JP2007262540A - Nozzle for supplying source gas in chemical vapor deposition treatment, film-forming method and grain-oriented electromagnetic steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle for use in supplying a source gas in a chemical vapor deposition process, which has such a structure as to spray the source gas uniformly in the width direction of a metallic strip. <P>SOLUTION: The nozzle for spraying the source gas onto the metallic strip introduced into a chemical vapor deposition treatment chamber has a pipe extending to a source gas discharge side from a source gas supply side. The pipe is sequentially branched from at least two parts to two paths from the supply side to the discharge side, has a discharge port at the end of the path of the final step branch, and is formed so as to equalize the conductances of the two paths which have been branched at respective steps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chemical vapor deposition process in which vapor deposition is performed on a metal strip, particularly in a chemical vapor deposition process in which a ceramic coating such as TiN, TiC and SiN is vapor deposited on a metal strip. It is related with the nozzle used when spraying the gas which becomes. The present invention also provides a method for forming a coating on the surface of a grain-oriented electrical steel sheet using this nozzle, particularly a ceramic coating capable of imparting a strong tension to the steel sheet, and the coating film is formed to significantly and uniformly reduce iron loss. The grain-oriented electrical steel sheet.

  It is common practice to increase the wear resistance by coating ceramic materials such as TiN, TiC and SiN on the surface of tools, etc., and chemical vapor deposition (CVD) film-forming methods are widely used as the means. It's being used. However, the chemical vapor deposition method is an industrial field in which a large number of small articles such as tools and blades are charged into a film forming furnace, and a long time is spent like a ceramic kiln to deposit ceramics on these articles. In general, there are few examples that are industrially used for ceramic coating on the surface of a long object having a continuous length such as a metal strip.

  In particular, manufacturing techniques for reducing loss by performing chemical vapor deposition on silicon steel plates used as electromagnetic steel plates and obtaining very high-efficiency transformer materials have been proposed. The technical significance of industrially applying a ceramic coating to steel sheets is extremely high.

  The electrical steel sheets are classified into non-oriented electrical steel sheets and directional electrical steel sheets. Non-oriented electrical steel sheets are mainly used for iron core materials such as rotating machines, and directional electrical steel sheets are used mainly for iron core materials for transformers and other electrical equipment. Used as. In any case, low iron loss is required in order to reduce energy loss. In addition, since electromagnetic steel sheets are mostly used by being laminated, an insulating coating is generally applied to ensure insulation between layers.

  The grain-oriented electrical steel sheet is also called a grain-oriented silicon steel sheet because it contains silicon as an alloy component in addition to iron. In order to reduce the iron loss of grain-oriented electrical steel sheets, there are methods such as reducing the plate thickness, increasing the Si content, and increasing the orientation of the crystal orientation, and further applying tension to the steel sheet. Is effective.

  As a method for imparting tension to the steel sheet, a technique is used in which a film made of a material having a smaller thermal expansion coefficient than that of the steel sheet is formed on the steel sheet surface. In other words, in the final annealing process, which finally serves as the secondary recrystallization to align the crystal orientation and the purification of the steel sheet, the oxide on the steel sheet reacts with the annealing separator applied to the steel sheet surface, and forsterite is the main component. However, this film has a large tension applied to the steel sheet and is effective in reducing iron loss. Furthermore, in order to increase the tension, it is common to apply a topcoat coating having a low thermal expansion coefficient on the forsterite film to obtain a product.

  At present, the tension-providing insulation coating applied to grain-oriented silicon steel sheets with forsterite coating is a treatment based on Al and alkaline earth metal phosphates and colloidal silica, chromic anhydride or chromic acid. Many are formed by applying and baking a liquid. The tension-providing insulation coating technology forms an inorganic coating typified by colloidal silica, which has a smaller coefficient of thermal expansion than steel plates, at high temperatures, and uses the difference in the thermal expansion coefficient between the base iron and the insulation coating during the cooling process. The steel sheet is made to express tension at normal temperature. The insulating film formed by this method can give a strong tension to the steel sheet and is effective in reducing iron loss. For example, Patent Documents 1 and 2 disclose the formation method.

