WO2011058916A1

WO2011058916A1 - Composite heat insulating material

Info

Publication number: WO2011058916A1
Application number: PCT/JP2010/069561
Authority: WO
Inventors: 渡邊敬一郎
Original assignee: 日本碍子株式会社
Priority date: 2009-11-11
Filing date: 2010-11-04
Publication date: 2011-05-19
Also published as: JPWO2011058916A1

Abstract

Provided is a composite heat insulating material which is inexpensively producible, is easily incorporated into an assembly, and, moreover, has thermal conductivity lower than 1.0 (W/m·K). The composite heat insulating material comprises: a rectangular tube-shaped honeycomb structure (16) having numerous housing spaces (14) which are divided from one another by thin walls (12); and ceramic powder (18) with which the insides of the respective housing spaces (14) of the honeycomb structure (16) are filled up. While the side faces of the honeycomb structure (16) are covered with outer walls (20) (for example, walls made of a material similar to that of the thin walls (12)), the upper and lower faces thereof are covered with plugging layers (22). A cross-sectional shape of the honeycomb structure (16) taken along a direction perpendicular to the axis thereof is a shape having the multiple thin walls (12) arranged in parallel with one another.

Description

Composite insulation

The present invention relates to a composite heat insulating material, for example, a composite heat insulating material suitable for use in a heat insulating material such as a continuous furnace (tunnel furnace).

For example, a continuous furnace (tunnel furnace) is often used when a ceramic molded body is fired to produce a ceramic sintered product. The continuous furnace is, for example, a ceramic molded body by placing a workpiece (ceramic molded body) on a base made of a ceramic sintered body and transporting the base from the inlet to the outlet of the continuous furnace by a carriage. Is a furnace for firing. In particular, it is possible to form various temperature distributions from the inlet to the outlet depending on the temperature zone division for the continuous furnace body and the conveyance speed. In addition, a chain conveyor, a pusher, etc. are used for conveyance of a trolley | bogie.

In such a continuous furnace, the outer wall is made of a heat insulating material so that the internal temperature distribution can be maintained (see, for example, JP-A-7-49181). Japanese Patent Application Laid-Open No. 2003-314970 discloses an example in which a refractory brick, a refractory heat insulating brick, a castable refractory, a ceramic fiber molded body, or the like is used as a heat insulating material for an electric furnace.

By the way, for the heat insulating material used in the continuous furnace and the electric furnace as described above, the thermal conductivity is an important parameter. Also, for furnaces that are large in scale, such as continuous furnaces, it is also important to be able to produce heat insulating materials at low cost and to be easily assembled in order to reduce the cost of products (ceramic sintered bodies, etc.) It becomes a big factor. Examples of the heat insulating material that can be manufactured at low cost and can be easily assembled include refractory bricks described in Patent Document 2. However, the thermal conductivity of refractory bricks, etc. is as high as 1.6 to 2.5 (W / m · K). For example, when used as a thermal insulation for a continuous furnace, it is difficult to maintain a set temperature distribution. There is a problem of becoming.

The present invention has been made in consideration of such problems. A composite heat insulating material that can be manufactured at low cost, is easy to assemble, and has a thermal conductivity of less than 1.0 (W / m · K). The purpose is to provide.

First, before completing the present invention, a heat insulating material composed of a combination of a gas having a low thermal conductivity and ceramic powder was assumed. For example, the case where air is selected as the gas having a small thermal conductivity is shown in Table 1 described later. As can be seen from Table 1, this heat insulating material has a low thermal conductivity of 0.04 to 0.11 at room temperature, indicating that the heat insulating effect is high. However, since such a mixture of gas and powder is indefinite and has no shape retention, a large amount of ceramic powder is placed in a ceramic box-like container such as alumina when it is configured as a realistic heat insulating material. It is conceivable to form a heat insulating material by filling. However, a box-shaped ceramic container is weak in strength and cannot maintain its shape due to breakage, so that it is difficult to assemble it into a continuous furnace or the like, and it is difficult to manufacture, and thus costs are high.

Therefore, in the present invention, the conventional problem is solved by the following configuration.

