JPH0338231B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a room-temperature self-hardening refractory composition containing, as a binder, a water-soluble yttrium salt whose solution is acidic.

[Conventional technology/problems] Ittria has a high melting point of 2410℃, has a small coefficient of thermal expansion, and has no crystal transition, and is attracting attention as a refractory material that is stable in high-temperature oxidizing atmospheres, and is used as lining materials, electronic materials, and nuclear reactors. Attempts are being made to apply it to industrial materials, etc. However, itria raw materials are generally commercially available as micro-order particles, and in order to make them into a form that can be put to practical use, it is necessary to mold them using isostatic pressing or hot pressing, which increases the product cost and furthermore However, even when prepared by the above-mentioned method, satisfactory thermal and mechanical properties were not always obtained.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an ittrian self-hardening composition that can be easily formed into molded products and has high heat resistance.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors conducted various studies on a binder and a curing system that form ittria by heating, and as a result, found that
It has been discovered that self-hardening can be obtained at room temperature by using a water-soluble yttrium salt whose aqueous solution is acidic as a binder, and using yttria or a water-insoluble yttrium compound alone or a fire-resistant mixed material mainly composed of these, and the present invention I was able to complete it.

Accordingly, the present invention resides in an aqueous solution of a water-soluble yttrium salt having an acidic concentration of 1 to 50% in terms of yttrium, and a yttria-based self-hardening fireproof composition containing yttria or a water-insoluble yttrium compound as an active ingredient.

[Function] Examples of water-soluble yttrium salts whose aqueous solutions are acidic include yttrium acetate, yttrium chloride, yttrium nitrate, and yttrium sulfate. It is desirable to use yttrium acetate in view of the fact that harmful gases are generated due to the decomposition of the binder component during the process, but yttrium chloride, yttrium nitrate, etc. have the advantage of being easy to obtain.

It is desirable that the aqueous solution of the above-mentioned yttrium salt has a concentration in terms of yttria of 1 to 50%. If the concentration of the aqueous solution in terms of yttria is less than 1%, the strength after curing will be insufficient, making it difficult to handle when molded. becomes difficult. Furthermore, if the concentration of the aqueous solution in terms of ittria exceeds 50%, the curing will be too rapid and will result in curing during kneading.

Ittria or a water-insoluble yttrium compound as an active ingredient of the composition of the present invention has a particle size of 1
It is desirable that it is less than mm. When the particle size exceeds 1 mm, the self-hardening property is significantly reduced. However, the particle size of the yttrium or water-insoluble yttrium compound as a filler constituting the fireproof composition is not limited.

Examples of water-insoluble yttrium compounds include yttrium carbonate and yttrium hydroxide. Usually, these compounds are sold in the form of fine powders of 0.1 mm or less, and there is no need to particularly consider particle size.

In the composition consisting of the above-mentioned components, large-sized raw material powder,
Self-hardening castables, self-hardening mortars, self-hardening lightweight refractories, etc. can be manufactured by appropriately adding and mixing organic substances, fiber raw materials, etc.

As the fiber raw materials, alumina-silica ceramic fibers, silica fibers, zirconia fibers, organic fibers, carbon fibers, etc. can be used, and the amount of refractory raw material powder and/or fiber raw materials added is based on 1 weight of yttrium salt. The amount added can be adjusted as appropriate in the range of 2 to 10 depending on the desired softness of the cup clay.

Note that organic fibers that are vaporized by heating and firing can be used as fibers added for the purpose of weight reduction, but the amount added must be 20 parts by weight or less per 100 parts by weight of other compounds. If the amount added exceeds 20 parts by weight, the strength after firing will decrease.

In addition, in order to obtain lightweight refractories, hollow spheres, porous spheres, and even organic spheres such as styrene and expanded polystyrene can be added to refractory raw materials, but the amount of addition is the same as that of organic fibers. It must be 20 parts by weight or less,
If the amount added exceeds 20 parts by weight, the strength after firing will decrease.

Furthermore, if viscosity adjustment is required when applying the composition of the present invention, a conventional water-soluble organic sizing agent such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, polyethylene oxide, etc. can be added.

[Examples] The present invention will be further explained below using Examples and Comparative Examples, but it should be understood that the present invention is not limited to the following Examples unless it departs from the gist thereof.

