JP2005297044A - Plate refractory for sliding nozzle and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a plate refractory for sliding nozzle, the plate refractory having improved high-temperature strength characteristic and the plate refractory for the sliding nozzle obtained by the manufacturing method. <P>SOLUTION: The manufacturing method for the plate refractory for the sliding nozzle comprises: adding a phenolic resin as a binder to the following blended material; kneading the material; forming the material into a prescribed shape; and then burning it. Therein, the above blended material is composed of: refractory aggregate; one or more kinds of components selected from the group consisting of a metal, carbide and nitride; 0.5-4 mass% of pitch powder having ≤20μm average grain diameter; and 1-8 mass% of fine carbon having ≤0.3μm average grain diameter. The plate refractory for the sliding nozzle is manufactured by the manufacturing method for the plate refractory for the sliding nozzle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a manufacturing method of a sliding nozzle plate refractory used for flow control at the time of discharge of molten steel in a ladle or tundish used as a molten steel container in the steel industry, and a sliding nozzle obtained by the manufacturing method. It relates to plate refractories.

  The sliding nozzle plate refractory has through holes and controls the flow rate of hot molten steel flowing through the holes. The portion exposed to the high-temperature molten steel stream is required to have a hot strength enough to withstand wear due to the flow, and at the same time, is required to have a thermal shock resistance against a rapid temperature rise when the molten steel begins to flow. Further, in recent years, the sliding refractory plate refractories are required to have further improved durability as the use conditions become severe.

  The sliding nozzle plate refractory is manufactured by adding a phenolic resin as a liquid binder to the refractory aggregate, kneading, putting the kneaded material into a mold, forming it with a press machine, etc., and then firing it. The method is general, and some products are impregnated with tar pitch if necessary. In the phenol resin generally used as a liquid binder, volatile components contained therein are removed during calcination and carbonized, and remain between the refractory aggregate particles. The residue after carbonization of this phenol resin is involved in the bonding between the aggregate particles, and is generally called carbon bond, and greatly contributes to the hot strength characteristics of the sliding nozzle plate refractory. Carbon also has excellent spalling resistance, such as high thermal conductivity and low elastic modulus, so improving carbon bonds is an effective technique for improving hot strength characteristics while maintaining spalling resistance. is there. Therefore, attempts have been made in the past to improve the binder by improving the carbon bond and improving the strength characteristics.

  For example, Patent Document 1 discloses that a pitch of a BS component of 40% or more and a QI component of 20% or less and a phenol resin having a number average molecular weight (Mn) of 1000 or less, and a pitch / phenol resin of 0.2 to 5 by weight ratio. A method for producing a carbon-oxide refractory characterized by using the above-mentioned binder is disclosed. The invention of Patent Document 1 uses a liquid binder in which the weight (mass) ratio of pitch / phenol resin is mixed at a ratio of 0.2 to 5, thereby making the carbon structure after carbonization of the binder into a mosaic structure and heat-resistant. It is intended to improve impact properties and hot strength characteristics.

  Further, Patent Document 2 is formed by molding a mixture of a refractory compound using a pitched binder prepared in advance and a refractory compound using a phenol resin as a binder, and the pitch is used as a binder. A high-durability sliding nozzle plate characterized in that the mixing ratio of the refractory composition made to the total amount of the mixture is 20 wt% (mass%) or more and 70 wt% (mass%) or less; A blend of refractory powder and phenol resin added to a refractory compound with a pitch as a binder, and a blending ratio of the refractory compound with the pitch as a binder relative to the total amount of the kneaded material. Disclosed is a high durability sliding nozzle plate (Claim 2) characterized by being 20 wt% (mass%) or more and 70 wt% (mass%) or less. There. In the invention of Patent Document 2, a kneaded product using a liquid pitch as a binder and a kneaded product using a phenol resin as a binder are mixed at an appropriate ratio to make use of the advantages of both.

  In addition, studies have been made to improve the properties of carbon bonds after carbonization by adding powder pitch in addition to the liquid binder. For example, in Patent Document 3, in a carbon-bonded brick mainly composed of a refractory material and a carbon material and a phenol resin as a binder, fixed carbon 70 to about 100 parts by weight (parts by mass) of the refractory material and the carbon material. There is disclosed a carbon-bonded refractory characterized by adding 0.1 to 8 parts by weight (mass part) of a pitch having a weight of 90% by weight (mass%) and a softening point of 250 to 350 ° C. That is, the invention of Patent Document 3 uses a pitch having a specific softening point.

  Further, Patent Document 4 discloses a pitch containing a thermosetting resin material and a mesophase having an anisotropic fraction of at least 80% with respect to an aggregate composed of one or more refractory inorganic materials. And the mixed material is kneaded, then molded, and then fired (Claim 1); the addition amount of the mesophase pitch is 0 in the external distribution. A method for producing a carbon-containing refractory, characterized in that it is not less than 5% by weight (mass%) and less than 20% by weight (mass%) (Claim 2); the carbonization yield of the mesophase pitch is not less than 70% There is disclosed a method for producing a carbon-containing refractory (Claim 3).