The composite heat insulating material according to the present invention includes a block-shaped honeycomb structure having a large number of accommodating spaces each partitioned by a thin wall, and ceramic powder filled in the accommodating spaces of the honeycomb structure. It is characterized by.

By filling ceramic powder into a large number of accommodation spaces partitioned by thin walls, first, heat transfer by heat conduction can be suppressed by the ceramic powder filled in the accommodation space. This is also clear from the fact that a heat insulating material made of a combination of air and ceramic powder described above exhibits a very low thermal conductivity and is expected to have a high heat insulating effect. And since it is only necessary to fill the ceramic powder in the accommodation space of the honeycomb structure, the production is easy, and the presence of the honeycomb structure can increase the strength of the structure and the shape. Since it can be maintained, assembly to a continuous furnace or the like becomes easy.

Also, the ceramic powder filled in the honeycomb structure space suppresses heat transfer due to convection by interfering with the gas flow.

In addition, although heat transfer by radiation accounts for a large proportion at high temperatures, such ceramic powder can also suppress heat transfer by radiation because light is scattered between particles.

That is, the present invention can provide a composite heat insulating material that can be manufactured at low cost, can be easily assembled, and has a thermal conductivity of less than 1.0 (W / m · K). Of course, the thermal conductivity (room temperature) can be 0.06 to 0.55 (W / m · K), which is one digit lower than that of refractory bricks.

And in this invention, the cross-sectional shape when the said honeycomb structure is cut | disconnected in the direction orthogonal to the axial direction may be a shape where several thin walls were located in parallel. In this case, the direction in which the plurality of thin walls are arranged (second direction) is smaller than the thermal conductivity in the direction in which the plurality of thin walls extend (first direction) because there is no heat conduction due to heat transfer of the thin walls. Thus, the thermal conductivity can be made anisotropic. The anisotropy of the thermal conductivity can be increased several times or more as will be described later. Therefore, for example, when assembling a composite heat insulating material in a continuous furnace, in a zone where heat is to be transmitted to the outside (a zone where the heat insulating effect is not so much necessary), the heat radiation direction and the first direction are substantially matched. In a zone where heat is not desired to be transmitted to the outside (a zone where a heat insulation effect is necessary), the heat radiation direction and the second direction may be substantially matched.

In the present invention, the cross-sectional shape when the honeycomb structure is cut in a direction orthogonal to the axial direction thereof may be a shape in which a plurality of thin walls are combined in a lattice shape.

¡Since this structure has high strength, there is no concern that the composite heat insulating material will collapse after assembly by assembling it in a portion where stress is concentrated.

In particular, if the angle of the lattice-like intersection is approximately 90 °, the heat conductivity does not depend on the assembling direction, so that it is possible to assemble without worrying about the directionality. Of course, the angle of the lattice-like intersection may be 30 to 60 °.

As described above, according to the composite heat insulating material according to the present invention, it can be manufactured at low cost, can be easily assembled, and has a thermal conductivity (room temperature) of less than 1.0 (W / m · K). can do.

It is a perspective view which shows a 1st composite heat insulating material partly fractured | ruptured. It is sectional drawing which shows the cross-sectional shape at the time of cut | disconnecting a honeycomb structure in the direction orthogonal to the axial direction about a 1st composite heat insulating material. It is sectional drawing which shows the cross-sectional shape at the time of cut | disconnecting a honeycomb structure in the direction orthogonal to the axial direction about a 2nd composite heat insulating material. It is sectional drawing which shows the cross-sectional shape at the time of cut | disconnecting a honeycomb structure in the direction orthogonal to the axial direction about a 3rd composite heat insulating material. It is a schematic diagram which shows the ceramic powder at the time of filling many ceramic particles (alumina or zirconia) in a specific gas layer. FIG. 6A is a front view showing a state in which the first to third Seralek honeycomb materials are installed in the opening of the box test firing furnace, and FIG. 6B is a front view showing the state shown in FIG. 6A. It is a side view which abbreviate | omits and shows a material.

Hereinafter, embodiments of the composite heat insulating material according to the present invention will be described with reference to FIGS. 1 to 6B.

