JP2000345240A - Production of sendust thin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an extremely thin sendust sheet having extremely excellent magnetic properties by obtaining a sintered body having an F-enriched phase and an Si-enriched Fe-Si solid solution phase, subjecting this stock to cold rolling, impregnating the cold rolling stock with Al and annealing this Al- impregnated material. SOLUTION: Preferably, the content of Si in the sintered body is 8.3 to 11.7 wt.%, additionally, the content of Al is 0 to 2.0 wt.%, and the balance Fe with inevitable impurities. The thickness of the sintered body is preferably controlled to <=5 mm. A powdery mixture obtd. by blending Fe powder and Fe-Si powder in a prescribed ratio is formed into the sintered body by a powder metallurgical method to produce a rolling stock of the sintered silicon steel in which an Fe-enriched phase enough in expansibility is remained, this is subjected to cold rolling, both sides of the obtd. rolled silicon steel sheet are stuck with Al by a vacuum deposition method, a sputtering method, a CVD method or the like, and, after that, heat treatment is executed to diffuse it to the inside of the thin sheet, by which a sendust thin sheet having extremely excellent magnetic properties is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing Fe which is difficult to roll.
-Si-Al alloy (Sendust)
A thin plate-shaped sintered body with a thickness of 5 mm or less consisting of an Fe-rich main phase and an Fe-Si phase is produced, and cold rolling is directly performed using this as a raw material, utilizing the excellent ductility of the Fe-rich phase crystal grains. The present invention also relates to a manufacturing method for obtaining an ultra-thin sendust thin plate having a required composition by allowing Al to adhere to both surfaces of a rolled thin plate and then performing heat treatment to diffuse and infiltrate into the inside of the thin plate.

[0002]

2. Description of the Related Art Sendust is very excellent as a soft magnetic material because of its high magnetic permeability, but it has been difficult to manufacture Sendust thin plates conventionally because it is very brittle and hard.

[0003] For this purpose, an ingot having a content of Fe less than the required components of Sendust is prepared and then crushed, and Fe powder is added to the crushed powder to obtain a required composition to make the Fe powder serve as a binder. , Rolling and heat treatment are repeated to achieve a thickness of 0.35
mm of sendust sheet (HHHelms and
E. Adams: J. Appl. Phys. 35 (1964) 3) was proposed.

[0004] The above-mentioned method using powder metallurgy has a problem that the magnetic properties are deteriorated due to insufficient diffusion of additional elements, and has not been widely used.

[0005]

For this purpose, a sendust crystal having few defects is prepared and thinly cut or formed on a required substrate by a sputtering method to form a sendust thin plate. Utilizing its excellent features.

That is, conventionally, since mass production is difficult and mass production is difficult in the past, the production amount of sendust thin plates is very small, and the application is limited at present.

[0007] In view of the present situation in which a sendust thin plate was difficult to manufacture and a laminated iron core or the like could not be constructed, a sendust thin plate can be manufactured by cold rolling, and has very excellent magnetic properties. It is an object of the present invention to provide a method for producing a sendust thin plate, from which a sendust thin plate can be obtained.

[0008]

Means for Solving the Problems In order to enable cold rolling of silicon steel having a Si content of 3 wt% or more, apart from the Fe-Si-Al alloy, the present inventors As a result of various investigations on the production method of silicon steel with good iron content, focusing on the composition within the crystal grains, unlike the conventional crystal grains of the phase in which Fe and Si were completely dissolved by slow melting and melting, Fe-rich It is possible to produce a sintered silicon steel with a mixed phase having a Fe-Si solid solution phase and a Si-rich Fe-Si solid solution phase, leaving a Fe-rich phase rich in ductility and rolling it by cold rolling. And especially the thickness of the steel
It has been found that the rolling can be performed relatively easily by setting the parallelism to 5 mm or less and the parallelism to 0.5 mm or less.

