JPS6350373A - Porous granular refractory material - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a porous particulate refractory material used as a raw material for refractory insulation materials, pore filters, electrolytic diaphragms, ion adsorbents, catalyst supports, and the like.

[Conventional technology]

Fireproof insulation materials, pore filters, electrolytic diaphragms, ion adsorption,
Raw materials such as catalyst carriers are required to be porous. From this point of view, natural porous + organic material 1 artificial balloons, bulk ceramic fibers, etc. are widely used as raw materials.

Furthermore, natural porous materials used as heat insulating materials include diatomaceous earth, perlite, and the like.

[Problem that the invention seeks to solve]

However, it is very difficult to obtain fine particles of 111 or less from these raw materials. For example, natural porous materials have relatively large pores, so when they are crushed, the pores break down and the substance increases, resulting in a decrease in insulation properties. Shirasu balloons obtained by heat treatment are hollow particles with excellent heat insulation properties, but have a low melting point and insufficient heat resistance.

Other naturally occurring porous materials also do not have sufficient heat resistance.

On the other hand, bulk ceramic m-fibers are excellent heat insulating materials, but when used alone as a structural material, there are various problems as described below.

1. Poor fiber dispersibility.

2. Poor liquidity.

3. Orient by applying pressure.

4. Weak strength.

50 Poor workability.

By the way, pore filters, electrolytic diaphragms, ion adsorbents,
Since air permeability and surface area are important considerations for catalyst carriers and the like, it is desirable to have a structure in which fibers are three-dimensionally connected. However, as mentioned above, bulk ceramic fibers have problems in actual construction due to poor fiber dispersion, poor fluidity, and orientation perpendicular to the direction of pressure. In this case, it is difficult to form a uniform three-dimensional structure.

Therefore, an object of the present invention is to provide a porous granular refractory material that eliminates the drawbacks of these conventional materials and allows easy production of porous bodies with excellent porosity.

[Means for Solving the Problems] In order to achieve the object, the porous granular refractory material of the present invention has a wire diameter of 0.1 to 5% and an aspect ratio of 50 to 500.
It is characterized by adding 1 to 100 parts by weight of a binder in terms of solids to 100 parts by weight of ceramic fibers and/or whiskers, and granulating the particles to a particle size of 10 to 3,000.

[Effect]

When producing porous bodies from fibrous raw materials, workability is very poor due to the low dispersibility and fluidity of the fibrous raw materials.Therefore, we conducted various studies on ways to improve workability. discovered that ceramic fibers and/or whiskers can be granulated by appropriately selecting the fiber diameter and aspect ratio. In this case, ceramic fibers and/or whiskers were three-dimensionally intertwined using only a binder to develop a porous granular refractory material that is resistant to thermal and mechanical spalling.

The ceramic fibers and/or whiskers used in the present invention include one or a combination of crystalline fibers such as zirconia, alumina, and mullite, various glass fibers, and whiskers such as potassium titanate, silicon carbide, and silicon nitride. can be used. Depending on the combination, the fire resistance of the porous granular refractory material as a product can be freely selected.

The wire diameter of this ceramic fiber and/or whisker is 0.1
There will be ~5 units, and the aspect ratio will be 50~5oo.

If the aspect ratio is less than 50, the characteristics as a fiber will be reduced, and if it exceeds 500, granulation becomes difficult. Moreover, if the wire diameter is larger than 5 wires, the surface area becomes small and granulation becomes difficult.

The binder to be mixed with the ceramic fibers and/or whiskers may be either inorganic or organic, or a combination of both.

Examples of inorganic binders include silicate binders such as sodium silicate, potassium silicate, and lithium silicate, monobasic aluminum phosphate, monobasic calcium phosphate, monobasic magnesium phosphate,
Condensed sodium phosphate 1 Phosphoric acid binder such as phosphoric acid,
Sol binders such as colloidal silica, colloidal alumina, and colloidal zirconia, and ethyl silicate are suitable.

On the other hand, polyvinyl alcohol, C
MC, zansal extract, wax lacquer, etc. are suitable.

This bonding agent is made of ceramic fibers and/or whiskers.
It is added in a proportion of 1 to 100 parts by weight in terms of solids relative to 0 parts by weight.

When placing emphasis on the hot strength of porous granular refractory materials, it is better to use an inorganic binder; if the amount of binder is less than 1 part by weight, granulation is difficult and the strength of the granules cannot be obtained. do not have. If the amount exceeds 10 parts by weight, the porosity will be inhibited and the fire resistance will decrease due to the binder.

If the fiber properties are to be fully exhibited, it is preferable to use an organic binder; however, if the amount of the organic binder is less than 5 mm parts, granulation is difficult and the strength of the granules cannot be obtained. Moreover, if it exceeds 100 parts by weight, the amount of binder that enters the fiber bonding portion increases, and the three-dimensional connection of the fibers deteriorates.

A general binder such as polyvinyl alcohol or CMC is preferably used in an amount of 5 to 10 parts by weight on a solid basis, and in special cases where the wax is used by thermal melting, an appropriate amount is 70 to 100 parts by weight.