  In recent years, methods for smoothing the surface of a steel sheet and improving magnetic properties have been developed. One of the methods is a method for intentionally suppressing the formation of the forsterite film in the final annealing step, and the other method is a method for smoothing the surface after removing the formed forsterite film. However, the iron loss can be significantly reduced by either method.

For example, Patent Document 3 discloses a method in which a surface product is removed by pickling after finish annealing and then finished into a mirror state by chemical polishing or electrolytic polishing. Patent Document 4 discloses a method of performing thermal etching at a temperature of 1000 to 1200 ° C. in an H ₂ atmosphere after removing the forsterite film. The reason why the iron loss is reduced by such a surface treatment is that the number of pinning sites on the surface of the steel plate that hinders the domain wall movement in the magnetization process is reduced.

Further, Patent Document 5 discloses that one type selected from nitrides and carbides on the surface of the smoothed grain-oriented silicon steel plate by a CVD method or a PVD method such as ion plating or ion implantation. Alternatively, it is disclosed that extremely low iron loss can be obtained by depositing two or more kinds of tension coatings.
In this case, in particular, nitrides and carbides that are hard and have a small thermal expansion coefficient are effective for applying tension using thermal residual stress. However, since many of these nitrides and carbides have high tension, non-uniform film thickness results in non-uniform magnetic characteristics, especially magnetization characteristics and iron loss at low magnetic flux densities, and distorts the shape of the steel sheet. There was a risk of falling.

  Here, in order to uniformly form a nitride or carbide ceramic coating continuously by applying a chemical vapor deposition method to a metal strip, using the above magnetic steel sheet as a typical example, the coating is applied to the metal strip in the processing furnace. It is important that the source gas concentration in the vicinity of the surface of the metal strip is made uniform evenly in the width direction of the metal strip. The raw material gas is usually introduced into the processing furnace and supplied to the metal strip through a nozzle. Therefore, it is preferable that the source gas is sprayed from the nozzles uniformly in the width direction of the metal strip.

  Regarding a nozzle used for supplying a raw material gas in a chemical vapor deposition method, Patent Document 6 describes that a porous body is introduced into a gas nozzle to make the pressure constant. Here, in order to form a homogeneous ceramic coating, it is important to realize a high-speed jet. However, in the nozzle of Patent Document 6, it is necessary to insert a large porous body into the nozzle, which realizes a high-speed jet. This has the disadvantage that the entire nozzle has to be very large. A further major problem is that the manufacturing cost of the nozzle is very high. This is a big problem for industrialization.

Patent Document 7 discloses that a blow-out hole is formed in an outer cylinder of a concentric double cylinder. In this structure, the source gas can be heated by passing the source gas through the inner cylinder, which contributes to performing chemical vapor deposition under advantageous conditions. However, since the source gas is sprayed from the blowout holes, there is room for improvement where it is difficult to equalize the spraying.
Japanese Patent Publication No.53-28375 Japanese Patent Publication No.56-52117 Japanese Patent Publication No.52-24499 JP-A-5-43943 Japanese Patent Publication No. 63-54767 JP 2001-54746 A Japanese Unexamined Patent Publication No. 7-278819

Therefore, the present invention is intended to provide a nozzle used for supplying a source gas in a chemical vapor deposition method with a structure in which the spray of the source gas is uniform in the width direction of the metal strip.
Another object of the present invention is to propose a method for uniformly forming a ceramic coating that gives a strong tension to a steel plate by chemical vapor deposition.

  The inventors have intensively studied a structure that can obtain a uniform jet flow between the discharge ports with respect to a nozzle having a plurality of discharge ports. As a result, the nozzles are sequentially divided into two paths from the source gas supply side to the discharge side. The present inventors have found that it is important to maintain equal conductance between two paths in a piping structure that repeats branches, and have completed the present invention.

That is, the gist configuration of the present invention is as follows.
(1) A nozzle that blows a raw material gas toward a metal strip introduced into a processing furnace that performs chemical vapor deposition, and a pipe extending from the raw material gas supply side to the raw material gas discharge side is discharged from the supply side. Branches that are sequentially divided into two paths toward the side are repeated in at least two stages, and a discharge port is provided at the end of the path of the final stage branch, and conductances in the paths after branching in each stage are equal to each other in the two paths A nozzle for supplying a raw material gas for chemical vapor deposition.