[0009] Further, as a method for producing sintered silicon steel, the inventors of the present invention sinter a powder mixture obtained by mixing Fe powder and Fe-Si powder at a predetermined ratio by powder metallurgy to obtain a desired average A sintered body having a crystal grain size can be produced. As a powder metallurgy method, after molding by metal injection molding, compaction molding, slip cast molding in a slurry state, etc., sintering is performed at a predetermined temperature. It has been found that a method or a method of producing by a hot forming method such as hot pressing or plasma sintering can be adopted.

[0010] Furthermore, the present inventors used a sintered body in which an Fe-rich phase was left for the purpose of producing an Fe-Si-Al alloy, and examined the ductility of crystal grains having the Fe-rich phase. Al is vapor-deposited on both sides of the sintered silicon steel sheet obtained by cold rolling using various conditions, and then heat-treated, whereby Al diffuses from the surface to the inside, and the magnetic permeability is also silicon. The present inventors have found that a sendust thin plate having excellent magnetic properties can be obtained by remarkably improving as compared with a steel plate, and the present invention has been completed.

[0011] That is, the present invention is to roll a sintered silicon steel having a Fe-rich phase and a Si-rich Fe-Si solid solution phase,
Vacuum evaporation method, sputtering method, CVD (Chemical Vapor Depos
After impregnating both surfaces of a sintered silicon steel sheet with Al by the method, etc., annealed and diffused and permeated, this is a method for producing sendust thin sheets that can be made extremely thin and have excellent magnetic properties. .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for producing a sintered body by mixing a powder mixture of Fe powder and Fe-Si powder at a predetermined ratio by a powder metallurgical method, and leaving an Fe-rich phase rich in ductility. After preparing a rolled material of sintered silicon steel that has been subjected to cold rolling, the Al is deposited on both sides of the obtained rolled silicon steel sheet by a vacuum deposition method, a sputtering method, a CVD method, etc., followed by heat treatment. This is a manufacturing method of obtaining a sendust thin plate having very excellent magnetic properties by diffusing into the inside of the thin plate.

[0013] In the present invention, as the components of the sintered silicon steel as a raw material, the content of Si in the steel is 8.3 to 11.7 wt%, and the content of Al is
It is desirable to have a required composition of 0 to 2 wt%. As the raw material powder used, Fe powder and Fe-Si powder or Fe powder
There is a method of using a mixed powder in which Fe-Si-Al powder is blended at a predetermined ratio, or an Fe-Si compound or a Fe-Si-Al compound powder having a predetermined composition.

[0014] As the mixed powder raw material, a gas atomized powder of Fe-Si compound which contains more Si than a desired composition and is a brittle and fragile component, or a powder obtained by crushing an ingot having the component and jet milling the same is used. A mixed powder containing carbonyl iron powder at a predetermined ratio, or a component containing more Si than desired and easily brittle,
It is desirable to use a gas-atomized powder of a Fe-Si-Al compound to which a trace amount is added, or a mixed powder obtained by crushing an ingot having the component and jet mill-crushing powder and carbonyl iron powder at a predetermined ratio.

[0015] The Fe-Si- (Al) compound used is β
Phase Fe ₂ Si compound, ε phase FeSi compound, and ζβ phase F
eSi ₂ compounds are preferred because they are liable to brittle fracture. Fe-Si
The Si content in the compound is preferably from 20 wt% to 51 wt%. If the Si content is out of this range, it becomes very susceptible to oxidation and causes deterioration of magnetic properties. The Al content in the Fe-Si compound is preferably 0 to 6.0 wt%. If the Al content is out of this range, cracks and cracks are liable to occur during cold rolling, and at the same time, oxidation is further liable to occur, resulting in deterioration of magnetic properties.

The average particle size of the powder of the Fe-Si compound or the Fe-Si-Al compound is most preferably in the range of 3 μm to 100 μm.
If it is less than 3 μm, the powder itself tends to contain a large amount of oxygen and the magnetic properties deteriorate, and if it exceeds 100 μm, the sintered body tends to become porous and the sintered density decreases,
This causes cracks and cracks during cold rolling.

