JP3101643B2 - Sealing material at the junction between the melt vessel and the nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material for a nozzle joint mounted on a molten metal container.

[0002]

2. Description of the Related Art Conventionally, mortar or a mixture of mortar and ceramic fibers has been used as a joint material at a nozzle joint of a slide gate attached to a molten metal discharge portion of a molten metal container. However, in these joint materials, there is a possibility that a minute gap may be formed at the joint. Then, once a gap is formed in the joint, the gap is not closed to the end, and on the contrary, the gap is often enlarged, and there is a risk that air may be sucked into the interior of the molten metal container.

[0003] In addition, in conventional joints, it is difficult to clean off old joint materials when exchanging nozzles, and the workability of exchanging nozzles is poor. In order to solve these problems, a plastic plate containing alumina-silica as a main component (Japanese Utility Model Publication No. 1-14211), a sealing material body in which refractory material and refractory fiber are impregnated with vinyl acetate, graphite, refractory material and refractory fiber Of a multilayer integrated structure consisting of a graphite part composed of graphite (Japanese Patent Publication No. 1-20943)
And so on.

[0004] According to these, the joint portion can be smoothly peeled off at the time of nozzle replacement, and the conventional problem of this point has been solved. However, even with these joint materials, the above-mentioned problem of the sealing property of the joint portion still remains, and this problem has not been solved at all.

That is, in the sealing material as described above, if a minute gap is present at the joint when joining the nozzles, air is drawn from the gap into the inside of the nozzle which is in a reduced pressure state during use, and this air flows through the inside of the nozzle. There has been a problem that the molten metal is oxidized by contact with the flowing molten metal, thereby deteriorating the quality.

[0006] Therefore, even if a minute gap is formed in the joint portion when joining the nozzles, it is ideal if a seal material that closes the gap naturally during use appears.
As such a sealing material, the applicant has already filed Japanese Patent Application No. Hei.
No. 5840 was proposed. This seal material is a seal material that closes the gap naturally during use even if a small gap is formed at the joint part of the nozzle joint, and also smoothly peels off the joint part when replacing the nozzle The above request was substantially satisfied. However, this sealing material has another problem that it hardens due to a change with time and loses flexibility, and it has been further demanded to solve it today.

[0007]

According to the present invention, even if a small gap is formed in the joint portion when the nozzle is joined, if the temperature of the nozzle rises during use, the sealing material softens accordingly and this gap is formed. Is intended to obtain a sealing material that does not lose its flexibility due to hardening due to a change with time.

[0008]

According to the present invention, there is provided a method for producing a powder of 4 to 6% by weight of alumina powder, 44 to 66% by weight of silica powder,
_To a mixture of 4 to 14% by weight of ₂ O (R represents Na and K) and 18 to 36% by weight of alumina-silica fiber, 2 to 5% by weight of a methylcellulose-based binder as an organic binder, Glycerol or ethylene glycol as an organic solvent is added in an amount of 40 to 50% by weight, respectively, and the mixture is mixed to form a sheet. A sealing material for joining a molten metal container and a nozzle (claim 1), alumina powders 4 to 6 % By weight and 44 to 66% by weight of silica powder
When, R ₂ O (R represents Na, the K.) 12 to 14 wt%
And a mixture of 18-30% by weight of alumina-silica fiber, 2-5% by weight of a methylcellulose type binder as an organic binder and 40-50% by weight of glycerose or ethylene glycol as an organic solvent. The sealing material (claim 2), the alumina powder and the silica powder of the molten metal container and the nozzle joint, which are mixed to form a sheet, are 0.01 to 1 mm in diameter.
The average particle size of the sealing material (claim 3), the alumina powder, and the silica powder at the junction of the molten metal container and the nozzle according to claim 1 or 2 is 0.1 mm or less.
Sealing material between the molten metal container and the nozzle joint as described in claim 4
It is. Hereinafter, these inventions are further described.

The sealing material according to the first aspect of the present invention comprises alumina powder, silica powder, R ₂ O (R represents Na and K), alumina-silica fiber, a methylcellulose binder as an organic binder and an organic solvent as an organic solvent. It consists of a mixture of glycerol or ethylene glycol.

