Method of manufacturing an ultra-low iron loss oriented electrical steel sheet

Abstract

The present invention provides a method of manufacturing an ultra-low iron loss oriented electrical steel sheet. The method of manufacturing an oriented electrical steel sheet of the present invention includes a process of reheating a steel billet, hot rolling, annealing a hot rolled sheet, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing, wherein, using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD), a ceramic precursor in a gaseous phase is made to undergo a contact reaction in a plasma state, thereby forming a ceramic coating on one side or both sides of a portion or all of the steel sheet subjected to the primary recrystallization annealing, and then performing secondary recrystallization annealing.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method of manufacturing an oriented electrical steel sheet. BACKGROUND

[0002] Generally, the oriented electrical steel sheet refers to an electrical steel sheet including a Si component of about 3.1% in the steel sheet and having a texture in which the grain orientation is arranged in the direction of {100} <001>

[0002] , and thus has extremely excellent magnetic properties in the rolling direction. Such a {100} <001> texture can be obtained by a combination of various manufacturing processes, and in particular, a series of processes of very strictly controlling the composition of a billet and heating, hot rolling, hot rolled sheet annealing, primary recrystallization annealing, and final annealing thereof are required. Specifically, the oriented electrical steel sheet exhibits excellent magnetic properties by a secondary recrystallization texture obtained by inhibiting the growth of primary recrystallization grains and selectively growing grains having a {100} <001> orientation in the grains in which the growth is inhibited, and thus more importantly, a growth inhibitor of the primary recrystallization grains. Also, one of the main matters of the manufacturing technology of the oriented electrical steel sheet is that, in the final annealing process, grains having a texture of the {100} <001> orientation can be stably grown in the grains in which the growth is inhibited. The growth inhibitor of the primary grains that can satisfy the above conditions and is widely used in the industry at present is MnS, AlN, and MnSe, etc. Specifically, after MnS, AlN, and MnSe, etc. contained in the billet are dissolved by re-heating at a high temperature for a long time, and the above components having an appropriate size and distribution become precipitates in the subsequent cooling process, and thus can be used as the growth inhibitor. However, this has a problem that the billet must be heated to a high temperature. In this regard, in recent years, efforts have been made to improve the magnetic properties of the oriented electrical steel sheet by a method of heating the billet at a low temperature. For this, a method of adding an antimony (Sb) element in the oriented electrical steel sheet has been proposed, but since the grain size is not uniform and is coarse after the final high-temperature annealing, it has been pointed out that there is a problem in that the noise quality of the transformer is deteriorated.

[0003] In addition, in order to minimize the power consumption of the oriented electrical steel sheet, an insulating thin film is generally formed on the surface thereof, and the insulating thin film is required to have high electrical insulation and excellent adhesion to the material, and to have a uniform color without defects in appearance. In addition, in recent years, due to the strengthening of international standards for transformer noise and the intensification of competition in the related industry, in order to reduce noise, it is necessary to study the magnetostriction phenomenon of the insulating thin film of the oriented electrical steel sheet. Specifically, when a magnetic field is applied to an electrical steel sheet used as a transformer core, a vibration phenomenon is induced by repeated contraction and expansion, and due to this vibration, vibration and noise in the transformer are induced. In the case of the oriented electrical steel sheet known in general, an insulating thin film is formed on a steel sheet and a thin film based on forsterite, and a tensile stress is imparted to the steel sheet using the difference in the thermal expansion coefficient of the insulating thin film, thereby obtaining the effect of improving the iron loss and reducing the noise caused by magnetostriction, but there is a limitation in satisfying the noise level of the advanced oriented electrical steel sheet required recently. In addition, as a method of reducing the 90° magnetic domain of the oriented electrical steel sheet, a wet coating method is known. Among them, the 90° magnetic domain refers to a region of magnetization at a right angle to the

[0010] magnetic field application direction, and the less the amount of such 90° magnetic domain, the smaller the magnetostriction. However, the ordinary wet coating method has the disadvantages of requiring a thick film to be coated to a thick coating thickness, and thus has a problem in that the transformer space factor and efficiency are deteriorated.

