JP7610109B2 - Method for manufacturing carbon-containing slide plate refractory - Google Patents

Description

The present invention relates to a method for manufacturing a carbon-containing slide plate refractory material used to control the flow rate of molten steel in the steel smelting process.

In steel smelting, slide plate refractories are commonly used to control the flow rate of molten steel. Two or three slide plate refractories with internal holes are stacked on top of each other, restrained, and subjected to surface pressure. The amount of molten steel discharged from a vessel such as a ladle or tundish can be controlled by adjusting the aperture of the holes through sliding the slide plate refractories. Slide plate refractories used under such harsh conditions must have all the following: mechanical strength to withstand restraint and surface pressure, spalling resistance to withstand the sudden thermal shock when receiving steel, and corrosion resistance to erosion by molten steel.

First, in order to ensure the spalling resistance of the slide plate refractory, it is common for the slide plate refractory to contain carbon. In other words, refractory materials that contain carbon are generally used to make up the slide plate refractory. Here, for example, alumina, spinel, magnesia, zirconia, etc. are used as the aggregate raw material that makes up the refractory material, and alumina is particularly used.

However, refractory materials consisting only of aggregate raw materials and carbon have the problem that the strength of slide plate refractory materials made from such refractory materials is low because the bonds between the raw material particles are formed only by carbon bonds. To address this problem, it is known that adding metallic silicon to refractory materials is effective. This is because ceramic bonds such as silicon carbide and silicon oxide (silica), which have stronger binding strength than carbon bonds, are formed inside the slide plate refractory during heat treatment (or firing).

For example, Patent Document 1 discloses a plate refractory for a sliding nozzle, which is formed from 5 to 20% by weight of a carbonaceous raw material, 3 to 10% by weight of metallic silicon, 1 to 20% by weight of a zirconia raw material, and the remainder being a neutral and/or basic refractory raw material. However, a part of the metallic silicon blended in the plate refractory for a sliding nozzle reacts with the carbonaceous raw material in the plate refractory to form silicon carbide, but both the metallic silicon and the silicon carbide are converted to silica during use of the plate refractory. Since silica has low corrosion resistance to molten steel, there is a problem in that the added metallic silicon significantly reduces the corrosion resistance of the plate refractory to steel types that are prone to erosion of refractories, such as high manganese steel, high oxygen steel, and calcium-treated steel.

To address this issue, the addition of metallic aluminum to slide plate refractories has been proposed. This is because the added metallic aluminum eventually changes into alumina, which has significantly higher corrosion resistance to molten steel than silica. However, when a slide plate refractory with added metallic aluminum is heat treated, the added metallic aluminum reacts with carbon to produce aluminum carbide, which is easily hydrated. If a large amount of aluminum carbide is produced, the slide plate refractory has the disadvantage that its hydration resistance decreases, hydration occurs inside the slide plate refractory during storage, causing cracks and making it unusable.

Various proposals have been made to suppress the formation of aluminum carbide in slide plate refractories to which metallic aluminum has been added as described above, and to improve the hydration resistance of slide plate refractories.

For example, Patent Document 2 discloses an alumina-carbon slide gate plate that is characterized by containing an alumina refractory aggregate and a carbon-containing raw material with a carbon content of 1 to 10 mass% and an Al-Si alloy with an outer percentage of 1 to 15 mass%, and being fired at a temperature range of more than 1000°C and up to 1500°C.

Patent document 3 also discloses a method for manufacturing a plate for a slide gate, which is characterized by kneading and molding a mixture of fire-resistant raw material, phenolic resin, and aluminum powder made of spherical atomized powder, and then heat treating the mixture at a temperature of 550 to 650°C.

