KR101132670B1 - A composition for repairing edge dam - Google Patents

Abstract

The present invention relates to a repair composition used for repairing edge dams (edge dams or side dams) used for sealing molten steel at the side of casting rolls of sheet metal rolls and sealing edges, and more specifically, 60 to 97 wt% of a corrosion resistant material. ; And 3 to 40% by weight of reinforcing material; And a method for repairing an edge dam using the repair composition.

Strip Casting, Edge Dam, Side Dam, Corrosion, Repair

Description

Edge dam repair composition {A COMPOSITION FOR REPAIRING EDGE DAM}

The present invention relates to an edge dam repair composition used to repair an edge dam (Edge Dam or Side Dam) used to seal molten steel on the side of a casting roll of a thin sheet machine, and a method of repairing an edge dam using the composition.

The edge dam is a structure for sealing molten steel on the side of the casting roll of the thin plate player, and is composed of a substrate refractory at the portion in contact with the molten steel and a lubricating ceramic such as Boron Nitride (BN) at the portion in contact with the casting roll. . Edge dams are repeatedly heated and cooled during preheating and operation, and because they are large members bound to steel structures, cracks due to thermal shock and thermal expansion behavior occur in edge dam refractory materials. On the other hand, the interface between the substrate refractory and the lubricating ceramic material is spaced apart by the difference in thermal expansion coefficient between the two materials, so that a scull is attached to the edge of the thin plate in which molten steel penetrates into the gap during operation. Therefore, cracking of edge dam and the like becomes a factor of generated thin plate defect.

Japanese Patent Application Laid-Open No. JP 04-224050 proposes a method of blowing a gas from the dam surface to form a gas film between the dam and the molten steel in order to reduce cracks, melt damage and the like of the edge dam. US 6,296,046 also proposes a method of changing the position of the edge dam corresponding to the location of the solidification point during casting, thereby reducing the rotational force to reduce the melting of the edge dam and improve the quality of the edge area around the strip. However, the above methods could not prevent the generation of cracks or cracks due to thermal deformation and thermal shock of the edge dam refractory itself, and thus prevent the penetration of cracks in molten steel.

Accordingly, there is a need in the art for a method for effectively repairing cracks, corrosion, and the like formed on edge dams.

The present invention is a composition for repairing the edge dam used for sealing the molten steel on the side of the casting roll of the sheet metal player; And it aims at providing the repair method of an edge dam using the said composition.

The present invention is 60 to 97% by weight of the corrosion resistant material; And it provides an edge dam (edge dam) repair composition comprising 3 to 40% by weight of the reinforcing material.

The corrosion resistant material used by this invention uses a normal basic fireproof aggregate or powder as a main component of the edge dam repair composition of this invention. Basic refractory aggregates or powders used as corrosion resistant materials include alumina / titania mixtures; Or an alumina / titania / spinel mixture, more preferably an alumina / titania / spinel mixture, but not limited thereto. Since alumina, titania, and spinel raw materials have high corrosion resistance against molten steel such as stainless steel (SUS) and carbon steel, they are suitable for the edge dam repair composition of the present invention. In particular, alumina and titania form aluminum titanate (AlTiO ₅ ) at the operating temperature. This material has a low coefficient of thermal expansion and low wettability to molten steel, thereby achieving both thermal shock characteristics and corrosion resistance to molten steel. The content ratio of alumina and titania used in the corrosion resistant material is not particularly limited, but in order to form a sufficient amount of aluminum titanate (AlTiO ₅ ) at high temperature, the weight ratio of alumina and titania is 1: 0.6 to 1: 1.5. Do. Raw materials of alumina, titania and spinel may be used as, but are not limited to, sintered raw materials or artificial raw materials of electrolysis. The purity of the basic refractory aggregate or powder is not particularly limited but is preferably at least 90%.

The content of the corrosion resistant material included in the repair composition is 60 to 97% by weight, preferably 70 to 95% by weight based on the total weight of the repair composition. If the content of the corrosion resistant material is less than 60% by weight, the corrosion resistance and thermal shock resistance to the molten steel is lowered, which is not preferable. If the content exceeds 97% by weight, the hot strength is lowered and the erosion by the molten steel increases, which is not preferable.