First, the composite heat insulating material (hereinafter referred to as the first composite heat insulating material 10A) according to the first embodiment includes a large number of accommodation spaces 14 each partitioned by a thin wall 12, as shown in FIGS. And a ceramic powder 18 filled in the accommodation space 14 of the honeycomb structure 16. The side surface of the honeycomb structure 16 is closed by an outer wall 20 (for example, a wall made of the same material as the thin wall 12), and the upper and lower surfaces of the honeycomb structure 16 are plugged layers 22 (made of the same material as the thin wall material). (See FIG. 1). That is, all the openings are sealed. Moreover, the planar shape of the upper surface and the lower surface of the honeycomb structure 16 is a quadrangle (a square in the example of FIG. 2).

When the first composite heat insulating material 10A is manufactured, the honeycomb structure 16 having the upper surface opening and the lower surface opening is manufactured, and then the plugging layer 22 is formed on the lower surface of the honeycomb structure 16, for example. At this stage, the honeycomb structure 16 having an upper surface opening is manufactured. Thereafter, the ceramic powder 18 is inserted and filled into each housing space 14 from the upper surface opening, and then the upper surface opening is closed with the sealing layer 22, thereby producing the first composite heat insulating material 10 </ b> A.

Further, as shown in FIG. 2, the honeycomb structure 16 of the first composite heat insulating material 10A has a plurality of thin walls when the cross-sectional shape when the honeycomb structure 16 is cut in a direction orthogonal to the axial direction is viewed. 12 is arranged in parallel. In FIG. 2, two outer walls (first outer wall and second outer wall) facing each other of the honeycomb structure 16 and a plurality of thin walls are arranged in parallel.

The material of the thin wall 12 is an oxide, carbide, nitride or a mixture thereof, and as constituent elements other than oxygen, carbon and nitrogen, sodium, potassium, calcium, magnesium, strontium, barium, titanium, manganese, An inorganic material containing at least one of iron, aluminum, and silicon can be used. In this embodiment, the main crystal phase is a ceramic material of mullite _{_{_{(3Al 2 O 3 · 2SiO 2}}} ) consisting of porosity thermal conductivity 30% 2.5 (W / m · K) .

Next, a composite heat insulating material (hereinafter referred to as a second composite heat insulating material 10B) according to the second embodiment will be described with reference to FIG.

This second composite heat insulating material 10B has substantially the same configuration as the first composite heat insulating material 10A described above, but when the honeycomb structure 16 is cut in a direction orthogonal to the axial direction as shown in FIG. When the cross-sectional shape is viewed, the difference is that a plurality of thin walls 12 are combined in a lattice shape. In the example of FIG. 3, two outer walls (first outer wall 20 a and second outer wall 20 b) facing each other of the honeycomb structure 16 and a plurality of thin walls 12 a extending in one direction are arranged in parallel, and the honeycomb structure 16 other two outer walls (third outer wall 20c and fourth outer wall 20d) facing each other and a plurality of thin walls 12b extending in the other direction (a direction orthogonal to one direction) are arranged in parallel. It has become.

Next, a composite heat insulating material (hereinafter referred to as a third composite heat insulating material 10C) according to a third embodiment will be described with reference to FIG.

The third composite heat insulating material 10C has substantially the same configuration as the above-described second composite heat insulating material 10B. However, as shown in FIG. 4, each thin wall 12 has a first outer wall 20a and a second outer wall 20b. It has a grid shape with an inclination of 45 ° and an inclination of 45 ° with respect to the third outer wall 20c and the fourth outer wall 20d.

Of course, combinations of various cross-sectional shapes other than the first composite heat insulating material 10A to the third composite heat insulating material 10C described above are conceivable. In addition, the outer shape of the honeycomb structure 16, particularly the planar shape of the upper surface and the lower surface, is a square, but other shapes include a rectangle, a rhombus, a parallelogram, a trapezoid, a hexagon, an octagon, and the like. Of course, it is not limited to these, and when assembled, it can take a large contact area with other composite heat insulating materials, and in addition, a polygon with a plane portion so that loading is easy during assembly It is preferable that

Next, for the first composite heat insulating material 10A to the third composite heat insulating material 10C, the thermal conductivity in the arrow X direction and the arrow Y direction illustrated in FIGS. 2 to 4 and the Z direction which is the extrusion direction of the honeycomb structure is simulated. And obtained by actual measurement.