Furthermore, Patent Document 4 discloses a plate for a slide gate, which is characterized by being made of a fired refractory material obtained by kneading, molding, and firing a mixture of 100% by weight of raw materials consisting of (A) 73% to 96% by weight of refractory aggregate made of one or more fire-resistant inorganic materials, (B) 0.1% to 0.5% by weight of fibrous metallic aluminum, (C) 1% to 5% by weight of flaky metallic aluminum powder, (D) 2% to 10% by weight of carbonaceous powder, and (E) 0.1% to 5% by weight of metallic silicon powder, to which 3% to 10% by weight of a thermosetting resin is added as an external binder, and the mixture is then kneaded, molded, and fired.

However, the slide plate refractories disclosed in Patent Documents 2 to 4 have problems in that they lack hydration resistance when stored for long periods of time and also have insufficient corrosion resistance against calcium-treated steel.

To address this issue, for example, Patent Document 5 discloses a slide plate refractory that is characterized by containing a refractory material made of refractory aggregate and carbonaceous raw material, and an aluminum-chromium alloy.

Furthermore, Patent Document 6 discloses a slide plate refractory material that is characterized by containing a refractory material made of refractory aggregate and a carbonaceous raw material, and an aluminum-chromium-silicon-based metal additive.

Patent Document 7 also describes a method for producing a carbon-containing refractory plate for a sliding nozzle, which comprises kneading a mixture of 60 to 97.4 mass% of a refractory inorganic material, 1 to 10 mass% of a carbonaceous material, 0.5 to 12 mass% of Al or an Al-containing alloy, 0.1 to 10 mass% of a nitride in which the standard Gibbs energy of formation per mole of _nitrogen atom in the _nitride at the highest temperature during heat treatment is greater and more negative than the standard Gibbs energy of formation of AlN, and 1 to 8 mass% of a binder, and forming the resulting molded body into a predetermined shape. The molded body is heat-treated at a maximum temperature of 800 to 1400°C in a non-oxidizing atmosphere mainly composed of N2, with an O2 concentration of 0.1% by volume or less and a CO + _CO2 concentration of 20% by volume or less; the nitride in which the standard Gibbs energy of formation per mole of nitrogen atom in the nitride at the highest temperature during heat treatment is greater and more negative than the standard Gibbs energy of formation of AlN is _Si3N4 , _Mg3N2 , or the _{like .} It is disclosed that the material is one or more selected from the group consisting of BN, CrN and _CrN2 (Claim 2).

Furthermore, Patent Document 8 discloses that, for the purpose of providing a sliding nozzle plate having excellent heat spalling resistance and improved oxidation resistance, at least one refractory aggregate raw material such as alumina, silica, zirconia, magnesia, spinel, etc., 0.2 to 10.0% by weight of expanded graphite, and 0.1 to 8.0% by weight of at least one metal as an oxidation inhibitor are added (claim 1); and further, at least one carbide such as ZrC, TiC, SiC, B ₄ C, etc., or a boride such as TiB ₂ , ZrB ₂ , AlB ₂ is added in an amount of 0.05 to 10.0% by weight as the oxidation inhibitor (claim 2, paragraph [0014]).

Japanese Patent Application Laid-Open No. 58-99161 JP 2012-192430 A JP 2000-94121 A Japanese Patent Application Laid-Open No. 11-199313 JP 2018-114507 A JP 2018-144088 A JP 2017-190254 A JP 2003-245770 A

However, although the slide plate refractories disclosed in Patent Documents 5 to 8 have improved hydration resistance and corrosion resistance, the hydration resistance of the slide plate refractories is insufficient when stored for long periods in humid locations, and the corrosion resistance of the slide plate refractories is insufficient when Ca-treated steel is cast in multiple furnaces.

The object of the present invention is therefore to provide a method for producing a carbon-containing slide plate refractory material that has sufficient mechanical strength and spalling resistance while at the same time having higher hydration resistance and corrosion resistance.

To conduct various investigations into carbon-containing slide plate refractories with added titanium carbide and/or metallic titanium, the inventors press-molded a mixture of various raw materials to obtain a molded body, which was then heat-treated under various conditions. After evaluating the properties of the slide plate refractory after the heat treatment, they obtained the following findings.

