JPH11199313A - Plate for slide gate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate for a slide gate, having a small apparent porosity, a narrow pore diameter distribution and an improved balance among strength, heat shock resistance and corrosion resistance in comparison with conventional plates, and to provide a method for producing the same. SOLUTION: This plate for a slide gate comprises a sintered refractory obtained by adding 3-10 outer wt.% of a thermosetting resin as a binder to 100 wt.% of a mixture comprising (A) 73-96 wt.% of a refractory aggregate comprising one or more kinds of refractory inorganic materials, (B) 0.1-0.5 wt.% of fibrous metal aluminum, (C) 1-5 wt.% of flaky metal aluminum powder, (D) 2-10 wt.% of carbonaceous powder, and (E) metal silicon powder in an amount of 0.2-2 times the total wt.% of the fibrous metal aluminum and the flaky metal aluminum powder, kneading the mixture, molding the kneaded product and sintering the molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slide gate plate used for controlling the flow rate of hot metal and molten steel in the steel industry and a method of manufacturing the same, and more particularly, to a refractory aggregate as a starting material. For example, using a blended raw material of a specific composition in which fibrous and flake powder metal aluminum and metal silicon powder are combined and blended at a specific amount ratio, molding and firing, the apparent porosity is small, Also, the present invention relates to a slide gate plate having a narrow pore size distribution and markedly improved strength, thermal shock resistance and corrosion resistance as compared with conventional products, and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, when secondary processing and continuous casting in a ladle have become common, as a member for controlling the flow rate of molten metal, a slide gate plate is widely used as an indispensable refractory member in the steel industry. . Since this slide gate plate is the part that controls the flow of molten metal such as molten steel, it requires extremely high performance, and has excellent characteristics that can respond to various severe conditions even in the material surface. It is necessary to have a good balance. That is, in addition to the physical effects such as rapid thermal shock and friction caused by the flow of molten metal, the slide gate plate has a chemical erosion effect (collision) caused by molten metal and molten slag, and furthermore, a chemical effect. And physical action are combined to cause electrolytic corrosion (erosion), etc., and the properties to be provided include excellent thermal shock resistance, abrasion resistance, corrosion resistance, strength properties, etc., and an apparent porosity of It is required that the product is made of a material that is small and has a narrow pore size distribution.

[0003] In order to equip the slide gate plate with the above-mentioned various properties in a well-balanced manner, conventionally, in the steel industry, alumina / metal having the most stable durability as a material has been used.
(Zirconia) Carbon-based refractories are widely used. Techniques for manufacturing slide gate plates made of alumina / (zirconia) / carbon materials include, for example, refractory inorganic aggregates such as alumina, zirconia, silica, carbon, silicon carbide, pitch, graphite, etc. To a carbon raw material, a thermosetting resin (a phenol resin is commonly used) as a binder is added, compounded, kneaded, molded into a predetermined shape, and then fired in a non-oxidizing atmosphere. A method of performing pitch or tar impregnation after firing or the like has been implemented.

Some inventions for further improving the above-mentioned various properties have already been proposed.
Japanese Patent Application Laid-Open No. 3-11312 discloses that a raw material having a composition obtained by adding metal aluminum powder and boron carbide to the above-mentioned refractory inorganic aggregate, carbonaceous powder and the like is used and reacts with the refractory powder and carbon powder during firing. There has been proposed a method for manufacturing a slide gate plate in which the corrosion resistance and the mechanical strength are improved. Japanese Patent Publication No. 63-57380 proposes a sliding nozzle member in which a low melting point metal powder such as aluminum powder is added to improve the corrosion resistance and the like. Furthermore, Japanese Patent Publication No. 3-3631 describes a method for manufacturing a slide gate plate in which a metal Al fiber is added and baked in order to improve thermal shock resistance, and pitch is impregnated after firing.