(2) When forming a film by a chemical vapor reaction method by spraying a raw material gas on the surface of the metal strip, at least two branches that are sequentially divided into two paths from the raw material gas supply side to the discharge side are provided. When the source gas is blown onto the surface of the metal strip via the source gas supply nozzle having a discharge port provided at the end of the path of the final stage branch, the path after the branch of each stage is repeated. A method for forming a film on a metal strip, wherein the conductance is adjusted equally between the two paths.

(3) When forming a nitride and / or carbide film by a chemical vapor reaction method by spraying a raw material gas on the surface of a grain-oriented electrical steel sheet without an inorganic film, the material gas is supplied from the supply side to the discharge side. Branches that are sequentially divided into two paths toward the end are repeated in at least two stages, and a raw material gas is sprayed onto the surface of the steel sheet through a raw material gas supply nozzle provided with a discharge port at the end of the final stage branch. In this case, the method for forming a coating on a grain-oriented electrical steel sheet is characterized in that the conductance in the paths after branching in each stage is adjusted equally between the two paths.

(4) A grain-oriented electrical steel sheet having a nitride and / or carbide coating formed by the method described in (3) above.

Here, the conductance is a coefficient representing the ease of fluid flow in the pipe. Specifically, the pressure on the upstream side of the pipe is P ₁ and P ₂ , and the mass flow rate Q is a pressure difference ΔP = P. ₁ when it is assumed to be proportional to the -P _2, the proportionality constant of conductance. When this conductance is represented by C, the following relationship is established.
Q = C · ΔP

  Since the nozzle of the present invention can eject the raw material gas uniformly and efficiently, it is extremely effective particularly when it is desired to form a uniform film by chemical vapor deposition.

  Moreover, according to the film forming method of the present invention, a ceramic film that gives a strong tension to the steel sheet can be formed uniformly by chemical vapor deposition, which greatly contributes to the provision of a grain-oriented electrical steel sheet with uniform magnetic properties. Is. Furthermore, since it is possible to appropriately control the ceramic coating having a large tension imparting effect to a thickness corresponding to the operating frequency of the electromagnetic steel sheet, good coating adhesion and a very low high-frequency iron loss value can be obtained.

  First, FIG. 1 schematically shows the inside of a vertical processing furnace of a chemical vapor deposition (hereinafter referred to as CVD) apparatus to which the nozzle of the present invention is applied. As shown in FIG. 1, in a vertical processing furnace, a steel strip 1 as a metal strip is passed in the vertical direction, and a nozzle 2 and a steel strip 1 disposed respectively at positions facing each other across the steel strip 1. Is surrounded by a large number of heaters 3. A plurality of discharge ports 2a of the nozzle 2 are arranged in the width direction of the steel strip 1, in the drawing, in the front and back direction of the paper surface, and will be described in detail later. And while heating the steel strip 1 and the nozzle 2 with the heater 3, the raw material gas 4 is sprayed on the steel strip 1 from the discharge port 2a of the nozzle 2, and between this raw material gas 4 and the gas 5 supplied in the furnace A chemical reaction is caused to form a coating 6 on the surface of the steel strip 1.

  In the nozzle 2 used in such a CVD apparatus, the raw material gas 4 supplied therefrom needs to be a jet that is uniform in the width direction of the steel strip 1. For example, when a TiN film is formed by a vapor deposition reaction, the jet velocity of the raw material gas 4 from the nozzle 2 needs to be, for example, 0.5 m / s or more, and preferably 1.5 m / s or more. At that time, the temperature in the furnace, the steel plate 1, the nozzle gas 5 and the temperature in the furnace gas 6 must be 600 ° C. or higher, preferably 1000 ° C. or higher. Under these conditions, the film 6 is formed only on the surface of the steel strip by a chemical reaction.

  What is important here is to uniformly inject the raw material gas 4 from the nozzle 2 in the width direction of the steel strip 1, for which purpose the structure of the nozzle 2 is important. Therefore, a study was made on a nozzle in which branching was repeated from the supply side of the source gas toward the discharge side, and a plurality of discharge ports were provided at the ends.