On the other hand, the carbonyl iron powder is preferably a commercially available powder having a particle size of 3 to 10 μm and containing as little oxygen as possible.
In any case, the oxygen content of the mixed powder of Fe powder and Fe-Si compound powder or Fe powder and Fe-Si-Al compound powder,
The smaller the better, the better, but preferably at least 3000 ppm or less.

When a raw material powder having a desired composition is used, a gas atomized powder or a water atomized powder containing the component from the beginning is suitable, and the average particle size is 10 to
100 μm is desirable. The oxygen content of the raw material powder used is preferably as small as possible, but at least 3000 ppm
The following is desirable.

When the average particle size of the atomized powder is less than 10 μm, the density of the sintered body is improved, but since the powder itself contains a large amount of oxygen, cracks and cracks are likely to occur during cold rolling, and It also causes deterioration of magnetic characteristics. If the average particle size exceeds 100 μm, the sintered body tends to be porous and the sintering density decreases, which also causes cracks and cracks during cold rolling.

Sintered Silicon Steel Before Rolling Powder metallurgy can be used to produce a sintered body before rolling. A sintered body by metal injection molding, powder compaction, slip casting, etc. Production of a sintered body by a hot forming method such as plasma sintering is suitable. Specifically, metal injection molding, compaction molding, and slip cast molding are methods in which a binder is added to silicon steel powder and molding is performed, and after molding, the binder is removed and sintering is performed. The hot forming method is a method in which a raw material powder is placed in a carbon mold, and pressure and pressure are applied during hot (1000 ° C. to 1300 ° C.) to simultaneously perform forming and firing.

[0021] The obtained sintered silicon steel is a mixed phase having a Fe-rich main phase and a Si-rich Fe-Si solid solution phase, in which a large number of Fe-rich phases rich in ductility are formed. . Note that here, the case where the amount of Si in the phase exceeds 10% is Si-rich,
The case not exceeding this is called Fe-rich.

In general, silicon steel powder containing a large amount of Si is very easily oxidized, and when a binder is used for molding, it is particularly oxidized or carbonized. Therefore, debinding and controlling the atmosphere during sintering are indispensable. It is. In addition, since the oxidized and carbonized sintered body is hard and brittle, when cold-rolled, cracks,
At the same time as cracking occurs, the magnetic properties after annealing are significantly reduced. For this reason, the amount of oxygen and the amount of carbon contained in the sintered body are desirably 3000 ppm and 200 ppm or less, respectively.

The sintering temperature varies depending on the composition of the mixed powder, the average particle size, the molding method, etc., and the sintering atmosphere such as an inert gas atmosphere, a hydrogen gas atmosphere, or a vacuum at a temperature of 1100 ° C. to 1250 ° C. You can use them properly according to the method. However, if deformation during sintering is not prevented as much as possible, cracks and cracks may occur during cold rolling.

In particular, it is important to perform sintering at a temperature slightly lower than the original sintering temperature in order to leave a Fe-rich phase rich in ductility after sintering. During sintering, deformation during sintering is prevented as much as possible, and the parallelism for 50 mm length is 0.5 m
If it is not less than m, cracks and cracks may occur during cold rolling.

Rolled silicon steel is hard and brittle compared to general metals, so the roll diameter for cold rolling and its peripheral speed need to be changed depending on the thickness before rolling and its parallelism. . That is, if the sheet thickness before rolling is large and the parallelism is poor, it is desirable to perform rolling at a small roll diameter and at a low peripheral speed.