The mixing ratio of the alumina powder is 4 to 6% by weight. If it is less than 4% by weight, the melting point decreases and the shape is not maintained at the target temperature (maximum 1400 ° C.). If it exceeds 6% by weight, the melting point increases and the required temperature at the target temperature (minimum 600 ° C.). No viscosity is obtained.

The silica powder accounts for 44 to 66% by weight. If it is less than 44% by weight, no glaze occurs at the target temperature, and if it exceeds 66% by weight, the shape cannot be maintained at the target temperature.

Alumina powder and silica powder have a particle size of 0.0
A range of 1 to 1 mm is preferred. If the fine particles are out of this range, when softened, they flow out of the fine gaps and cause large gaps to be generated, and if the upper limit is exceeded, roughening may deteriorate the close contact properties and gaps may be formed.
The average particle size of the alumina powder and the silica powder is preferably 0.1 mm or less.

Although the temperature around the molten metal may be as high as 1600 to 1400 ° C., if the alumina powder and the silica powder have the above-mentioned particle size, the sealing material is gasified sequentially from the vicinity of the molten metal,
A molten layer, a semi-molten layer, and an unmelted layer are sequentially formed, and the sealing property can be improved.

R ₂ O is, for example, Na ₂ O or K ₂ O, and is preferably powdered sodium silicate which is slightly dissolved in water.
TE NA-P (trade name of Aichi Chemical Industry Co., Ltd.) is preferably used. The mixing ratio of these is 4 to 6% by weight. According to the present invention, if the content is less than 4% by weight, the melting point increases and the viscosity cannot be obtained at a target temperature. If the content exceeds 6% by weight, the melting point decreases and the sealing material softens and flows out before reaching the target temperature. It is not preferable because it no longer serves its role.

[0015] The alumina-silica fiber is 18 to
36% by weight. If the amount is less than 18% by weight, it is difficult to maintain the sheet shape, and if it exceeds 36% by weight, it becomes difficult to form the sheet. Alumina-silica fibers are particularly suitable for the present invention because they are easy to control the melting point and are inexpensive. Most preferably, the ratio of alumina to silica is about 55:45 by weight. By blending the alumina-silica fiber, the shape retention of the sheet is further improved, and it can be easily formed in advance into a shape that can be fitted to the nozzle to be used.

Methylcellulose binders as organic binders include the above-mentioned alumina powder, silica powder, R
₂ to 5% by weight based on the total amount of ₂ O and alumina-silica fiber. If it is less than 2% by weight, it cannot be formed into a sheet, and if it exceeds 5% by weight, the required viscosity of rubber clay cannot be obtained.

Examples of the methylcellulose-based binder include Selander (trade name of YB-135C, manufactured by Yuken Industries Co., Ltd.).
Alternatively, YB-135B) is preferably used. Further, as the organic solvent, glycerol or ethylene glycol having a molecular weight of 7000 or less is used, and the compounding ratio is the same as that of the organic binder, with respect to the total amount of alumina powder, silica powder, R ₂ O, and alumina-silica fiber. 40 outside
To 50% by weight. When the compounding ratio of the organic solvent is less than 40 parts by weight, a rubber clay-like viscosity cannot be obtained, and when it exceeds 50 parts by weight, the viscosity is reduced and the shape retention is reduced.

The above-mentioned raw material mixture is kneaded well and kneaded so as to have a rubber clay-like hardness to form a sheet. In order to maintain the shape retention of the sheet material or to improve the releasability after use, the sheet material has a thickness of 0.5 to
It is effective to attach a 1.0 mm alumina fiber sheet. Further, in order to improve the releasability of the sheet, it is effective to coat one or both sides of the sheet with graphite paste or alumina fine powder.

This sealing material is soft at a temperature from normal temperature to about 800 ° C., and has fine pores inside. However, at a high temperature of about 1000 ° C., the sealing material becomes fluid and becomes The existing pores disappear and disappear. In particular, since the inside of the nozzle of the molten metal container has a negative pressure during use, the sealing material that has softened at a high temperature and has flowability is sucked into the nozzle, and a gap is formed between the sealing material used as the joint and the gap. Even if a gap occurs, the gap is naturally sealed during use.