In examining this nozzle structure, first, the function evaluation was performed by the film thickness distribution in the film formation with respect to the grain-oriented electrical steel sheet. The experimental results are described in detail below.
An ingot made of steel containing Si: 3 mass% was used as a slab, then hot rolled to a predetermined plate thickness and cold rolled to a final plate thickness of 0.23 mm. This cold-rolled sheet is sheared to a width of 150 mm, then decarburized and subjected to primary recrystallization annealing, and then an annealing separator containing MgO as the main component and antimony chloride is applied, and the final process including the secondary recrystallization process and the purification process. Annealing was performed to obtain a grain-oriented silicon steel sheet adjusted to a mirror-like smooth surface without a forsterite film.

After that, chemical vapor deposition is performed at a temperature of 1100 ° C. using an ordinary slit nozzle in an atmosphere mainly composed of TiCl ₄ gas, H ₂ gas, and N ₂ gas to smooth the directional silicon steel sheet. A TiN film was formed on the surface. Subsequently, the coating liquid which has a phosphate and colloidal silica as a main component was apply | coated, and it baked at 850 degreeC. Thereafter, the specimen was cut into a length of 280 mm and a width of 30 mm, and a test piece was collected and subjected to strain relief annealing at 800 ° C. for 3 hours in an N ₂ gas atmosphere to evaluate the film thickness and iron loss.

In parallel with the case of the slit nozzle, at the temperature of 1100 ° C., in the atmosphere mainly composed of TiCl ₄ gas, H ₂ gas, and N ₂ gas, each source gas and carrier gas supply are shown in FIG. As shown in the figure, the branch that is sequentially divided into two paths from the gas supply side to the discharge side is repeated in four stages, and the discharge port 2a is provided at the end of the path of the fourth branch in the final stage. Chemical vapor deposition was performed using a nozzle (hereinafter referred to as a two-branch type nozzle) in which conductances in the paths after branching were made equal in the two paths.

  When the film thickness distribution in the width direction of the steel strip was investigated for the coating thus obtained, the results shown in FIG. 3 were obtained. In other words, the film thickness distribution in the width direction occurred at 40% or more of the average value with the normal slit nozzle, whereas the film thickness distribution was suppressed to 10% or less of the average value when the two-branch type nozzle was used. I understand that

Subsequently, the iron loss and magnetic flux density of the test piece having a width of 30 mm were measured. As shown in FIG. 4, the measurement result of W _17/50 value (iron _loss value at 1.7 T at 50 Hz, the same applies to the following) corresponds to the film thickness distribution. In contrast to the width direction distribution, the 2-branch type nozzle has a good width direction distribution of 4% or less. In addition, as shown in FIG. 5, the measurement result of the magnetic flux density B ₈ value (magnetic flux density at a magnetizing force of 800 A / m, hereinafter the same) shows a distribution in the width direction of about 1% with a normal slit nozzle, A good distribution in the width direction of about 0.7% was obtained with the 2-branch type nozzle.

  Furthermore, as a result of conducting a bending adhesion test by winding a test piece around a 10 mmφ round bar, it was confirmed that when a two-branch type nozzle was used, the TiN film was not peeled off and was good.

From the above experimental results, it is possible to obtain a uniform film thickness by using a two-branch type nozzle, and as a result, magnetic characteristics, in particular, good iron loss width direction distribution can be obtained and the average value of iron loss. Was found to be improved.
That is, by using a two-branch type nozzle, equalizing the Kong dance from the branch of each stage to the next branch, and repeating this, the spraying speed at each outlet can be made uniform. The film thickness distribution of the coating can be made uniform.

Next, the above-described two-branch type nozzle will be described more specifically.
For example, when the film is continuously formed on the directional electromagnetic steel strip, the nozzle piping system repeats the branching of the two paths from the gas supply side to the discharge port side shown in FIG. The nozzle having the structure shown in FIG. 2 is used as one system, and the two systems are connected in parallel in the conveying direction of the steel strip 1 shown in FIG. 1 (see FIG. 6). A structure in which the belt 1 is connected in parallel in the transport direction (see FIG. 7) is suitable. In any form, it is important that the conductance is equivalent between the two paths after branching.

  In addition, when a coating is formed on a stationary steel plate in a batch manner, for example, a piping system in which a plurality of outlets are arranged on a single plane by repeating branching two-dimensionally as shown in FIG. 8 is suitable. .