[0004] In addition, as a method of imparting a high tensile property to the surface of the oriented electrical steel sheet, a coating method by vacuum deposition such as physical vapor deposition (PVD) and chemical vapor deposition (CVD) is known. However, the coating method has a problem in that it is difficult to produce industrially, and the insulating properties of the oriented electrical steel sheet manufactured by the method are poor. SUMMARY

[0005] TECHNICAL PROBLEM TO BE SOLVED

[0006] The present application provides a method of manufacturing an oriented electrical steel sheet, which forms a ceramic coating layer on one side or both sides of a steel sheet subjected to a primary recrystallization annealing process by an APP-CVD method.

[0007] In addition, the technical problems to be solved by the present application are not limited to the above-mentioned technical problems, and other technical problems not mentioned can be clearly understood by those having ordinary knowledge in the art to which the present application pertains according to the following description.

[0008] TECHNICAL SOLUTION

[0009] One embodiment of the present invention relates to a method of manufacturing an oriented electrical steel sheet, the method including a process of reheating a steel slab, hot rolling, annealing a hot rolled sheet, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing, wherein a ceramic coating is formed on one side or both sides of the steel sheet after the primary recrystallization annealing by using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD) in which a ceramic precursor in a gas phase is allowed to undergo a contact reaction in a plasma state, and then the secondary recrystallization annealing is performed.

[0010] In addition, the present invention relates to a method of manufacturing an oriented electrical steel sheet, the method including the steps of preparing a steel sheet for manufacturing an oriented electrical steel sheet after primary recrystallization annealing, forming a ceramic coating on one side or both sides of the steel sheet by using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD) in which a ceramic precursor in a gas phase is allowed to undergo a contact reaction in a plasma state, and performing secondary recrystallization annealing on the steel sheet on which the ceramic coating is formed.

[0011] The ceramic coating can be formed by mixing a first gas composed of one or more of Ar, He, and N2 and a ceramic precursor in a gas phase and allowing them to undergo a contact reaction on the surface of a steel sheet in a state in which a plasma is generated by using a high-density radio frequency to form an electric field on the surface of the steel sheet under atmospheric pressure conditions.

[0012] The ceramic coating can be formed by further mixing a second gas composed of one of H2, O2, and H2O with the first gas and the ceramic precursor and allowing them to undergo a contact reaction on the surface of a steel sheet.

[0013] The first gas and the second gas are preferably heated to a temperature above the vaporization point of the ceramic precursor.

[0014] When the ceramic coating is TiO2, Titanium Isopropoxide (TTIP, Ti{OCH(CH3)2}4) or TiCl4 can be used as the ceramic precursor.

[0015] The primary recrystallization annealing process can be a process in which the steel sheet is decarburized while being nitrided, or is nitrided after being decarburized, and is annealed to obtain a decarburized annealed steel sheet.

[0016] The secondary recrystallization annealing process can be a high-temperature annealing process in which the steel sheet on which the ceramic coating is formed is heated in two stages and then is subjected to a soaking treatment.

[0017] After the secondary recrystallization annealing process, a process of forming an insulating thin film on the surface of the oriented electrical steel sheet on which the ceramic coating is formed can be further included.

[0018] The steel sheet can include, in terms of weight %, silicon (Si): 2.6-4.5%, aluminum (Al): 0.020-0.040%, manganese (Mn): 0.01-0.20%, the balance of Fe and other inevitable impurities.

[0019] Advantageous Effects

[0020] According to the present application described above, the ceramic coating layer is formed in a primary recrystallization annealing process to play a role of an annealing separator, thereby replacing the coating of an annealing separator on the surface of the steel sheet, so that a primary soaking process in a subsequent secondary recrystallization process can be omitted, and thus productivity can be improved.

[0021] In addition, unlike a general MgO annealing separator, the ceramic coating layer of the present application is a thin film layer having a high tension, and thus does not need to be removed, and due to the high tension, can effectively provide an oriented electrical steel sheet having excellent iron loss characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a diagram illustrating a manufacturing process of a conventional oriented electrical steel sheet.

[0023] Figure 2 is a diagram illustrating a manufacturing process of an oriented electrical steel sheet of the present application.

[0024] Figure 3 (a) and (b) of FIG. 1 are diagrams illustrating an annealing heat treatment process in a secondary recrystallization annealing process, (a) illustrates a prior art example, and (b) illustrates an inventive example of the present application.

[0025] Figure 4 is a diagram illustrating a mechanism of forming a ceramic coating layer on the surface of a steel sheet subjected to a primary recrystallization annealing using an APP-CVD process according to the present application.