Example 1 A mold (4
cm x 4 cm x 16 cm), and the curing status was investigated at room temperature (25°C, relative humidity 60%). the result,
Condensation started in about 40 minutes, and a compressive strength of 45 kg/cm ² was obtained after 2 hours.

After drying this cured product, it was fired at temperatures of 1000℃ and ¹⁸⁰⁰ ℃.
It was found that a compressive strength of 200 Kg/cm ² was obtained, and a good refractory was obtained without a temperature range in which the strength deteriorated significantly.

Example 2 Yttrium chloride aqueous solution with 2% yttrium concentration
To 100 parts by weight (2 parts by weight of Ittria to be formed), 20 parts by weight of Ittria, 300 parts by weight of unstabilized zirconia (ZrO ₂ purity 99%, particle size 40μ or less) as a filler, and 30 parts by weight of Ittria stabilized zirconia fibers were added and kneaded. The cup clay was made into a wooden mold (23cm x 11cm x
6cm) at room temperature (25℃, relative humidity 60%)
The development of hardening was investigated. As a result, it started to set in about 2 hours, and showed a compressive strength of 50 kg/cm ² after 8 hours.

After drying this cured product, it was fired at temperatures of 1000℃ and ¹⁸⁰⁰ ℃.
It was found that a compressive strength of 70 Kg/cm ² was obtained, and a good refractory was obtained without a temperature range in which the strength decreased significantly.

Example 3 Cup soil was prepared using the same formulation and method as in Example 2, except that the amount of ittria added was 70 parts by weight,
It was poured into a mold and the hardening status was investigated.

As a result, coagulation started in about 1 hour, and a compressive strength of 50 kg/cm ² was obtained after 3 hours.

After drying this cured product, it was fired at temperatures of 1000℃ and ¹⁸⁰⁰ ℃.
It was found that a compressive strength of 110 Kg/cm ² was obtained, and a good refractory was obtained without a temperature range in which the strength deteriorated significantly.

Example 4 Ittria nitrate aqueous solution with 30% ittria concentration
100 parts by weight (30 parts by weight of ittria formed) of yttrium hydroxide (yttria content 50%, particle size
100μ or less) 80 parts by weight, unstabilized zirconia as filler (ZrO ₂ purity 99%, particle size 40μ or less) 250
Add and knead the cup clay by weight part into a mold (23cm x 11cm x
6 cm), and the hardening development at room temperature was investigated.
As a result, it started to set in about 3 hours, and showed a compressive strength of 100 kg/cm ² after 6 hours.

After drying this cured product, it was fired at temperatures of 1000℃ and ¹⁸⁰⁰ ℃.
It was found that a compressive strength of 100 Kg/cm ² was obtained, and a good refractory was obtained without a temperature range in which the strength deteriorated significantly.

Comparative Example 1 A mold (4
cm x 4 cm x 16 cm), and the curing status was investigated at room temperature (25°C, relative humidity 60%).

As a result, the onset of setting is unclear and 24
Even after more than an hour had passed, the curing remained incomplete.

Comparative Example 2 Yttrium chloride aqueous solution with 55% yttrium concentration
70 parts by weight of ittria and 300 parts by weight of unstabilized zirconia were added and kneaded to 100 parts by weight (55 parts by weight of ittria to be formed), but coagulation started before the kneading was completed, making it difficult to pour into the mold.

[Effects of the Invention] The self-hardening yttrium fireproof composition of the present invention provides the following effects: yttria or a non-aqueous yttria compound acts as an active ingredient and as a hardening agent, thereby basically A pure ittrian self-hardening refractory composition without contamination by other elements can be obtained.

It has self-hardening properties at room temperature and can be used as a material for obtaining high-strength ittria molded bodies without using expensive molding equipment. In addition, it has self-hardening properties that are suitable for the production of lightweight refractory materials obtained by adding air bubbles caused by surfactants, organic spheres, organic fibers, or air bubbles and hollow spheres of refractory raw materials, which are burned out by firing and form pores. It is a fire-resistant composition.

Claims (1)

[Scope of Claims] 1. A self-hardening yttrium refractory composition comprising an aqueous solution of a water-soluble yttrium salt having an acidic yttrium concentration of 1 to 50% in terms of yttrium, and yttria or a water-insoluble yttrium compound as active ingredients. 2. The ittria self-hardening fire-resistant composition according to claim 1, which contains one or more components selected from the group consisting of refractory raw materials, organic substances, and fiber raw materials.