However, conversely, if the plate thickness is small and parallelism is good,
This condition is relaxed considerably. In particular, in the case of hot rolling, since the composition of silicon steel is easily deformed, the conditions of the roll diameter and the peripheral speed are remarkably relaxed as compared with the cold rolling. It is effective to perform hot rolling before cold rolling, but finally, if cold rolling is not performed, rolling of a thin plate becomes impossible. This is because the surface layer is oxidized and the magnetic properties deteriorate. In any method, unless the parallelism of the steel sheet before rolling is set to 0.5 mm or less, a good rolled silicon steel sheet cannot be produced.

According to the present invention, in the case of a silicon steel sheet having an Fe-rich phase, when the sheet thickness before rolling is 5 mm or less and the parallelism is 0.5 mm or less (for a length of 50 mm), the roll diameter is 80 mm or less, and the roll peripheral speed is Under the condition of 60 mm / sec or less, cold rolling can be performed without an annealing step at the time of cold rolling and without causing cracks and cracks.

In the present invention, when the thickness of the silicon steel sheet becomes 1 mm or less, rolling with a roll having a smaller roll diameter improves rolling efficiency and thickness dimensional accuracy, and furthermore, cracks and cracks are less likely to occur. Tend.

When the average crystal grain size of the silicon steel exceeds 300 μm, cracks and cracks occur during rolling regardless of the roll diameter and the roll peripheral speed. The production of silicon steel sheet having an average crystal grain size of less than 5 μm can be produced only by powder metallurgy sintering method, which is a method of sintering by lowering the sintering temperature or lowering the molding density. Even with the method described above, a sintered body having a high porosity is obtained, so that cracks and cracks always occur during rolling.

The thickness of the sheet after rolling should be 1 mm or less.
l easily diffuses into the silicon steel plate. Furthermore, it was found that cold rolling can be easily performed to a thickness of 50 μm under optimum rolling conditions.

[0031] The silicon steel sheet rolled by the above method can be processed by a cutting machine or a punching machine after rolling, and can be used for sendust thin sheets of various shapes by performing Al impregnation described later after the processing. It is.

[0032] The rolled silicon steel sheet utilizing plastic deformation due to the Fe-rich phase according to the present invention has a direction in which the (100) plane has a texture unlike a normal oriented silicon steel sheet having a (110) plane as a texture. It has the characteristics of a conductive silicon steel sheet.

Al impregnation In order to produce a sendust thin plate having a desired composition, both sides of a sheet-shaped rolled silicon steel sheet are impregnated with Al. Specifically, Al is impregnated by a vacuum evaporation method, a sputtering method, a CVD method, or the like. ,
After the diffusion, the film is adhered and formed to have a predetermined composition, and then impregnated by heat treatment. The adhesion and film formation amount of Al may be appropriately determined so that the final components after diffusion are Al: 2 to 6 wt%, Si: 8 to 11 wt%, and the balance Fe.

The above adhesion and film formation conditions differ depending on the thickness, composition, and vapor deposition method of the rolled silicon steel sheet. However, when the vapor deposition is performed directly on the silicon steel sheet whose surface has been cleaned after cold rolling, Al diffuses uniformly. It is easy to improve the magnetic properties. That is, the crystal grain size after rolling is smaller than the crystal grain size after annealing, and the residual crystal strain is large, so that Al is easily diffused at the grain boundary.

The heat treatment for impregnating Al must be appropriately selected depending on the composition of the silicon steel sheet, the amount of Al attached, and the average crystal grain size before rolling. This temperature is preferably set as low as 1000 to 1100 ° C. in the case of heat treatment in a vacuum, and is preferably set to a slightly higher temperature of 1100 to 1200 ° C. in the case of heat treatment in an inert gas atmosphere.

Further, the rolled silicon steel sheet according to the present invention has the characteristics of a directional silicon steel sheet having a (100) plane texture unlike a normal directional silicon steel sheet having a (110) plane texture. In addition, since the rolled surface is not the closest surface, there is an advantage that intracrystalline diffusion is liable to occur during heat treatment after vapor deposition.