[0026] Figure 5 is a diagram illustrating a state in which TTIP, which is one example of a ceramic precursor, is dissociated in a plasma region generated by an RF power source in an APP-CVD process according to the present application.

[0027] BEST MODE FOR CARRYING OUT THE INVENTION

[0028] Hereinafter, embodiments of the present application will be described in detail so that those having ordinary knowledge in the art to which the present application pertains can easily practice the present application. However, the present application can be implemented by various embodiments, and is not limited to the embodiments described below.

[0029] Figure 1 is a diagram illustrating a manufacturing process of a conventional oriented electrical steel sheet.

[0030] As Figure 1 shown, first is an annealing pickling process (Annealing & Pickling Line (APL)), which functions to remove scale of a hot-rolled sheet, to ensure cold-rolling property, and to precipitate and disperse an inhibitor (AIN) of the hot-rolled sheet to facilitate magnetism. Next is a cold-rolling process (Sendzimir Rolling Mill), by which a final product thickness required by a customer company is rolled, and which functions to ensure crystal orientation that facilitates magnetism. Then is a first recrystallization annealing process, which is a decarburizing nitriding annealing process (Decarburizing & Nitriding Line (DNL)), by which [C] of a material is removed, and primary recrystallization is formed through an appropriate temperature and nitriding reaction. Subsequently is a second recrystallization annealing process, which is a high-temperature annealing process (COF), by which a base coating (Mg2SiO4) layer is formed, and secondary recrystallization is formed. Finally is an HCL process, by which a material shape is corrected, and an insulating thin film layer is formed after the annealing release agent, thereby imparting tension to a surface of an electrical steel sheet.

[0031] At this time, in the related art, after the decarburizing nitriding treatment in the primary recrystallization process, a process of coating an annealing release agent MgO is performed. And, after the primary heating in the secondary recrystallization annealing process, a primary soaking treatment is performed, and then, after the secondary heating, a secondary soaking treatment is performed.

[0032] In addition, Figure 2 is a view showing a manufacturing process of an oriented electrical steel sheet according to the present application.

[0033] As Figure 2 shown, in the present application, a ceramic coating layer is formed using an APP-CVD process in the primary recrystallization annealing process, instead of coating an annealing release agent on a steel sheet. And, with the formation of the ceramic coating layer, in the subsequent secondary recrystallization annealing process, a process of performing a primary soaking treatment after heating in two stages is performed.

[0034] Figure 3 (a) and (b) of FIG. 1 are views showing an annealing heat treatment process in a secondary recrystallization annealing process, (a) of which shows a related art example, and (b) of which shows an inventive example according to the present application. As Figure 3 shown, unlike the related art, the primary soaking treatment process can be omitted in the present application, and thus it is known that productivity can be improved. Also, unlike the related art, the present application has an advantage that the annealing release agent does not need to be removed in the above-described HCL process.

[0035] As described above, in the manufacturing process of the oriented electrical steel sheet according to the present application, the process before the primary recrystallization annealing process is substantially the same as the prior art.

[0036] That is, in the present application, in manufacturing the oriented electrical steel sheet, the conventional process of reheating the steel slab, hot rolling, annealing the hot rolled sheet, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing is used similarly to the prior art. Among them, the primary recrystallization annealing process can be a process of decarburizing the steel sheet while nitriding, or decarburizing and then nitriding, and annealing to obtain a decarburization annealed steel sheet.

[0037] However, unlike the prior art, a ceramic coating layer is formed on one side or both sides of the steel sheet subjected to the primary recrystallization annealing process by using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD) in which a ceramic precursor in a gas phase is subjected to a contact reaction in a plasma state.

[0038] Also, in the secondary recrystallization annealing process, a high-temperature annealing process is used, which is a process of heating the steel sheet on which the ceramic coating layer is formed in two stages, followed by a soaking treatment once, and then furnace cooling.

[0039] First, in the present application, a cold-rolled steel sheet for manufacturing an oriented electrical steel sheet subjected to primary recrystallization annealing is prepared.

[0040] In the present application, the steel sheet can include, in wt%, silicon (Si): 2.6-4.5%, aluminum (Al): 0.020-0.040%, manganese (Mn): 0.01-0.20%, the balance of Fe and other inevitable impurities. Hereinafter, reasons for limiting the composition and content of the steel sheet in the present application are described.

