass of the inorganic fiber molded body. As a result, an increase in thermal conductivity at high temperatures can be suppressed.
The lower limit of the alumina fiber content is, for example, 15% by mass or more, preferably 20% by mass or more, based on 100% by mass of the inorganic fiber molding. Thereby, the bulk density of the inorganic fiber molded article can be reduced.

As a method for producing alumina fibers, a known method can be employed, and a method including the following stock solution preparation step, spinning step, cotton collection step and firing step may be used. Thereby, bulk alumina fibers (cotton-like fibers) can be produced.

(Undiluted solution preparation process)
As the alumina source, for example, an aluminum oxychloride aqueous solution, alumina sol, etc. are used, and as the silica source, for example, silica sol, polysiloxane, etc. are used. Polyvinyl alcohol, polyethylene glycol, and the like can be used as spinning aids as needed. A spinning dope is obtained by mixing these in a desired ratio and concentrating under reduced pressure.

(Spinning process)
The spinning stock solution prepared in the stock solution preparation step is extruded into the air through pores using a spinning device to form an alumina fiber precursor. The spinning device to be used is not particularly limited, and a blowing spinning device, a rotating disk spinning device, or the like can be used. From the viewpoint of preventing fusion of fibers extruded from pores and producing alumina fibers having a high surface pressure, the rotating disk spinning method described in JP-A-2010-31416 is preferably used.

By adjusting the pore size and extrusion conditions, it is possible to control the average fiber diameter and fiber diameter distribution of the obtained alumina fibers, as well as the content of non-fiberized substances called shot. Typically, the average fiber diameter of alumina fibers is adjusted in the range of 3 μm or more and 8 μm or less. The content of shots with a length of 50 μm or longer is preferably less than 1%.

(Cotton collection process)
The alumina fiber precursor obtained in the spinning step is collected by sucking from the lower part of the net conveyor installed in the cotton collection chamber, thereby obtaining an aggregate of the alumina fiber precursor. By adjusting the speed of the net conveyor, the thickness and surface weight of the resulting assembly are adjusted.

(Baking process)
The alumina fiber precursor obtained in the cotton collection step is fired in the firing step. In the firing process, a degreasing process and a crystallization process are performed in this order using a firing device.

The inorganic fiber molding may contain a binder selected from at least one of an inorganic binder and an organic binder.
By using the inorganic binder that remains in the inorganic fiber molded article after baking, it is possible to suppress the peeling and peeling of the inorganic fiber and the inorganic porous filler, and to reduce the heat shrinkage of the inorganic fiber molded article.
The organic binder can bind inorganic fillers such as inorganic fiber fillers and inorganic porous fillers to each other during the manufacturing process of the inorganic fiber molded body, for example, in the papermaking body described later.

The inorganic binder may contain one or more selected from the group consisting of silica sol, alumina sol, and water-curable alumina.

The upper limit of the content of the inorganic binder is, for example, 8% by mass or less, preferably 7% by mass or less, based on 100% by mass of the inorganic fiber molding.
The lower limit of the inorganic binder is, for example, 2% by mass or more, preferably 3% by mass or more in 100% by mass of the inorganic fiber molding.
By setting the thickness within the range as described above, it is possible to achieve a balance between heat insulating properties and adhesion to fibers.

The organic binder may contain, for example, one or more selected from the group consisting of polyvinyl alcohol, polyethylene oxide, polyethylene glycol, starch, (meth)acrylate copolymer, and polyoxyethylene alkyl ether. In addition, epoxy-based, phenol-based, acrylate-based, polyurethane-based, isocyanate-based, polyimide-based, vinyl-acetate-based adhesives, and various rubber-based adhesives may be used as the organic binder.

As the (meth)acrylic acid ester copolymer, for example, a copolymer of (meth)acrylic acid esters, a copolymer of (meth)acrylic acid ester and a monomer other than (meth)acrylic acid ester, etc. may be used. can be done.

The content of the organic binder is, for example, 1% by mass to 10% by mass, preferably 3% by mass to 7% by mass, based on the total 100% by mass of the inorganic fiber filler, inorganic porous filler and inorganic binder.

The inorganic fiber molded body is composed of a paper-made molded body. That is, the inorganic fiber molded article is obtained by forming a slurry containing raw material components into paper and molding.

A method for producing an inorganic fiber molded article includes, for example, a slurry process, a papermaking process, and a molding process.

In the slurry process, fiber raw materials such as inorganic fiber filler, inorganic porous filler, inorganic binder, and organic binder are dissolved or dispersed in water to prepare an aqueous slurry. The aqueous slurry may optionally contain additives generally used in the papermaking method such as a flocculant.

Subsequently, in the papermaking step, the obtained slurry is passed through a net having a predetermined mesh to dehydrate the water in the slurry, leaving the fiber raw material on the net to obtain a papermaking body. Suction may be done from below the net. Drying may be performed after or during dehydration. Moreover, the surface shape of the net is appropriately selected, and may be planar or partially provided with a three-dimensional structure.

