KR101461578B1 - Method for preparing refractory and the refractory - Google Patents

Abstract

The present invention relates to a refractory manufacturing method and a refractory, comprising the steps of: preparing a carbon powder coated with a coating film; preparing a mixture by mixing the carbon powder coated with the coating film and a refractory raw material; The method comprising the steps of: preparing a solution containing a metal precursor; preparing a metal precursor film on the surface by mixing carbon powder into the solution; And separating and heating the carbon powder having the metal precursor film formed thereon. A coating film is formed on the surface of the carbon powder, and a refractory having improved oxidation resistance, fracture strength and service life of the refractory can be manufactured A refractory manufacturing method and a refractory are presented.

Description

FIELD OF THE INVENTION The present invention relates to refractories,

TECHNICAL FIELD The present invention relates to a refractory manufacturing method and a refractory, and more particularly, to a refractory manufacturing method and a refractory containing carbon whose oxidation is suppressed.

In general, MgO-C refractory is used as a material for protecting the inside of various equipment for processing molten metal in steel manufacturing process. Here, the carbon contained in the essential magnesia refractory serves to prevent the refractory from being damaged by erosion of the molten metal.

Carbon contained in the essential magnesia refractory is oxidized at a high temperature atmosphere during operation. When the carbon contained in the magnesia-based refractory is oxidized, the corrosion resistance and strength of the magnesia-based refractory are reduced and the porosity is increased. Thus, the oxidation of carbon causes the life span of the magnesia-based refractory to be limited. Therefore, an expensive antioxidant capable of preventing the oxidation of carbon is added to the magnesia-based refractory. As the antioxidant, a substance having a higher degree of oxidation than carbon is used, and examples thereof include aluminum, silicon carbide, calcium boride, and the like.

Such an antioxidant has a shorter lifetime than that of the magnesia-based refractory, and therefore, the antioxidant has a limitation in inhibiting the oxidation of the essential magnesia-based refractory during the desired operating time. In addition, theoretically, the oxidation of carbon should proceed after the oxidation of the antioxidant is completed, but the oxidation of the carbon may proceed even before the oxidation of the antioxidant is completed, and thus the antioxidant has a limitation in preventing the oxidation of carbon . In addition, the addition of the antioxidant increases the production cost of the magnesia-based refractory.

The present invention provides a refractory manufacturing method and refractory capable of effectively suppressing or preventing oxidation of carbon.

The present invention provides a refractory manufacturing method and a refractory capable of suppressing or preventing oxidation of carbon and improving the heat resistance of the refractory.

A refractory manufacturing method according to an embodiment of the present invention includes the steps of: preparing a carbon powder coated with a coating film; Preparing a mixture by mixing the carbon powder coated with the coating film and the refractory raw material; And molding the mixture to produce a molded body.

The process of preparing the carbon powder coated with the coating film includes: preparing a solution by dissolving a metal precursor in a solvent; Mixing a carbon powder in the solution to form a metal precursor film on the surface of the carbon powder; Separating the carbon powder having the metal precursor film formed thereon from the solution; And heating the carbon powder having the metal precursor film formed thereon.

Wherein the solvent comprises water, the metal precursor is dissolved in the water to generate ions, and the metal precursor film is adsorbed on the surface of the carbon powder dispersed and distributed in the solution, Film.

The metal material may include at least one of aluminum, manganese, silicon, lithium, and magnesium.

The process of forming the metal precursor film may last from 1 minute to 1 hour.

The heating process may include: drying the carbon powder having the metal precursor film formed thereon at a temperature of 80 ° C to 120 ° C; And heat-treating the dried carbon powder at a temperature of 200 ° C to 500 ° C.

The drying process may be continued for 30 minutes to 3 hours, and the heat treatment process may be continued for 30 minutes to 1 hour.

The refractory according to the embodiment of the present invention is a refractory material having fire resistance; And

And carbon powder distributed in the refractory material and coated with a coating film.

Wherein the carbon powder comprises at least one of graphite, graphite and carbon black, and the coating film is formed by adsorbing a metal precursor on the surface of the carbon powder, and the metal material is selected from the group consisting of aluminum, manganese, silicon, lithium, and magnesium And may include at least any one of them.

Wherein the weight of the refractory material is greater than the weight of the carbon powder coated with the coating film and the weight of the antioxidant or the organic binder is at least one of carbon It may be smaller than the weight of the powder.

According to the embodiment of the present invention, a coating film is formed on the surface of carbon contained in various refractories, and a refractory having improved oxidation resistance can be produced by using the coating film.