(Thermal conductivity of powder)
First, as shown in FIG. 5, the thermal conductivity kp of the ceramic powder 18 when a specific gas layer 30 is filled with a large number of ceramic particles 32 (alumina or zirconia) is expressed by the following exact formula and simplified formula: I asked for it.
(Exact formula)
kp = kc [1 + 2vd (1-kc / kd) / {(2kc / kd) +1}] / [1-vd (1-kc / kd) / {(kc / kd) +1}] (1 )
(Simple formula)
kp = kc (1 + 2vd) / (1-vd) (2)

Here, kc is the thermal conductivity of the gas, kd is the thermal conductivity of the ceramic particles, and vd is the ceramic volume fraction, indicating the volume ratio of the ceramic in the ceramic powder.

Here, air was selected as the gas. The thermal conductivities of air, alumina and zirconia at room temperature are 0.027 (W / m · K), 30 (W / m · K) and 2 (W / m · K), respectively. Therefore, the thermal conductivity kp with respect to the ceramic volume fraction at room temperature is as shown in Table 1 below from the equations (1) and (2).

As can be seen from this result, even if the thermal conductivity of ceramic particles is 30 W / m · K (alumina) larger than 2 W / m · K (zirconia), the thermal conductivity of the powder is ceramic. By using a powder that is almost determined by the volume fraction and has a small ceramic volume fraction, the thermal conductivity of the ceramic powder can be reduced. Since the ceramic volume fraction is proportional to the bulk density of the ceramic powder, the thermal conductivity can be reduced by selecting a powder with a low bulk density.

The thermal conductivities of air, alumina and zirconia at 1,000 ° C. are 0.076 (W / m · K), 6 (W / m · K) and 2.3 (W / m · K), respectively. It is. Therefore, the thermal conductivity kp of the ceramic powder with respect to the ceramic volume fraction at 1,000 ° C. is as shown in Table 2 below.

As can be seen from this result, even when the thermal conductivity of the powder is 6 W / m · K (alumina) or more than twice as large as 2.3 W / m · K (zirconia), the thermal conductivity of the powder is increased. Is almost determined by the ceramic volume fraction, and by using a powder having a small ceramic volume fraction, the thermal conductivity of the powder can be reduced. Since the ceramic volume fraction of the powder is proportional to the bulk density of the powder, the thermal conductivity can be reduced by selecting a powder with a low bulk density.

Example 1
As shown in FIG. 2, the heat conductivity about the arrow Y direction in 10 A of 1st composite heat insulating materials was calculated | required. The arrow Y direction is a direction connecting the third outer wall 20c and the fourth outer wall 20d, and is also an extending direction of each thin wall 12.

Mullite composition as the honeycomb structure _{_{_{(3Al 2 O 3 · 2SiO 2}}} ) become such clay 55 wt% (high purity _{_{_{kaolinite: Al 2 Si 2 O 5 (}}} OH) 4) and ordinary alumina powder 45 wt% (purity: 99.6%, average particle size: 55 μm) After adding a suitable amount of water and binder to the mixture of the mixture ratio and kneading it into a clay, a columnar clay that has been deaerated with a vacuum kneader is prepared. Extrusion molding was carried out using a die. The obtained honeycomb structure formed body was dried and then fired in air at 1,450 ° C. for 3 hours to produce a cubic honeycomb structure of 100 mm × 100 mm × 100 mm. In addition, a sample having a cross-sectional shape of 30 mm square and a thickness of one cell in the X direction and a sample having a thickness of 6 mm in the Y direction were also prepared for thermal conductivity measurement. The thickness of the thin wall after firing was 1 mm, the cell pitch in the X direction was 5 mm, and the aperture ratio was 0.8.