As an example of papermaking, water slurry is poured into a box-shaped container with a net plate on the bottom, dewatered while sucking under the net, and the cake on the net surface is dried. Examples include a method in which a flat mesh is submerged and the cake is dried by suction, and a method using continuous papermaking equipment such as a cylinder papermaking machine and a fourdrinier papermaking machine. Drying of the cake may be performed by hot air drying.

After that, in the molding step, the obtained molded body is heat-treated to manufacture a paper molded body having a predetermined shape. For example, the heating and pressurizing treatment may be performed by pressing. The paper molded product may be processed into a board.
If necessary, the surface of the paper-molded article may be subjected to a known surface treatment.

The thickness of the inorganic fiber molded article made from a paper sheet is not particularly limited, but may be 1 mm to 100 mm, preferably 10 mm to 60 mm. As a result, an inorganic fiber molded article having excellent handleability can be realized.

The upper limit of the bulk density of the inorganic fiber molding may be, for example, 0.90 g/cm ³ or less, preferably 0.89 g/cm ³ or less. Thereby, weight reduction can be achieved.
The lower limit of the bulk density is, for example, 0.20 g/cm ³ or more, preferably 0.21 g/cm ³ or more, and more preferably 0.22 g/cm ³ or more. Thereby, scale resistance can be improved.

The upper limit of the thermal conductivity of the inorganic fiber molding at 1400° C. is, for example, 0.45 W/m·K or less, preferably 0.43 W/m·K or less, more preferably 0.40 W/m·K or less. . As a result, it is possible to realize an inorganic fiber molded article having excellent heat insulating properties at high temperatures.
The lower limit of the thermal conductivity may be, for example, 0.27 W/m·K or more, 0.30 W/m·K or more, or 0.31 W/m·K or more. This makes it possible to achieve a balance with other properties such as heat shrinkage and bulk density.

In the present specification, "-" means including upper and lower limits unless otherwise specified.
In the present specification, the term "paper product" is generally used as a technical term indicating the state of a product obtained by using a method of making a fiber material.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can be adopted. Moreover, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the description of these Examples.

<Preparation of inorganic fiber molding>
Each raw material component shown in the table is as follows.
(Inorganic fiber filler)
Alumina fiber (manufactured by Denka, product name: B80K2, composition ratio (mass ratio) Al ₂ O ₃ : SiO ₂ = 80%: 20%, bulk, true specific gravity: 3.4, average fiber length (diameter): 3 .0 μm, mullite content: 59%, shot content with a length of 50 μm or more measured according to ISO 10635: 1.0%)
(Inorganic porous filler)
· CA ₆ particles: CA ₆ particles containing CaO 6Al ₂ O ₃ in the crystal phase (porous particles mainly composed of CaO 6Al ₂ O ₃ , average particle size (D50): 18.5 µm, bulk density: 0.72 g/ ^cm3 )
(Inorganic non-porous filler)
Alumina powder: (manufactured by Sumitomo Chemical Co., Ltd., product name AM-210: average particle size: 4.8 μm, bulk density: 1.28 g/cm ³ )
(inorganic binder)
・ Silica sol (solid content concentration 30% by mass, manufactured by Nissan Chemical Industries, Ltd.)
(organic binder)
・Starch (manufactured by Nippon Starch Chemical Co., Ltd.)

(Examples 1 to 3, Comparative Example 1)
According to the blending ratio in Table 1, alumina fiber (inorganic fiber filler), CA ₆ particles (inorganic porous filler), silica sol (inorganic binder), and starch (organic binder) were wet-mixed for 20 minutes to obtain a slurry concentration (inorganic An aqueous slurry (mixture) was prepared in which the total content of fiber filler, inorganic porous filler, organic binder and inorganic binder) was 2.0% by mass.

A cylindrical mold provided with a wire mesh having an opening of 80 mesh and a diameter of 210 mm was immersed in the resulting water slurry while sucking from below the bottom mesh with a vacuum pump. By sucking the water slurry, the raw material was deposited on the wire mesh, and when the thickness of the deposited layer exceeded 30 mm, the mold was removed from the water slurry to produce a cylindrical paper product.
After stopping the suction and demolding, the plate-shaped paper product was dried in a hot air dryer at 100° C. for 16 hours, and then the upper and lower parts of the paper product were cut and polished to a thickness of 25 mm to obtain a plate-like product. A paper-making molded article (inorganic fiber molded article) was produced.

The obtained inorganic fiber molded articles of Examples and Comparative Examples were evaluated based on the following evaluation items. Table 1 shows the evaluation results.

(bulk density)
The obtained 25 mm-thick inorganic fiber molded article (plate-shaped paper molded article) was cut to prepare a rectangular parallelepiped sample having length×width×thickness: 35 mm×35 mm×25 mm.
The volume of the obtained sample was determined based on the dimensions, the weight was measured, and the weight was divided by the volume to calculate the bulk density (g/cm ³ ) of the inorganic fiber molding.

(Thermal conductivity)
The thermal conductivity of the heat insulating plate member was measured in the temperature range from room temperature (RT) to 1400° C. in accordance with JIS R2251-1. Table 1 shows the thermal conductivity (W/m·K) at 1400°C.