For example, when applied to an essentially refractory material of magnesia, a metal precursor film is formed on the surface of the carbon powder contained in the refractory, and the oxidation of carbon can be suppressed or prevented by the metal precursor film. When the oxidation of carbon contained in the refractory is suppressed or prevented, an increase in the porosity of the refractory caused by the oxidation of carbon is suppressed or prevented, and the strength and service life of the refractory can be improved.

Further, by using the carbon powder having improved oxidation resistance characteristics in the production of the refractory, the addition amount of the antioxidant to be added to the refractory material can be reduced as compared with the prior art in order to suppress or prevent oxidation of carbon.

1 is a conceptual view showing refractories according to an embodiment of the present invention;
2 is a process flow diagram of a refractory manufacturing method according to an embodiment of the present invention.
FIG. 3 is a photograph of a carbon powder according to an embodiment of the present invention photographed by a scanning electron microscope. FIG.
4 is a photograph of carbon powder according to an embodiment of the present invention taken by an electron transmission microscope.
Fig. 5 is a photograph of carbon powder taken before and after combustion according to Examples and Comparative Examples of the present invention. Fig.
6 is a composition table of refractories according to Examples and Comparative Examples of the present invention.
7 is a graph showing fracture strengths of refractory specimens according to Examples and Comparative Examples of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Like reference numerals refer to like elements throughout.

First, refractories according to embodiments of the present invention will be described.

1 is a conceptual view showing refractories according to an embodiment of the present invention.

Referring to FIG. 1, the refractory according to the embodiment of the present invention includes a refractory material 10 having fire resistance and a carbon (C) powder 20 distributed in the refractory material 10 and coated with the coating film 30 do.

The refractory material 10 is a material that can withstand physical and chemical influences at high temperatures. That is, the refractory material 10 exhibits properties such as low melting point, nonflammability, corrosion resistance, strength and heat insulation at high temperature. Examples of the refractory material 10 include silicon, aluminum, magnesium, zirconium, calcium, and the like, and oxides, carbides, silicides, and nitrides having melting points at high temperatures. Examples of the oxide include magnesia (MgO), alumina (Al2O3), silicon oxide and the like.

The carbon powder 20 is a material containing carbon and may be in the form of fine or granular powder, spherical particles, flakes of a plate-like structure, or the like. In addition, the carbon powder 20 may include at least one of graphite, graphite, and carbon black depending on its internal structure. The carbon powder 20 is dispersed and distributed in the refractory material, and plays a role of suppressing or preventing the damage of the refractory due to the thermal shock and corrosion of the refractory material generated by the contact of the high-temperature molten metal with the refractory material. Particularly, the carbon powder 20 serves to prevent the refining from being pollinated due to the erosion of the refractory by the high-temperature molten metal. The coating film 30 coated on the surface of the carbon powder 20 suppresses or prevents the oxidation of the carbon powder 20 into the thin film containing the metal. Accordingly, the metal may include a metal having a high oxidizing property. For example, the metal may include at least one of aluminum (Al), manganese (Mn), silicon (Si), lithium (Li), and magnesium (Mg). The coating film 30 may be formed in various ways, for example, by immersing the carbon powder 20 in a solution in which a metal precursor is dissolved to adsorb a metal precursor on the surface of the carbon powder 20 have. The coating film 30 formed on the surface of the carbon powder 20 may block or obstruct the contact of the carbon powder 20 with oxygen and oxygen may contact the metal to oxidize the metal. The oxidation of the carbon powder 20 can be suppressed or prevented.

As the oxidation of the carbon powder 20 in the refractory is suppressed or prevented, the carbon powder 20 plays a role of preventing inherent functions such as thermal shock and damage caused by corrosion of the refractory. Particularly, the carbon powder 20 can efficiently prevent the polling phenomenon of the refractory. On the other hand, when the carbon powder 20 is evaporated by oxidation, pores increase inside the refractory. The carbon powder 20 according to the present embodiment can suppress or prevent oxidation during a desired operating time and thereby suppress or prevent the evaporation of the carbon powder 20 and suppress or prevent the increase of the porosity of the refractory. In addition, the coating film 30 coated on the surface of the carbon powder 20 reacts with the refractory material 10, such as magnesia, contained in the refractory in a high-temperature operation atmosphere, and by this reaction a spinel phase can be formed in the refractory . The refractory formed with the spinel phase can have improved fracture strength as compared with the prior art.

