JPH0440420B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a soft magnetic sintered alloy for producing a Fe-Co-V based sintered alloy. [Prior art] In Fe-Co-V alloy, 49Fe-
49Co-2V alloy has the highest magnetic flux density and high electrical resistance among soft magnetic alloys, and therefore plays an important role in magnetic circuit components such as yoke armatures. In addition, Fe-Co-10V alloy is
Used as a semi-hard material in magnetic circuit parts. However, this 49Fe-49Co-2V alloy has poor workability, and although it can be cold rolled and punched, it cannot be subjected to bending such as drawing. Therefore, industrially, only parts with relatively simple shapes can be produced. In some cases, parts with complex shapes can be manufactured by cutting, but the processing costs are high relative to the weight of the parts, making it difficult to produce them industrially. On the other hand, powder metallurgy is a method for industrially producing metal parts with complex shapes. However, conventional powder metallurgy techniques use upper and lower punches to form compacts by compression molding, so there is a limit to the complexity of the product shapes that can be manufactured. As a method to solve this drawback, a metal powder injection molding method that combines plastic molding technology and powder metallurgy technology has recently attracted attention. When producing a sintered alloy using this injection molding method, the important techniques are the particle shape and particle size distribution of the metal powder, and the selection of the binder. In order to obtain the fluidity necessary for molding, metal powder is required to have a small specific surface area, that is, to have a smooth surface shape. Moreover, the binder content is approximately 3% by weight compared to compacts made using conventional powder metallurgy technology.
Since it contains as much as 10%, fine powder with an average particle size of about 10 μm is required to obtain a high sintered density. These metal powders having particle shapes and particle size distributions suitable for injection molding are industrially produced by water atomization or gas atomization. [Problems to be Solved by the Invention] However, when Fe-Co-V alloy powder is produced by the conventional water atomization method or gas atomization method, the viscosity of the molten metal increases due to the inclusion of V, and V is oxidized. The molten metal injection is not stable due to its strong properties, and as a result, there is a problem in that the recovery rate of fine powder with an average particle size of about 10 μm is poor and unstable. Furthermore, due to the instability of molten metal injection, there is a problem that the V content in the obtained fine powder is not constant. Therefore, in view of the above-mentioned drawbacks, the technical problem of the present invention is to provide a manufacturing method for injection molding or extrusion molding a Fe-Co-V-based sintered alloy as a sintered alloy with stable formability and stable composition. That's true. [Means for solving the problem] Fe-Co-V-based raw material powder containing 0.5% or more and 15% or less of vanadium V by weight is mixed and kneaded with a thermoplastic resin, and injection molding or extrusion molding is performed. In the method for producing a soft magnetic sintered alloy, in which the obtained compact is degreased and sintered to produce a sintered body, the Fe-Co-V raw material powder is composed of an iron-cobalt alloy powder and an iron-cobalt alloy powder. A method for producing a soft magnetic sintered alloy characterized by including a mixed powder with a vanadium alloy powder is obtained. That is, the present invention has a content of 0.5% or more and 15% by weight.
In a method for producing an iron-cobalt-vanadium sintered alloy containing V of % or less, a molded body is prepared by mixing and kneading metal powder and a thermoplastic resin and injection molding or extrusion molding, and then this molded body is In the method of producing an iron-cobalt-vanadium sintered alloy by degreasing and sintering, Fe--2, which has a particle size distribution of 44 μm (325 mesh) in maximum particle size and 5 to 15 μm in average particle size, is used as metal powder. This is a method for producing an iron-cobalt-vanadium-based sintered alloy, which is characterized by using a mixed powder of a Co-based powder and an Fe-V-based powder. The present inventors have conducted intensive studies on a method for obtaining iron-cobalt-vanadium-based sintered parts using injection molding or extrusion molding, which can produce sintered parts with good dimensional accuracy without post-processing. As a result, stable moldability is possible by using a powder that is a mixture of iron-cobalt alloy powder and iron-vanadium alloy powder as the metal powder, and
It has been found that the composition and properties of the sintered body obtained therefrom are stable. Below, the reasons for limiting the scope of the claims will be described. First, in order to obtain an iron-cobalt-vanadium-based sintered alloy by a powder metallurgy method, it is most preferable to use an alloy powder adjusted to a desired composition as a raw material powder. However, when producing a molded body through an injection molding or extrusion molding process, which is the object of the present invention, the mixture of alloy powder and thermoplastic resin must have sufficient fluidity. ,