For example, when a molded body for a carbon-containing slide plate refractory to which titanium carbide and/or metallic titanium has been added is heat-treated under atmospheric pressure in a nitrogen atmosphere with a nitrogen partial pressure of 0.85 atm or more, calculated as a total pressure of 1 atm, the titanium carbide and metallic titanium can easily take up nitrogen in the atmosphere, and a nitrogen-containing phase containing titanium nitrides such as titanium carbonitride or titanium nitride and containing 1 to 20 mass% of nitrogen element (hereinafter collectively referred to as "nitrogen-containing phase") can be generated in situ, and both the corrosion resistance and hydration resistance of the resulting slide plate refractory to molten steel can be significantly improved. The generation of the nitrogen-containing phase can be confirmed by electron probe microanalyzer (EPMA) analysis.

The reason for improved corrosion resistance to molten steel is that the nitrogen-containing phase is generated in situ, which reduces the number of pores in the slide plate refractory, reduces the pore size, and makes the refractory structure denser. In addition, the nitrogen-containing phase itself is less likely to dissolve in molten steel and liquid inclusion slag in molten steel. Even if a small amount of the nitrogen-containing phase does dissolve, the viscosity of the molten steel and liquid inclusion slag can be significantly increased, making it difficult for the molten steel and liquid inclusion slag to penetrate into the slide plate refractory.

The reasons for the improved hydration resistance of the slide plate refractory are believed to be as follows:
First, when metallic aluminum is not added, aluminum carbide is not generated, and the nitrogen-containing phase is not hydrated, so the slide plate refractory is not hydrated. Also, when titanium carbide and/or metallic titanium are used in combination with metallic aluminum, metallic aluminum constantly absorbs nitrogen from the atmosphere through the nitrogen-containing phase that has already been generated during heat treatment, and changes to aluminum nitride, so that the generation of aluminum carbide is suppressed, and the nitrogen-containing phase generated in situ is very active, so that nitrogen is easily transferred from the atmosphere to metallic aluminum via the nitrogen-containing phase, and as a result, even when titanium carbide and/or metallic titanium are used in combination with metallic aluminum, the slide plate refractory is not hydrated.

On the other hand, even if a molded body for a slide plate to which metallic aluminum is added, but no titanium carbide and/or metallic titanium is added, is heat-treated in the same nitrogen atmosphere, the metallic aluminum is unlikely to change to aluminum nitride. Even if it does change to aluminum nitride, the amount of aluminum nitride produced is very small, and most of the metallic aluminum changes to aluminum carbide, which is easily hydrated.

Based on the above findings, the present inventors have completed the present invention.
That is, the present invention provides a method for producing a carbon-containing slide plate refractory material, characterized in that a slide plate molded body containing 0.5 to 8 mass % of titanium carbide and/or metallic titanium in outer percent relative to a main raw material composed of a refractory aggregate made of alumina and alumina-zirconia or a refractory aggregate made of alumina, alumina- zirconia and zirconia-mullite and a carbonaceous raw material is heat-treated under atmospheric pressure in a nitrogen atmosphere having a nitrogen partial pressure of 0.85 atm or more when converted to a total atmospheric pressure of 1 atm, at a temperature of 400 to 1400°C.

In addition, the manufacturing method of the carbon-containing slide plate refractory material of the present invention is characterized in that the slide plate molded body contains aluminum, silicon, magnesium, chromium or alloys thereof, silicon carbide, boron carbide, silicon nitride, boron nitride in an amount of 8 mass% or less in outer percentage relative to a main raw material composed of a refractory aggregate made of alumina and alumina-zirconia or a refractory aggregate made of alumina, alumina-zirconia, and zirconia-mullite and a carbonaceous raw material.

Furthermore, the manufacturing method of the carbon-containing slide plate refractory of the present invention is characterized in that the particle size of the titanium carbide and metallic titanium is 180 μm or less, and the heat treatment time is within the range of 3 to 30 hours.