A paste made by adding an appropriate amount of water and a binder to the same mixture of clay and alumina as the honeycomb structure on one end face of the honeycomb structure was press-fitted uniformly about 5 mm from one side, dried and sealed.

Next, alumina powder was filled into the container formed in the gap between the thin walls from the opening on the opposite side with the sealed surface down. The alumina powder used was coarse alumina with an alumina purity of 99.6%, an average particle size of 75 μm, a specific surface area of 0.6 m ² / g, a bulk density of 1 g / cc when filled, and a ceramic volume fraction of 0.25. Met.

After filling this alumina powder, a paste made by adding an appropriate amount of water and a binder to the same clay and alumina mixture as the honeycomb structure at the opening end portion was pressed uniformly about 5 mm from one side, dried and sealed. .

The honeycomb structure thus obtained was fired in the atmosphere at 1,400 ° C. for 3 hours to produce a block-shaped composite heat insulating material of 100 mm × 100 mm × 100 mm. In addition, a 30 mm square × 6 mm composite thermal insulation sample for measuring the thermal conductivity for one cell in the X direction and a 30 mm square × 6 mm composite thermal insulation sample for measuring the thermal conductivity in the Y direction having a thickness of 6 mm. Obtained. The thin wall portion made of mullite had a porosity of 30% and a thermal conductivity of 2.5 W / m · K at room temperature.

Since the ceramic volume fraction of the ceramic powder 18 filled in the accommodation space 14 of the honeycomb structure 16 is 0.25, the thermal conductivity (room temperature) of the ceramic powder portion is 0.05 (W / m · K) [From Table 1] Since the thermal conductivity (room temperature) of the thin wall 12 is 2.5 (W / m · K), the thermal conductivity in the arrow Y direction in the first composite heat insulating material 10A was determined.

The calculation formula of the thermal conductivity in this case is as the following formula (3).
kp _y = v ₁ k ₁ + v ₂ k ₂ (3)

Here, v ₁ is the honeycomb aperture ratio (opening area of the accommodation space 14 / upper surface area of the honeycomb structure 16), v ₂ is 1-v ₁ , k ₁ is the thermal conductivity of the ceramic powder 18, and k ₂ is thin This is the thermal conductivity of the wall 12.

In the case of the first composite heat insulating material 10A, the Z direction, which is the extrusion direction of the honeycomb, has the same structure as the Y direction, so the thermal conductivity in the Z direction is equal to the thermal conductivity in the Y direction.

Next, the thermal conductivity in the arrow X direction in the first composite heat insulating material 10A was determined. The arrow X direction is a direction connecting the first outer wall 20a and the second outer wall 20b, and is also a direction orthogonal to the extending direction of each thin wall 12.

The thermal conductivity in the arrow X direction in the first composite heat insulating material 10A is expressed by the following equation (4).
kpx = k ₁ k ₂ / (v ₁ k ₂ + v ₂ k ₁ ) (4)

Therefore, the calculated values kpx and kpy of the thermal conductivity (room temperature) with respect to the honeycomb aperture ratio in the directions of the arrows X and Y (Z) in the first composite heat insulating material 10A are as shown in Table 3 below.

When the thermal conductivity in the X direction and the Y direction was measured by the laser flash method using the sample for thermal conductivity measurement obtained at the same time, the calculated values agreed.

Thus, the thermal conductivity was 9 times different between the X and Y directions.

(Example 2)
As shown in FIG. 3, the heat conductivity about the arrow X direction and the Y direction in the 2nd composite heat insulating material 10B was calculated | required. In the second composite heat insulating material 10B, the thin walls 12 are continuously connected with respect to the cross sections in the X direction and the Y direction, and the ceramic powder 18 exists therebetween. In this case, the thermal conductivity is expressed by equation (5).
kpxy = k ₂ {1 + 2v ₁ (1-k ₂ / k ₁ ) / (2k ₂ / k ₁ +1)} / {1-v ₁ (1-k ₂ / k ₁ ) / (k ₂ / k ₁ +1) } ・・・・ (5)

When k ₂ > k ₁ , it is approximately expressed by equation (6).
kpxy≈k ₂ (1−v ₁ ) / (1 + v ₁ ) (6)

The Z direction which is the extrusion direction of the honeycomb has the same structure as the Y direction of the first composite heat insulating material 10A, and can be obtained by Expression (3).