Annealing That is, conventionally, annealing of a rolled silicon steel sheet is always performed after rolling several times in order to prevent cracks and cracks during rolling. However, in the present invention, the diffusion and infiltration of impregnated Al The purpose of the present invention is to increase the crystal grain size for the purpose of reducing crystal grain boundaries which hinder domain wall movement, lowering coercive force and improving magnetic permeability. In addition, when a nonmagnetic metal element such as Ti, V or the like is added alone or in a combination of 0.01 to 1.0 wt%, a Fe-rich phase and a Si-rich phase are likely to form a solid solution at the time of annealing, and promote the growth of crystal grains. I can do it.

In the present invention, the annealing heat treatment temperature is:
After Al diffuses and infiltrates by the Al impregnation heat treatment described above, 12
The temperature is raised to a temperature of 00 to 1300 ° C. to increase the crystal grain size.
The annealing heat treatment can be performed continuously with the heat treatment for impregnating Al.

In a vacuum, if the annealing temperature is too high, Al
Evaporates from the steel sheet and becomes difficult to diffuse and permeate. If the temperature after Al diffusion is too high, the crystal grains will grow abnormally abnormally and the steel sheet will become very brittle.On the contrary, if the temperature is too low, the grains will not grow and the magnetic properties will not improve, so The above temperature range is the optimum temperature. The average crystal grain size can be grown to about 0.5 to 3 mm by annealing at the above temperature. It was confirmed that the magnetic properties of the sendust thin plate obtained by this annealing were similar to those of a normal ingot.

Conventionally, Sendust alloys are hard and brittle, so that it has been difficult to roll and it is impossible to produce thin sheet materials. However, in the present invention, using a powder mixture of Fe powder and Fe-Si-Al powder or a powder mixture of Fe powder and Fe-Si-Al powder in a predetermined ratio or a powder of a desired composition as a starting material, the sinterability is improved after sintering. By producing a thin plate having a rich Fe-rich phase remaining with a thickness of 5 mm or less, cold rolling became possible.

Further, in the present invention, Al is deposited on both sides of the rolled silicon steel sheet, a film is formed, and then heat treatment is performed to diffuse Al and increase the crystal grain size. It was confirmed that a sendust thin plate with excellent magnetic properties could be produced, which was almost equivalent to the ingot material of No. 1.

Further, the rolled silicon steel sheet of the material is cut after rolling,
Since processing such as punching is possible and various types of sendust thin plates can be manufactured according to various applications, there is an advantage that it is possible to manufacture sendust thin plates with low cost, high characteristics, and high dimensional accuracy.

[0043]

Example 1 As a raw material powder for a sintered silicon steel sheet, an ingot was produced by high-frequency melting to obtain an Fe-Si compound and an Fe-Si-Al compound having the components shown in Table 1 and then forming an ingot. Pulverization and jet mill pulverization produced powder having an average particle size as shown in Table 1.

[0044] Carbonyl iron powder having the components and average particle size shown in Table 1 was used as the iron powder. The Fe-Si compound or Fe-Si-Al compound and carbonyl iron powder were blended in the ratio shown in Table 2 and then mixed with a V cone.

Further, as the powder having the desired composition, the components shown in Table 3 and gas atomized powder having an average particle size were used.
The PVA (polyvinyl alcohol) binder, water, and plasticizer were added to each raw material powder in the amounts shown in Table 4 to form a slurry, and the slurry was heated with nitrogen gas using a completely sealed spray dryer with hot air at the inlet temperature. Granulation was performed at a temperature of 100 ° C. and an outlet temperature of 40 ° C.

[0046] The granulated powder having an average particle size of about 80 µm was pressed into a shape as shown in Table 5 with a compression press at a pressure of ² ton / cm ² , and then debindered as shown in Table 5 in a vacuum. Sintering was performed at the sintering temperature to obtain a sintered body having the dimensions shown in Table 6. FIG. 6 shows the parallelism of the obtained sintered body, and Table 7 shows the content of the iron-rich phase, the residual oxygen content, the residual carbon content, the average crystal grain size, and the relative density. The content of the iron-rich phase depends on the specific maximum X-ray diffraction intensity of the FeSi compound and the silicon steel having the body-centered cubic structure (bcc).
Relative evaluation was made based on the (110) diffraction intensity ratio.

