METHOD FOR MANUFACTURING CERAMIC STEEL SHEET

Abstract

The present invention relates to a method for manufacturing a ceramic steel sheet and, more particularly, to a method for coating ceramic on one surface of a steel sheet, the method comprising the steps of: (a) installing a mold made of a refractory material for a thermite reaction on one surface of a plate-shaped steel sheet; (b) injecting a thermite mixture (M) as a reaction material into the mold so as for the thermite mixture to be uniformly distributed at a predetermined height on one surface of the steel sheet; (c) injecting an ignition material (I) onto the thermite mixture (M) after the step (b) and then igniting the ignition material (I) to induce a thermite reaction of the thermite mixture (M); and (d) pressing a press machine against the thermite mixture (M) in a molten state after the step (c) to form a ceramic layer having a predetermined shape on one surface of the steel plate.

Description

TECHNICAL FIELD

The present invention relates to a method of coating one surface of a steel sheet with ceramics by inducing a thermite reaction.

BACKGROUND ART

Generally, in the fields of chemistry, construction, metallurgy, furnaces, and plant industries, a high level of properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance are required for facilities including pipes or steel plates for transportation or heat exchange. Ceramics exhibit excellent heat resistance, corrosion resistance, chemical resistance, and abrasion resistance. However, ceramics inherently have low toughness, low elongation and high brittleness, and raise issues regarding workability, bonding property and partial replacement in a facility.

In order to overcome such issues, metal double pipes (plates) and metal-ceramic composite pipes (plates) have been actively studied and some thereof have become commercially available.

Metal double pipes are manufactured using centrifugal casting. In centrifugal casting, when molten stainless steel is poured into a rotating metal tube, it is applied onto to the inside of the metal tube by centrifugal force, and thus closely adheres to the metal tube. However, such processes by centrifugal casting are inefficient due to high initial costs for equipment including melting equipment and are complicated. Further, they raise many issues in the production process, as high power consumption and additional costs are required to move molten metal to a centrifugal machine. In addition, metal-ceramic composite pipes are currently mainly manufactured by an insulator spraying technique. In this technique, a ceramic slurry is dried or sintered while being sprayed onto the inside of a rotating pipe through a nozzle. However, this process is disadvantageous because it is difficult to produce an inner thick-film ceramic layer, the manufacturing process time is long, and cracks and separation of the joints easily occur after coating.

In order to overcome such issues, the present applicant has proposed a technique disclosed in Patent No. 10-1384301, whereby a metal-ceramic composite pipe having a uniform coating layer and a strong joining strength can be manufactured by a simple and economical process. However, the patented invention proposed by the present applicant can be used only in a closed space as in a case of forming a ceramic layer inside a tube, and cannot be used in an open space. Thus, conventional techniques are still used for flat plates which are essentially used in the fields of chemistry, construction, metallurgy, furnaces, and plants. In other words, when the thermite reaction is induced on a flat plate in an open space, the respective components are scattered due to the reaction, and thus the thermite reaction cannot be smoothly induced, which prevents a ceramic layer from being formed on the flat plate. For this reason, the existing complex and costly method is still used in order to coat the flat plate with a ceramic layer.

Therefore, there is a need for a process for manufacturing a metal-ceramic composite plate that has a simple and economical process and provides a uniform coating layer and strong bonding force even for a flat plate as proposed by the applicant in the present invention.

DISCLOSURE

Technical Problem

Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide a method for manufacturing a ceramic steel sheet having improved properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance by inducing a thermite reaction on the steel sheet in an open space such that a ceramic layer is formed on one surface of the steel sheet.

Technical Solution

In accordance with one aspect of the present invention, provided is a method for coating one surface of a steel sheet with ceramic, including the steps of (a) installing a mold made of a refractory material for a thermite reaction on one surface of a plate-shaped steel sheet, (b) introducing a thermite mixture (M) as a reaction material into the mold so as to be uniformly distributed at a predetermined height on one surface of the steel sheet, (c) introducing an ignition material I to the thermite mixture (M) after step (b) and then igniting the ignition material I to induce the thermite reaction of the thermite mixture (M), and (d) pressing the thermite mixture (M) in a molten state with a press machine after step (c) to form a ceramic layer having a predetermined shape on the one surface of the steel plate.