As in Example 1, 55% by weight of clay (high purity kaolinite: Al ₂ Si ₂ O ₅ (OH) ₄ ) and ordinary alumina with a mullite composition (3Al ₂ O ₃ .2SiO ₂ ) as a honeycomb structure. After adding 45% by weight of powder (purity: 99.6%, average particle size: 55 μm) to a mixture of a mixture ratio, water and a binder are added in an appropriate amount, kneaded to form a clay, and then degassed with a vacuum kneader. A clay was prepared and extruded using a predetermined die. The obtained honeycomb structure formed body was dried and then fired in air at 1,450 ° C. for 3 hours to produce a cubic honeycomb structure of 100 mm × 100 mm × 100 mm. In addition, a sample with an extrusion length of 30 mm for measuring the thermal conductivity in the X direction and a sample with an extrusion length of 20 mm for measuring the thermal conductivity in the Z direction was also prepared. The thickness of the thin wall after firing was 0.25 mm, the cell pitch in the X direction and the Y direction was 5 mm, and the aperture ratio was 0.9.

After filling this alumina powder, a paste made by adding an appropriate amount of water and a binder to the same clay and alumina mixture as the honeycomb structure at the open end was press-fitted uniformly about 5 mm from one side, dried and sealed. .

The honeycomb structure thus obtained was fired in the atmosphere at 1,400 ° C. for 3 hours, and 100 mm × 100 mm × 100 mm, 100 mm × 100 mm × 30 mm, 100 mm × 100 mm × 20 mm block composite heat insulating materials were produced. The thin wall portion made of mullite had a porosity of 30% and a thermal conductivity of 2.5 W / m · K at room temperature.

Since the ceramic volume fraction of the ceramic powder 18 filled in the accommodation space 14 of the honeycomb structure 16 is 0.25, the thermal conductivity (room temperature) of the ceramic powder portion is 0.05 (W / M · K). Since the thermal conductivity (room temperature) of the thin wall 12 is 2.5 (W / m · K), the thermal conductivity in the direction of the arrow X in the second composite heat insulating material 10B is calculated from the equation (6) in the Z direction. The thermal conductivity of was determined from equation (3).

For measuring the thermal conductivity in the X direction and the Y direction, one cell was cut out from a sample with a length of 30 mm in the Z direction, processed to a 30 mm square, and the thermal conductivity was measured by a laser flash method. The heat conductivity in the Z direction is cut out from the sample with a thickness of 20 mm in the Z direction by machining about 30 mm square parts for 6 cells in the X and Y directions, and the plugged portions are cut off from the upper and lower surfaces in the Z direction. The thickness of the part was finished so as to be about 1 mm, and the thermal conductivity was measured by a laser flash method.

(Example 3)
As shown in FIG. 4, the heat conductivity about the arrow X direction and the Y direction in 10 C of 3rd composite heat insulating materials was calculated | required. Also in this case, similarly to the second composite heat insulating material, the thin walls 12 are continuously connected with respect to the cross sections in the X direction and the Y direction, and the ceramic powder 18 is present therebetween. In this case, the thermal conductivity is expressed by equation (5). When k ₂ > k ₁ , it is approximately expressed by equation (6).

As in Example 1, 55% by weight of clay (high purity kaolinite: Al ₂ Si ₂ O ₅ (OH) ₄ ) and ordinary alumina with a mullite composition (3Al ₂ O ₃ .2SiO ₂ ) as a honeycomb structure. After adding 45% by weight of powder (purity: 99.6%, average particle size: 55 μm) to a mixture of a mixture ratio, water and a binder are added in an appropriate amount, kneaded to form a clay, and then degassed with a vacuum kneader. A clay was prepared and extruded using a predetermined die. The obtained honeycomb structure formed body was dried and then fired in air at 1,450 ° C. for 3 hours to produce a cubic honeycomb structure of 100 mm × 100 mm × 100 mm. In addition, a sample having an extrusion length of 30 mm for measuring the thermal conductivity in the X direction and a 20 mm extrusion length for measuring the thermal conductivity in the Z direction was also prepared. The thickness of the thin wall after firing was 0.4 mm, the cell pitch in the X and Y directions was 5 mm, and the aperture ratio was 0.85.

