JP4850868B2 - Ceramic sintered body in which flat continuous pores are laminated and oriented, and method for producing the same - Google Patents

Description

The present invention relates to a method for producing a porous ceramic body having continuous pores in which a silicate raw material foamed by firing is formed into a flat plate shape, and individual particles are foamed and welded by firing. In particular, the present invention relates to a ceramic sintered body having a completely novel pore shape and structure in which flat continuous pores are laminated and oriented.

In the present invention, precipitation of CaO, Al2O3, 2SiO2 and CaOSiO2 crystals from about 800 ° C. is effected by heating the amorphous glass in the component range already registered in Patent No. 2,899,954 as a “porous crystallized glass composition”. When the low-melting-point liquid phase clay generated by phase separation becomes 105 poise or less, the SO2 gas in which FeS2 and MaS in the component are thermally decomposed is explosively released and foamed, and these are welded. It was discovered that it becomes a continuous through-pore. Furthermore, these amorphous glasses were found to have an approximate composition of slag produced as water tanks during the production of ductile cast iron. Japanese Patent Application No. 2000-233972 “Ceramic Porous Material and Method for Producing the Same” describes the particle size, composition The inventors filed the application by limiting the ratio, molding method and firing conditions.

These technologies are used for industrial production and are supplied to the market as sound-absorbing materials, heat-insulating materials, and greening materials. However, as the market expands, especially in the low frequency range from 400 Hz to 630 Hz. Improvement in sound absorption performance and higher energy saving efficiency as a heat insulating material are required, and as a result of these improvements, earnest research and development have been carried out to complete the present invention.
JP 10-7433 JP 2002-47075 A

First, the pore structure of mass-produced products according to the prior art is analyzed in detail. The shape of millimeter-size pores is deformed into various shapes of the cube, and the welded pores are irregularly distributed. Had many micron-sized independent pores, had a bulk density of 0.55 to 0.6, and a porosity of 65% to 70%.

Further, the slag particles used were those having a particle size of 1 mm or more in a cubic shape, but the particles became smaller as the particles became smaller. When the cross section of the dough obtained by adding clay to these slags and extruding was observed, the thickness of the clay connecting the slag particles was extremely uneven.

The object of the present invention is a technical condition for producing a highly accurate product having higher porosity and no variation in quality, and therefore the first problem is the shape of slag particles. The feature of this technology is that the slag particles are explosively foamed at a high temperature, and the maximum porosity is achieved by concentrating these expansions in the thickness direction of the compact by expanding the volume. It is a factor. Further, it is a shape of slag particles with good orientation that can be molded with less clay in the blending ratio of slag and clay, that is, with low plastic flow resistance in extrusion molding.

The second problem is the improvement of the sound absorption coefficient in the low frequency sound range. Most of the sound absorbing materials widely used in the low frequency range are made of a material obtained by loosely molding glass wool or the like. The structure of these materials is that the pores are oriented so that the incident sound wave is dispersed in the horizontal direction. The same effect can be expected in heat conduction.

The first problem is the shape of the slag particles. The ideal porous structure has a thin outer skin (cell) that wraps pores, and there are few gaps between pores, and the structure is regularly oriented. The main point of the improved technique of the present invention is that the slag particles are scaled. It is to be. When the flaky particles are extruded into a cylindrical shape by using a vacuum clay kneader, the scale-like particles are easily oriented in the direction of extrusion and flow resistance is reduced, so that a smaller amount of clay can be formed. Next, by using a roller mill in the same direction as the extrusion direction, it can be molded to a desired thickness without disturbing the orientation. Further, the rolled compact is continuously fired by a roller hearth kiln in a series of flows to obtain a ceramic sintered body in which flat continuous pores are laminated and oriented.

Furthermore, the molded product had a very preferable structure in which scaly grains were laminated, but the glassy and “friable” slag was tested using various crushing and crushing equipments, but the aspect ratio was in the range of 2-3. there were.

When these slag particles having a particle size of 0.5 mm to 1.0 mm are fired to 75% by weight ratio of 25% bentonite under extrusion molding (Claim 3), the thickness is about 3 times that of the dough. An unprecedented novel composition of continuous pores having a double expansion rate and having millimeter-sized pores flat and regularly oriented and laminated was obtained. These fired products had a porosity of about 10% greater than that of conventional products having a bulk specific gravity of 0.48 to 0.5.

The second problem is that the average sound absorption coefficient of 400 Hz to 630 Hz required as a sound absorbing material for roads is improved to 0.86 from 0.83 of the conventional product by making these flat pore bodies. It was.

In order to improve the physical properties that satisfy the quality demanded by many users already supplied to the market as an industrial product by the same inventor as an improved technology, the present invention has been laminated with flat pores that are unprecedented as this kind of material. The developed organizational structure was developed as a new product design. In particular, the flat pores were able to greatly improve the quality in terms of sound absorption characteristics and heat insulation characteristics.

Examples of the present invention will be described below.

1) Grinding and sizing of slag The slag was pulverized to 1.5 mm or less by an edge runner mill by a compression rolling method, and the fine powder content of 0.25 mm or less was sized to 20% or less.
The slag after the sizing had an aspect ratio in the range of 2-3.
2) Mixing ratio (weight ratio)
75% slag, 25% bentonite, 15% moisture (outer)
3) Extrusion into a cylindrical shape with an outer diameter of 300 mm and a wall thickness of 30 mm using a vacuum kneader with a forming vacuum degree of -720 mmHg and an extrusion pressure of 25 to 30 kg / cm 2. It was formed into a fabric having a size of 15 mm, a width of 500 mm, and a length of 1,000 mm.
4) Drying and firing Heat treatment for 10 minutes on a far-infrared irradiation conveyor, and further drying with a hot air dryer at 300 ° C., using a roller hearth kiln, up to 850 ° C., a heating rate of 10 ° C./min, 850 ° C.-1 , 050 ° C. was rapidly heated at 20 ° C./min, kept at 1050 ° C. for 10 minutes, and then cooled.
5) Tables 1 to 3 show the comparison of the baked product with the conventional product in terms of expansion, product properties and sound absorption characteristics.

As is clear from the results shown in Table 1, Table 2, and Table 3, the structure in which flat pores are stacked has a porosity close to 80%, and in particular, the incidence of sound waves and heat diffuses in the horizontal direction. The effect is high performance.

Claims (1)

The cast iron slag produced as a water tank during the manufacture of ductile cast iron is sized into scaly particles having an aspect ratio of 2 or more in a particle size range of 0.25 mm to 1.5 mm by a compression rolling method using an edge runner mill.
The cast iron slag is blended in the range of 60% to 75% by weight and the plastic clay is blended in the range of 25% to 40% by weight. Extruded into a cylindrical shape, developed into a flat plate shape, rolled and formed so that scaly particles are laminated and oriented in the same direction as the extrusion direction with a roller rolling mill,
After drying this with far infrared rays, it is heated at 10 ° C / min or less up to 850 ° C using a roller hearth kiln, and the temperature range of 850 ° C to 1050 ° C is rapidly heated to 20 ° C / min or more to double the volume. A method for producing a ceramic sintered body, characterized by laminating and orientation of flat continuous pores by foaming and firing so as to expand as described above.