Advantageous Effects

According to embodiments of the present invention, by forming an Al2O3 structure on one surface of a steel sheet through a thermite reaction, properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance can be improved. In addition, since the thermite reaction progresses slowly from one side to the other side by the titanium carbide on one surface of the steel sheet in the open space, there is no scattering of the reactants. Accordingly, the thermite reaction occurs stably, and a ceramic layer more excellent than the ceramic layer manufactured by the conventional thermite reaction can be formed.

DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart of a method for manufacturing a ceramic steel sheet according to the present invention.

FIGS. 2A to 2E are views showing a process of manufacturing a ceramic steel sheet.

FIG. 3 is a cross-sectional view showing the kinds of press plates used in the present invention.

FIG. 4 is a view showing kinds of molds used in the present invention.

BEST MODE

Hereinafter, a method for manufacturing a ceramic steel sheet according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flowchart of a method for manufacturing a ceramic steel sheet according to the present invention, and FIGS. 2A to 2E are views showing a process of manufacturing a ceramic steel sheet.

FIG. 3 is a cross-sectional view showing the kinds of press plates used in the present invention, and FIG. 4 is a view showing kinds of molds used in the present invention.

The present invention is directed to a method for manufacturing a ceramic steel sheet, and more particularly, to a method for coating one surface of a steel sheet with ceramic, the method including the steps of: (a) installing a mold 200 made of a refractory material for a thermite reaction on one surface of a plate-shaped steel sheet; (b) introducing a thermite mixture M as a reaction material into the mold 200 so as to be uniformly distributed at a predetermined height on one surface of the steel sheet 100; (c) introducing an ignition material I onto the thermite mixture M after step (b) and then igniting the ignition material I to induce the thermite reaction of the thermite mixture M; and (d) pressing the thermite mixture M in a molten state with a press machine 300 after step (c) to form a ceramic layer having a predetermined shape on the one surface of the steel plate.

The present invention is directed to a method for manufacturing a ceramic steel sheet having excellent properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance by forming a ceramic layer on one surface of a flat steel sheet in an open space by a thermite reaction, the method including the steps (a) to (d).

Generally, in the fields of chemistry, construction, metallurgy, furnaces, and plant industries, a high level of properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance is required for facilities including pipes or steel plates for transportation or heat exchange. A ceramic material is one of materials exhibiting excellent heat resistance, corrosion resistance, chemical resistance, and abrasion resistance. However, the ceramic material inherently has low toughness, low elongation and high brittleness, and raises issues regarding workability, bonding property and partial replacement in a facility.

In order to overcome such issues, metal double pipes (plates) and metal-ceramic composite pipes (plates) have been actively studied and some thereof have become commercially available.

Metal double pipes are manufactured using the centrifugal casting technique. In the centrifugal casting technique, when molten stainless steel is poured into a rotating metal tube, it is applied onto to the inside of the metal tube by the centrifugal force, and thus closely adheres to the metal tube. However, such processes by centrifugal casting are inefficient due to high initial costs for equipment including melting equipment and are complicated. Further, they raise many issues in the production process, as high power consumption and additional costs are required to move molten metal to a centrifugal machine. In addition, metal-ceramic composite pipes are currently mainly manufactured by an insulator spraying technique. In this technique, a ceramic slurry is dried or sintered while being sprayed onto the inside of a rotating pipe through a nozzle. However, this process is disadvantageous because it is difficult to produce an inner thick-film ceramic layer, the manufacturing process time is long, and cracks and separation of the joints easily occur after coating.

In order to overcome such issues, the present applicant has proposed a technique disclosed in Patent No. 10-1384301, whereby a metal-ceramic composite pipe having a uniform coating layer and a strong joining strength can be manufactured in a simple and economical process. However, the patented invention proposed by the present applicant can be used only in a closed space as in a case of forming a ceramic layer inside a tube, and cannot be used in an open space. Thus, conventional techniques are still used for flat plates which are essentially used in the fields of chemistry, construction, metallurgy, furnaces, and plants. In other words, when the thermite reaction is induced on a flat plate in the open space, the respective components are scattered due to the reaction, and thus the thermite reaction cannot be smoothly induced, which prevents a ceramic layer from being formed on the flat plate. For this reason, the existing complex and costly method is still used in order to coat the flat plate with a ceramic layer.

