KR20140103758A - Basic hot reparing material - Google Patents

Abstract

The present invention relates to an alkali hot-press injection repair material used for a steel refining equipment, for example Ruhrstahl Heraeus pipe. The present invention provides the alkali hot-press injection repair material which comprises 50-80 wt% of sea water and a fused magnesia raw material; 10-40 wt% of an alumina raw material; 3-7 wt% of alumina cement; and 5 wt% or less of microsilica.

Description

[0001] BASIC HOT REPARING MATERIAL [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a basic hot press-fitting repair material used in a vacuum degassing (RH: Ruhrstahl Hereaus) pipe which is a steelmaking refining facility.

Generally, an acid-neutral material containing sintered alumina as a main material and adding a small amount of magnesia is used as a hot-press-fit repair material for a vacuum degassing (RH) rising tube reflux / immersion tube, which is a typical refining facility of steelmaking. This acid neutral material has the effect of preventing shedding due to sintering shrinkage and having an excellent resistance against the temperature change since it induces high expansion and texture densification by forming spinel in a part after hot pressing.

However, there is a problem that the lifetime is lowered due to the erosion phenomenon as the operation is progressively harsh, and the support for the production of clean steel due to the inclusion of alumina inclusions is limited.

In order to solve this problem, the magnesia refractory was used as the main raw material instead of the existing sintered alumina as the hot-press repellent as a repair material. However, such magnesia refractory has a problem that the corrosion resistance is excellent but the anti-sloshing property is poor and the strength is low compared with the sintering shrinkage property.

Therefore, there is a need to develop a hot-press-fitting repair material of magnesia which is excellent in anti-scratch resistance and anti-corrosive properties.

An aspect of the present invention is to provide an indentation repairing material which is excellent in resistance to corrosion, high-temperature sintering strength, and the like, and is suitable for use even in severe operation, in an indentation repairing material used in a steel refining facility.

An aspect of the present invention provides a basic hot stamping and repellent material comprising, by weight, 50 to 80% of magnesia raw material, 10 to 40% of alumina raw material, 3 to 7% of alumina cement and 5% do.

According to the present invention, by mixing the magnesia raw material and the alumina raw material in an appropriate amount, it is possible to provide a hot-press-impregnated repair material excellent in anti-corrosive properties as well as anti-corrosive properties.

Further, it is possible to expect the effect of supporting the manufacture of clean steel through the improvement of the life of the refining facility in which the hot-press-fitting repair material according to the present invention is installed and suppressing the generation of alumina inclusions.

Fig. 1 shows the results of the workability evaluation.
Fig. 2 shows the evaluation results of the plasticity strength.
3 shows the results of the corrosion resistance evaluation.
Fig. 4 shows the results of the evaluation of the anti-scrubbing property and the scratch resistance.

Conventional alumina hot-press repellent materials have an advantage of excellent workability and anti-spalling properties. However, there is a problem that the lifetime is lowered due to an increase in erosion property as the steelmaking operation becomes severer in recent years.

The spalling of the hot indentation repair material is mainly caused by repeated shrinkage and expansion of the repair material as the temperature difference between RH operation and standby is changed to about 600 ° C or more. The erosion is mainly caused by the loss of molten steel and gas flow, which causes the incorporation of alumina inclusions.

Therefore, in order to suppress the spoiling and erosion phenomenon of the repair material in the operation after the hot-press repellent material is applied in the recent harsh environment, the shrinkage and expansion phenomenon of the hot- Should be applied.

The inventors of the present invention have conducted intensive researches to provide a hot-press-fit repair material having an excellent resistance to corrosion as well as an anti-corrosive property in comparison with a conventional hot-press-fit repair material. As a result, it has been found that a magnesia refractory It is possible to provide a hot-press-impregnated repair material excellent in resistance to scrubbing and corrosion when mixed with a proper amount of alumina raw material known as a material inducing spinel formation, and completed the present invention.

That is, according to the present invention, in order to form a spinel having a chemical structure of MgAl ₂ O ₄ , it is necessary to mix a magnesia refractory of MgO and an alumina raw material in an appropriate amount, and the hot- . Therefore, the hot-press-impregnated repair material of the present invention can ensure the corrosion resistance of the magnesia refractory, which is the main raw material, while securing the anti-scrubbing property by the spinel formation, and also securing excellent corrosion resistance.

Hereinafter, the present invention will be described in detail.

The present invention provides a basic hot-press-fitting repair material comprising, by weight, 50 to 80% of magnesia raw material, 10 to 40% of alumina raw material, 3 to 7% of alumina cement, and 5% or less of micro silica.