The method for producing a carbon-containing slide plate refractory of the present invention has the effect of providing a carbon-containing slide plate refractory that has not only sufficient mechanical strength and spalling resistance, but also excellent corrosion resistance and hydration resistance.

1A shows the results of an electron probe microanalyzer (EPMA) analysis of a titanium carbide-containing slide plate refractory specimen (after heat treatment), and FIG. 1B shows the results of an electron probe microanalyzer (EPMA) analysis of a titanium metal-containing slide plate refractory specimen (after heat treatment).

The method for producing a carbon-containing slide plate refractory material of the present invention is characterized in that a slide plate molded body containing 0.5 to 8 mass% titanium carbide and/or metallic titanium as an outer percentage of the main raw material composed of refractory aggregate and carbonaceous raw material is heat-treated under atmospheric pressure in a nitrogen atmosphere with a nitrogen partial pressure of 0.85 atm or more when converted to a total pressure of 1 atm.

By heat treating a molded body for slide plates containing titanium carbide and/or metallic titanium in a nitrogen atmosphere with a nitrogen partial pressure of 0.85 atm or more when converted to a total pressure of 1 atm, the titanium carbide and/or metallic titanium in the molded body easily take up nitrogen in the atmosphere, and generate in situ a nitrogen-containing phase containing 1 to 20 mass% of nitrogen element containing titanium nitride such as titanium carbonitride or titanium nitride, thereby reducing the number of pores in the obtained slide plate refractory, reducing the pore size, and densifying the structure of the slide plate refractory. In addition, the nitrogen-containing phase itself is difficult to dissolve in molten steel and liquid inclusion slag in molten steel, and even if a small amount of the nitrogen-containing phase dissolves, the viscosity of the molten steel and liquid inclusion slag can be greatly increased.

Due to the dense structure, low solubility and increased viscosity of this slide plate refractory, it becomes difficult for molten steel and liquid inclusion slag in the molten steel to penetrate into the refractory, significantly improving the corrosion resistance of the refractory to molten steel.

Furthermore, the nitrogen-containing phase does not react with water and therefore does not cause hydration. Even when metallic aluminum is used in combination, the metallic aluminum constantly absorbs nitrogen from the atmosphere through the nitrogen-containing phase that has already been formed during heat treatment and changes to aluminum nitride, suppressing the formation of aluminum carbide. The nitrogen-containing phase formed in situ is highly active, and aluminum nitride is likely to be formed via the nitrogen-containing phase. As a result, even when metallic aluminum is used in combination, the slide plate refractory is unlikely to hydrate.

The nitrogen atmosphere in which the slide plate molded body is heat-treated may contain, in addition to the nitrogen component, components other than the nitrogen component, such as CO, _CO2 , _H2 , and _H2O . In the heat treatment under atmospheric pressure, the nitrogen partial pressure of the nitrogen atmosphere is 0.85 atm or more, preferably 0.90 atm or more, when the total pressure is converted to 1 atm.

Here, if the nitrogen partial pressure converted to a total atmospheric pressure of 1 atm is less than 0.85 atm, the titanium carbide and/or metallic titanium in the slide plate compact will not react with the nitrogen in the nitrogen atmosphere during heat treatment, and therefore a nitrogen-containing phase cannot be generated in situ. As a result, the resulting slide plate refractory will have insufficient corrosion resistance to molten steel and hydration resistance, which is undesirable.

The heat treatment temperature is 400 to 1400°C, preferably 500 to 1200°C. If the heat treatment temperature is less than 400°C, the rate at which the nitrogen-containing phase is formed will be slow and the amount produced will be small, so that the resulting slide plate refractory may have insufficient corrosion resistance to molten steel and hydration resistance. If the heat treatment temperature exceeds 1400°C, the reaction to form the nitrogen-containing phase will be too fast, and fine cracks may occur in the slide plate refractory during the heat treatment, resulting in reduced corrosion resistance and hydration resistance.