Therefore, there is a need for a process for manufacturing a metal-ceramic composite plate that has a simple and economical process and provides a uniform coating layer and strong bonding force even for a flat plate as proposed by the applicant in the present invention.

Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide a method for manufacturing a ceramic steel sheet having improved properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance by inducing a thermite reaction on the steel sheet in an open space such that a ceramic layer is formed on one surface of the steel sheet.

That is, according to embodiments of the present invention, by forming an Al2O3 structure on one surface of a steel sheet through a thermite reaction, properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance can be improved. In addition, since the thermite reaction progresses slowly from one side to the other side by the titanium carbide on one surface of the steel sheet in the open space, there is no scattering of the reactants. Accordingly, the thermite reaction occurs stably, and a ceramic layer vastly superior to the ceramic layer manufactured by the conventional thermite reaction can be formed.

In step (a), the mold 200 is installed on the steel plate 100 to be processed. That is, in step (a), the mold 200 made of a refractory material for the thermite reaction is installed on one surface of the plate-shaped steel plate 100. The steel sheet 100 can have various shapes according to uses thereof in the chemical, construction, metallurgy, furnace, and plant industries. The mold 200 is installed on one surface of the steel plate 100 so as to prevent the reactants (powder and molten state) from being separated from the steel plate 100 in order to form a ceramic layer on one surface of the steel plate 100 by inducing a thermite reaction. The mold 200 may be formed of a refractory material to withstand high temperatures caused by the thermite reaction and may be formed to be closed along the outer surface of the steel sheet 100 of various shapes. For example, the mold may be formed in a rectangular ring shape along the outer surface of the rectangular steel plate 100. The mold 200 having a certain shape may be formed on one surface of the steel sheet 100 in order to form a ceramic layer having a certain shape on one surface of the steel sheet 100.

Step (b) is a step of introducing a thermite mixture M into the mold installed on the steel plate (100). That is, in step (b), the thermite mixture M is introduced into the mold 200 as a reaction material so as to be uniformly distributed at a predetermined height on one surface of the steel sheet 100. The thermite mixture M is a reaction material composed of iron oxide (Fe₂O₃), aluminum (Al) and titanium carbide (TiC), and the mixture ratio of the mixture of Fe₂O₃ and Al to TiC may be 9:1. Here, the mixture ratio of Fe₂O₃ to Al may be 3:1. Here, the iron oxide is a powder having an average particle size of 10 to 30 mesh, the aluminum is a powder having an average particle size of 30 to 80 mesh, and the titanium carbide is a powder having an average particle size of 5 to 40 mesh. If the average particle size of the powder is smaller than the above-proposed reference sizes, the thermite reaction may occur instantaneously, causing an explosion, and thus a ceramic layer having a dense structure cannot be formed due to the very short reaction time. In addition, without titanium carbide (TiC) in the reaction, the thermite reaction occurs relatively quickly, and the reactants are scattered. As a result, the thermite reaction cannot occur smoothly. That is, without titanium carbide (TiC), a ceramic layer cannot be formed on a flat steel plate in an open space.

In step (c), the thermite reaction of the thermite mixture M is caused by the ignition material, and the thermite mixture M is melted on one surface of the steel sheet. That is, in step (c), an ignition material I is introduced onto the thermite mixture M after step (b), and then the ignition material I is ignited to induce the thermite reaction of the thermite mixture M.

The ignition material I is powder which is evenly introduced onto all or part of the thermite mixture M. The ignition material I may be magnesium (Mg) powder as powder to be introduced into the thermite mixture M. When the ignition material I is introduced, the ignition material I is ignited using an ignition tool T (e.g., gas torch). The thermite mixture M is ignited by the ignition material I to exhibit the thermite reaction. The thermite reaction progresses from one side of one surface of the steel sheet 100 toward the other side due to heat of reaction of the thermite mixture M, and thus the thermite mixture M is gradually burned naturally.