[0005]

However, in the method disclosed in Japanese Patent Publication No. 63-11312 in which the metal Al powder is added, a reaction of Al (for example, Al + N → AlN, etc.) is carried out in the stage of molding and firing. Volume expansion occurs,
For this reason, there have been problems such as cracks occurring during firing and a decrease in thermal shock resistance due to an increase in the elastic modulus of the product.
Further, in the method disclosed in Japanese Patent Publication No. 3-3631 in which the metal Al fiber is added and fired, the heat shock resistance is improved when the metal Al fiber is added in an amount of 1% by weight or more. If more than 1% by weight is actually mixed, metal fibers will be entangled during kneading,
Fibers cannot be dispersed homogeneously, and the density of the molded article does not increase during molding, and it is difficult to keep the product sufficiently dense. Furthermore, even if pitch impregnation processing is performed after firing, there is a problem that the product is digested in the drying step after processing, causing swelling, surface pulverization, and collapse in extreme cases.

The present invention has been made in order to solve the above-mentioned technical problems of the above-mentioned conventional alumina / (zirconia) / carbon slide gate plate,
To provide a slide gate plate having a small apparent porosity, a narrow pore diameter distribution, and significantly improved strength, thermal shock resistance, and corrosion resistance as compared with conventional products, and a method of manufacturing the slide gate plate. The purpose is to provide.

[0007]

According to the present invention, (A)
73% by weight or more and 96% by weight or less of refractory aggregate composed of one or more kinds of refractory inorganic materials; (B) 0.1% by weight or more and 0.5% by weight or less of fibrous metallic aluminum; ) Flaky metal aluminum powder
1% to 5% by weight, (D) carbonaceous powder from 2% to 10% by weight, and (E) metal silicon powder from 0.1% to 5% by weight. A mixture of 100% by weight of the resulting mixture and a thermosetting resin as an external binder in an amount of 3% by weight or more and 10% by weight or less, and kneading, molding, and firing to obtain a fired refractory. A featured slide gate plate is provided.

Further, according to the present invention, a compounding composition in which a thermosetting resin binder is externally added in an amount of 3% by weight or more and 10% by weight or less is kneaded with 100 parts by weight of a mixture composed of the above-mentioned raw materials. After molding, under a non-oxidizing atmosphere,
A method for manufacturing a slide gate plate, characterized in that the firing is performed at a temperature of 800 ° C. or more and less than 1400 ° C.

In the slide gate plate of the present invention, a specific amount of each of the fibrous metallic aluminum (Al) and the flaky metallic Al powder and
A remarkable structural feature is that it is composed of a baked product obtained from a raw material blend in which a specific amount ratio of metallic silicon is combined in combination with the total amount of l.

A so-called non-smoking carbon bond material typified by an alumina- (zirconia) -carbon-based material is provided with a metal Al powder such as a flaky flake powder or a spherical atomized powder in a range of 0.5 to 10%. The slide gate plate obtained by blending in a range of weight%, adding a binder thereto, and performing predetermined treatments such as kneading, molding, and baking is known as described above (Japanese Patent Publication No. 113
No. 12) Also, a slide gate plate obtained by blending fibrous metal Al with the carbon bond material in a range of 1 to 15% by weight and subjecting the mixture to a predetermined treatment is already known. (Japanese Patent Publication No. 3-3631).

However, a very small and specific amount of fibrous metal Al (0.1% to 0.5% by weight) is combined with a specific amount of flake metal Al (1% to 5% by weight). The raw material composition of the present invention, in which a specific proportion of metal Si powder is added to the total amount of both Al and compounded, is used in the kneading, forming and sintering processes to achieve the following unique concerted action. As a result, the present invention provides a slide gate plate having a small apparent porosity and a narrow pore diameter distribution, and having well-balanced and significantly improved strength, thermal shock resistance and corrosion resistance as compared with conventional products.
That is, since the amount of the fibrous metal Al is small, the entanglement at the time of kneading is small, and it can be sufficiently homogeneously dispersed. Therefore, at the time of firing, the reaction is caused by the reaction of the highly reactive flake-shaped metal Al powder. Appropriate voids capable of absorbing volume expansion are uniformly formed in the structure of the molded body.