Furthermore, in order to apply the piping system of FIG. 8 to continuous film formation on a steel strip, the piping system is inclined at a predetermined angle with respect to the conveying direction of the steel strip 1, as shown in FIG. Thus, the film can be formed with better uniformity.
In this case, as shown in FIG. 10, four discharge rollers may be connected as one unit by four pipes having the same conductance.

As shown in FIG. 8, the inclination angle of the piping system in the case where the same number of outlets are provided on the front, rear, left, and right sides, that is, the source gas supply port when the rotation angle in FIG. If the rotation angle is sin ^-1 (W / n / d), where W is the width of the steel strip, d is the interval between the discharge ports of the source gas, and n is the number of discharge ports, the purpose of ensuring uniformity Is the most convenient. This is because in such a relationship, the interval when the source gas discharge port is projected onto a surface parallel to the steel strip width direction becomes uniform. As shown in FIG. 8, when the number of discharge ports is 64, the inclination angle is preferably sin ⁻¹ (W / 64d).

  Further, when using a plurality of source gases, as shown in FIG. 11, two systems having the structure shown in FIG. 8 or FIG. An arrangement that promotes uniformity is preferred.

  In addition to the above-described raw material gas supply piping, it is also possible to provide a drain piping for effectively locally discharging unreacted gas or reaction products from the inside of the processing furnace. Also for this drain pipe, the same structure as the above-described source gas supply pipe can be used. FIG. 12 shows a typical example of a piping system with such a drain and using two kinds of source gases.

  Here, the piping structure shown in FIGS. 8 to 12 can of course be constituted by three-dimensional piping, but it takes time to manufacture the piping structure, and maintenance when piping clogging occurs is difficult. Therefore, as a simpler method, a groove similar to the branch pattern shown in FIGS. 8 to 12 is engraved on a flat metal or ceramic plate, and two plates after the groove formation are bonded together. A method of finishing the pipe by covering the plate after forming the groove with a plate having no groove is recommended. In this case, by attaching a short pipe having the same conductance to the end of each pipe as a discharge pipe, an effect equivalent to that of a pipe system formed by connecting the pipes can be obtained.

  Further, since the piping patterns shown in FIGS. 8 to 12 are approximate fractal patterns, if further uniformity is required, the patterns can be made fine according to the same principle. Since such a pattern can be easily produced using a numerically controlled (NC) machine tool, the above-described pattern engraving method is recommended when producing the pipe of the present invention.

  In order to equalize the conductance between the two paths after branching in the two-branching type nozzle, it is convenient to make the shape of the length, inner diameter, curvature and angle of the bent portion the same. The shape of each path may be adjusted so that the conductance is the same between the two paths while actually measuring the conductance from after the branch to the next branch.

When a ceramic coating is formed on a grain-oriented electrical steel sheet using the nozzles described above, chemical vapor deposition and physical vapor deposition are typical methods for forming the ceramic coating. Any method may be used. That is, as a well-known method of growing nitrides and carbides using chemical vapor deposition, a metal chloride gas such as TiCl ₄ and, if nitrides, N ₂ , NH ₃ , (CH ₃ ) 3N, (CH ₃ ) 2NH gas, etc. For carbides, CH ₄ , CO, C ₂ H ₄ , C ₃ H ₈ , C ₂ H ₆ , IC ₅ H ₁₂ etc. are used as raw material gas and mixed together A technique for obtaining a nitride or carbide coating by heating a steel sheet in a heated atmosphere can be employed. Of course, both can be mixed to form a charcoal film. In addition, Ar gas or the like is used as a balance gas.

  In addition, the so-called MO-CVD method using an organometallic gas as a metal source, and a CVD method that is aimed at lowering the temperature by using plasma, laser, or photo-induction, etc. are being actively performed in recent years. A thermal CVD method that heats the entire chemical vapor deposition tank is more suitable. However, any combination of the above methods for the purpose of improving the deposition rate is acceptable as long as it is within the scope of the present invention.

  The resulting ceramic coating is a nitride and / or carbide of Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Co, Ni, Al, B, Si, two or more of these May be laminated. When two or more layers are laminated, the film thickness may be determined in consideration of the molar ratio of nitrogen and / or carbon to metal elements in the entire laminated film.