The reinforcing material used in the present invention is an auxiliary component used to secure workability, hot strength, corrosion resistance, volume stability, etc. of the edge dam repair material using the repair composition of the present invention. matrix). The reinforcing material according to the invention is selected from the group consisting of clay powder, calcined alumina, silica, alumina cement, phosphate powder and mixtures thereof. Although raw materials, such as calcined alumina and silica, are not specifically limited, It is preferable to use the ultra-fine powder used for normal amorphous refractory manufacture.

The content of the reinforcing material included in the repair composition is 3 to 40% by weight, preferably 5 to 30% by weight based on the total weight of the repair composition. If the content of the reinforcing material is less than 3% by weight, the hot strength is low, and if the content of the reinforcing material is more than 40% by weight, the corrosion resistance or the thermal shock resistance is low, which is not preferable. The purity of the reinforcing material is not particularly limited, but is preferably 90% or more.

Preferably, the composition for repairing edge dams according to the present invention may further include additives for securing the formability of the refractory aggregate and the powder which are corrosion resistant materials, and improving hot strength and thermal shock resistance. Additives used to secure formability include fluidizing agents; Curing regulators; Thickeners; Dispersing agent; Peptising agent; And pulp fibers. Examples of preferred glidants include melanin glidants; Naphthalin-based fluidizing agents; Lignin-based fluidizing agents; And Na-P-based fluidizing agents. Examples of preferred curing regulators include sulfate-based curing regulators; And acetate salt curing modifiers. Examples of preferred thickeners include polyvinylacetate; Natural clay powders such as bentonite or kaolin; Ultra fine clay; Polyvinyl alcohol; And methylcellulose. Examples of preferred peptizing agents include sodium phosphate based peptising agents such as sodium hexametaphosphate; Potassium phosphate; Calcium phosphate; Sodium silicate; And potassium silicate. Examples of preferred pulp fibers include wood flour; Expandable inorganic fibers; Polypropylene fibers; share; And alumina-silica fibrous fibers. The purity and amount of the additives are not particularly limited, but it is preferable to add the additives in purity and content for securing moldability, workability, and the like of a conventional amorphous refractory material. More preferably, the content of the fluidizing agent, the curing regulator, the thickener, the dispersant, the peptizer and the pulp fiber is not particularly limited, but preferably 0.1 to 1 weight, respectively, based on 100 parts by weight of the total weight of the corrosion resistant material and the reinforcing material. Parts, 0.1 to 0.5 parts by weight, 0.1 to 2 parts by weight, 0.1 to 2 parts by weight, 0.1 to 1 part by weight, and 0.1 to 0.3 parts by weight.

Additives for improving hot strength and thermal shock resistance include, but are not limited to, potassium titanate and aluminosilicate inorganic fibers. The shape, amount, purity, etc. of the additives are not particularly limited, but are preferably used as a standard generally used for amorphous refractory materials. More preferably, the content of the additive is independently 0.1 to 0.5 parts by weight based on 100 parts by weight of the total weight of the corrosion resistant material and the reinforcing material.

In addition, the present invention comprises the steps of preparing the edge dam repair material by mixing the repair composition with water; And repairing an edge dam by using the repairing material.

The content of water used to prepare the edge dam repair material according to the present invention may be freely selected in consideration of the components of the repair composition and the viscosity of the edge dam repair material finally formed, but preferably the total of the repair composition. The weight is 10 to 20 parts by weight based on 100 parts by weight. The method of mixing the repair composition with water can be freely selected from a known mixing method such as a kneader, but the repair composition according to the present invention has a large pressure because it is close to a plastic amorphous material having a low water content. It must be kneaded to allow uniform mixing of raw materials. Therefore, it is preferable to mix water and the composition for repair of this invention using a kneader. The manufactured edge dam repair material is used to repair cracks generated in the edge dam, or to seal the substrate refractory and the highly lubricated ceramic edge, thereby preventing the penetration of molten steel into the inside of the edge dam during operation. Defects can be reduced.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are only intended to aid the understanding of the present invention and are not intended to limit the scope of the present invention in any sense. Those skilled in the art will be able to embody the present invention in other forms based on the raw materials and methods of preparation of conventional amorphous refractory materials.