In the method for producing a carbon-containing slide plate refractory of the present invention, the slide plate molded body subjected to heat treatment in a nitrogen atmosphere contains titanium carbide and/or metallic titanium in an amount of 0.5 to 8 mass %, preferably 1 to 6 mass %, based on the main raw material consisting of refractory aggregate and carbon raw material. If the titanium carbide and/or metallic titanium content is less than 0.5 mass %, the amount of nitrogen-containing phase generated in situ is too small, and the corrosion resistance and hydration resistance of the obtained slide plate refractory to molten steel are insufficient, which is not preferable. If the titanium carbide and/or metallic titanium content exceeds 8 mass %, the amount of nitrogen-containing phase generated in situ is too large, which is not preferable, as there is a possibility that cracks will occur in the slide plate molded body during heat treatment.

The particle size of the titanium carbide and/or metallic titanium raw materials to be added is preferably 180 μm or less, and more preferably 150 μm or less. If the particle size of the titanium carbide and/or metallic titanium raw materials exceeds 180 μm, the particle size becomes too large, the rate at which the nitrogen-containing phase is generated slows down, and the amount generated also decreases, so that the corrosion resistance and hydration resistance of the resulting slide plate refractory to molten steel may be insufficient. Here, the "particle size" described in this specification is the particle size sieved using JIS Z8801-1 test sieve - Part 1: metal mesh sieve.

The heat treatment time is in the range of 3 to 30 hours, preferably 4 to 25 hours. Here, the heat treatment time refers to the total time spent in the temperature range of 400°C or higher. If the heat treatment time is less than 3 hours, the amount of nitrogen-containing phase generated in situ is too small, and the resulting slide plate refractory may have insufficient corrosion resistance to molten steel and hydration resistance. Furthermore, if the heat treatment time exceeds 30 hours, the heat treatment effect saturates, which is not economically preferable.

The titanium carbide raw material to be added to the mixture for producing the slide plate molded body can be titanium carbide alone, titanium-containing composite carbides and carbonitrides, such as composite carbides and carbonitrides consisting of titanium and one or more of aluminum, silicon, zirconium, chromium, nickel, molybdenum, tungsten, boron, etc. When titanium-containing composite carbides and carbonitrides are used, they are used in an amount such that the titanium carbide content is in the range of 0.5 to 8 mass%.

The raw material for metallic titanium to be added to the mixture for producing the molded body for the slide plate may be metallic titanium itself, a titanium-containing alloy, for example, an alloy of titanium with one or more of aluminum, silicon, magnesium, iron, manganese, nickel, copper, zirconium, chromium, molybdenum, tungsten, boron, etc., or a titanium compound, for example, titanium hydride. When using a titanium alloy or titanium compound, it is used in an amount such that the titanium content is in the range of 0.5 to 8 mass% in terms of titanium carbide.

The mixture for producing the slide plate molded body is composed of a main raw material consisting of a refractory aggregate and a carbonaceous raw material, where the refractory aggregate is not particularly limited, and for example, conventional raw materials such as alumina, magnesia, zirconia, alumina-zirconia, zirconia-mullite, spinel, and mullite can be used alone or in combination. These raw materials can be used as sintering raw materials or electrofusion raw materials.

Furthermore, the carbonaceous raw material constituting the main raw material may be, for example, carbon black, pitch, coke, natural graphite, artificial graphite, etc., which may be used alone or in combination.

The ratio of the refractory aggregate to the carbonaceous raw material is in the range of 1 to 10 mass% of the carbonaceous raw material, preferably 2 to 8 mass%. If the ratio of the carbonaceous raw material is less than 1 mass%, the spalling resistance of the resulting slide plate refractory may decrease. Also, if the ratio of the carbonaceous raw material exceeds 10 mass%, the in-situ formation of the nitrogen-containing phase may be inhibited.