The refractory material may further include at least one of the antioxidant 40 and the organic binder 40. The weight of the refractory material 10 is greater than the weight of the carbon powder 20 coated with the coating 30 and the weight of the antioxidant 40 or the organic binder 40 is less than the weight of the carbon powder 20 coated with the coating 30 (20). That is, the refractory material contains the most amount of refractory material, followed by the carbon powder having the coating film formed thereon, and the antioxidant and the organic binder contain trace amounts. The amount of the organic binder may be included more than the amount of the antioxidant, and conversely, the amount of the organic binder may be less than that of the antioxidant.

The antioxidant 40 is a substance which can be added to a general refractory such as a magnesia-based refractory to inhibit or prevent the oxidation of components of the refractory, such as carbon. Such antioxidants may include aluminum (Al), silicon (Si), Al-Mg alloy, carbide, boron based compounds. In the embodiment of the present invention, unlike the prior art, the carbon powder having the coating film formed therein is contained in the refractory material, and the oxidizing property is effectively suppressed, so that the antioxidant 40 may be added to the refractory material less or not.

Hereinafter, a refractory manufacturing method according to an embodiment of the present invention will be described.

2 is a process flow chart for explaining a refractory manufacturing method according to an embodiment of the present invention.

Referring to FIG. 2, a refractory manufacturing method according to an embodiment of the present invention includes the steps of preparing a carbon powder coated with a coating film (S100), preparing a mixture by mixing a carbon powder coated with a coating film and a refractory raw material And a step of forming a molded body by molding the mixture (S300).

In the step S100, a solution containing a metal precursor is prepared (S101), a step of forming a metal precursor film on the surface by mixing carbon powder into a solution (S102) (S103) of separating the powder in which the metal precursor film is formed from the solution (S103), and heating the powder in which the metal precursor film is formed (S104).

First, a metal precursor is dissolved in a solvent to prepare a solution (S101). The metal precursor may be dissolved in the solution to produce ions, and the solution may have ions resulting from the metal precursor. Here, the solvent includes water, and the metal material may include at least one of aluminum (Al), manganese (Mn), silicon (Si), lithium (Li), and magnesium (Mg). Here, the reason for using the solution having ions in the process of preparing the carbon powder is as follows. The ions generated in the solution by the metal precursor may be dispersed widely in the solution. And can effectively react with the carbon powder mixed in the solution. Therefore, it is possible to uniformly and effectively coat the metal precursor film on the surface of the carbon powder by using the solution. Solvents that can be used in the preparation of such solutions include water, a polar solvent, and ethanol, a non-aqueous polar solvent. In this embodiment, as a solvent, water can be easily secured and the production of pollutants after operation is small.

The carbon powder is mixed with this solution to form a metal precursor film on the surface of the carbon powder (S102). The process of forming the metal precursor film may last from 1 minute to 1 hour. The surface of the carbon powder mixed with the solution is formed into a film that adsorbs metal precursors, that is, ions, to surround the surface of the carbon powder. Wherein the carbon powder comprises at least one of graphite, graphite and carbon black. The carbon powder may be modified so that the surface of the carbon powder has a hydrophilic surface before being added to the solution.

The carbon powder having the metal precursor film formed thereon is separated from the solution (S103). Various methods for separating the carbon powder having a coating film, which is a desired material, from the solution can be applied to the carbon powder separation method. For example, the carbon powder having the coating film formed thereon can be separated from the solution by filtration. The powder in which the metal precursor film is formed is heated to prepare a carbon powder coated with the coating film (S104). The heating process may include a process of drying the carbon powder having the coating film formed thereon at a temperature of 80 ° C to 120 ° C and a process of heat-treating the carbon powder at a temperature of 200 ° C to 500 ° C. The carbon powder having a coating layer may be dried to remove a solvent such as water remaining in the carbon powder having the coating layer formed thereon. In addition, the carbon powder having the coating film formed thereon can improve the cohesion of the coating film through the heat treatment process, and the coating film can be stabilized on the surface of the carbon powder. For this, the drying process lasts from 30 minutes to 3 hours, and the heat treatment process can last from 30 minutes to 1 hour. However, the duration of the drying process and the heat treatment process may be increased or decreased by the operator's desired time for the stabilization of the carbon powder coating film. Through the series of steps S101, S102, S103, and S104, the process of preparing the carbon powder having the metal precursor film is completed (S100).

Next, a mixture is prepared by mixing the carbon powder coated with the coating film and the refractory raw material (S200). Here, the refractory raw material includes a refractory material such as magnesia (MgO), and may further include at least one of an antioxidant and an organic binder.

