KR20030034980A - Coating material for porous and nozzle refractories - Google Patents

Abstract

PURPOSE: A coating material is provided, which is applied (coated) to the surface of the porous and nozzle refractory material to prevent the permeation of molten steel and to allow the permeated nonmetal material to be molten and removed. CONSTITUTION: The coating material comprises 20-80 wt% of a permeation preventing material which comprises at least one selected from the group consisting of Si3N4, AlN, BN, Sialon, Al2O3 and ZrO2, and has a purity of 90% or more and a size of 0.1 mm; 20-80 wt% of a molten material-forming material which comprises at least one selected from the group consisting of Na2O, B2O3, K2O, Al2O3 and ZrO2, has a purity of 90% or more and a size of 0.1 mm, and is coated on the upper or lower layer of the permeation preventing layer; 10-40 wt% of a binder which comprises at least one or two selected from the group consisting of vinyl acetic acid, emulsified resin, phosphoric acid, SiO2, Al2O3 sol and phenol resin; and a solvent which is an alcohol, water or their mixture.

Description

Coating material for porous and nozzle refractories {Coating material for porous and nozzle refractories}

The present invention relates to a porous refractory material and a nozzle refractory material for preventing infiltration of molten steel and adhesion of inclusions, and more particularly, to a porous and nozzle refractory material for controlling oxides attached to the surface of various refractory materials to reduce casting unevenness and steel quality. It relates to a coating applied to.

In general, in the production of molten steel, in order to equalize the temperature of the molten steel, uniformly disperse the alloying components, prevent clogging during casting, and to separate the inclusions in the molten steel, argon or porous refractory materials used in various refining furnaces such as ladles and tundishes are used. A bubbling process with nitrogen injection is applied.

In addition, the porous refractory material for gas injection used in the bubbling process must withstand chemical and physical erosion by molten steel or non-metallic inclusions in use, in addition to the desired air flow rate and uniform bubbling performance, and due to thermal shock during preheating or casting. There should be no cracks, and molten steel adhesion and infiltration should be minimized.

In order to improve the function of bubbling, which is one of the most important functions of the gas refractory refractory material for satisfying the above requirements, it is necessary to control the fine structure of the porous refractory material.

That is, the bubble depends on the pore size of the porous refractory material, and the larger the bubble, the lower the trapping performance of the inclusions, while the floating separation function is improved, so that the optimum pore size and porosity are required.

In addition, the pore size is determined by the particle size of the porous refractory material to be produced, and changes depending on the sintering agent, the firing temperature, the pressing force and the like.

Uniform pore distribution has the disadvantage that the size of the bubbles to be formed is uniform, thereby minimizing the problems of coalescing when the bubbles rise, while deteriorating the bubbling performance and service life due to infiltration of molten steel.

Therefore, the resistance between molten steel and non-metallic inclusions is limited by the pore size and porosity of the porous refractory material.

In addition, oxides generated on the surface of the porous refractory material, the steel grade produced, the casting temperature, the component of the refractory material, the amount of aluminum added, the amount of dissolved oxygen, the components in the steel, and the composition of the slag are important factors in clogging.

In addition, efforts have been made to improve the blockage as described above, and examples thereof include the following. In other words, by forming irregularities in the structural surfaces of various nozzle refractory materials, it is possible to improve the drift of molten steel and prevent physical adhesion of the adhesion inclusions, and to increase the deposits by physical stirring by injecting argon gas into the nozzle refractory material and the temperature decrease. Formation of slit or heat insulation layer to suppress, adhesion suppression technology by minimizing carbon content, easy reduction to aluminum in molten steel Minimize the ingredients and form inclusions In the nozzle refractories to form low melt , , A chemical method is used in which the deposit is washed off in molten steel by the addition of a component or the like.

However, aluminum added as a deoxidizer in molten steel reacts with oxygen in molten steel or oxygen in a refractory material to form an oxide, and There is a problem that easy melting due to the formation of low melt of the system.