The magnesia raw material constituting the basic hot press-fit repairing material according to the present invention is added in order to improve the solubility (ability to withstand erosion) of the repair material. When the addition amount is too small, the addition effect can not be sufficiently obtained, But the content of the magnesia raw material is preferably limited to 50 to 80% by weight.

In the present invention, the magnesia raw material means seawater magnesia and fused magnesia raw material (clinker), preferably 10 to 20 wt% and 40 to 60 wt%, respectively. Among them, the raw material of seawater magnesia means magnesia produced by reacting magnesium component contained in seawater with lime oil to obtain precipitated magnesium hydroxide, followed by washing, filtering and drying, and finally calcining at high temperature.

The alumina raw material contained together with the magnesia raw material is added in order to improve the anti-spalling property of the repair material. If the addition amount is too small, the effect of addition can not be sufficiently obtained. On the other hand, It is preferable that the content of the alumina raw material is limited to 10 to 40% by weight because the corrosion resistance and the incorporation of inclusions may occur.

The raw materials including the alumina component can be roughly classified into artificial raw materials and natural raw materials. Among the artificial raw materials, there are sintered alumina and fused alumina having a high purity containing 98% or more of alumina component. % Or more of bauxite. Fused alumina has higher erosion resistance than sintered alumina but is expensive, and sintered alumina is known to be superior to fused alumina in terms of workability.

Therefore, in the present invention, the alumina raw material containing 10 to 40 wt% is preferably a mixture of fused alumina and sintered alumina, and the content thereof is preferably 10 to 30 wt% and 5 to 10 wt% .

In addition to the above-mentioned magnesia and alumina raw materials, the basic hot press-fit repair material according to the present invention may contain alumina cement and micro silica in an amount of 3 to 7 wt% and 5 wt% or less, respectively.

Alumina cement plays a role in increasing the workability and strength properties. When the content of alumina cement is low, the workability and the indentation strength are lowered. On the other hand, when the amount of the alumina cement is too high, the problem of poor workability due to early curing and deterioration in high temperature may occur. Do. In consideration of this, it is preferable to limit the content of alumina cement to 3 to 7 wt% in the present invention.

In addition, microsilica serves not only to increase the strength by promoting the sintering at the intermediate temperature and the high temperature, but also to enable the indentation even in the low moisture state. If the content of microsilica exceeds 5% by weight, shrinkage is increased, the hot strength is lowered, and corrosion resistance is lowered, which is not preferable.

Meanwhile, in addition to the components constituting the basic hot stamping material of the present invention, the binder may further include a binder. At this time, the binder may include one or more of a fluidizing agent, a vinyl fiber, and a curing agent, each of which may be added in an amount of 2 wt% or more.

It is preferable that the particle size of the press-fit material can be controlled in order to secure the excellent workability of the hot-press-fit material having the above-mentioned composition. More specifically, it is preferable that the hot-press material has a particle size of 5 mm or less at 90 wt% or more.

Hereinafter, the present invention will be described more specifically by way of examples. It should be noted, however, that the following examples are intended to illustrate the present invention by way of illustration and not to limit the scope of the present invention. The scope of the present invention is determined by the matters set forth in the claims and the matters reasonably inferred therefrom.

( Example )

In order to examine the physical properties of specimens prepared mainly containing magnesia as compared with the products currently used as hot embossing materials (current products), hot rolled steel material specimens were first prepared in the composition (% by weight) as shown in Table 1 below. At this time, as a binder, a fluidizing agent, a vinyl fiber and a curing agent were used in an amount of 2% by weight or more.

Then, the physical properties of each of the prototypes thus manufactured were evaluated by the following evaluation methods.

Physical properties were evaluated by basic analysis such as component analysis and particle size analysis, workability evaluation, plasticity evaluation, erosion resistance, NASPOLING property, and thermal resistance.

In this case, XRF was used for the composition analysis, and a dry type automatic analyzer was used for the particle size analysis. The results (% by weight) are shown in Table 2 below.

The water content and pot life were measured based on the test piece slurry of 15 kg, and the curing temperature was based on 25 ° C. The results are shown in Fig.

The compressive strength and shrinkage of each of the sintering temperatures (100 ° C. (drying), 1000 ° C., and 1500 ° C.) were measured. The results are shown in FIG.

Rotor erosion was used for the evaluation of erosion resistance. The erosion condition was carried out under the condition of reacting the slag and the reinforcing bar for 30 minutes at a temperature of 1600 ° C or higher for 6 times. The results are shown in Fig.