Thereafter, the mixture is compression molded to produce a molded body to complete the manufacture of the refractory (S300). A method of compression molding a mixture can be applied, for example, by injecting a mixture into a mold having a predetermined internal space and compressing the mixture to produce a refractory formed body.

The refractory produced by the refractory manufacturing method according to this embodiment can coat the surface of the carbon powder used as a raw material of the refractory with the metal precursor film and the oxidation resistance of the carbon powder can be improved. Evaporation due to the oxidation of the carbon powder can be suppressed or prevented by the improved carbon powder, and the lifetime of the entire refractory can be improved compared to the prior art.

In describing embodiments of the present invention, a method of manufacturing a mixture by mixing a carbon powder coated with a coating film and a refractory material in the refractory manufacturing method described above, and a method of molding a manufactured mixture to produce a molded body, There is no need to limit the method. A method of mixing refractory raw materials used in a general refractory manufacturing method and a method of molding a manufactured mixture may be used.

A coating film such as a metal precursor film may be uniformly formed on the surface of the carbon powder produced by the refractory manufacturing method described above.

In the following, a carbon powder according to an embodiment of the present invention was prepared, and the carbon powder was photographed by an electron microscope and an electron transmission microscope to confirm a coating film formed on the carbon powder and the carbon powder.

FIG. 3 is a photograph of a carbon powder according to an embodiment of the present invention taken by an electron scanning microscope, and FIG. 4 is a photograph of an electron transmission microscope of a carbon powder according to an embodiment of the present invention. Fig. 3 (b) is a graph showing the distribution of the carbon components in the carbon powder according to the embodiment of the present invention. Fig. 3 (a) is a photograph of particles of the carbon powder with a coating film formed thereon by a scanning electron microscope, 3 (c) is a photograph of the distribution state of aluminum (Al) in a carbon powder according to an embodiment of the present invention, which is photographed by a scanning electron microscope. 3 (d) is a photograph of the distribution of oxygen (O) in the carbon powder according to the embodiment of the present invention, taken by an electron microscope. 4 (a) and 4 (b) are photographs of carbon powder coated with a metal material by an electron transmission microscope.

First, a carbon powder according to this embodiment is manufactured through the above-described refractory manufacturing method. At this time, aluminum nitride is used to produce a metal precursor, and graphite powder is prepared as a carbon powder. After the aqueous solution is prepared by dissolving aluminum nitride in a solvent such as water, the prepared graphite powder is mixed to form a coating film such as an aluminum (Al) metal precursor film on the surface of the graphite powder. The graphite powder having the metal precursor film formed thereon is filtered and separated from the aqueous solution, dried at 100 ° C for 1 hour, and heat-treated at 500 ° C for 1 hour to complete the production of a graphite powder coated with a coating film such as a metal precursor film.

The coated graphite powder was photographed with an electron microscope and an electron transmission microscope to confirm the particles of the coated graphite powder. As a result, it was confirmed that aluminum as a component of the metal precursor was detected on the surface of the particles. (See Figs. (See FIG. 4 (a)). Particularly, when photographs taken by an electron transmission microscope were confirmed, it was confirmed that a coating film having a thickness of about 400 nm was uniformly coated on the entire surface of the particles. Was observed only around the particles, and no magnetic cohesion phenomenon was observed. In addition, by analyzing the elements of the coated graphite powder, it was confirmed that the distribution of the respective components was uniformly detected in the graphite powder coated with aluminum, which is a component of the carbon precursor and the precursor of the metal precursor. (Fig. 3 (b) And FIG. 3 (c)). Therefore, it can be confirmed that the method of coating the carbon powder using the solution is effective in forming a uniform coating film on the surface of the carbon powder.

The coating film is uniformly formed on the surface of the carbon powder produced by the above-described refractory manufacturing method, so that oxidation phenomenon of the carbon powder can be effectively suppressed or prevented.

Hereinafter, the carbon powder and the conventional carbon powder according to the embodiment of the present invention are prepared, and the oxidation resistance characteristics of each of the carbon powder after burning are compared.

Fig. 5 is a photograph of the carbon powder according to Examples and Comparative Examples of the present invention taken before and after the combustion. 5 (a) is a photograph of a state of a conventional carbon powder before combustion, and Fig. 5 (b) is a photograph of a state of a conventional carbon powder after combustion. Fig. 5 (c) is a photograph of the state of the carbon powder before burning according to this embodiment, and Fig. 5 (d) is a photograph of the state after burning of the carbon powder according to this embodiment.