Further, in the present invention, the fibrous metal Al
The amount of flake-form metal Al powder (1% to 5% by weight) is at least 2 times, usually about 10 times the amount of (1% to 0.5% by weight) And many more. For this reason, at the time of firing, the flake-like Al powder is preferentially reacted and consumed for the reasons described below, and at least a part of the compounded fibrous metal Al remains in a metal fiber state even after firing. However, when used as a slide gate plate, a harmful oxide that damages the refractory as a constituent material thereof, for example, an oxide such as FeO can be effectively reduced and made harmless by, for example, a reaction exemplified below. Play. 3FeO + 2Al = 3Fe + Al ₂ O ₃

Further, since the metallic silicon is blended in a specific ratio to the total amount of the added Al, the metallic silicon, when baked, surrounds the powdered flake metal Al and especially the fibrous metal Al with SiO _2. It acts to protect the metal Al from digestion. During the firing, the flake Al powder is preferentially reacted and consumed,
The reason why the fibrous Al remains as a metal in the molded body is considered as follows. That is, Al present in the compact exists in voids in the breath (fine carbonaceous material such as coke fine powder and pitch fine powder) when subjected to heat of a melting point (660 ° C.) or more, such as during firing. CO, CO ₂ ,
Reacts mainly with CO, CO ₂ , O ₂ , N ₂ gas generated from a carbon source such as O ₂ , N ₂ gas or an added binder. In this case, the flake-shaped metal Al powder is originally a fine particle, so that the particle surface area /
In addition to a large volume ratio, the thickness from the surface to the inner central portion is thin, so that it easily reacts with the CO, CO ₂ , O ₂ , N ₂ gas and the like, is consumed, and does not leave metal Al after firing.

On the other hand, the fibrous metal Al has a distance from the surface to the central portion, and the surface area / volume ratio is remarkably smaller than that of the flake-like Al powder particles. But first CO, CO
It reacts with ₂ , O ₂ , N _{2 and the} like to form a thin film layer such as an oxide film, a carbide film, a nitride film, and the like, and the reaction progress to the central portion is diffusion-controlled in this portion. Therefore, fibrous metal Al
Can be fired at a temperature above its melting point, or even after firing,
At least the central portion often remains in a metallic state.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The slide gate plate of the present invention comprises (A) a refractory aggregate, (B) a fibrous metallic aluminum, (C) a flaky metallic aluminum powder,
It is obtained by blending a thermosetting resin as a binder with a raw material mixture composed of (D) carbonaceous powder and (E) metallic silicon powder, and kneading, molding and firing. In the present invention, as the refractory inorganic material used as the refractory aggregate (A), a material used for an ordinary slide gate plate can be used, and it is not particularly limited. However, for example, alumina materials such as sintered alumina, synthetic mullite, aluminosilicate, spinel, zirconia materials such as stabilized zirconia and electrofused zirconia, silica sand, fused silica, amorphous silica, silica materials such as silica alumina And other materials, for example, one or a mixture of two or more refractory inorganic materials such as silicon carbide, sillimanite, and magnesia. Among them, alumina-based materials, zirconia-based materials, and silica-based materials, particularly, alumina-zirconia-based, alumina-zirconia-silica-silicon carbide-based mixed aggregates can be preferably used.

The fibrous metallic aluminum (B) usually has an Al purity of 90% or more, especially 95% or more, an average fiber diameter of about 10 μm to 500 μm, and an aspect ratio of about 10 to 100, particularly an average diameter of 5 to 5 μm.
It is preferable to use one having a range of 0 μm to 150 μm and an aspect ratio of 20 to 50 from the viewpoints of dispersibility at the time of kneading and the rate control of the reaction at the time of firing. As the fibrous metallic aluminum, an alloy of Al and another low melting point metal, for example, an alloy of Al and Zu, Sn, Mg, etc. may be used as long as the above-mentioned Al purity of 90% or more is maintained. .

The flake-form metallic aluminum powder (C) usually has an Al purity of 95 or more, especially 98
% Or more, and it is preferable to use a scale powder having a particle size of 0.1 μm or more and 100 μm or less. As the flaky metal aluminum powder (C), an alloy of Al and another low melting point metal, for example, an alloy of Al and Zu, Sn, Mg or the like may be used.