In addition, for the purpose of further improving the oxidation prevention effect of the carbonaceous raw material and the mechanical strength of the slide plate refractory, metals such as aluminum, silicon, magnesium, and chromium, or alloys thereof, carbides such as silicon carbide and boron carbide, and nitrides such as silicon nitride and boron nitride can be appropriately blended into the slide plate molded body. The content of these components is 8% by mass or less, preferably 6% by mass or less, based on the main raw material consisting of the refractory aggregate and the carbonaceous raw material. If the content of these components exceeds 8% by mass, based on the main raw material consisting of the refractory aggregate and the carbonaceous raw material, the effect of the nitrogen-containing phase generated in situ may decrease.

Furthermore, tar, phenolic resin, etc. can be used as a binder in the molded body for slide plates. The amount of these binders added is not particularly limited, and they can be used in the conventional amounts, that is, in the range of 1 to 10% by mass, preferably 2 to 8% by mass, based on the total amount of the above components constituting the molded body for slide plates.

The molded body for slide plate used in the manufacturing method of the carbon-containing slide plate refractory of the present invention can be obtained by adjusting and kneading the above-mentioned raw materials in a predetermined mixing ratio, forming the mixture into a predetermined shape, and drying it.

The slide plate refractory obtained by the manufacturing method of the carbon-containing slide plate refractory of the present invention can be applied to the entire plate, but it can also be applied to only a part of the plate, for example, only near the working surface that comes into contact with molten steel.

Example 1
A molded body for slide plate was prepared with the blending ratios shown in Tables 1 to 8 below, and various carbon-containing slide plate refractory specimens were obtained by performing heat treatment under atmospheric pressure under the heat treatment conditions shown in Tables 1 to 8. The obtained specimens were subjected to hydration resistance evaluation tests and corrosion resistance evaluation tests. In addition, when preparing the molded body for slide plate, phenolic resin was used as a binder in an outer amount of 4 mass%, and a hydraulic press method was used for molding. In addition, the nitrogen partial pressure (atm) of the nitrogen atmosphere indicates the nitrogen partial pressure when the total atmospheric pressure is converted to 1 atm.
The "hydration resistance evaluation test" used a cube with a side length of 50 mm as a test specimen, and held the test specimen at 154°C for 8 hours under a pressure of 0.51 MPa using an autoclave device, and measured the mass increase rate of the sample before and after the test. The smaller the mass increase rate, the smaller the degree of hydration of the test specimen and the higher the hydration resistance;
In the "corrosion resistance evaluation test", a specimen measuring 25 mm wide x 25 mm wide x 250 mm high was used, and calcium-treated steel (Ca content = 40 ppm) was melted in an argon atmosphere in a high-frequency furnace, and the specimen was immersed in the melted steel at 1560°C for 5 hours. After the test, the width of the immersed part of the specimen was measured, and the change in the width of the specimen before and after the test was taken as the amount of corrosion loss. The smaller the amount of corrosion loss, the higher the corrosion resistance;
The "overall judgment" was made based on a comprehensive assessment of the hydration resistance evaluation test and the corrosion resistance evaluation test. A "◎" was given to a case in which both the hydration resistance evaluation test and the corrosion resistance evaluation test were excellent, a "○" was given to a case in which either of them tended to be slightly inferior, a "△" was given to a case in which some of the results of both evaluation tests were inferior but within the acceptable range, and an "×" was given to a case in which either or both of these evaluation tests were inferior.
The results are shown in Tables 1 to 8.

Tables 1 and 2 show the effect of the nitrogen partial pressure in the nitrogen atmosphere for the present invention and comparative examples. Table 3 shows the effect of the amount of titanium carbide added for the present invention and comparative examples. Table 4 shows the effect of the titanium carbide particle size for the present invention. Table 5 shows the effect of the maximum temperature of the heat treatment for the present invention. Table 6 shows the effect of the heat treatment time for the present invention. Table 7 shows an example of the present invention using a titanium alloy. The titanium alloy used was a titanium-aluminum alloy with a titanium content of 45 mass%. Table 8 shows an example of the present invention using alumina, alumina-zirconia, and zirconia-mullite as refractory aggregates, and an example of the present invention not containing metallic aluminum or metallic silicon.