It is difficult to use a powder obtained by mechanically crushing a lump of iron-cobalt-vanadium alloy. In other words, the most preferable raw material powder is a powder with a smooth surface made by water atomization or gas atomization. When iron-cobalt-vanadium alloy powder is produced by water atomization method or gas atomization method, the fluidity of melt spraying is significantly reduced due to the presence of vanadium, and the yield of powder with the desired particle size is reduced. Since the content of iron is also unstable, it is virtually impossible to stably obtain iron-cobalt-vanadium alloy powder industrially by water atomization or gas atomization. On the other hand, since iron-cobalt alloy powder can be easily pulverized by water atomization or gas atomization, it can be used industrially as a raw material powder. In other words, by mixing iron-cobalt powder made by water atomization method or gas atomization method with iron-vanadium alloy powder made by mechanical pulverization etc. to contain the desired vanadium, it is inexpensive and moldable. raw material powder can be obtained. In addition, as raw material powder, iron powder, cobalt powder, iron-
A mixed powder of vanadium powder is also considered, but due to the difference in atomic diffusion coefficient between iron and cobalt, it is impossible to obtain a homogeneous solid body by sintering using powder with an industrially usable particle size, so it is practically not used. It's impossible. However, since vanadium has an atomic diffusion coefficient equivalent to that of cobalt, it is possible to form a uniform solid pair even when mixed in the form of iron-vanadium alloy powder, which led to the present invention. Next, regarding the particle size of the powder, in injection molding or extrusion molding, the raw material for molding is a kneaded mixture of metal powder and thermoplastic resin. The fluidity of this kneaded material in a plasticized state determines its moldability. The factors that determine the fluidity of the kneaded product are the shape, particle size, particle size distribution of the metal powder, and the components of the resin. It can be said that the fluidity of the kneaded product is determined by the components of the thermoplastic resin, but various requirements such as thermal stability during molding, decomposition and volatilization during degreasing, and recyclability must be met. Therefore, the actual ingredients are in an extremely limited range. Therefore, it is not always possible to produce a sintered body no matter what kind of metal powder properties are used, and ultimately the properties of the metal powder must be limited. The following limitations are required in such circumstances. Among the powder properties, factors that influence the fluidity and sinterability of the kneaded material include particle shape, average particle size, particle size distribution, specific surface area, etc. Here, the shape of the particles can be represented by the specific surface area. Generally, the amount of thermoplastic resin blended is 40 to 50% by volume. Therefore, the filling rate of metal powder is 10% compared to a molded body made by normal press molding.
% or more. Therefore, in order to achieve a sufficiently high sintered density, it is necessary to make the particle size smaller than that of the powder normally used in powder metallurgy. However, as the particle size becomes smaller, the fluidity of the kneaded product decreases. Therefore, the powder has an average particle size of 5 to 15μ, which has sufficient sinterability and kneadability.
m The maximum particle size must be within the range of 4 μm or less. When the average particle size is 5 μm or less, the sintered density improves, but the kneaded material does not exhibit sufficient fluidity and a molded product with good precision cannot be obtained. Also, the average particle size is 15μ
If it exceeds m, the kneaded material will exhibit sufficient fluidity, but the sintered density of the sintered body will be less than 85%, making it impossible to obtain good properties, so the average particle size must be 15 μm or less. Furthermore, if the maximum particle size exceeds 44 μm, the particles remain as unsintered particles and a uniform sintered body structure cannot be obtained, so the maximum particle size must be 44 μm or less. [Example] Next, an example according to the present invention will be described. First Example 17.3 made by mechanical grinding with water atomized powder of 50% Fe-50% Co in wt% with maximum particle size 31 μm.
%Fe-82.7%V and 49%Fe-51%V alloy powders with particle sizes shown in Table 1 are mixed to form a raw material powder, and 9wt% of the binder shown in Table 2 is blended and mixed and kneaded. By injection molding, the inner diameter is φ20 mm and the outer diameter is φ.
A ring-shaped sample with a thickness of 5 mm was prepared.