First, a carbon powder, for example, a coated graphite powder according to an embodiment of the present invention is prepared and a conventional carbon powder such as a conventional graphite powder is prepared as a comparative object. Then, each graphite powder is burned at 1000 캜 for one hour. 5 (a) and 5 (b), it is observed that the color of the surface of the conventional graphite powder before combustion (Fig. 5 (a)) and after combustion (Fig. 5 . This change is caused by the evaporation of the carbon component contained in the conventional graphite by burning. Thus, it can be confirmed that the conventional graphite powder is completely oxidized after combustion.

On the contrary, when the graphite powder after the burning is compared with the state before the burning, no change is observed in the graphite powder of Fig. 5 (c) and Fig. 5 (d). That is, it can be confirmed that even after burning the graphite coated with the carbon component contained in the coated graphite, it is contained in the graphite. Therefore, it can be confirmed that the coating film formed on the carbon powder according to this embodiment effectively prevents the oxidation of the carbon powder.

The refractory produced by the above-described refractory manufacturing method can increase the breaking strength of the refractory.

The fracture strength of the refractory specimen according to the embodiment of the present invention will be described below in comparison with the prior art.

FIG. 6 is a composition table of refractories according to Examples and Comparative Examples of the present invention, and FIG. 7 is a graph showing fracture strength of refractory specimens according to Examples and Comparative Examples of the present invention. Here, FIG. 7 (a) is a result value showing the fracture strength before the combustion test in the comparative example, and FIG. 7 (b) is the result value showing the fracture strength after the combustion test in the comparative example. Fig. 7 (c) is a result value showing the fracture strength before the combustion test in the embodiment, and Fig. 7 (d) is the result value showing the fracture strength after the combustion test in the embodiment.

First, coated graphite powder and conventional graphite powder are prepared. Further, 83.74 g of magnesia, 4.93 g of an antioxidant and 1.48 g of an organic binder were further prepared as a raw material of the refractory specimen (see Fig. 6). Each prepared graphite powder was mixed with 8.85 g of the raw material of the refractory specimen, Cool Isostatic Press, CIP) is used to form each specimen. Here, the comparative example is a refractory specimen molded using conventional graphite powder, and the embodiment is a refractory specimen molded using coated graphite powder.

The fracture strengths of the comparative examples and the examples are tested using a universal testing machine. At this time, the experiment was performed five times in the 4-point bending mode, 0.5 mm / min and the room temperature, and the results were averaged to be shown in FIG. 7, it can be seen that the embodiment of the present invention shows that the fracture strength after combustion test is greatly improved (see FIGS. 7 (c) and 7 (d)). But also due to the formation of the spinel phase by the reaction between the magnesia used as the raw material of the specimen and aluminum, which is a component of the coating film. Therefore, it can be seen that the refractory according to the embodiment of the present invention has improved fracture strength as compared with the prior art.

Although the above embodiment of the present invention exemplifies the case of the magnesia-based refractory, it can also be applied to the manufacture of various refractories other than the above. It should be noted that the above-described embodiments of the present invention are for explanation purposes only, and are not for the purpose of limitation. It is to be understood that various modifications may be made by those skilled in the art without departing from the scope of the present invention.

10: refractory material 20: carbon powder
30: Coating film 40: Antioxidant, organic binder

Claims (10)

A method of manufacturing a refractory,
Preparing a solution by dissolving a metal precursor in water;
Mixing a carbon powder in the solution to form a metal precursor film on the surface of the carbon powder;
Separating the carbon powder having the metal precursor film formed thereon from the solution;
Drying the carbon powder having the metal precursor film formed thereon at a temperature of 80 ° C to 120 ° C;
Heat-treating the dried carbon powder at a temperature of 200 ° C to 500 ° C to prepare a carbon powder coated with a coating film;
Preparing a mixture by mixing the carbon powder coated with the coating film and the refractory raw material; And
And molding the mixture to produce a molded body,
Wherein the metal precursor is dissolved in the water to produce ions,
Wherein the metal precursor film is formed by adsorbing the ions dispersed and distributed in the solution on the surface of the carbon powder.
delete delete The method according to claim 1,
Wherein the metal material comprises at least one of aluminum, manganese, silicon, lithium, and magnesium.
The method according to claim 1,
Wherein the process of forming the metal precursor film is continued for 1 minute to 1 hour.
delete The method according to claim 1,
The drying process lasts from 30 minutes to 3 hours,
Wherein the heat treatment process is continued for 30 minutes to 1 hour.
delete delete delete

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