In the thermite reaction process, a reaction product is ejected at a certain speed in a certain direction. In the case where the reaction product is ejected irregularly in all directions, the ceramic layer C described below cannot be uniformly formed on the steel sheet. However, when the titanium carbide (TiC) can retard the progress of the thermite reaction by limiting scattering of the reaction product and the like during the reaction, such that the reaction of the thermite mixture can occur for a sufficient reaction time.

Step (d) is a step of pressing the thermite mixture M in a molten state to form a ceramic layer having a certain shape on one surface of the steel sheet 100. That is, in step (d) , a ceramic layer having a certain shape is formed on one surface of the steel sheet 100 by pressing the thermite mixture M in a molten state with a press machine 300 after step (c). The press machine 300, which is used to form a ceramic layer on one surface of the steel sheet, is a machine that is generally used on industrial sites. The press machine 300 may further include a press plate 310 configured to press the thermite mixture M in a molten state, a portion of a lower surface of the press plate being formed to protrude in various shapes. That is, a portion of the lower surface of the press plate 310 is protruded. Thus, in step (d), a ceramic layer may be formed on one side of the steel plate 100 by the press plate 310 so as to conform to a protruding shape of the press plate 310. Accordingly, ceramic steel sheets of various shapes required in chemistry, construction, metallurgy, furnace, and plant industries can be manufactured.

Although a preferred embodiment of the method for manufacturing a ceramic steel sheet according to the present invention has been described above, this is merely an example and the technical idea, composition and operation of the present invention are not limited thereto. The scope of the technical idea of the present invention is not defined/limited by the drawings or the description with reference to the drawings. It is also to be understood that the concepts and embodiments of the inventions set forth herein may be used by those skilled in the art to which the invention pertains as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. Various changes, substitutions and alterations can be made without departing from the scope of the present invention as defined in the appended claims.

DESCRIPTION OF REFERENCE NUMERALS

I: Ignition material

M: Thermite mixture

C: Ceramic layer

T: Ignition tool

100: Steel plate

200: Mold

300: Press machine

310: Press plate

INDUSTRIAL APPLICABILITY

The present invention provides a method for manufacturing a ceramic steel sheet having improved properties such as heat resistance, corrosion resistance, chemical resistance, and abrasion resistance by inducing a thermite reaction on the steel sheet in an open space such that a ceramic layer is formed on one surface of the steel sheet, and is industrially applicable.

Claims

1. A method for coating one surface of a steel sheet with ceramic, comprising the steps of:

(a) installing a mold made (200) of a refractory material for a thermite reaction on one surface of a plate-shaped steel sheet;

(b) introducing a thermite mixture (M) as a reaction material into the mold (200) so as to be uniformly distributed at a predetermined height on one surface of the steel sheet (100);

(c) introducing an ignition material (I) to the thermite mixture (M) after the step (b) and then igniting the ignition material (I) to induce the thermite reaction of the thermite mixture (M); and

(d) pressing the thermite mixture (M) in a molten state with a press machine (300) after the step (c) to form a ceramic layer having a predetermined shape on the one surface of the steel plate.

2. The method of claim 1, wherein the thermite mixture (M) for the reaction material comprises iron oxide powder having a size of 10 to 30 mesh, aluminum powder having a size of 30 to 80 mesh, and titanium carbide powder having a size of 5 to 40 mesh,

wherein the ignition material (I) is made of magnesium powder

wherein, in the step (c), a reaction rate is lowered by the titanium carbide during the thermite reaction to prevent each constituent powder from being scattering by the reaction such that the thermite reaction is easily caused.

3. The method of claim 1, wherein a weight ratio of a mixture of the iron oxide powder and the aluminum powder to the titanium carbide powder is 9:1.

4. The method of claim 1, wherein the mold (200) is fabricated to match shapes of various steel sheets and is installed on the one surface of the steel sheet (100).

5. The method of claim 1, wherein the press machine (300) further comprises a press plate (310) configured to press the thermite mixture (M) in a molten state, a portion of a lower surface of the press plate being formed to protrude in various shapes,

wherein a ceramic layer is formed on the one surface of the steel plate (100) by the press plate (310) in the step (d) so as to conform to a protruding shape of the press plate (310).