JP2644841B2 - Plate-like inorganic material sintered body and its manufacturing method - Google Patents

Description

The present invention relates to a plate-like inorganic material sintered body and a method for producing the same.

[Prior Art] Plate-shaped ceramics are widely used as kiln tools, as unglazed ceramics, as shelves for painting, or as refractory materials for tunnel kilns. The main characteristics commonly required of these materials are high heat resistance, high strength, and high resistance to thermal shock. In order to satisfy these characteristics, silicon carbide, alumina, cordierite with a low coefficient of thermal expansion, etc. are used as the material.Furthermore, in order to improve the structure of ceramics, close-packing using coarse particles and spherical particles is used. Methods such as compounding are employed.

However, even if these modifications and improvements have been made, the general-purpose plate-like ceramics conventionally used have a thickness of 7 mm.
It was considered extremely difficult to:

[Problems to be Solved by the Invention] In view of such circumstances, the present invention provides a plate-shaped inorganic material sintered body that is thin and lightweight, has high strength at high temperatures, and has excellent thermal shock resistance, and a method for producing the same. It is the purpose.

Means for Solving the Problems The inventors of the present invention have been continuously researching to solve the above problems, but to obtain a desired sintered body by selecting an inorganic substance of a sintering material. Find out what you can do,
Further, the present inventors have found suitable production conditions, and have reached the present invention.

That is, the present invention relates to (1) at least one kind selected from the group consisting of plate-like inorganic substances having an aspect ratio of 5 or more and needle-like or columnar inorganic substances having a length-to-diameter ratio (L / D) of 3 or more. Wherein the plate-like, needle-like, and columnar inorganic substances are oriented in a certain direction parallel to a plane. Plate-like inorganic material sintered body, (2) a small number of members selected from the group consisting of plate-like inorganic materials having an aspect ratio of 5 or more and needle-like or columnar inorganic materials having a length-to-diameter ratio (L / D) of 3 or more Water is added to an inorganic substance containing 30 to 90% by weight of the total inorganic substance and kneaded, and then extruded into a cylindrical shape with an extruder.
After cutting this cylinder open and rolling in the extrusion direction, 800-1
This is a method for producing a plate-like inorganic material sintered body, which is characterized by sintering at 200 ° C.

When the microstructure of the plate-like inorganic material sintered body of the present invention is viewed in a cross section cut at right angles to the plate and parallel to the orientation direction, the plate-like, needle-like, and columnar inorganic materials have a layered structure in which a part thereof is partially bonded. The gap between the layered substances is occupied by the other substances and voids. The present invention has found that a sintered body having such a structure exhibits high strength and high thermal shock resistance.

Such a structure, 30-90% by weight of at least one inorganic substance selected from the above-mentioned plate-like, needle-like, and columnar inorganic substances,
The remaining inorganic material can be obtained by extruding with a kneader, orienting by rolling, and then sintering at an appropriate temperature. It is particularly desirable to use a well-sintered material having a small coefficient of thermal expansion as the plate-like, needle-like, or column-like inorganic material from the viewpoint of improving thermal shock resistance.

The aspect ratio of the plate-like inorganic substance used in the present invention, which is the ratio of the diameter to the thickness of the plate-like particles, is 5 or more, preferably 7 or more, and more preferably 10 or more for obtaining a higher strength. Examples of such a plate-like inorganic substance include wollastonite and cordierite. Particularly, sintered cordierite obtained by pulverizing into a plate shape is the most preferable material in the present invention.

As the inorganic material having an L / D of 3 or more needle-like or columnar used in the present invention, for example, alumina fiber,
Wollastonite and the like can be mentioned.

By using these plate-like, needle-like, or columnar inorganic substances in the range of 30 to 90% by weight of the total inorganic material, the obtained plate-like inorganic substance sintered body can exhibit great strength and high impact resistance. However, the preferred range is 35-60% by weight, and even more preferably 35-60% by weight.

As the other inorganic substance used together with the plate-like, needle-like, and columnar inorganic substances, those having fire resistance and particles having a shape close to a sphere are used. Such materials include, for example, alumina, mullite, clay, talc and the like. These materials act as plasticizers during extrusion.

After adding water to these inorganic substances and kneading with a kneading machine,
Extrude into a cylinder with an extruder. The extrusion pressure at this time is 10
~ 50 kg / cm ² is appropriate. In addition, a known kneading machine or extruder can be used. Next, the cylindrical extruded product is cut open and rolled in the extrusion direction. After rolling,
The plate is fired.

If the sintering temperature is too high, the bonding between particles progresses too much, losing the structure intended by the present invention. Conversely, if it is too low, the bonding between particles becomes insufficient and sufficient strength cannot be obtained. In sintering, an appropriate temperature is selected according to the raw materials to be used. It is preferable that sintering is not completely performed, leaving 5 to 30% of voids in the sintered body.