Further, as the carbonaceous powder (D), a carbonaceous material usually blended with this kind of refractory composition may be used, and is not particularly limited.
Use graphites such as adjacent, earthy, quiche, pyrolytic graphite, pitches such as coal or petroleum pitch powder, cokes such as petroleum or coal coke, anthracite, charcoal, carbon black, etc. it can.

As the metallic silicon powder (E), usually,
Purity 80% or more, especially 90% or more, particle size 1 μm or more1
A metal silicon powder having a size of 00 μm or less, particularly 200 μm or less is used.

As the composition of the above (A) to (E),
In the present invention, the refractory aggregate (A) contains 73% by weight or more and 96% by weight or less, and fibrous metallic aluminum (B)
Is from 0.1% by weight to 0.5% by weight, preferably,
0.1% by weight or more and 0.2% by weight or less, flake-like metallic aluminum powder (C) is 1% by weight or more and 5% by weight or less, preferably 1% by weight or more and 2% by weight or less, carbonaceous powder (D) Is 2% by weight or more and 10% by weight or less, preferably 2% by weight or less.
5% by weight or less and 5% by weight or less of metal silicon powder (E)
0.1% by weight or more and 5% by weight or less, preferably 1% by weight
More than 3% by weight is blended.

In the above composition, the amount of the fibrous metallic aluminum (B) is limited to 0.1 to 0.5% by weight because the amount of the fibrous metallic aluminum is 0.1% by weight. In the following cases, it is difficult to form sufficient voids to allow for expansion when the flake-shaped metallic aluminum powder (C) added in combination therewith reacts in the firing step. Cracking or explosion of the body is caused, which is not preferable.

When the amount of the fibrous metallic aluminum is more than 0.5% by weight, the composition matrix after kneading becomes sufficiently homogeneous and dense due to excessive entanglement of the fibers during kneading. This is because the bulk density of the molded article formed using this does not improve, the porosity is large, and a porous material having a wide pore diameter distribution is formed, and it is easy to digest when wet with water. This is because

Next, the reason why the content of the flaky metallic aluminum (C) is limited to 1% by weight or more and 5% by weight or less is that when the amount is 1% by weight or less, the product strength after firing is low. If it exceeds 5% by weight, the volume expansion when reacting with CO, CO ₂ , O ₂ , N ₂ gas, etc. present in the atmosphere in the firing step becomes too large, so This is because cracks or explosions occur and the hardness becomes too high, which leads to a disadvantage that thermal shock resistance is remarkably reduced. Further, the carbonaceous powder (D) is
The reason why the content is 2% by weight or more and 10% by weight or less is that when the content is 2% by weight or less, the thermal shock resistance is reduced, and when the content is 10% by weight or more, the corrosion resistance is reduced. Further, the amount of the metallic silicon powder (E) was adjusted to the total weight% of the fibrous metallic aluminum and the flaky metallic aluminum powder.
((B) + (C)) is limited to a ratio (weight%) of 0.2 to 2 times that the mixing ratio of metallic silicon is Al
If the amount exceeds twice the total amount (% by weight), the amount of metallic silicon is too large and the corrosion resistance of the product is reduced. If the compounding ratio is less than 0.2 times, the amount of metallic silicon is too small. Therefore, it is difficult to form a silicon O ₂ coating layer around the metal Al, which causes a problem in digestion resistance.

In the present invention, a thermosetting resin is used as a binder for sintering the molded article, and the thermosetting resin used is a phenol resin, a furan resin, an epoxy resin, a silicone resin, or the like. However, the use of a phenol resin is preferred in view of the amount of fixed carbon and cost. The slide gate plate of the present invention is characterized in that it is made of a material having a small apparent porosity and a narrow pore size distribution.
0% to 15%, average pore diameter is 0.5 μm or less, 3 μm
It is in the above range.