  The thickness of the ceramic coating is advantageously in the range of 0.01 μm to 5 μm. That is, when the thickness is less than 0.01 μm, a sufficient tension imparting effect and film adhesion cannot be obtained, while when it exceeds 5 μm, the adhesion and space factor of the film itself are disadvantageous.

  The surface of the steel sheet after finish annealing to which the film formation of the present invention is applied is effective even on the surface of the steel plate from which the inorganic film such as forsterite is simply removed, but it is more effective to apply a smoothing treatment to the surface. It is more effective in reducing the value. The steel plate surface that has undergone the smoothing treatment is, for example, a surface finished to a mirror surface by minimizing the roughness of the surface by thermal etching, chemical polishing, etc., or crystal orientation enhancement treatment by electrolysis in a halide submerged liquid. The resulting graining-like surface can be mentioned.

  In addition, use directional silicon steel sheets with emphasis on workability such as punching, changing the main component of the annealing separator used in finish annealing, and adding additives to suppress the formation of coating during finish annealing. There is no problem.

  As the insulating coat formed on the nitride or carbide ceramic coating formed by chemical vapor deposition, an inorganic coating used for the grain-oriented silicon steel sheet can be used. In particular, in order to achieve ultra-low iron loss, a combination of a coating having a tension-imparting effect and a grain-oriented silicon steel sheet with a smooth surface is extremely effective. As a kind of such tension-imparting coating, a coating containing silica that lowers the thermal expansion coefficient is effective, and phosphate-colloidal silica conventionally used for grain-oriented silicon steel sheets having a forsterite film- A chromate-based coating or the like is preferable from the viewpoint of its effect and cost, uniform processability, and the like. The thickness of the coating is preferably in the range of about 0.3 μm or more and 10 μm or less from the viewpoint of tension imparting effect, space factor, film adhesion, and the like.

  Incidentally, oxides such as boric acid-alumina proposed as other tension-providing coatings in JP-A-6-65754, JP-A-6-65755, JP-A-6-299366, etc. It is also possible to apply a system coating.

Next, the desirable component composition of the silicon steel plate targeted in the present invention will be described.
As a component of the steel sheet used in the present invention, it is desirable to contain Si at 1.5 to 7.0 mass%. In other words, Si is an effective component for increasing the electrical resistance of steel and reducing iron loss, and if it is less than 1.5 mass%, transformation occurs during final finish annealing and a stable secondary recrystallized structure is obtained. Absent. On the other hand, if it exceeds 7.0 mass%, the hardness becomes too high, which may make it difficult to produce and process.

Moreover, crystal orientation can be further improved by containing 0.006 mass% or more of Al as an inhibitor element in steel in the initial stage of melting. The upper limit of Al is about 0.06 mass%, and if it exceeds this, the crystal orientation deteriorates again.
N has the same effect as Al, and the upper limit is preferably about 100 ppm from the limit of occurrence of blister defects. On the other hand, the lower limit is not particularly specified, but it is difficult to make it 20 ppm or less in consideration of economy.

  Further, a process of performing nitriding treatment after primary recrystallization annealing is also applicable. When nitriding treatment is not performed, it is essential to contain 0.01 mass% or more and 0.06 mass% or less Se + S in the steel in the initial stage of melting, and in addition, 0.02 to 0.2 mass is required for precipitation as an Mn compound. It is preferable to contain about% Mn. If the amount is too small, the amount of precipitates for causing secondary recrystallization is too small. If the amount is too large, solid solution before hot rolling becomes difficult. When nitriding is not performed, Mn is not always necessary, but can be added as appropriate for the purpose of improving the ductility of steel.

In addition to the above elements, the steel contains known inhibitor components suitable for the production of grain-oriented silicon steel sheets, such as B, Bi, Sb, Mo, Te, Sn, P, Ge, As, Nb, Cr, Ti, Cu, Pb, Zn and In are known, and these elements can be contained alone or in combination.
In addition, impurities such as C, S, and N all have harmful effects on the magnetic properties, and particularly deteriorate iron loss, so that C: 0.003 mass% or less, S: 0.002 mass% or less, and N: 0.002 mass, respectively. % Or less is preferable.