Each test specimen was charged into an electric furnace, heated for 10 minutes at 1400 ° C., cooled for 10 minutes (air-cooled), and then heated again. The resistance to thermal shock was evaluated 30 times, Was evaluated by putting each test piece into an electric furnace at 800 ° C after curing for 1 day. The results of the above-described evaluation of the resistance to the scrubbing and the resistance to scratching are shown in Fig.

ingredient Test piece 1 Test piece 2 Test piece 3 Test piece 4 Molten magnesia - - - 10 Seawater magnesia 72 72 72 62 Fused and sintered alumina 21 21 21 21 Calcined alumina - - 12 - Micro silica 3 3 3 3 Sintered alumina 6 6 0 6 Alumina cement 4 4 4 4

(The seawater magnesia used in Test Specimens 1 and 2 were 95% MgO and 98% MgO, respectively. The particle size of the magnesia was adjusted to 5 mm or less).

division Current product Test piece 1 Test piece 2 Test piece 3 Test piece 4 Chemical composition Al ₂ O ₃ 79.3 18.9 20.1 19.5 22.4 MgO 15.2 74.5 75.6 73.9 72.3 SiO 3.0 3.4 2.9 3.5 2.9 CaO 0.3 1.3 1.2 1.4 1.1 Granularity 2.80 mm + 11.3 0.6 1.0 1.3 1.0 1.0 mm + 35.6 34.2 36.4 37.5 38.3 0.075mm- 30.8 34.6 32.2 31.6 30.1

(+ Means more than the above-mentioned particle size, and - means less.

In the above, the unit means% by weight.)

As shown in Table 2, it can be seen that the content of MgO in the test piece according to the present invention is higher than that of Al ₂ O ₃ . On the contrary, in the case of the current product, the content of Al ₂ O ₃ is much higher than that of MgO.

As a result of evaluating the physical properties, the workability time of the test results of the workability evaluation test (see FIG. 1) was similar to that of the current product, but the moisture content was about 2% lower than that of the current product.

In the results of the plastic strength evaluation (see Fig. 2), in the case of the current product, the compressive strength is lowered as the firing temperature is increased, and high expansion characteristics are exhibited. On the other hand, in the case of the test pieces, the compressive strength was increased as the firing temperature was increased. Particularly, in the case of the test pieces 1 to 3, the expansion characteristics after firing were deteriorated. However, in the case of the test piece 4, since the increase in the compressive strength according to the firing temperature was small and the coefficient of expansion after firing increased to 1.52% as compared with the test pieces 1 to 3, It is considered that the phenomenon occurring can be improved.

The results of the corrosion resistance evaluation (see FIG. 3) show that all of the test pieces have excellent corrosion resistance compared to the current product.

It is considered that the resistance to thermal shock according to the temperature change is equivalent to that of the present product in the case of the evaluation of the resistance to fire polish and the resistance to scratch resistance (see FIG. 4). In the result of the explosion test, the upper crack was partially generated in the test piece 2, The feats are judged to be equivalent. However, the test piece 1 could not carry out the explosion test due to the lack of samples.

As a result of synthesizing the above physical properties,

The water content was decreased and the pot life was similar to that of the existing product. In addition, the corrosion resistance evaluation showed excellent results compared with the existing products, and the results of the evaluation of the resistance to scratching and scratching were equal except for Test pieces 1 and 2.

Therefore, while the test pieces 1 to 3 showed excellent water reduction and erosion resistance, it is considered that the sintering shrinkage may cause a dropout after the hot application. In the case of the test piece 4, 1.5% As a result, it is considered that there is no problem of shedding due to sintering and shrinkage during press-fitting.

Therefore, the most suitable material for the indentation repairing material is the same material as that of the existing product by adding a proper amount of alumina raw material, a small amount of microsilica, sintered alumina and alumina cement while using the molten magnesia and seaweed magnesia raw material as main components like the test piece 7 Can be developed.

Claims (5)

Wherein the alumina cement comprises 3 to 7% by weight of alumina cement and 5% by weight or less of microsilica as the alumina raw material, wherein the alumina raw material comprises 50 to 80% by weight of magnesia raw material, 10 to 40%
The method according to claim 1,
Wherein the magnesia raw material comprises 10 to 20 wt% of a molten magnesia MgO component and 40 to 60 wt% of a seaweed magnesia MgO component.
3. The method of claim 2,
The seawater magnesia MgO component has a MgO purity of 94 to 98.5 wt%.
The method according to claim 1,
Wherein the alumina raw material is composed of 10 to 30 wt% of fused alumina and 5 to 10 wt% of sintered alumina.
The method according to claim 1,
Wherein the basic hot-press-impregnated and repaired basic material has a particle size of not more than 5 mm as not less than 90 wt%.

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