Next, a method of manufacturing the slide gate plate of the present invention will be described. First, (A) refractory aggregate, (B) fibrous metallic aluminum, (C)
Mixing predetermined amounts of flake-like metal aluminum powder, (D) carbonaceous powder, and (E) metal silicon powder,
A thermosetting resin as a binder is added to the mixture at 3 to 10 parts by weight based on 100 parts by weight of the mixture, and the mixture is kneaded at room temperature or under heating. The kneaded material is molded into a plate using a normal molding machine used for molding a refractory brick or the like, for example, a friction press, an oil press, a rubber press, and the like. In an atmosphere of an inert gas such as N 2 gas or argon gas, the object is fired at a temperature of 800 to less than 1400 ° C. in a reducing atmosphere in which an object to be fired is embedded. The fired molded body thus obtained is impregnated with a coal tar pitch, a synthetic resin or the like on the surface as required, and an iron band frame is fitted on the outer periphery thereof, and the sliding surface is processed to form a slide gate. Plate.

[0026]

EXAMPLES Examples 1 to 6 Sintered alumina-based raw materials, electrolytic zirconia-based raw materials, silica-based raw materials, silicon carbide, carbonaceous raw materials (pitch), fibrous metallic aluminum, flake-like metallic aluminum powder, and metallic silicon powder Were mixed in the mixing ratios shown in Table 1, respectively, and the thermosetting resin (phenol resin) was added to each 100 parts by weight in the amount shown in Table 1 and kneaded. Each of the obtained kneaded materials was molded into a plate shape, and a plurality of molded body samples of Examples 1 to 6 were produced for each of them. Next, the temperature of these molded body samples was raised to 200 ° C., and volatile components were volatilized and evaporated. Each molded body was heated in a reducing atmosphere filled with breathe for 12 hours.
Fired at 00 ° C.

Thereafter, a belt-shaped iron shell was fitted on the outer periphery of each of the fired refractories (compacts) of Examples 1 to 6, and the sliding surface was processed to obtain a slide gate plate. . The apparent porosity (%) and compressive strength (MPa) of each of the sample fired refractories of Examples 1 to 6 were measured, a part thereof was cut out, and a digestion acceleration test was performed on each of the cut sample pieces. After the test, the state was observed. Note that the digestion acceleration test was performed at φ40 × 35 mm
After holding the cut sample pieces in water at 20 ° C. for 7 days,
After drying at 0 ° C. for 12 hours, the surface texture of each sample piece, particularly the presence or absence of cracks, was observed. "Yes" in Tables 1-3
"No" indicates the presence or absence of cracks, and "Large" indicates that the crack width is 5m
m, and “small” indicates that the crack width is less than 5 mm. The sample slide gate plate was mounted on a ladle with a capacity of 200 tons, and a field test was conducted to determine the number of service life and damage near the hole diameter (corrosion resistance).
Were compared and observed.

Apparent porosity (%) of each sample fired refractory,
Table 1 shows the measured values of the compressive strength (MPa), the presence or absence of cracks in the digestion test, the number of service times in the above-mentioned field test of the slide gate plate sample, and the damage (visual corrosion resistance) evaluation results near the hole diameter. FIG. 2 is a diagram showing the pore size distribution (pore distribution) of the samples of Examples 1 and 5. FIG. 1 shows the structure of the refractory obtained by firing the molded body shown in Example 5 at 1400 ° C.

(Comparative Examples 1 to 8) Sintered alumina-based raw material,
Electrolytic zirconia-based raw material, silica-based raw material, silicon carbide, carbonaceous raw material (pitch), fibrous metallic aluminum, flake-like metallic aluminum powder and metallic silicon powder were mixed at the mixing ratios shown in Tables 2 and 3, respectively. The thermosetting resin (phenolic resin) was added to the parts by weight and mixed in the amounts shown in Tables 2 and 3 and then kneaded. 1 to 6) were obtained and evaluated in the same manner as in the examples. The results are shown in Tables 2 and 3. FIG. 2 shows the pore size distribution (pore distribution) of the samples of Comparative Examples 3 and 4.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

From Tables 1 and 2, 3 and FIGS. 1 and 3, the fired refractory for forming the slide gate plate of the present invention has a good balance of compressive strength, corrosion resistance and thermal shock resistance. It turns out that it has sufficient service life as a plate for gates. On the other hand, it can be seen that the fired refractories of Comparative Examples 1 to 8 other than the constitution specified in the present invention are inferior in any of the above-mentioned characteristics, and as a result, are inferior in practical useful life.