Next, the essential conditions and reasons for the manufacturing method of the electromagnetic steel sheet will be described.
Steel slabs adjusted to the prescribed components are usually subjected to slab heating and then hot rolled into hot rolled coils. The heating temperature of this slab is about 1300 ° C or higher or 1250 ° C or lower. Any of the low-temperature regions may be used. In recent years, a method of directly performing hot rolling after continuous casting without performing slab heating has been developed. However, this method can also be applied to the case of hot rolling by this method.

  The hot-rolled steel sheet is subjected to hot-rolled sheet annealing as necessary, and is made into a final cold-rolled sheet by rolling once or a plurality of times sandwiching intermediate annealing. About these rolling, what was called warm rolling aiming at dynamic aging, and what carried out the aging between passes aiming at static aging may be given.

  The steel sheet after the final cold rolling is subjected to primary recrystallization annealing that also serves as decarburization annealing, and further subjected to secondary recrystallization treatment by final finishing annealing, thereby imparting magnetic directionality. When the final finish annealing is performed, an annealing separator is usually applied after the primary recrystallization annealing, thereby forming an oxide film. By adjusting the composition of the annealing separator, the oxide on the steel sheet surface is adjusted. It is also possible to suppress the formation of a film.

  For the purpose of further reducing iron loss, the obtained steel sheet is irradiated with a laser or a plasma flame to subdivide the magnetic domain without any problem in the adhesion of the insulating coating. It is also effective as a means of further reducing iron loss to form grooves at regular intervals by etching or tooth profile rolls on the steel sheet surface for magnetic domain fragmentation at any stage of the production process of grain-oriented silicon steel sheets. It is.

Electrolytic etching for the purpose of magnetic domain refinement on a cold rolled sheet rolled to a final sheet thickness of 0.23mm, containing Si: 3mass% and Mn: 0.07mass%, with the composition of the balance Fe and inevitable impurities. After forming linear grooves at intervals of 4 mm, decarburization and primary recrystallization annealing are applied, followed by the application of an annealing separator mainly composed of MgO, and a final finish annealing plate having a smooth surface without a forsterite film. Got. Next, chemical vapor deposition is performed on the smooth surface of the grain-oriented silicon steel sheet at a temperature of 1150 ° C. in an atmosphere mainly composed of TiC1 ₄ gas, H ₂ gas and N ₂ gas, and has various film thicknesses. A TiN film was formed.

Here, TiC1 ₄ gas, H ₂ gas, and N ₂ gas are each independently a two-branch type with five-stage branching, in which another branch is added to the four-stage piping system shown in FIG. A nozzle and a conventional slit nozzle were used to spray on the surface of the steel plate, and a film material was generated on the surface of the steel plate by chemical vapor deposition.

Further, with respect to another of the steel sheet, it was formed on the steel sheet both sides of TiC at various thickness in an atmosphere consisting of TiC1 _4, a mixed gas of H ₂ and CH _4. H ₂ gas and CH ₄ gas is used as a mixed gas, TiC1 ₄ gas was density adjustment H ₂ gas as a carrier gas.

Here, H ₂ and CH ₄ mixed gas and TiC1 ₄ gas are each independently a two-branch type with a five-stage branching in which another branch is added to the four-stage piping system shown in FIG. A nozzle and a conventional slit nozzle were used to spray on the surface of the steel plate, and a film material was generated on the surface of the steel plate by chemical vapor deposition.

  In addition, the conductance between the two paths after branching in the two-branch type nozzle was equalized by making the pipe shape of the part from the branch to the next branch the same in each stage. Moreover, the structure of the conventional slit nozzle shall be what inserted the porous body made from ceramics into the inside of a nozzle as described in the cited reference 6. FIG.

Thereafter, 30 parts by weight of 30% colloidal silica was mixed with an aqueous solution obtained by adding 15 parts by weight of potassium dichromate to primary magnesium phosphate, and then applied with a roll coater and baked at 800 ° C. for 1 minute to form an insulating film. A test piece for magnetic measurement was taken from this steel plate, subjected to strain relief annealing at 800 ° C. for 2 hours, and then subjected to magnetic measurement.
As shown in Table 1, it can be seen that the uniformity of magnetic characteristics is improved by the two-branch type nozzle.