【table】

[Table] Kneading was performed at 130°C for 20 minutes using a pressure kneader.
Injection molding was performed at a temperature of 190° C. and a gauge pressure of 100 Kg/cm ² . This molded body was placed on an alumina setter, placed in a degreasing furnace with an internal volume of 216 mm, and Ar gas
/min, the temperature was raised from room temperature to 600°C at a heating rate of 10°C per hour, held for 2 hours, and then cooled to room temperature to obtain a defatted body. Next, this degreased body was placed in a hydrogen furnace, and the temperature was raised from room temperature to 1200°C at a rate of 200°C per hour, held for 5 hours, and then cooled to room temperature to obtain a sintered body. Table 3 shows the sintered density and residual Fe of the sintered body obtained.
-Presence or absence of V particles The results of component analysis using an X-ray microanalyzer in crystal grains and remaining particles are shown.

【table】

[Table] From the table, the maximum particle size is 44 μm or less, and the average particle size is 5 to 5.
By using 15μm raw material powder, the sintered density was 90% or more in relative ratio, there were no residual particles, and vanadium was diffused in the crystal grains at 1.7 to 2.0% by weight.
It can be seen that a sintered body of 49Fe-49Co-2V (commonly known as permendium) was obtained. When the magnetic properties of the samples with no residual particles were evaluated, the properties shown in Table 4 were obtained. In particular, as a result of the solid solution of vanadium within the crystal grains, the electrical resistivity increases from 48 to
It has a high electrical resistance of 50μΩcm, about 10 times that of iron-cobalt alloys.

[Table] From the above results, it is possible to produce an iron-cobalt-vanadium sintered alloy with stable properties and composition using the injection molding process using a mixed powder of iron-cobalt powder and iron-vanadium powder that has the required powder properties. It was shown that it is possible. Second example Average particle size 10.8 μm, maximum particle size 31 μm, weight% 50
%Co−50%Fe water atomized powder with average particle size
Mechanically crushed 49Fe- with a maximum particle size of 9.7μm and 37μm.
A raw material powder was prepared by mixing 3.9% of 51V powder. Add ethylene vinyl acetate copolymer to 100 parts by weight of this raw material powder.
5.5 parts by weight, 2.7 parts by weight of high-density polyethylene, and 1.6 parts by weight of dioctyl phthalate were mixed and kneaded to obtain a raw material for extrusion molding. Next, the raw materials were put into a cylinder heated to 130° C. and extruded at a constant extrusion speed of 1 m/min to form a plate-shaped molded product with a thickness of 2 mm and a width of 50 mm. This molded body was placed in the degreasing furnace used in Example 1,
hourly from room temperature with Ar gas flowing 5/min.
The temperature was raised to 600°C at a heating rate of 10°C, and then cooled to room temperature to obtain a defatted body. Next, this degreased body was placed in a hydrogen furnace, and the temperature was raised from room temperature to 1200°C at a heating rate of 200°C per hour, held for 5 hours, and then cooled in the furnace to room temperature to obtain a sintered body. No unsintered iron-vanadium particles were found in the sintered body. The sintered density was 7.70 g/cc, and the amount of vanadium in the crystal grains was 1.82% by weight. A ring of φ20×φ30×t1.6 was cut out from the plate-shaped sintered body by laser processing, and hydrogen annealed at 830°C for 2 hours. The magnetic properties of this were B ₁₀₀ = 21.0 KG and H _C35 = 1.65 Oe. Third Example: An alloy powder made by gas atomization of 50% Fe-50% Co with a maximum particle size of 37 μm and an average particle size of 12.1 μm by weight was mechanically crushed to have a maximum particle size of 37 μm and an average particle size of 9.7 μm. 49%Fe-51%V alloy powder in weight%
Two kinds of mixed powders were prepared: a 3.9% mixed powder and a 2% V powder having an average particle size of 10.1 μm and a maximum particle size of 37 μm mixed with the above Fe-Co powder. Using these as raw materials, 9% by weight of the binder shown in Table 2 was blended, mixed and kneaded, and a ring-shaped sample having an inner diameter of 20 mm, an outer diameter of 30 mm, and a thickness of 5 mm was produced by injection molding.
Kneading was performed at 130°C for 20 minutes using a pressure kneader.
Injection molding was carried out at a temperature of 190° C. and a gauge pressure of 100 Kg/cm ² . This molded body was placed on an alumina setter, placed in a degreasing furnace with an internal volume of 216 mm, and heated from room temperature to 600°C at a rate of 10°C per hour with Ar gas flowing at 5/min for 2 hours. After being held, it was cooled to room temperature to obtain a defatted body. Next, this degreased body was placed in a hydrogen furnace, and the sound was raised from room temperature to 1200°C at a rate of 200°C per hour and held for 5 hours.
A sintered body was obtained by cooling in a furnace to room temperature. Table 5 shows the properties of the obtained sintered body, and Table 6 shows the compositional analysis values.