[0041] Si: 2.6-4.5 wt%

[0042] Silicon (Si) functions to reduce iron loss by increasing the electrical resistivity of the steel. When the content of Si is too small, the electrical resistivity of the steel becomes small, resulting in poor iron loss characteristics, and there is a phase transformation range at high-temperature annealing, so there can be a problem of unstable secondary recrystallization. When the content of Si is too large, the brittleness increases, so there can be a problem of difficulty in cold rolling. Therefore, the content of Si can be adjusted within the above range. More specifically, 2.6-4.5 wt% of Si can be included.

[0043] Al: 0.020-0.040 wt%

[0044] Aluminum (Al) is a component that becomes a nitride in the form of AlN, (Al, Si)N, (Al, Si, Mn)N, and functions as an inhibitor. When the content of Al is too small, sufficient effects as an inhibitor cannot be expected. Further, when the content of Al is too large, Al-based nitrides are precipitated and grow to be too coarse, and thus the effects as an inhibitor can be insufficient. Therefore, the content of Al can be adjusted within the above range.

[0045] Mn: 0.01 to 0.20 wt%

[0046] Like Si, Mn has an effect of reducing iron loss by increasing the electric resistivity, and Mn and Si together react with nitrogen introduced by the nitriding treatment to form a precipitate of (Al, Si, Mn)N, and thus Mn is an important element that causes secondary recrystallization by inhibiting the growth of primary recrystallized grains. However, when the content of Mn is too large, the austenite transformation is promoted during hot rolling, and thus the size of the primary recrystallized grains is reduced, resulting in unstable secondary recrystallization. Further, when the content of Mn is too small, as an austenite-forming element, the effects of increasing the fraction of austenite when hot rolling is performed, increasing the solid solution amount of the precipitate, and thus preventing the primary recrystallized grains from growing too large by the effects of the refinement of the precipitate and the formation of MnS at the time of re-precipitation can be insufficient. Therefore, the content of Mn can be adjusted within the above range.

[0047] Next, in the present application, by using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD), a ceramic precursor in the gas phase is caused to undergo a contact reaction in a plasma state, thereby forming a ceramic coating on one side or both sides of a portion or the entire steel sheet subjected to the primary recrystallization annealing treatment.

[0048] The process used in the present application to form a ceramic coating is hereinafter referred to as an atmospheric pressure plasma chemical vapor deposition process (Atmospheric Pressure Plasma enhanced-Chemical Vapor Deposition, APP-CVD).

[0049] Compared to the existing chemical vapor deposition (CVD), low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), and plasma enhanced chemical vapor deposition (PECVD), the APP-CVD has a higher density of radicals, and thus a high deposition rate. In addition, unlike other CVDs, it does not require a high or low vacuum vacuum equipment, and thus has the advantage of low equipment cost. That is, since there is no vacuum equipment, the equipment is relatively easy to operate, and has excellent deposition performance.

[0050] Also, in the APP-CVD process of the present application, in a state in which plasma is generated by forming an electric field on the surface of a steel sheet using a high-density radio frequency under atmospheric pressure conditions, a first gas consisting of one or more of Ar, He, and N2 as a main gas and a ceramic precursor in a gas phase are mixed, and then supplied to a reaction furnace and subjected to a contact reaction on the surface of the steel sheet.

[0051] Figure 4 is a schematic diagram showing the mechanism of forming a ceramic coating on the surface of a steel sheet using the APP-CVD process of the present application.

[0052] As shown in Figure 4 In the APP-CVD process, an electric field is formed on one side or both sides of a steel sheet using a high-density radio frequency (RF) (for example, 13.56 MHz) under atmospheric pressure conditions. Also, when a first gas (Primary Gas) such as Ar, He, or N2 is injected using a hole, line, or face nozzle, electrons are separated and radicalized under the electric field, and thus show polarity.

[0053] In the present application, an RF plasma source can use a plurality of line sources or a 2D square source depending on the situation. This can change the type of source depending on the optimized coating speed and the speed of the substrate layer.

[0054] Next, under 50-60 Hz alternating current between the radio frequency power source and the steel sheet, Ar radicals and electrons reciprocate in the reaction furnace, and collide with a ceramic precursor (for example, titanium isopropoxide (TTIP, Ti{OCH(CH3)2}4)) in a gas phase mixed with the first gas, dissociate the precursor, and form radicals of the precursor.