Then, the obtained foreign metal product is granulated to a particle size of 10 to 3,000 particles. In addition, when using an inorganic binder and an organic binder together, the blending ratio of the inorganic binder and -f organic binder may be in the range of 1 to 100 parts by weight depending on the purpose of use of the porous granular fireproof material. It is best to choose accordingly.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained with reference to Examples.

Example 1 100 parts by weight of potassium titanate (KzTiJ+z) short fibers having a diameter of 0.1 to 0.5 mm and a length of 10 to 30 JJl, and 239i8 of lithium silicate as an inorganic binder.
While adding 70 parts by weight of water to 25 parts by weight of liquid (5.75 parts by weight in terms of solids), 10~
The particles were granulated to a size of 100) m to obtain porous, nearly spherical particles (porous spherical particles).

When the porous spherical particles obtained in this way are observed with an SEM, as shown in Figure 1, the whiskers are connected only at their intersections, and the voids are completely continuous.
They were porous spherical particles that were dimensionally entangled. These porous spherical particles have a packed bulk density of 0.29 and an apparent density of 0.29.
61 and the porosity was 88%.

Example 2゜Example! , 96 parts by weight (38.4 parts by weight in terms of solids) of paraffin wax emulsion (average particle size 2, concentration 40%) was added as a organic binder to 100 parts of the same potassium titanate whisker. At the same time, it was granulated to a particle size of 10 to 200% using a Spartan granulator, and heated at 50°C.
It was dried.

When the porous spherical particles obtained in this way are observed with an SEM, the whiskers are connected by paraffin particles at their intersections, and the voids are completely continuous3.
They were porous spherical particles that were dimensionally entangled. The obtained porous spherical particles had a particle size of 44 to 250 m, a packed bulk density of 0.33, an apparent density of 0.91, and a porosity of 64%.

Example 3: For 100 parts by weight of crystalline mullite fibers (A!zOi 80%) with a wire diameter of 3 to 5P and an aspect ratio of 100 to 400, silica ratio of 2.5.7 and a degree of delivery of 36% was used as an inorganic binder. 14 parts by weight of sodium silicate (solid equivalent: 5.03!1ff
Part i) was granulated using a Spartan granulator while adding 82 parts by weight of water to a particle size of 500 to 2000 particles, and dried at 300°C to obtain porous spherical particles.

Observation of the porous spherical particles obtained in this way using an SEM shows that the crystalline mullite fibers are bonded only at the intersections, as shown in Figure 2, and the voids are completely continuous three-dimensional. They were porous spherical particles entangled with each other. The porous spherical particles had a packed bulk density of 0.40, an apparent density of 0.89, and a porosity of 58%.

Note that Example 1. 10 parts by weight of a 23% lithium silicate solution was added as an inorganic binder to 100 parts by weight of the porous spherical particles obtained in 230 x 230 at 20 kg/c+J.
When the heat transfer rate was measured after being molded into the shape of X30 and heat treated at 800°C, it was found to be 0.
It is 32Kcal/m, h, 'c, and the result of measuring the air permeability after heat treatment is 30ad - as / cJ ・cm,
It was H2o.

Therefore, since the molded body made from this porous granular refractory material 4 has small drying shrinkage and firing shrinkage, it can be expected to improve the dimensional accuracy and yield of the product.

Moreover, FIG. 3 is an enlarged SEM photograph of the same potassium titanate fiber as the granulation fiber of the first example. As you can see from this photo, when you stir the non-granulated material,
Although the voids look good locally, there is no strength to maintain the voids, and the fibers tend to become entangled in the longitudinal direction and form bundles, and if used as is, the dispersibility is poor.
It is difficult to obtain a dimensionally connected structure.

〔Effect of the invention〕

As explained above, in the present invention, bulk fibers with very poor dispersibility and fluidity are granulated into a nearly spherical shape, so the fibers can be used in the same state as particles. can. Further, since the porous granular fireproof material of the present invention is made by granulating fine fibers, dust generation is greatly reduced. The granulated product has a structure in which the fibers are three-dimensionally entangled, so it is porous and has strength as a particle. Used as granular refractory material. Furthermore, when granulated with a small amount of binder, the thermal properties are improved and the material is used as a porous granular refractory material with excellent mechanical spalling properties.

[Brief explanation of drawings]

Figure 1 shows an SEM (scanning electron microscope) of the granulated material (particle size: 80 particles) made of potassium titanate fibers in the first example.
Fig. 2 shows the particle structure of the granulated material (particle size: 12
00JJII+) observed by SEM (scanning electron microscope), and FIG. 3 shows the fiber structure of ungranulated potassium titanate fiber observed by SEM (scanning electron microscope). Patent Applicant FA Saki Ceramics Co., Ltd. Agent Masu Kodo (and 2 others) No. 1-21, 22, Wara 3

Claims (1)

[Claims] 1. Wire diameter 0.1-5μm and aspect ratio 50-500
Porous granules characterized by adding 1 to 100 parts by weight of a binder in terms of solids to 100 parts by weight of ceramic fibers and/or whiskers, and granulating the particles to a particle size of 10 to 3000 μm. Fireproof material.