The microstructure of the specimen (after heat treatment) of Example 2 of the present invention was analyzed by an electron probe microanalyzer (EPMA) and the results are shown in Figure 1 (a). It was confirmed that the titanium carbide contained 63.7% by mass of titanium, 26.9% by mass of carbon, and 9.4% by mass of nitrogen, and that a nitrogen-containing phase containing 1 to 20% by mass of nitrogen was present. It was also confirmed that the metallic aluminum used in combination was changed to a mineral phase composed of nitrogen, aluminum, etc.
Furthermore, the results of the microstructure obtained by the electron probe microanalyzer (EPMA) analysis of the specimen (after heat treatment) of Example 5 of the present invention are shown in Figure 1 (b). It was confirmed that the mixed metallic titanium was changed to a nitride with a titanium content of 83.6 mass% and a nitrogen content of 16.4 mass%, and that a nitrogen-containing phase containing 1 to 20 mass% of nitrogen was present. It was also confirmed that the metallic aluminum used in combination was changed to a mineral phase composed of nitrogen, aluminum, etc.
It was also confirmed that the test specimens obtained in other examples of the present invention also contained a nitrogen-containing phase containing 1 to 20 mass % nitrogen.
Furthermore, in Examples 30 to 33 of the present invention, which used a titanium-aluminum alloy, it was confirmed that both the titanium and aluminum constituting the titanium-aluminum alloy were changed to a mineral phase composed of nitrogen and aluminum, etc., and a nitrogen-containing phase containing titanium nitrides such as titanium carbonitride and titanium nitride and containing 1 to 20 mass % nitrogen element.

As is clear from the results shown in Tables 1 to 8, the test specimens obtained by the method of the present invention were significantly higher in both hydration resistance and corrosion resistance than the comparative examples.
Furthermore, the test specimens obtained by the method of the present invention had sufficient mechanical strength and spalling resistance.

Example 2
The carbon-containing slide plate refractory obtained in Example 2 of the present invention in Table 1 was used as a ladle slide plate refractory for casting calcium-treated steel in an actual plant. The service life of the ladle slide plate refractory made of the carbon-containing slide plate refractory obtained in Comparative Example 1 was 4ch, whereas the service life of the ladle slide plate refractory made of the carbon-containing slide plate refractory obtained in Example 2 of the present invention reached 6ch.
In addition, the carbon-containing slide plate refractory obtained in Example 2 of the present invention did not develop any cracks even when left in a place with a high humidity of 70% or more for about two years, but the carbon-containing slide plate refractory obtained in Comparative Example 1 developed many large cracks.

The carbon-containing slide plate refractory obtained by the method of the present invention has sufficient mechanical strength and spalling resistance, while at the same time having excellent corrosion resistance and hydration resistance, making it highly applicable in the steel industry.

Claims (4)

A method for producing a carbon-containing slide plate refractory material, comprising heat-treating a molded body for a slide plate, the molded body comprising refractory aggregate made of alumina and alumina-zirconia, or refractory aggregate made of alumina, alumina-zirconia, and zirconia-mullite, and a carbonaceous raw material as a main raw material, with titanium carbide and /or metallic titanium being contained in an outer percentage of 0.5 to 8 mass % relative to the main raw material, the outer percentage being ... 2. The method for producing a carbon-containing slide plate refractory material according to claim 1, wherein the slide plate molded body contains aluminum, silicon, magnesium, chromium or alloys thereof, silicon carbide, boron carbide, silicon nitride, or boron nitride in an amount of 8 mass% or less in terms of outer percentage based on a main raw material composed of a refractory aggregate made of alumina and alumina-zirconia or a refractory aggregate made of alumina, alumina-zirconia, and zirconia-mullite and a carbonaceous raw material. The method for producing a carbon-containing slide plate refractory material according to claim 1, wherein the particle size of the titanium carbide and metallic titanium is 180 μm or less. The method for producing a carbon-containing slide plate refractory material according to any one of claims 1 to 3, wherein the heat treatment time is within the range of 3 to 30 hours.