Since the ceramic volume fraction of the ceramic powder 18 filled in the accommodation space 14 of the honeycomb structure 16 is 0.25, the thermal conductivity (room temperature) of the ceramic powder portion is 0.05 (W / M · K). Since the thermal conductivity (room temperature) of the thin wall 12 is 2.5 (W / m · K), the thermal conductivity in the direction of the arrow X in the third composite heat insulating material 10C is calculated from the equation (6) in the Z direction. The thermal conductivity of was determined from equation (3).

Example 4
A commercial product (Ceralek) having a cordierite composition (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ) was used as the honeycomb structure. The size of the honeycomb after firing is a honeycomb structure in which the X direction and the Y direction are 100 mm × 100 mm and the Z direction is 50 mm, the thin wall thickness is 0.9 mm, and the cell pitch in the X direction and the Y direction is 5.9 mm. The aperture ratio was 0.72.

Because the raw paste (a mixture of talc, kaolin, alumina, and silica) having the same cordierite composition as that of the honeycomb structure was previously press-sealed uniformly about 5 mm from one side at one opening end face of the honeycomb structure, The opening on one side of the fired honeycomb structure was sealed.

The alumina powder was filled about 5 mm lower than the upper end of the opening, and after filling, a raw paste having the same cordierite composition as the honeycomb structure was pressed into the end of the honeycomb uniformly from one side, dried and sealed.

The honeycomb structure thus obtained was fired in the air at 1,350 ° C. for 3 hours to produce a block-shaped composite heat insulating material of 100 mm × 100 mm × 50 mm. The thin wall portion made of cordierite had a porosity of 45%, and the thermal conductivity of this honeycomb wall was 1.3 W / m · K at room temperature and 1.0 W / m · K at 800 ° C.

The actual insulation performance at high temperature of the composite insulation material in which the cordierite honeycomb was filled with alumina powder was evaluated by the following method.

As shown in FIG. 6A and FIG. 6B, a box test firing furnace 40 having a front opening size of width 282 mm, height 200 mm and depth 400 mm is prepared. Two first seralek honeycomb materials 42A having an X direction and a Y direction of 120 mm × 48 mm and a height of 200 mm in the Z direction, and two second seracle honeycomb materials 42A having an X direction and a Y direction of 42 mm × 48 mm and a Z direction of 75 mm The REC honeycomb material 42B was covered with one third Ceralek honeycomb 42C) having 42 mm × 48 mm in the X and Y directions and 50 mm in the Z direction. The first Ceralek honeycomb 42A to the third Cerarec honeycomb 42C are not filled with an alumina material. When the furnace temperature was maintained at 1,000 ° C. in such a state, the surface temperature of the third Ceralek honeycomb 42C (42 mm × 48 mm × 50 mm) installed in the center was 282 ° C.

Next, instead of the third Ceralek honeycomb 42C installed at the center, a B-class fireproof insulating brick (made by Isolite, catalog thermal conductivity 0.39 W / m · K or less) cut out to 42 mm × 48 mm × 50 mm When the furnace temperature was kept at 1,000 ° C., the surface temperature of the class B fireproof heat insulating brick installed at the center was 266 ° C.

Further, instead of the third Ceralek honeycomb 42C installed in the center, a composite heat insulating material in which the third Ceralek honeycomb 42C is filled with alumina powder is cut into 42 mm × 48 mm in the X and Y directions and 50 mm in the Z direction. When the furnace temperature was kept at 1,000 ° C., the surface temperature of the composite heat insulating material installed at the center was 244 ° C.