[0047] The sintered body having the dimensions shown in Table 8 was first cold-rolled to a rolling reduction of 50% at a roll peripheral speed of 60 mm / sec with a two-stage roll having an outer diameter of 60 mm, and further rolled with a four-stage roll having an outer diameter of 20φ. Cold rolling was performed to the thickness shown in Table 8 at the same roll peripheral speed. Table 9 shows the rolling state.

Further, after rolling, a 20φ × 10φ ring was punched out, and then Al was vacuum-deposited on both surfaces of the steel sheet to a thickness shown in Table 10,
Heat treatment was performed at an annealing temperature as shown in FIG. 10, and DC magnetic characteristics were measured. Table 10 shows the results. In the rolling state in Table 9, ◎ indicates very good, ○ indicates good, △ indicates occurrence of cracks on the end face of the rolled sheet, and × indicates occurrence of cracks on the entire surface.

Comparative Example As a comparative example of the magnetic properties, Table 10 shows the magnetic properties of the ingots of ordinary Fe-6.5Si and Sendust alloy.

[0050]

【table 1】

[0051]

[Table 2]

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

[Table 7]

[0057]

[Table 8]

[0058]

[Table 9]

[0059]

[Table 10]

[0060]

According to the present invention, it is possible to manufacture a sendust thin plate which has been conventionally difficult to manufacture by cold rolling, and an extremely thin sendust plate can be easily mass-produced. Also, a sendust thin plate having excellent magnetic properties equivalent to that of the ingot material can be obtained. Therefore, its applications will be dramatically expanded in a wide range such as transformers and yoke materials in the future.

Further, the sendust thin plate according to the present invention is capable of processing such as cutting and punching of a rolled silicon steel sheet, and can produce products of sendust thin plate of various shapes according to various uses, thereby reducing costs. It is possible to produce sendust thin plate with high characteristics and high dimensional accuracy.

Continued on the front page (72) Inventor Masao Nomi 2--15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Sumitomo Special Metals Co., Ltd. Yamazaki Works (72) Inventor Tsunekazu Saigo 2--15, Egawa, Shimamoto-cho, Mishima-gun, Osaka −17 Sumitomo Special Metals Co., Ltd. Yamazaki Works F-term (reference) 4K018 AA26 CA12 CA30 FA02 FA08 FA35

Claims (7)

[Claims] A step of obtaining a sintered body having a Fe-rich phase and a Si-rich Fe-Si solid solution phase, a step of cold-rolling the sintered body material, a step of impregnating a cold-rolled material with Al, The Al
A method for producing a sendust sheet including a step of annealing an impregnating material. 2. The method for producing a sendust thin plate according to claim 1, wherein the content of Si in the sintered body is 8.3 to 11.7 wt%. 3. The sintered body has a Si content of 8.3 to 11.7 wt%, Al
The method for producing a sendust thin plate according to claim 1, wherein the content is 0 to 2.0 wt%. 4. The composition of the obtained sendust sheet is Si: 8
2. The method for producing a sendust thin plate according to claim 1, wherein the Al is 2 to 6 wt%, the balance being Fe and unavoidable impurities. 5. The method for producing a sendust thin plate according to claim 1, wherein the thickness of the sintered body is 5 mm or less. 6. A powder metallurgy method of molding and sintering by powder injection molding, compaction molding, slip casting, or a hot compacting method such as hot pressing or plasma sintering. A sintered body with a Fe-rich phase remaining
6. The method for producing a sendust thin plate according to 5. 7. The method for producing a sendust thin plate according to claim 1, wherein Al is deposited or formed on both surfaces of the cold-rolled material and then impregnated with Al by heat treatment.