In particular, infiltration of iron oxides and their inclusions by infiltration and oxidation of molten steel results in a decrease in breathability due to formation and infiltration of constituents and low melt of the refractory.

On the other hand, in order to improve bubbling, high porosity and proper pore size as well as low wettability are required, and carbon is mainly used as a material for porous refractory materials, but it is not suitable for high grade steel due to the disadvantage of dissolving carbon in steel. do.

In addition, in recent years, the cost reduction of the old material for multi-company use is desired, and the high durability of the fireproof material used as the old material is required.

Therefore, the present invention has been made to overcome the above-mentioned problems, the aluminum and the aluminum oxide formed during the refining process is attached to the porous fire retardant and the nozzle fire retardant to deteriorate casting quality and steel quality In order to solve the problem, an object of the present invention is to provide a coating that can improve the surface of the porous and nozzle refractory materials and reduce the cost by using multiple times.

1 is a cross-sectional view of the porous refractory material to which the coating agent of the present invention is applied, FIG. 2 is a cross-sectional view of the inner and outer immersion nozzle to which the present coating agent is applied, and FIG. 3 is a cross-sectional view of the inner and outer shroud nozzles to which the present coating agent is applied.

Explanation of symbols on the main parts of the drawings

1: Porous Refractory 2: Deposition Nozzle (inside)

3: immersion nozzle (external) 4: internal shroud nozzle

5: outer shroud nozzle

The present invention relates to a porous refractory material and a nozzle refractory material, which is coated on the surface of the porous to various nozzle refractory materials to prevent infiltration of molten steel and to form a low melt during infiltration.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of the porous refractory material to which the coating agent of the present invention is applied, FIG. 2 is a cross-sectional view of the inner and outer immersion nozzle to which the present coating agent is applied, and FIG. 3 is a cross-sectional view of the inner and outer shroud nozzles to which the present coating agent is applied.

First, the present invention is coated on the surface of the porous or nozzle refractory to prevent infiltration of molten steel, and is composed of a coating agent as shown in Table 1 so that the non-metal inclusions and low melt infiltrated during use are easily washed in the molten steel.

* Table 1 *

Composition of raw material Configuration Example 1 (molten steel infiltration prevention) Structural Example 2 (Low Melt Formation) , , , , , (1 or 2 types), particle size 0.1mm or less 20-80 - , , , , (1 or 2 types), particle size 0.1mm or less - 20-80 Binders (vinyl acetate, emulsion resins, phosphoric acid, , SOL, Phenolic Resin) 10-40 10-40 Alcohol or water 10-40 10-40 Application method Spray, quench, brush Spray, quench, brush Coating thickness (mm) 0.1-2.0 0.1-2.0

Coating agent to which the present invention is applied as shown in Table 1 above, the purity of more than 90% , , , , , Raw materials, such as these, are comprised by 1 type (s) or 2 or more types, and the coating is made into the particle size below 0.1 mm.

This, the configuration is formed during use of the infiltration layer or the raw material to prevent infiltration of molten steel Non-metallic inclusions such as these may cause clogging and formation of these components and low melts. , , , , Raw materials, such as these, may be composed of one kind or two or more kinds, and the particle size thereof is limited to 0.1 mm or less.

The reason for limiting the particle size of the raw material to 0.1mm or less is that when the coating becomes 0.1mm or more, the coating layer is uneven during coating, and it becomes difficult to form a low melt due to the nonuniformity of the composition.

The composition thus formed serves to allow non-metallic inclusions and low melt formed during coating to be washed down into the molten steel.

In addition, the addition range of the composition for preventing infiltration is added in the range of 20-80%.

The reason for limiting the range as described above is that if the addition of 20% or less takes a lot of time to form the coating layer, 80% or more is difficult to form a uniform coating layer due to poor workability during coating.

In addition, the composition range for forming the low melt forming layer is 1-5%, 40-80%, + 7-50%, 0-10%, 0-15%, C + SiC + Si 0-20%, CaO + MgO + It consists of 0-10%.