[0055] At this time, in the present application, a ceramic precursor such as TTIP is mixed with a first gas (Primary Gas) composed of one or more of Ar, He, and N2, and then passes through a radio frequency power source and flows into a reaction furnace through a gas injection nozzle.

[0056] In addition, a ceramic precursor such as TTIP is stored in a liquid state and is vaporized through a heating process of 50-100°C. Also, when the first gas passes through a location containing TTIP, the first gas is mixed with the ceramic precursor, passes through a radio frequency power source, and flows into a reaction furnace through a gas injection nozzle.

[0057] As described above, the ceramic precursor of the present application can be used in various kinds as long as it is in a liquid state and can be easily vaporized when heated to a temperature that is not high. For example, TTIP, TiCl4, TEOT, etc. can be used. That is, in the present application, when the ceramic coating is TiO2, the ceramic precursor can be titanium isopropoxide (TTIP, Ti{OCH(CH3)2}4) or TiCl4, etc.

[0058] At this time, in the present application, in order to improve the quality of the coating, a second gas composed of one of O2, H2, and H2O (secondary gas) can be added together with the first gas, if necessary, thereby improving the purity of the coating. That is, in order to improve the deposition quality of the coating, a second gas can be added, and the coating that is not needed can be removed through a reaction with the gas. In the present application, whether or not to add the secondary gas can be determined according to various conditions such as whether or not to heat (Heating) a substrate layer.

[0059] As described above, in the present application, the liquid ceramic precursor is heated to a vaporization point or more by a heater, and the first gas and the second gas are heated to a temperature of the vaporization point of the ceramic precursor or more in advance by a steam heater or an electric heater, and then are mixed with the ceramic precursor and are supplied to the inside of the reaction furnace in a gaseous state, so that the vaporized ceramic precursor gas can be supplied as a plasma source.

[0060] At this time, preferably, the inflow amounts of the first gas, the second gas, and the ceramic precursor are 100-10000 SLM, 0-1000 SCCM, and 10-1000 SLM, respectively, to form a ceramic coating.

[0061] Also, in the present application, the dissociated radicals collide with an electrically grounded (ground) or a positively (-) polarized electrical steel sheet and form a ceramic coating (for example, TiO2) on the surface.

[0062] In the present invention, the principle of plasma generation is that electrons are accelerated under an electric field imparted by a high-density radio frequency power source and collide with neutral (Neutral) particles such as atoms and molecules to undergo ionization, excitation, and dissociation. Among them, the activated species formed by excitation and dissociation can react with radicals to form the final desired ceramic coating.

[0063] Although the exact deposition mechanism is not known, as an example, when the ceramic TiO2 deposition mechanism is simplified and explained, it can be explained as follows that the ceramic precursor TTIP is decomposed by plasma under an electric field and deposited on the surface of the substrate layer.

[0064] Ti(OR)4→ Ti*(OH) x-1 (OR) 4-x → (HO) x (RO) 3-x Ti-O-Ti(OH) x-1 (OR) 4-1 → Ti-O-Ti network

[0065] Figure 5 is a diagram showing the state in which TTIP, which is an example of a ceramic precursor in the APP-CVD process of the present invention, is dissociated in the plasma region generated by the radio frequency power source.

[0066] In addition, in the present invention, in order to deposit a thickness of 0.05-0.5 μm on a steel plate having a width of 1 m at a speed of 100 mpm using APP-CVD, a radio frequency power source of about 500 kW-10 MW can be required. Also, one or more radio frequency power sources can maintain a stable electric field through a power matching system.

[0067] Then, in the present invention, a high-temperature annealing process is performed in a secondary recrystallization annealing process, which is a soaking treatment performed once after heating the steel plate forming the ceramic coating in two stages. Compared to the prior art in which one soaking treatment and two soaking treatments are performed, the present invention can omit the one soaking treatment, which is technically significant in this regard.

[0068] After that, in the present invention, after the shape of the steel plate is corrected in the HCL process, a process of forming an insulating thin film on the surface forming the ceramic coating can be further included.

[0069] That is, an insulating thin film layer containing metal phosphates can also be formed on the ceramic coating. By further forming an insulating thin film layer, the insulation properties can be improved.