Although it is not clear at present why the substance having the structure having the structure of the present invention exhibits high strength and high thermal shock resistance, a skeleton formed of a plate-like, needle-like, or columnar inorganic substance Large strength is expressed by the layer structure of
It is considered that the thermal expansion is absorbed by the substance and the voids between the layer structures, and as a result, high thermal shock resistance is exhibited. For example, when a cordierite having a small thermal expansion coefficient is used for a plate-like inorganic substance and a clay substance having a large thermal expansion coefficient is blended, the value of the thermal expansion coefficient actually obtained tends to be smaller than the value of the thermal expansion coefficient calculated from the blending ratio. This also supports the idea described above.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Water was added to a composition of cordierite 40% having an average particle diameter of 0.53 mm and an average aspect ratio of 12, 20% of synthetic mullite powder having a square particle diameter crushed to 147 microns, and 40% of Hotonoku clay. after kneading, extrusion in a cylindrical pressure of 20 kg / cm ^2, cut open the cylinder and rolled in multiple stages, 400 mm × 600 mm × 50
mm plates were produced. This plate was fired at 1180 ° C. using a roller hearth kiln. The properties of the resulting refractory material were as follows.

Volume specific gravity 2.01 Apparent porosity 22.1% Thermal expansion coefficient 3.4 × 10 ^-6 / ° C Bending strength 155kgf / cm ² Hot bending strength 800 ° C 121kgf / cm ² 1000 ° C 178kgf / cm ² Example 2 Cordierite 30% of Example 1 A composition comprising 10% of mullite powder, 20% of wollastonite from the United States, 5% of talc powder and 35% of Hotonoku clay was used as a refractory material plate in the same manner as in Example 1. The properties were as follows:

Volume specific gravity 1.92 Apparent porosity 27.6% Thermal expansion coefficient 4.2 × 10 ^-6 / ℃ Flexural strength 210kgf / cm ² Hot flexural strength 800 ℃ 112kgf / cm ² 1000 ℃ 212kgf / cm ² Comparative Example 1 In Example 1, only cordierite was used. Average particle size 0.
A refractory plate was prepared in the same manner as in Example 1 except that the plate was replaced with one having a size of 56 mm and an average aspect ratio of 4.5. The properties were as follows:

Volume specific gravity 2.06 Apparent porosity 17.6% Thermal expansion coefficient 3.8 × 10 ^-6 / ℃ Bending strength 87kgf / cm ² Hot bending strength 800 ℃ 62kgf / cm ² 1000 ℃ 89kgf / cm ² Comparative example 2 Average particle diameter as cordierite 0.53mm A composition comprising 25% of an average aspect ratio of 12 and 20% of synthetic mullite powder having a square particle shape crushed to a diameter of 147 microns, and 55% of Hotonoku clay in the same manner as in Example 1 was used as a refractory material plate. And The properties were as follows:

Volume specific gravity 1.92 Apparent porosity 20.8% Thermal expansion coefficient 6.2 × 10 ^-6 / ℃ Flexural strength 96kgf / cm ² Hot flexural strength 800 ℃ 78kgf / cm ² 1000 ℃ 96kgf / cm ² Comparative example 3 Cordierite 50% in Example 1 , Toyokudoku clay 8
%, 42% of a wollastonite produced in the United States was used as a refractory plate in the same manner as in Example 1, but the rolled plate was cracked and defective.

Comparative Example 4 The composition of Example 1 was granulated and pressed under a pressure of 200 kg / cm ² to produce a 100 mm × 100 mm × 5 mm plate.
A refractory plate was prepared in the same manner as described above. The properties were as follows:

Volume specific gravity 2.22 Apparent porosity 9.8% Thermal expansion coefficient 5.3 × 10 ^-6 / ℃ Bending strength 92kgf / cm ² Hot bending strength 800 ℃ 63kgf / cm ² 1000 ℃ 70kgf / cm ² [Effect of the invention] As explained above In addition, the plate-like inorganic material sintered body of the present invention is extremely excellent in strength and thermal shock resistance, and makes it possible to manufacture thin shelf boards and hearth materials which could not be made with conventional refractory materials. The range of application as a material can be expanded.

Claims (2)

(57) [Claims] 1. An inorganic material selected from the group consisting of a plate-like inorganic material having an aspect ratio of 5 or more and a needle-like or columnar inorganic material having a length-to-diameter ratio (L / D) of 3 or more. A plate-like inorganic material obtained by firing an inorganic material containing 30 to 90% by weight of the total inorganic material, and wherein the plate-like, needle-like, and columnar inorganic materials are oriented in a certain direction parallel to a plane. Sintered body. 2. An inorganic material selected from the group consisting of a plate-like inorganic material having an aspect ratio of 5 or more and a needle-like or columnar inorganic material having a length-to-diameter ratio (L / D) of 3 or more. Water is added to an inorganic substance containing 30 to 90% by weight of the total inorganic substance, kneaded, and extruded into a cylindrical shape by an extruder. This cylinder is cut open, rolled in the extrusion direction, and then sintered at 800 to 1200 ° C. A method for producing a plate-shaped inorganic material sintered body, which is a feature.