When heat insulation is performed only with Ceralek material, the heat insulation material is poor in the space formed by the honeycomb cells due to the effect of convection by air and radiant heat, but by filling the alumina powder, the heat of convection and heat radiation is reduced. Transmission was suppressed and the surface temperature was lowered by 38 ° C. to improve the heat insulation. Furthermore, the temperature was lower than that of Class B fireproof insulating bricks and showed excellent heat insulating properties.

(Discussion)
Heat is transmitted mainly by heat conduction, convection and radiation. In the composite heat insulating material according to the present embodiment, first, heat transfer by heat conduction can be suppressed by the low heat conductivity of the ceramic powder 18 filled in the accommodation space 14. This is also clear from the fact that the thermal conductivity of the ceramic powder 18 composed of a combination of the gas layer 30 and a large number of ceramic particles 32 shown in FIG. Since the ceramic powder 18 only needs to be filled in the accommodation space 14 of the honeycomb structure 16, the production is simple, and the presence of the honeycomb structure 16 can increase the strength and shape. Since it can be maintained, assembly to a continuous furnace or the like is also simplified.

Also, heat transfer by radiation accounts for a large proportion at high temperatures, but in such powders, light is scattered between particles, so that heat transfer by radiation can also be suppressed.

That is, this embodiment can provide a composite heat insulating material that can be manufactured at low cost, can be easily assembled, and has a thermal conductivity of less than 1.0 (W / m · K). Of course, the thermal conductivity (room temperature) can be 0.06 to 0.55 (W / m · K), which is one digit lower than that of refractory bricks.

And in this Embodiment, when the cross-sectional shape at the time of cut | disconnecting the honeycomb structure 16 in the direction orthogonal to the axial direction like the 1st composite heat insulating material 10A is seen, several thin wall 12 is parallel. If the shapes are arranged, the direction in which the plurality of thin walls 12 are arranged (the second direction: the figure) rather than the thermal conductivity in the direction in which the plurality of thin walls 12 extend (the first direction: the Y direction in FIG. 2). 2 in the X direction) (see Example 1) is reduced by about one digit. Therefore, for example, when assembling the first composite heat insulating material 10A in a continuous furnace, in a zone where heat is to be transmitted to the outside (a zone where the heat insulation effect is not so necessary), the heat radiation direction and the first direction are substantially matched. In a zone where heat is not desired to be transmitted to the outside (a zone where a heat insulation effect is necessary), the heat radiation direction and the second direction may be substantially matched.

Further, in the present embodiment, when the cross-sectional shape when the honeycomb structure 16 is cut in a direction orthogonal to the axial direction, as in the second composite heat insulating material 10B and the third composite heat insulating material 10C, a plurality of shapes are obtained. If the thin walls 12 are combined in a lattice shape, the overall strength will be high, so that there is no concern that the composite heat insulating material will collapse after assembly by assembling it in a portion where stress is concentrated. In particular, if the angle of the grid-like intersection is approximately 90 °, the heat conductivity does not depend on the assembling direction, so that it is possible to assemble without worrying about the directionality.

It should be noted that the composite heat insulating material according to the present invention is not limited to the above-described embodiment, but can of course have various configurations without departing from the gist of the present invention.

Claims

A block-shaped honeycomb structure (16) having a large number of accommodating spaces (14) each partitioned by a thin wall (12);
A composite heat insulating material comprising ceramic powder (18) filled in the accommodation space (14) of the honeycomb structure (16).
The composite heat insulating material according to claim 1,
The composite heat insulating material, wherein a cross-sectional shape of the honeycomb structure (16) when cut in a direction perpendicular to the axial direction is a shape in which the plurality of thin walls (12) are arranged in parallel.
The composite heat insulating material according to claim 1,
A cross-sectional shape of the honeycomb structure (16) when cut in a direction perpendicular to the axial direction thereof is a composite heat insulation characterized in that a plurality of the thin walls (12) are combined in a lattice shape. Wood.
In the composite heat insulating material according to claim 3,
A composite heat insulating material characterized in that an angle of the lattice-like intersection is approximately 90 degrees.
The composite heat insulating material according to claim 1,
A composite heat insulating material having a thermal conductivity of 0.06 to 0.55 (W / m · K).