  Patent Document 5 discloses 50 to 97% by weight (mass%) of a mixture of one or more refractory oxides, nitrides, borides and carbides, and 3 to 50% by weight (mass%) of a carbon raw material. 85 to 99.5 wt% (mass%) of the refractory aggregate and 0.5 to 15 mesophase pitch powder with a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy % (Mass%) is added and blended, and a carbon-containing refractory (Claim 1) is disclosed.

Further, Patent Document 6 discloses a blending batch for a sliding nozzle plate composed of one or more oxides, carbides, nitrides or borides having a fire resistance of SK No. 20 or more and silicon powder and an average particle diameter of 100 mμ. A sliding nozzle plate comprising 0.2 to 15% by weight (mass%) of carbon black having an average specific surface area of m ² / g or more, mixed uniformly using an organic binder, and then reduced and fired. A method for manufacturing a refractory for a vehicle is disclosed.

Japanese Patent Laid-Open No. 58-204866 Patent Claim Japanese Patent Application Laid-Open No. 60-60973 Claims JP-A-8-119717 Patent Claims JP, 6-92719, A Claims Japanese Patent Publication No. 6-99182 gazette Japanese Patent Publication No. 58-20901 Patent Claim

  However, since the liquid binder used in Patent Document 1 or 2 is carbonized while the volatile components are removed, the mass of the carbon remaining finally becomes about 30 to 40% of the original liquid binder, and volatilizes. Since the voids are formed after the components are removed, the strength is adversely affected and the effect of strengthening the carbon bond is not exhibited.

  In addition, the powder pitch has the effect of reinforcing the carbon bond by melting in the initial stage of heating to fill the gaps in the refractory aggregate and then carbonizing it, and has less volatile components than phenolic resin. It is considered that the adverse effect on the strength due to the volatile component is smaller than that of the resin. In particular, the addition of pitch powder such as mesophase as described in Patent Documents 3 to 5 is effective to some extent in improving the hot strength characteristics. It has not yet been improved.

  Furthermore, in order to improve the hot strength characteristics of the refractory, a method of increasing the amount of addition of metals such as Si and Al is also known. This is not preferable because the thermal shock resistance is lowered.

  In addition, the use of carbon black as described in Patent Document 6 utilizes the fact that carbon black has a property that it is difficult to dissolve in molten steel, but may adversely affect hot strength characteristics. There is not preferable.

  In the conventional techniques as described above, the improvement of the hot strength characteristics due to the improvement of the binder and the addition of the pitch powder is not sufficiently obtained because the volatile components contained in the binder and the pitch disappear during the firing. This is thought to be because the generation of gaps or gaps adversely affects the hot strength characteristics.

  Therefore, the objective of this invention is providing the plate refractory for sliding nozzles obtained by the manufacturing method of the plate refractory for sliding nozzles which improved the hot strength characteristic, and this manufacturing method.

  In order to improve the hot strength characteristics of the sliding nozzle plate refractory, the present inventors need to reinforce the carbon bond so that the disappearance of volatile components contained in the binder and pitch does not lead to strength deterioration. And the present invention has been completed.

  That is, the method for producing a plate refractory for a sliding nozzle according to the present invention comprises a refractory aggregate; one or more components selected from the group consisting of metal, carbide and nitride; pitch powder having an average particle size of 20 μm or less. 0.5 to 4% by mass; and 1 to 8% by mass of fine carbon having an average particle size of 0.3 μm or less, a phenol resin was added as a binder, kneaded, molded into a predetermined shape, and then fired It is characterized by that.

  Moreover, the manufacturing method of the plate refractories for sliding nozzles of this invention is characterized by the mesophase content of pitch powder being 80% or more.

  Furthermore, this invention provides the plate refractory for sliding nozzles manufactured by the manufacturing method of the plate refractory for sliding nozzles.

  According to the present invention, the pitch powder and fine carbon having a specific average particle size are simultaneously added to the sliding nozzle plate refractory, and the pitch powder and fine carbon are dispersed widely and uniformly in the refractory, thereby firing. It is possible to reinforce the carbon bond generated by the oxidation of the phenol resin therein, thereby improving the hot strength characteristics of the sliding nozzle plate refractory.

  The sliding nozzle plate refractory according to the present invention is widely dispersed by adding a fine powder particle size to the pitch powder to be added, and having almost no volatile components by firing, and adding stable fine carbon to widely disperse. The carbon bond is reinforced to improve the hot strength characteristics. Although the details of the reason why the hot strength characteristics are improved by the present invention are not clear, the fine carbon and fine pitch powder are uniformly mixed and dispersed, so that the fine carbon that does not change during firing is caused by carbonization of pitch and phenol resin. This is presumed to be because the carbon bonds were uniformly dispersed and reinforced.

  The refractory aggregate used for the sliding nozzle plate refractory of the present invention is not particularly limited, and as a general refractory material such as alumina, magnesia, spinel, zirconia, alumina / zirconia, zirconia / mullite, etc. One or more of the raw materials used can be used. The amount of the refractory aggregate added is in the range of 78 to 98.5% by mass, preferably 85 to 97% by mass. If the added amount of the refractory aggregate is less than 78% by mass, it is not preferable because the strength is lowered. If the added amount exceeds 98.5% by mass, relatively fine carbon, pitch powder, etc. This is not preferable because the amount of slag decreases and the spalling resistance decreases.