Since the temperature rise of the nozzle during use differs depending on the temperature of the molten metal, the material of the nozzle, and the like, it is preferable to select a raw material mixing ratio that matches the use temperature. For example, the operating temperature is 1000 ° C., 4% by weight of alumina powder, 60% by weight of silica powder, 10% by weight of R ₂ O, 26% by weight of alumina-silica fiber, operating temperature of 1
At 200 ° C., alumina powder 5% by weight, silica powder 55
%, R ₂ O 10% by weight, alumina-silica fiber 30% by weight, at an operating temperature of 1400 ° C., alumina powder 6% by weight, silica powder 50%, R ₂ O 8% by weight, alumina-silica fiber 36% by weight is there.

When a methyl cellulose-based binder as an organic binder is used, for example, a celander, the preferable addition amount is 16,2 at the above-mentioned respective temperatures.
0.24% by weight (outside ratio) and a molecular weight of 7 as an organic solvent
When ethylene glycol of 000 is used, the preferable addition amount is 50, 45, 40% by weight (outer part) at each of the above temperatures.

While the softened seal material is sucked in the direction of the inside of the nozzle, it enters the gap between the seal materials and closes the pores, but it has excessive fluidity and flows out of the joint. Never. Further, when the sealing material is cooled, it becomes glassy and solidifies, and can be easily removed.

The suppression of the curing of the sealing material according to the change in diameter with time can be achieved by the combined use of an organic binder and an organic solvent. That is, the methylcellulose-based organic binder easily becomes fibrous when dissolved in an organic solvent. For this reason, the amount of the binder added can be greatly reduced as compared with the conventional one, and the flexibility of the sealing material can be greatly improved. Further, since glycerol or ethylene glycol is used as the organic solvent, evaporation of the solvent and reaction with an alkali component in the sealing material are suppressed, so that a change with time can be suppressed. Furthermore, in the invention of the present application, the use of an organic binder and an organic solvent having excellent thermal decomposability suppresses smoking.

According to a second aspect of the present invention, the proportion of R ₂ O is specified to be 12 to 14% by weight within the scope of the first aspect of the present invention. In this case, the mixing ratio of the alumina-silica fiber is set to 18 to 30% so that the total becomes 100%.

According to a third aspect of the present invention, the particle size of the silica powder is set to 0.1.
01 to 1 mm, and the invention of claim 3
The average particle size of the alumina powder and the silica powder is set to 0.1 mm or less. The reason for specifying the particle size of the silica powder within this range is as described above.

[0026]

According to the present invention, nozzle bonding is performed by mixing a predetermined amount of alumina, silica, alkali, or ceramic fiber with a mixture of a methylcellulose binder as an organic binder and glycerol or ethylene glycol as an organic solvent at a specified mixing ratio. Part of the sealing material,
The sealing material itself becomes fluid by heating when the nozzle is used. Even if a gap is formed in the joint formed by the sealing material, the sealing material fluidized during use naturally fills the gap. Will be. In this case, since the inside of the nozzle is in a depressurized state, the softened and fluidized sealing material is sucked into the gap, and the sealing is performed more reliably.

Furthermore, since a methylcellulose-based binder is used as the organic binder and glycerol or ethylene glycol is used as the organic solvent, the organic binder is easily dissolved in the organic solvent, and the evaporation of the solvent and the removal of the solvent from the alkali in the sealing material. The reaction is suppressed, and the effect of suppressing the hardening due to the time change of the seal is performed. (Experimental Example) The air permeability of the joint using the sealing material according to the present invention was tested using the test apparatus shown in FIG. In FIG. 1, reference numeral 1 denotes an electric furnace, and an alumina porcelain container 2 having a recess therein and an alumina porcelain plate 3 are hermetically bonded with a sealing material 4 of the present invention, and in this state, a weight of 59 KPa is applied from above the alumina porcelain plate. Was applied.

A suction hole 5 was provided in the lower part of one end of this alumina porcelain container. A suction tube 6 was sealed in the suction hole 5 of the alumina porcelain container 2, and a vacuum pump (not shown) was connected to the suction tube 6 to reduce the pressure in the alumina porcelain container. The shape of the sealing material forming the joint formed between the alumina porcelain container and the alumina porcelain plate was as shown in FIG. The sealing material used here was the one shown in Examples below.