As a binder for forming the infiltration prevention layer and the low melt forming layer configured as described above, vinyl acetate, emulsified resin, phosphoric acid, , Sol or phenol resin is composed of one or two species at a rate of 10-40%.

In addition, the reason for limiting the binder to 10-40% is that the adhesion strength of the refractory materials such as nozzles when the 10% or less is weak, and when the 40% or more, there is a problem that the melt quickly during use.

On the other hand, the formation of the low melt is effective in the beginning, but the drawback gradually occurs during repeated use, so in order to continue the effect of forming a low melt on the infiltration layer or an infiltration layer on the low melt layer is also effectively applied.

In addition, when the number of times of use is low, the infiltration prevention layer or the low melt forming layer may be one layer, but when the use life is long, the infiltration prevention layer and the low melt forming layer are repeatedly coated.

In addition, Table 2 shows the appearance and the physical properties of the coating according to the present invention variously applied.

Table 2

characteristic Porous Refractory Upper, lower nozzle Shroud Nozzle Immersion nozzle Properties Porosity (%) 23-28 5-20 14-20 15-20 Volume specific gravity 2.7-3.0 2.2-3.1 2.2-2.5 3.4-3.9 Compressive strength (㎏ / ㎠) 250-400 200-1500 200-400 200-500 Chemical composition (%) 86-88 60-90 40-75 - 3-5 - 9-30 70-85 1-5 C 4-30 C 10-30 C 10-30 Aeration rate (Nℓ / min at 0.5 Bar) 120-130 - - -

As shown in Fig. 2 to Fig. 3, the inside and the deposition nozzle (inner, 2), the deposition nozzle (outer, 3), the inner shroud nozzle (4), the outer shroud nozzle (5) of the porous refractory material (1) Coating the surface of the.

In addition, as a method of coating, it is preferable to wet the coating with a spray, a brush or a cotton swab, and the coating is limited to a thickness of 0.1-2.0 mm.

The reason for the above limitation is that if the thickness of the coating is too thick, it will cause peeling by the difference in thermal expansion during use and non-uniform coating during manufacturing, and if too low, the prevention of infiltration of the molten steel and the prevention of adhesion of inclusions will be reduced.

As described above, the coating agent applied to the porous and nozzle refractory materials according to the present invention prevents infiltration of molten steel by coating the present invention on conventional porous or various nozzle refractory materials, and forms infiltrated nonmetallic inclusions and low melts in the molten steel stream. It is a very useful design to prevent the cause of casting unevenness and deterioration of steel quality by washing down.

In the above description of the preferred embodiment of the present invention, but the present invention is not limited to the specific preferred embodiment described above, it is common in the art to which the invention belongs without departing from the spirit of the invention claimed in the claims below. Those skilled in the art will be able to make various modifications.

Claims (4)

Coating on the surface of the porous to various nozzle refractory material to prevent infiltration of molten steel, to form a low melt during infiltration coating applied to the porous and nozzle refractory material. The method of claim 1, The coating agent has a purity of 90% or more , , , , , Infiltrate preventing material composed of one or two or more of these, 20-80% ratio, 0.1mm particle size, Is coated on the upper layer or the lower layer of the infiltration layer, the purity of more than 90% , , , , A low melt forming material composed of one or two or more thereof, a ratio of 20-80%, and a particle size of 0.1 mm; Mixed with the infiltration prevention material, low melt forming material, vinyl acetate, emulsified resin, phosphoric acid, , A binder comprising one or two or more sol and phenol resins in a ratio of 10-40%, The coating agent is applied to the refractory and nozzle refractory material, characterized in that mixed with the infiltration prevention material, low melt forming material, a binder, including alcohol, water or a solvent used to mix them. The method of claim 1, The composition range of the raw material to form the low melt is 1-5%, 40-80%, + 7-50%, over 10, 0-15%, C + SiC + Si 20% or more, CaO + MgO + A coating agent applied to a porous and nozzle refractory material, characterized in that composed of more than 10%. The method of claim 1, The coating agent is a coating agent applied to the porous and nozzle refractory material, characterized in that the applied thickness is 0.1-2.0mm.