(alkali resistance index)
The procedure of the alkaline gas exposure test for determining the index of alkali resistance will be described with reference to FIG.
First, using the obtained inorganic fiber molded body, a test plate 1 having dimensions of length×width×thickness: 50 mm×50 mm×25 mmt was prepared.
4. Subsequently, an alkaline gas source 3 comprising a mixture of lithium carbonate and cobalt oxide in a molar ratio of 1:1 between lithium element and cobalt element was placed in an alumina crucible 2 having an opening of φ32 mm. 8 g was added. The opening of the crucible 2 is covered with the test plate 1, and these are heated in the furnace 4 at 1100° C. for 8 hours. 11 was contacted. This treatment was regarded as one cycle, and 5 cycles were repeated.
After that, the surface 11 of the test plate 1 was measured using a three-dimensional shape measuring machine (VR-3000, manufactured by KEYENCE Co., Ltd.), as shown in FIG. The distance from the reference surface in the area where the coating was not applied was measured, and this distance was obtained as the alkali resistance index (μm) described above.
In addition, before and after the alkali gas exposure test, the surface of the inorganic fiber molded body exposed to alkali gas was almost unchanged in Example 3, cracked in Examples 1 and 2 but less eroded, and in Comparative Example 1 cracked. In addition, the presence of erosion was visually confirmed.

(Scale resistance)
The inorganic fiber molded bodies of each example and each comparative example were used as heat insulating members for skid posts of heating furnaces, and the degree of erosion by molten iron (scale) was evaluated. When the erosion was deep and there was a problem in practical use, it was evaluated as ×, and when there was no problem in practical use, it was evaluated as ○.
It was found that the inorganic fiber moldings of each example were less susceptible to erosion by molten iron than the comparative examples, and could be used for furnace members without practical problems.

The inorganic fiber molded articles of Examples 1 to 3 showed excellent results in terms of heat insulation and scale resistance as compared with Comparative Example 1. In addition, the inorganic fiber moldings of Examples 1 to 3 had low bulk densities after sintering and were light in weight.
Such inorganic fiber molded bodies of Examples 1 to 3 can be suitably used in a firing furnace for forming an alkali metal-containing material.

1 test plate 2 crucible 3 alkaline gas source 4 furnace 11 surface

Claims (10)

An inorganic fiber molded body containing an inorganic fiber filler and an inorganic porous filler,
The inorganic porous filler comprises CA ₆ particles containing CaO 6Al ₂ O ₃ in the crystal phase,
An inorganic fiber molded article configured to have an alkali resistance index of −1800 μm or more and +1800 μm or less, which is determined based on the alkali gas exposure test described below.
(Alkaline gas exposure test)
A test plate having a thickness of 25 mmt is prepared using the inorganic fiber molded body.
Subsequently, 4.8 g of an alkaline gas source obtained by mixing lithium carbonate and cobalt oxide so that the molar ratio of lithium element and cobalt element is 1:1 is put into an alumina crucible having an opening of φ32 mm. The opening of the alumina crucible is covered with the test plate, these are heated in a furnace at 1100 ° C. for 8 hours, and the alkali gas generated from the alkali gas source is introduced into the test plate located in the opening. The process of contacting the surface of the plate is regarded as one cycle, and this process is repeated for 5 cycles.
After that, on the surface of the test plate, a three-dimensional shape measuring machine is used to measure the distance between the center point in the area exposed to the alkaline gas and the reference surface in the area not exposed to the alkaline gas. This distance is defined as the alkali resistance index (μm). The inorganic fiber molded article according to claim 1,
The inorganic fiber molded article, wherein the content of the CA ₆ particles is 25% by mass or more and 79% by mass or less in 100% by mass of the inorganic fiber molded article. The inorganic fiber molded article according to claim 1 or 2,
When D50 is the particle diameter at which the cumulative value is 50% in the volume frequency particle size distribution of the CA ₆ particles measured by a laser diffraction scattering method, D50 in the CA ₆ particles is 10 μm or more and 40 μm. body. The inorganic fiber molded article according to any one of claims 1 to 3,
An inorganic fiber molding containing an inorganic binder. The inorganic fiber molded article according to claim 4,
The inorganic fiber molded body, wherein the content of the inorganic binder is 2% by mass or more and 8% by mass or less in 100% by mass of the inorganic fiber molded body. The inorganic fiber molded article according to any one of claims 1 to 5,
The inorganic fiber molding, wherein the inorganic fiber filler contains alumina fibers. The inorganic fiber molded article according to claim 6,
The inorganic fiber molded body, wherein the content of the alumina fiber is 15% by mass or more and 70% by mass or less in 100% by mass of the inorganic fiber molded body. The inorganic fiber molded article according to any one of claims 1 to 7,
An inorganic fiber molded article having a bulk density of 0.20 g/cm ³ or more and 0.90 g/cm ³ or less. The inorganic fiber molded article according to any one of claims 1 to 8,
An inorganic fiber molded article having a thermal conductivity of 0.27 W/m·K or more and 0.45 W/m·K or less at 1400°C. The inorganic fiber molded article according to any one of claims 1 to 9,
An inorganic fiber molded body used in a part of a firing furnace for forming an alkali metal-containing material.

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