Example : Edge dam  Preparation of repair compositions and repair materials

Corrosion resistant materials of the compositions shown in Table 1 below; Reinforcement material containing 40% ultra-fine alumina (A-161SG, Japan Showa Denko; particle size-5 microns), 40% ultra-fine silica (RH24, Rhodia Silica) and 20% alumina cement (UAC 80N, Union cement) ; 0.3 part by weight of hexamethine soda (monochemical) as a Na-P-based peptizer with a total weight of the corrosion resistant material and the reinforcing material as 100 parts by weight; And 100 parts by weight of the edge dam repair composition consisting of 1 part by weight of ultra fine clay (Bentonite, Shanxi Huading Co.) as a clay-based thickener was first mixed with 15 parts by weight of water, and then kneaded secondly using a kneader Edge dam repair materials of Examples 1 to 8 were prepared.

Experimental Example

The hot strength of the specimen, the corrosion resistance by the molten steel, and the thermal shock resistance were evaluated as follows using a conventional amorphous material test method.

Hot strength: The bending strength was measured using a refractory hot bending strength tester of the specimen at 1400 ℃ hot.

Corrosion resistance: The test piece was constructed inside a crucible installed inside by induction melting and dissolved by adding SUS304 pellets. After maintaining for 1 hour, the specimens were collected and the erosion thickness was measured.

Thermal shock resistance: 50 × 50 × 50mm to prepare a specimen and dried for 24 hours at 100 ℃, charged in an electric furnace maintained at 1400 ℃ and maintained for 30 minutes and then quenched using water at room temperature 5 times The compressive strength before and after the test was measured, and the thermal shock resistance of the specimen was evaluated from the rate of decrease of the compressive strength using a refractory compressive strength measuring instrument.

The composition and physical property measurement results of the repairing material according to the embodiment are shown in Table 1 below. The physical properties were expressed in terms of percentage index, with the test result of Example 1 being 100.

Example
number Corrosion resistant material (% by weight) foundation
(weight%) Hot strength
Indices Corrosion resistance
Indices Thermal shock resistance
Indices Alumina Titania Spinel One 30 30 0 40 100 100 100 2 48 49 0 3 65 120 120 3 24 56 0 20 100 80 70 4 56 24 0 20 100 85 75 5 20 20 10 50 105 95 100 6 35 30 15 20 105 120 120 7 45 40 0 15 100 130 130 8 45 35 0 20 105 125 125

※ Alumina: SA-37, Daehan Ceramics; Titania: R-O2, Jameel Al Hawamdeh Trading Est .; And spinel: AM70, Luoyang Hongfeng.

As shown in Table 1, the repair material according to the present invention exhibits high mechanical strength, corrosion resistance, and thermal shock resistance, and thus is suitable for repairing cracks and the like of edge dams.

The edge dam repair composition according to the present invention has good mechanical durability, corrosion resistance and heat shock resistance to molten steel, and thus repairs cracks generated in the edge dam, or seals the substrate refractory and the highly lubricating ceramic edge, thereby damaging the edge dam during operation. By preventing the penetration of the molten steel to the inside there is an effect that can reduce the thin plate edge defects due to the skull generation.

Claims (8)

60 to 97% by weight of corrosion resistant material; And 3-40 weight percent of reinforcing material, A composition for repairing edge dams, further comprising an additive selected from the group consisting of glidants, curing regulators, thickeners, dispersants, peptizing agents, pulp fibers, potassium titanate and aluminosilicate inorganic fibers. The composition of claim 1, wherein the corrosion resistant material comprises alumina and titania. The composition of claim 2, wherein the weight ratio of alumina and titania is 1: 0.6-1: 1.5. The composition of claim 2, wherein the corrosion resistant material further comprises a spinel. The composition of claim 1, wherein the reinforcing material is selected from the group consisting of clay powder, calcined alumina, silica, alumina cement, phosphate powder, and mixtures thereof. The composition of claim 1, wherein the corrosion resistant material and the reinforcing material are 70 to 95% by weight and 5 to 30% by weight, respectively. delete Preparing an edge dam repair material by mixing the edge dam repair composition according to any one of claims 1 to 6 with water; And Repairing an edge dam using the edge dam repair material.