In the experiment, the temperature was raised to 1100 ° C. in an electric furnace maintained at 700 ° C. at a temperature rising rate of 200 ° C./hrs, and the air flow rate (Nl / min) of the sealing material at each temperature was measured. The results are shown in FIG. In FIG. 3, the broken line is the sheet of the present invention, and the solid line is the conventional sheet. The sheet of the present invention is 1000
When the temperature exceeded ℃, almost complete sealing was observed.

[0030]

EXAMPLES The particle size distribution is 1 to 0.01 mm and the average particle size is 0.1 mm.
5% by weight of Al ₂ O _{3 of} 1 mm, 55% by weight of SiO _{2 having} the same particle size distribution and average particle size, 10% by weight of a mineral containing NaO ₂ and K ₂ O having the same particle size distribution and average particle size, alumina
30% by weight of silica-based ceramic fiber was mixed.
A sealer was added to the mixture by adding and blending 20 wt% of a binder (above trade name) and 42 wt% of ethylene glycol as a binder.

Although this sealing material had rubber-like hardness, it could be filled into joints of a molten steel container.
When this was heated to 1200 ° C., it was remarkably softened,
It did not flow and flowed out of the joint. The same sealing material was used as a joint material for the lower nozzle and the long nozzle of the molten steel container, and casting of molten steel at 1614 ° C was performed. Observation of the joint after pouring showed that the sealing material was sufficiently melted to prevent gas intrusion. When the N ₂ content of the cast steel slab was examined, it was found to be reduced by about 67% as compared with the case where the conventional sealing material was used.

[0032]

According to the sealing material of the present invention, the airtightness of the joints of the molten steel container is further ensured, air does not enter from the joints, and the molten metal is oxidized to lower its quality. Can now be prevented.

Further, when the sealing material of the present invention is used, even when the nozzle is replaced, the sealing material is vitrified after cooling and can be easily peeled off. It no longer takes a long time to clean the part.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an experimental device for testing the airtightness of a sealing material according to the present invention.

FIG. 2 is a dimensional diagram showing sizes of sealing materials used in the experiment shown in FIG.

FIG. 3 is a diagram showing the relationship between the temperature of a sealing material and air permeability.

[Explanation of symbols]

1: electric furnace, 2: alumina porcelain, 3: alumina porcelain plate,
4 ... Seal material, 5 ... Suction hole, 6 ... Suction tube.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI B22D 41/56 B22D 41/56 (72) Inventor Seiya Sugita 1 Minami Fuji, Ogakie-cho, Kariya-shi, Aichi Pref. 72) Inventor Hiroshi Yamada 1 Minamito, Ogakie-cho, Kariya-shi, Aichi Pref.Toshiba Ceramics Co., Ltd.Kariya Factory (72) Inventor Kenichi Mukaiyama 1-Nagato, Ogakie-cho, Kariya-shi Aichi Pref. Patent 2984521 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/66 B22D 11/10 B22D 41/56

Claims (4)

(57) [Claims] 1. An alumina powder of 4 to 6% by weight, a silica powder of 44 to 66% by weight, R ₂ O (R represents Na and K) 4 to 14% by weight, and an alumina-silica fiber 18 to 36% by weight of a mixture of 2% to 5% by weight of a methylcellulose binder as an organic binder, and glycerose or ethylene glycol as an organic solvent.
A sealing material for joining a molten metal container and a nozzle, wherein each of the molten metal and the nozzle is mixed to form a sheet. 2. 4 to 6% by weight of alumina powder, 44 to 66% by weight of silica powder, 12 to 14% by weight of R ₂ O (R represents Na and K), and 18 to 18% of alumina-silica fiber. To a mixture with 30% by weight, a methylcellulose-based binder was added as an organic binder in an amount of 2 to 5% by weight, and glycerol or ethylene glycol was added as an organic solvent in an amount of 40 to 50% by weight. Sealing material for the joint between the molten metal container and the nozzle. 3. The sealing material according to claim 1, wherein both the alumina powder and the silica powder have a particle size of 0.01 to 1 mm. 4. The seal material according to claim 1, wherein the alumina powder and the silica powder each have an average particle size of 0.1 mm or less.