[0070] Metal phosphates may contain at least one selected from Mg, Ca, Ba, Sr, Zn, Al, and Mn.

[0071] Metal phosphates can be formed by the reaction of metal hydroxides with phosphoric acid (H3PO4). 4) The chemical reaction yields the formation of compounds.

[0072] Metal phosphates can be formed from compounds obtained by the chemical reaction of a metal hydroxide with phosphoric acid (H3PO4), and the metal hydroxide can be at least one selected from Sr(OH)2, Al(OH)3, Mg(OH)2, Zn(OH)2 and Ca(OH)2. Detailed Implementation

[0073] The present invention will now be described in detail through examples.

[0074] (Example)

[0075] Prepare a steel billet comprising: silicon (Si): 3.4 wt%, aluminum (Al): 0.03 wt%, manganese (Mn): 0.15 wt%, antimony (Sb): 0.05 wt%, tin (Sn): 0.06 wt%, nickel (Ni): 0.03 wt%, and the balance being composed of Fe and other unavoidable impurities.

[0076] Next, the steel billet is heated at 1150°C for 220 minutes, and then hot-rolled to a thickness of 2.3 mm to obtain a hot-rolled plate. Then, the hot-rolled plate is heated to 1120°C and held at 920°C for 95 seconds, then rapidly cooled in water and pickled, and then cold-rolled to a thickness of 0.23 mm to obtain a cold-rolled plate.

[0077] The cold-rolled sheet is placed in a furnace maintained at 850°C, and then the dew point temperature and oxidation capacity are adjusted. It is then subjected to a single recrystallization annealing process involving simultaneous decarburization and nitriding in a mixed gas atmosphere of hydrogen, nitrogen and ammonia to obtain a decarburized annealed steel sheet.

[0078] Subsequently, a ceramic coating is formed on the surface of the steel sheet manufactured as described above, which has undergone a single recrystallization annealing process, using the APP-CVD process, without applying an annealing release agent.

[0079] Specifically, before the APP-CVD process, the oriented electrical steel sheet is indirectly heated to a temperature of 200°C, and then the steel sheet is loaded into the APP-CVD reactor.

[0080] In addition, at this time, in the APP-CVD process, an electric field is formed on one side or both sides of the oriented electrical steel sheet using a radio frequency of 13.56 MHz under atmospheric pressure, and Ar gas is flowed into the reaction furnace. Also, under an alternating current of 50-60 Hz between the radio frequency power source and the steel sheet, the liquid ceramic precursor TTIP is vaporized, and then mixed with Ar gas and H2 gas and added to the reaction furnace, thereby forming a TiO2 ceramic coating layer of different thicknesses on the surface of the electrical steel sheet.

[0081] Then, the steel sheet on which the ceramic coating layer is formed is subjected to final annealing. At this time, the soaking temperature at the time of final annealing is set to 1200°C, and the temperature interval in the temperature interval of the temperature rising section is set to 15°C / hour. In addition, until 1200°C, a mixed gas atmosphere of 50 vol% nitrogen and 50 vol% hydrogen is set, and after reaching 1200°C, the atmosphere is maintained in a 100 vol% hydrogen atmosphere for 15 hours, and then subjected to furnace cooling.

[0082] The electrical steel sheet on which the ceramic coating layer of different thicknesses is formed as described above is evaluated for magnetic properties under conditions of 1.7 T and 50 Hz, and shown in Table 1 below. In addition, the magnetic properties of the electrical steel sheet are generally represented using W17 / 50 and B8 as representative values. W17 / 50 represents the power loss that occurs when a magnetic field of 50 Hz is electromagnetized to 1.7 Tesla (T). Here, Tesla is a unit of magnetic flux density that represents the magnetic flux per unit area. B8 represents the magnetic flux density value that flows through the electrical steel sheet when an electric current of 800 A / m flows through a coil wound around the electrical steel sheet.

