JPS5950081A - Castable refractories - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a castable refractory having excellent strength, thermal shock resistance and workability.

Castasol refractories usually have a large amount of alumina cement added as a binder, so the CaO component in the cement forms a liquid phase at high temperatures during use, reducing the strength and thermal shock resistance of castasol refractories. There is.

For this reason, it is known to reduce the amount of alumina cement and add refractory fine powder and dispersant, but in the past, the curing after mixing with water was accelerated, and the pot life until casting was insufficient. Particularly when constructing large molten metal containers such as ladles and tank pushers, there are inconveniences such as the inability to cross-wire all at once. In addition, conventional products had insufficient strength and thermal shock resistance after construction.

As a result of research, the present inventors have solved the above-mentioned conventional drawbacks of castable refractories at once by limiting the particle size and addition amount of aggregate, cement, and refractory fine powder to specific ranges. It is something.

That is, the present invention provides the following (4), 03), (c'
l, (D) and chi.

(B) Alumina, chromium oxide with a particle size of 5 to 0.1μ,
One or two selected from zircon and zirconia
15-Q, 5wt% fine powder of seeds or higher.

(7-Q, 5 wt% of alumina cement or magnesia with carbon grain size of 100-2μ.

(B) The remainder of (G), (B) and (C) above is used as a refractory raw material with a particle size of 1 mm-1μ.

(0.5 wt% or less of pure dispersant.

As the aggregate, one or more types selected from well-known refractory raw materials such as acidic, neutral, and basic metal oxides, carbon, carbides, and nitrides are used.

If the maximum particle size exceeds 15 mm, fluidity during construction will decrease. If the proportion of 1 or more particles exceeds 70 vt%, the proportion of fine powder becomes relatively insufficient, the filling property of the matrix portion deteriorates, and high strength cannot be obtained. In addition, because the amount of fine powder is reduced, fluidity during construction is poor. If it is less than 40 wt%, on the other hand, there is a large amount of fine powder, so that the matrix portion becomes a continuous integrated structure, resulting in poor thermal shock resistance.

Fine powder consisting of one or more selected from alumina, chromium oxide, zircon and zirconia is polydispersed in a dispersant and then van der Waals force phenomenon occurs due to the action of Ca++ or Mg++ ions eluted from the binder. It expresses a strong bond. but,
If the particle size exceeds 5 μm, the fluidity during application will be reduced and the filling properties of the matrix portion will be poor. Moreover, if it is less than o, iμ, the water utilization reaction is fast, and furthermore, the cohesive force is large, so the pot life is short and the workability is poor. Particularly in the summer when the temperature is high, conventional products have almost no pot life, and the reality is that they cannot be used without some kind of cooling means. If the blending ratio exceeds 15 wt%, cracking will occur significantly due to drying and heating shrinkage, and furthermore, thermal shock resistance will be poor. If the amount is less than 0.5 wt%, the addition of fine powder has no effect and the strength becomes insufficient.

If the alumina cement or magnesia used as a binder has a particle size of less than 2μ, the elution rate of Ca++ ions from the alumina cement or Mg+1 ions from the magnesia will increase, and furthermore, the pot life will be significantly shortened due to the water use reaction with the added water. . If it exceeds 100μ, the surface area decreases and the binder becomes ineffective9, which is not preferable. The blending ratio is 7 wt%
If it exceeds 5 wt %, the corrosion resistance and thermal shock resistance will be poor, and if it is less than 5 wt %, the addition will have no effect.

The remaining refractory raw material with a thickness of 1 to 1μ is the above-mentioned 1ys
As with the refractory raw materials of m or more, one or more selected from acidic, neutral, basic metal oxides, carbon, carbides, nitrides, etc. are used.

The remainder serves as intermediate particles in terms of particle size and is used to densely pack the refractory structure.

Examples of the dispersant include sodium lignin sulfonate, sodium alkylbenzene sulfonate, sodium polyacrylate, sodium tetrapolysinate, sodium tripolyphosphate, sodium hexametasinate, and sodium ultrapolysinate. Use one or more species. Less than 0.5 wt% on the outside, preferably 0.03 to 0.3 w
Add t%. Q. If it exceeds 5 wt%, it takes too much time to cure.

The method for constructing castable refractories of the present invention is not particularly different from conventional methods; each raw material is mixed in a predetermined ratio (5), water is added in an amount of 3 to 7 wt%, and then kneaded. , It is constructed by casting or press-fitting into the formwork, furnace wall, etc. to be constructed.

As mentioned before, the castable refractory of the present invention has a long pot life, so there is no need to worry about hardening even if a large amount is kneaded at one time, so construction efficiency is high, and it maintains fluidity for a long time. It has excellent filling properties, strength, and thermal shock resistance. Therefore, it is suitable as a furnace material for industrial furnaces that are large and have severe operating conditions, such as ladles, tank pushers, converters, vacuum degassing furnaces, and the like.

Next, examples of the present invention and comparative examples thereof are listed, and their physical properties are tested, and the results are shown in Tables 1 to 3.

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Claims (1)

[Scope of Claims] A castable refractory comprising the following (4), (B), (c), (D) and (g). (4) Grains +□, 8□5~1°3. ) 4 flammable. Fee off. ~
4o myochi. (B) Alumina, chromium oxide with a particle size of 5 to 0.1μ,
15 to 0.5 wt of one or more types of fine powder selected from zircon and zirconia. (C) 7 to 0.5 wt% of alumina cement or magnesia with a particle size of 100 to 2 μm. (2) A refractory raw material containing the remainder of (A), (B) and (C) above and having a particle size of 1 to 1 μm. (g) The amount of dispersant is 0.5 wt% or less.