JPH0647502B2 - High-alumina casting material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a high-alumina casting material excellent in spalling resistance.

[Prior Art] In recent years, the diversification of steelmaking processes, namely (1) increase of continuous casting ratio and increase of degassing ratio, (2) introduction of ladle refining and (3)
The refractory lining on the ladle has become a severe operating condition due to the rise of the tapping temperature due to the transportation of molten steel, the extension of the residence time of molten steel, and the agitation of melting.

Conventionally, the lining refractory for ladle has been mainly made of low stone and zircon, but high alumina refractory is used for the diversification of the steel making process.

[Problems to be Solved by the Invention] High-alumina refractory has greater slag infiltration than low-rock refractory and zircon refractory, and the altered layer formed by slag infiltration easily causes structural spalling. It has drawbacks.

Further, in order to suppress the slag infiltration, it has been attempted to use carbon, silicon carbide or the like, but their role is not sufficiently fulfilled by oxidation.

For this reason, development of high alumina refractory materials with less slag infiltration is desired.

[Means for Solving the Problems] The inventors of the present invention have conducted diligent research to suppress the slag infiltration of the high-alumina casting material, and as a result, have a particle diameter of 0.3 mm.
It has been found that the intended purpose of the present invention can be achieved by using 5 to 20% by weight of the following loamy fine powder.

That is, the present invention is a high-alumina casting material,
High-alumina raw material 64-92% by weight, low-grain stone powder with a particle size of 0.3 mm or less 5-20% by weight, ultrafine powder 2-8% by weight
And a high-alumina casting material containing 1 to 8% by weight of a binder.

[Operation] The particle size of the apatite fine powder used in the high-alumina casting material of the present invention is 0.3 mm or less. If the particle size of the apatite fine powder exceeds 0.3 mm, microcracks are generated due to the expansion of the apatite, and the slag infiltration suppressing effect is reduced, which is not preferable. The addition amount of the raw stone fine powder is in the range of 5 to 20% by weight. If the addition amount is less than 5% by weight, the effect of suppressing slag infiltration is small, which is not preferable, and if the addition amount is more than 20% by weight, the slag resistance is deteriorated, which is not preferable.

The other components of the high-alumina casting material of the present invention are not particularly limited as long as they are used in a conventional high-alumina casting material, and it goes without saying that a refractory aggregate is blended as a main raw material. In addition, ultrafine powder, a binder, a deflocculant, a drying accelerator, a curing modifier and the like which are usually used are added and blended.

As the refractory aggregate, for example, fused alumina, sintered alumina, calcined alumina, bauxite, shale shale, andalusite, high alumina raw materials such as sillimanite can be used alone or in combination. .

The amount of the refractory aggregate added is in the range of 64-92% by weight. If the addition amount is less than 64% by weight,
It is not preferable because the function as an aggregate is lost, and when it exceeds 92% by weight, a sufficient structure cannot be obtained because the amount of the fine rock stone powder, the binder, etc. is small, which is not preferable.

The ultrafine powder has a particle size of 1 μm or less, and for example, refractory clay, silica ultrafine powder, calcined alumina, etc. can be used.

The addition amount of this ultrafine powder is in the range of 2 to 8% by weight. If the addition amount is less than 2% by weight, a sufficient structure cannot be obtained, and if it exceeds 8% by weight, shrinkage at high temperature becomes large, which is not preferable.

As the binder, for example, alumina cement, high alumina cement, colloidal silica or the like can be used. The amount of the binder added is in the range of 1 to 8% by weight. If the addition amount is less than 1% by weight, sufficient strength cannot be obtained, and if it exceeds 8% by weight, shrinkage at high temperature becomes large, which is not preferable.

As the deflocculant, for example, phosphates such as sodium pyrophosphate, sodium hexametaphosphate and sodium metaphosphate, lignin sulfonate (pulp waste liquor), polycarboxylate and the like can be used.

The amount of the deflocculant added and compounded is in the range of 0.01 to 0.5% by weight in the external application. If the addition amount is less than 0.01% by weight, a sufficient dispersing effect cannot be obtained, and if it exceeds 0.5% by weight, the optimum dispersion state cannot be obtained, which is not preferable. .

Further, as the drying accelerator, for example, metallic aluminum or the like can be used.

The compounding amount of this drying accelerator is 0 to 0.5% by weight on the outside.
Within the range of. If the addition amount is more than 0.5% by weight, a sufficient structure cannot be obtained due to the generated gas, which is not preferable.

Further, as the curing modifier, for example, borax, boric acid, citric acid or the like can be used. The amount of the curing modifier added and compounded is in the range of 0.01 to 0.5% by weight.
If the addition amount is outside these ranges, sufficient curing adjustment cannot be expected, which is not preferable.

The high alumina cast material of the present invention can be produced by simply mixing the above raw materials.

[Examples] The casting material of the present invention will be further described below with reference to Examples.

Table 1 below shows examples of the present invention in comparison with comparative examples. Each compound shown in Table 1 was added with predetermined water, kneaded, cast into a metal frame, and cured at 20 ° C. for 24 hours,
After being dried at 105 ° C. for 24 hours, each test shown below was used.

(1) Line change rate after heating (105 ℃ -24 hours, 1000 ℃ -3 hours,
1500 ℃ -3 hours): According to JIS R2555 (2) Compressive strength after heating (105 ℃ -24 hours, 1000 ℃ -3 hours,
1500 ℃ -3 hours): According to JIS R2553 (3) Apparent porosity after heating (105 ℃ -24 hours, 1000 ℃ -3 hours, 1500 ℃ -3 hours): According to JIS R2205 (4) Corrosion test equipment: Rotating drum erosion tester Sample shape: 50 x 200 x 65 mm Temperature / time: 1650 ° C-30 minutes Slag injection 15 minutes ↑ ↓ 20 minutes 800 ° C ↓ 1650 ° C-30 minutes 15 minutes ↑ ↓ 20 minutes 800 ° C 5 cycle slag: Converter slag (CaO / SiO ₂ = 3.65) 1.2 kg / cycle [Effects of the Invention] The casting material of the present invention has excellent spalling resistance as compared with the conventional high-alumina casting material because the slag infiltration is suppressed by the use of the low-calcium fine powder.

Therefore, in response to the recent diversification of the steelmaking process, the high-alumina casting material of the present invention is a material which has few cracks and peelings and can be stably used.

Claims (1)

[Claims] 1. A high-alumina casting material, which comprises 64-92% by weight of a high-alumina raw material, 5-20% by weight of low-grained fine powder having a particle size of 0.3 mm or less, 2-8% by weight of ultrafine powder, and a binder 1 A high-alumina casting material characterized in that the high-alumina casting material is contained.