Moreover, the plate refractory for a sliding nozzle of the present invention is blended with one or more components selected from the group consisting of metals, carbides and nitrides. These components are not particularly limited. For example, Si, Al, Si, or an alloy containing Al is used as a metal, SiC, B ₄ C, ZrC, or the like is used as a carbide, and Si ₃ N ₄ , AlN, BN, or the like is used. It can be used as a nitride. The addition amount of these components is in the range of 0.1 to 10% by mass, preferably 0.5 to 5% by mass. When the addition amount is less than 0.1% by mass, the effect of addition is not manifested, and when the addition amount exceeds 10% by mass, the effects of pitch powder and fine carbon are impaired. It is not preferable.

  The fine carbon used for the sliding nozzle plate refractory of the present invention has an average particle size of 0.3 μm or less, preferably 0.1 μm or less. If the average particle diameter of the fine carbon exceeds 0.3 μm, the dispersibility is deteriorated, so that the hot strength characteristics cannot be sufficiently provided, which is not preferable. The fine carbon to be added is not particularly limited. For example, carbon black such as channel black, furnace black, and thermal black can be used. The amount of fine carbon added is in the range of 1 to 8 mass%, preferably 2 to 5 mass%. Here, it is not preferable that the addition amount of fine carbon is less than 1% by mass because the addition effect does not appear, and even if the addition amount exceeds 8% by mass, no further addition effect can be obtained. It is not preferable.

  In addition to the fine carbon, carbon raw materials such as scale-like graphite, earth-like graphite, coke powder, and anthracite can be added to the sliding nozzle plate refractory of the present invention. The amount of carbon raw material (excluding fine carbon) added is in the range of 0.5 to 5 mass%, preferably 1 to 4 mass%. Here, if the addition amount of the carbon raw material is less than 0.5% by mass, it is not preferable because the addition effect cannot be exhibited, and if the addition amount exceeds 5% by mass, the strength adversely affects the characteristics. Is not preferable.

  The pitch powder used for the sliding nozzle plate refractory according to the present invention has an average particle diameter of 20 μm or less, preferably 10 μm or less. When the average particle diameter of the pitch powder exceeds 20 μm, the dispersion of the pitch powder in the refractory structure is deteriorated, and the effect of imparting hot strength is not obtained, which is not preferable. In addition, although pitch powder is not specifically limited, For example, pitch powder which used aromatic hydrocarbons, such as petroleum-type tar, coal-type tar, and naphthalene, etc. as a starting material can be used. In addition, since the mesophase content of the pitch powder affects the strength of the carbon bond after carbonization, it is preferably 80% or more, and more preferably 90% or more. The addition amount of pitch powder is 0.5-4 mass%, Preferably it exists in the range of 1-3 mass%. If the addition amount of the pitch powder is less than 0.5% by mass, the function is not sufficiently exhibited, which is not preferable. If the addition amount exceeds 4% by mass, the hot strength characteristics are adversely affected. It is not preferable because there is.

  The plate refractory for a sliding nozzle of the present invention can be obtained by adding a phenolic resin as a binder to a compound having the above composition, molding it into a predetermined shape, and baking it. In addition, the addition amount of a binder is in the range of 1 to 6% by mass, preferably 2 to 4% by mass with respect to 100% by mass of the blend. Firing is preferably performed, for example, within a range of 600 to 1500 ° C., preferably 800 to 1400 ° C. in a reducing atmosphere. In addition, after baking, you may perform a pitch impregnation process according to conventional operation.

Hereinafter, the plate refractory for sliding nozzle of the present invention will be further described with reference to examples.
A kneaded material obtained by blending the raw materials at the blending ratio shown in Table 1 below was molded into 230 mm × 114 mm × 50 mm and fired at 1400 ° C. in a coke breeze to obtain a specimen.
Details of the blended pitch powder are shown in Table 2.
Table 1 also shows the results of measuring the hot bending strength as an index of the hot strength characteristics of the obtained specimens.

  The sliding nozzle plate refractory of the present invention can be suitably used as a sliding nozzle plate refractory used for flow control when discharging molten steel in a ladle or tundish used as a molten steel container in the steel industry. it can.

Claims (3)

  Refractory aggregate; one or more components selected from the group consisting of metals, carbides and nitrides; 0.5-4 mass% pitch powder with an average particle size of 20 μm or less; and an average particle size of 0.3 μm or less A method for producing a plate refractory material for a sliding nozzle, comprising adding a phenol resin as a binder to a composition comprising 1 to 8% by mass of fine carbon, kneading, molding into a predetermined shape, and firing.   The manufacturing method of the plate refractory for sliding nozzles of Claim 1 whose mesophase content of pitch powder is 80% or more.   A sliding nozzle plate refractory manufactured by the method for manufacturing a sliding nozzle plate refractory according to claim 1.