[0034]

The slide gate plate of the present invention is
As described above, as the starting material, a refractory aggregate, a carbonaceous material, etc., using a blended raw material of a specific composition in which fibrous and flaky powdered metallic aluminum and metallic silicon powder are combined and blended in a specific quantitative ratio, A specific amount of a thermoplastic resin binder is blended into the mixture, and the mixture is obtained by kneading, molding, and firing. Therefore, the apparent porosity is small, and the pore size distribution is narrow. , Thermal shock resistance and corrosion resistance are well-balanced and remarkably excellent.

[Brief description of the drawings]

FIG. 1 is a view showing the structure of a refractory fired at 1400 ° C. (a refractory obtained by firing the molded body shown in Example 5 at 1400 ° C.) of the present invention.

FIG. 2 is a diagram showing a relationship between pore diameter distributions of Examples 1 and 5 and Comparative Examples 3 and 4.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Morita Osamu 1 Minamito, Ogakie-cho, Kariya-shi, Aichi Prefecture Toshiba Cellular Co., Ltd. Lamix Corporation Kariya Factory

Claims (8)

[Claims] 1. A refractory aggregate made of one or more refractory inorganic materials of at least 73% by weight and 96% by weight or less, and (B) a fibrous metallic aluminum of 0.1% or less.
(C) flake-like metal aluminum powder is 1% by weight or more and 5% by weight or less,
(D) the carbonaceous powder is at least 2% by weight and at most 10% by weight,
(E) 0.1% by weight or more and 5% by weight of metallic silicon powder
A fired refractory obtained by adding 3% by weight or more and 10% by weight or less of a thermosetting resin as an external binder as a binder to 100% by weight of a mixture composed of the following raw materials, and kneading, molding, and firing. A plate for a slide gate, comprising: 2. The method according to claim 1, wherein the ratio of the metallic silicon powder is 0.2 times or more and 2 times or less with respect to the total weight% of the fibrous metallic aluminum and the flake metallic aluminum powder. The described slide gate plate. 3. The slide gate plate according to claim 1, wherein the refractory aggregate is an alumina-zirconia-based refractory aggregate. 4. The refractory aggregate comprises 60% by weight to 75% by weight of a sintered alumina-based refractory material, 15% by weight to 25% by weight of a fused zirconia-based refractory material, and 0% by weight of a silica-based refractory material. The slide gate plate according to any one of claims 1 to 4, comprising 0.5 wt% to 5 wt%, and 0.5 wt% to 5 wt% of silicon carbide. 5. The slide gate according to claim 1, wherein a fiber diameter of the fibrous metallic aluminum is 10 μm or more and 500 μm or less, and an aspect ratio is 10 or more and 100 or less. Plate. 6. The slide gate plate according to claim 1, wherein the flake-shaped metal aluminum powder has a particle size of 0.1 μm or more and 100 μm or less. 7. The slide gate plate according to claim 1, wherein the thermosetting resin binder is a phenol resin. 8. A refractory aggregate made of one or more refractory inorganic materials, in a range of 73% by weight to 96% by weight, fibrous metallic aluminum in a range of 0.1% by weight to 0.5% by weight, flake-like metal The aluminum powder is 1 wt% to 5 wt%, the carbonaceous powder is 2 wt% to 10 wt%, and the metal silicon powder is 0.2 times the total weight% of the fibrous metallic aluminum and the flake metallic aluminum powder. A thermosetting resin is externally added to 100% by weight of a mixture composed of the raw material formulations mixed at a ratio of 2 times or less, 3% by weight or more and 10% by weight or less, kneaded, molded, and then non-oxidized. 800 ° C or higher in a neutral atmosphere
A method for manufacturing a slide gate plate, comprising firing at a temperature of less than 400 ° C.