[0083] [Table 1]

[0084] Category Coating substance Coating thickness (μm) Iron loss (W17 / 50, W / kg) Magnetic flux density (BB, T) Comparative Example 1 MgO 1.5 1.220 1.890 Comparative Example 2 MgO 3.7 0.957 1.912 Inventive Example 1 TiO2 0.5 0.892 1.922 Inventive Example 2 TiO2 1.2 0.864 1.920 Inventive Example 3 TiO2 1.5 0.815 1.927 Inventive Example 4 TiO2 2.7 0.780 1.935 Inventive Example 5 TiO2 5.7 0.792 1.935

[0085] As shown in Table 1, it can be confirmed that the inventive examples 1 to 5 of the present application, which form a TiO2 thin film using the APP-CVD process, show more excellent iron loss properties compared to Comparative Examples 1 to 2, which coat an annealing separator MgO on the surface of a steel sheet that has undergone a once-recrystallization annealing process, and have substantially the same manufacturing conditions as the inventive examples 1 to 5 of the present application.

[0086] The embodiments and inventive examples of the present application have been described in detail above, but the scope of the rights of the present application is not limited thereto, and various modifications and changes can be made within the scope of the technical idea of the present application recited in the claims, which will be apparent to those skilled in the art.

Claims

1. A method of manufacturing an oriented electrical steel sheet, the method comprising a process of reheating, hot rolling, annealing of the hot rolled sheet, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing of a steel slab, wherein contacting a first gas consisting of one or more of Ar, He, and N2 with a ceramic precursor of Ti(OCH(CH3)2)4 (TTIP) or TiCl4 in the gas phase using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD) under a condition where a high-density radio frequency is used to form an electric field on the surface of a steel sheet to generate plasma, thereby forming a TiO2 ceramic coating on one side or both sides of a portion or all of the steel sheet subjected to the primary recrystallization annealing process, and then performing secondary recrystallization annealing, wherein the ceramic coating functions as an annealing separator.

2. The method of manufacturing an oriented electrical steel sheet according to claim 1, characterized in that, The ceramic coating is formed by contacting the first gas and the ceramic precursor on the surface of a steel sheet after further mixing a second gas consisting of one of H2, O2, and H2O in the first gas and the ceramic precursor.

3. The method of manufacturing an oriented electrical steel sheet according to claim 2, characterized in that, The first gas and the second gas are heated to a temperature above the vaporization point of the ceramic precursor.

4. The method of manufacturing an oriented electrical steel sheet according to claim 1, characterized in that, The primary recrystallization annealing process is a process of decarburizing the steel sheet while nitriding, or after decarburizing, and annealing to obtain a decarburized annealed steel sheet.

5. The method of manufacturing an oriented electrical steel sheet according to claim 1, characterized in that, The secondary recrystallization annealing process is a high-temperature annealing process of soaking the steel sheet on which the ceramic coating is formed in two stages.

6. The method of manufacturing an oriented electrical steel sheet according to claim 1, characterized in that, Further comprising a process of forming an insulating thin film on the surface of the oriented electrical steel sheet on which the ceramic coating is formed after the secondary recrystallization annealing process.

7. The method of manufacturing an oriented electrical steel sheet according to claim 1, characterized in that, The steel sheet contains, in weight %, silicon (Si): 2.6-4.5%, aluminum (Al): 0.020-0.040%, manganese (Mn): 0.01-0.20%, the balance of Fe, and other unavoidable impurities.

8. A method of manufacturing an oriented electrical steel sheet, comprising the steps of: preparing a steel sheet for manufacturing an oriented electrical steel sheet subjected to primary recrystallization annealing; contacting a first gas consisting of one or more of Ar, He, and N2 with a ceramic precursor of Ti(OCH(CH3)2)4 (TTIP) or TiCl4 in the gas phase using an atmospheric pressure plasma chemical vapor deposition process (APP-CVD) under a condition where a high-density radio frequency is used to form an electric field on the surface of a steel sheet to generate plasma, thereby forming a TiO2 ceramic coating on one side or both sides of the steel sheet; and performing secondary recrystallization annealing of the steel sheet on which the TiO2 ceramic coating is formed, wherein the ceramic coating functions as an annealing separator.

9. The method of manufacturing an oriented electrical steel sheet according to claim 8, characterized in that, The ceramic coating is formed by contacting the first gas and the ceramic precursor on the surface of a steel sheet after further mixing a second gas consisting of one of H2, O2, and H2O in the first gas and the ceramic precursor.

10. The method of manufacturing an oriented electrical steel sheet according to claim 9, characterized in that, The first gas and the second gas are heated to a temperature above the vaporization point of the ceramic precursor.

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