【table】

[Table] In the sample where Fe-V powder is mixed with Fe-Co powder, no residual Fe-V particles are observed, and the electrical resistivity is 49.5 μΩcm, and V is uniformly dissolved in the crystal grains. There is. On the other hand, in the sample mixed with V powder, residual V particles were observed, and only about 0.3% was diffused within the crystal grains. Therefore, it is found that it is better to add Fe-V in the form of powder. Fourth example Average particle size 10.8 μm, maximum particle size 31 μm, weight% 50
%Fe−50%Co water atomized powder with average particle size
Mechanically milled 49% Fe with a maximum particle size of 9.7μm and 37μm
- 3.9% of 51% V powder, 5% of carbonyl Fe powder with an average particle size of 5.5 μm, and water atomization with an average particle size of 6.4%
Co powder was mixed at 5% to obtain a raw material powder. Blend 9% by weight of the binder shown in Table 2, mix and knead, and injection mold to a thickness of 20mm inner diameter, 30mm outer diameter, and 5mm thickness.
A ring-shaped sample was prepared. The kneading method and degreasing/sintering method were the same as in the first example. The resulting sintered body contained unsintered Fe-V
No particles, Fe particles, or Co particles were observed. The sintered density is 7.58g/cc, and the amount of vanadium in the crystal grains is
It was 1.76% by weight. Also, the magnetic properties are B ₁₀₀ =
It was 20.2KG, H _C35 = 1.730e. The above results show that even if pure Fe powder or pure Co powder is mixed for component adjustment, sintered bodies having similar compositions and properties can be obtained. Table 7 shows the properties of the obtained sintered body. Table 8 shows the analysis values within the crystal grains.

【table】

[Table] V is uniformly dissolved in the crystal grains and has a concentration of about 3% and about 4%.
%V sintered body was obtained. As the amount of vanadium increased, a sintered body with high electrical resistivity and good magnetic properties was obtained. Incidentally, Table 1 shows the properties and blending ratios of the raw material powders. Table 2 shows the composition of the binder used in injection molding. Table 3 shows the X of the sintered body obtained from the injection molded body.
The results of microanalysis using a line microanalyzer are shown. Table 4 shows the magnetic properties and electrical resistivity of the sintered bodies. Here, B ₁₀₀ indicates the magnetic flux density when a magnetic field of 100 Oe is applied, H _C35 350e, and the coercive force measured when it is applied. Table 5 shows the magnetic properties and electrical resistivity of the sintered bodies. Table 6 shows the results of microanalysis of the sintered body using an X-ray microanalyzer. Table 7 shows the magnetic properties and electrical resistivity of the sintered bodies. Table 8 shows the results of microanalysis using a sintered compact X-ray microanalyzer. [Effects of the Invention] As described above, according to the present invention, iron-cobalt water atomized powder or gas atomized powder and iron-cobalt water atomized powder or iron-cobalt water atomized powder or iron-cobalt water atomized powder
It has been found that by using a powder mixed with vanadium powder with desired properties as a raw material, stable formability can be obtained, and the sintered alloy can also have stable properties and composition. Therefore, it is extremely useful as a method for producing an iron-cobalt-vanadium sintered alloy having good precision and good magnetic properties using raw material powder that can be easily produced industrially.

Claims (1)

[Claims] 1 Fe-Co-V-based raw material powder containing 0.5% or more and 15% or less of vanadium V by weight and a thermoplastic resin are mixed and kneaded, and the mixture is injection molded or extruded, In a method for producing a soft magnetic sintered alloy, in which a sintered body is produced by degreasing and sintering the obtained compact, the Fe-Co-V raw material powder is composed of an iron-cobalt alloy powder and an iron-vanadium alloy powder. A method for producing a soft magnetic sintered alloy, the method comprising a mixed powder with a powder. 2. In the method for producing a soft magnetic sintered alloy according to claim 1, the Fe-Co-V raw material powder is a mixed powder of iron-cobalt alloy powder and iron-vanadium alloy powder, and iron powder is added to the mixed powder of iron-cobalt alloy powder and iron-vanadium alloy powder. , 1 of cobalt powder
A method for producing a soft magnetic sintered alloy, the method comprising a powder containing a seed or a mixture of the two.