For the purpose of magnetic domain fragmentation on a cold rolled coil with a width of 500 mm rolled to a final sheet thickness of 0.23 mm, containing Si: 3 mass% and Mn: 0.08 mass%, the composition of the balance Fe and inevitable impurities After forming linear grooves by electrolytic etching at intervals of 4 mm, decarburization and primary recrystallization annealing are applied, followed by the application of an annealing separator mainly composed of MgO, and a smooth surface having no forsterite film. A finish annealing coil was obtained. On the smooth surface of this coil, chemical vapor deposition is performed at 1150 ° C in an atmosphere mainly composed of TiC1 ₄ gas, H ₂ gas and N ₂ gas to form TiN coatings with various thicknesses. did.

Here, TiC1 ₄ gas, H ₂ gas, and N ₂ gas are each independently a two-branch type with five-stage branching, in which another branch is added to the four-stage piping system shown in FIG. Using a nozzle and a conventional porous nozzle, the film was sprayed on the surface of the steel sheet, and a film material was generated on the surface of the steel sheet by chemical vapor deposition.

  In addition, the conductance between the two paths after branching in the two-branch type nozzle was equalized by making the pipe shape of the part from the branch to the next branch the same in each stage. Moreover, the structure of the conventional perforated nozzle shall be what formed the blowing hole of equal intervals in the outer cylinder of the concentric double cylinder as described in the cited reference 7. FIG.

Then, an aqueous coating solution in which 15 parts by mass of potassium dichromate is added to 100 parts by mass of primary magnesium phosphate, and 30 parts by mass of 30 mass% corocadal silica are mixed on the coating film with a roll coater, An insulating film was formed by baking at 800 ° C. for 1 minute.
A test piece for magnetic measurement was collected from the coil thus obtained, subjected to strain relief annealing at 800 ° C. for 2 hours, and then subjected to magnetic measurement.
As shown in Table 2, it can be seen that the two-branch type nozzle improves the uniformity of the magnetic characteristics in both the width direction and the plate longitudinal direction.

It is a figure which shows the inside of the processing furnace in the CVD apparatus to which this invention is applied. It is a figure which shows the nozzle for raw material gas supply of this invention. It is a figure which shows distribution in the steel strip width direction of a film thickness. It is a figure which shows distribution in the steel strip width direction of iron loss _{W17 / 50} . It is a diagram illustrating a distribution of a steel strip width direction of the magnetic flux density B _8. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention. It is a figure which shows the other form of the nozzle for source gas supply according to this invention.

Explanation of symbols

1 Steel strip 2 Nozzle 2a Discharge port 3 Heater 4 Raw material gas 5 Furnace gas 6 Coating

Claims (4)

  A nozzle that blows a source gas toward a metal strip introduced into a processing furnace that performs chemical vapor deposition, and a pipe that extends from the source gas supply side to the source gas discharge side extends from the supply side to the discharge side. Branches that are sequentially divided into two paths are repeated in at least two stages, and a discharge port is provided at the end of the path of the final stage branch, and conductances in the paths after branching in each stage are equal to each other. A nozzle for supplying gas for chemical vapor deposition.   When forming a film by the chemical vapor reaction method by spraying the raw material gas onto the surface of the metal strip, the branching divided into two paths from the raw material gas supply side to the discharge side is repeated in at least two stages. When the source gas is sprayed onto the surface of the metal strip via the source gas supply nozzle provided with the discharge port at the end of the path of the final stage branch, the conductance in the path after the branch of each stage is 2 A method of forming a coating on a metal strip, characterized by equal adjustment between paths.   When forming a nitride and / or carbide coating by a chemical vapor reaction method by spraying a source gas on the surface of a grain-oriented electrical steel sheet without an inorganic coating, from the source gas supply side to the discharge side When the source gas is sprayed on the surface of the steel sheet through the source gas supply nozzle, which is provided with a discharge port at the end of the final stage branch path at least in two stages of branching that is sequentially divided into two paths, A method for forming a coating on a grain-oriented electrical steel sheet, wherein the conductance in the paths after branching at each stage is adjusted equally between the two paths.   A low iron loss grain-oriented electrical steel sheet having a nitride and / or carbide coating formed by the method according to claim 3.