JPH07173502A - Method for producing metal or ceramic sintered body - Google Patents

Abstract

PURPOSE:To produce a metallic or ceramic sintered body having high dimensional precision by carrying out uniform dispersion when metal powder or ceramic powder is mixed with an org. binder and kneaded to prepare starting material for molding. CONSTITUTION:Two or more kinds of org. high molecular compds. are mixed and kneaded to obtain an org. binder. Metal powder or ceramic powder is mixed with a plasticizer to prepare a powdery starting material mixture. This mixture is mixed with the org. binder, kneaded and crushed, the resultant pellets are formed into a molded body by injection molding or extrusion molding and this molded body is dewaxed and sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal or ceramics sintered body, and in particular, degreasing an injection molded body or an extrusion molded body composed of metal powder or ceramics powder and a binder containing an organic polymer compound as a main component. , A method for producing a sintered metal or ceramic sintered body.

[0002]

2. Description of the Related Art Generally, powder metallurgy has been used as a conventional method for producing a metal or ceramics sintered body.
The powder metallurgy method is a method in which a prepared raw material powder is pressed into a desired shape and then sintered to obtain a metal or ceramics sintered body. It is widely used industrially as the most suitable method for doing this.

However, with the recent technological development, not only the material characteristics but also the complicated shape as a structure is being demanded for a metal or ceramic sintered body. Since there is a limit in terms of shape to the above-mentioned press molding in response to these requirements, the injection molding method and the extrusion molding method which have been conventionally used for plastic molding can easily mold the complicated shape product. Since then, it has come to be incorporated into the manufacturing process of metals or ceramics.

That is, a metal powder or ceramic powder is mixed with a binder containing an organic polymer as a main component, and a kneaded product is subjected to injection molding using a mold having a cavity having a desired shape, or a desired cross section. Extrusion molding is performed using a die with a shaped opening, and then metal or ceramics is sintered through a degreasing process that removes only organic polymer compounds by heating and extraction operations and a sintering process that solidifies metal powders or ceramics powders. It is a manufacturing method for obtaining a body.

[0005]

The method for producing a metal or ceramics sintered body using the above-mentioned injection molding method or extrusion molding method utilizes the characteristic of these molding methods that mass-produced articles having complicated shapes can be produced. However, a large amount of metal powder or ceramic powder to the extent that the powder has a plasticity applicable to the injection molding method or the extrusion molding method, for example, 10 times the binder used in the press molding method. Above, it is necessary to disperse the organic polymer compound, and even though this dispersibility has a great influence on the degree of dimensional accuracy and shape deformation of the desired metal or ceramic sintered body, the organic polymer It has a drawback that it is difficult to uniformly disperse the compound.

That is, in the method for producing a metal or ceramics sintered body using the above-mentioned injection molding method or extrusion molding method, the homogeneity of the green compact density of the degreasing body to be subjected to the sintering step depends on the dimensional accuracy of the sintered body. It is known that the degree of shape deformation is greatly affected. On the other hand, in order to achieve both the moldability applicable to the injection molding method or the extrusion molding method and the degreasing property of the molded body, the metal powder or the ceramic powder must be mixed and kneaded with a plurality of kinds of organic polymer compounds. I won't. However, since the organic polymer compounds have different physical properties such as average molecular weight, softening point and melt viscosity for each type, there is a limit to the homogenous dispersion of these organic polymer compounds in the metal powder or the ceramic powder. When the molded product obtained by the injection molding method or the extrusion molding method is degreased while the dispersibility of these organic polymer compounds with respect to the metal powder or the ceramic powder has a coarse and dense distribution, the powder compact of the degreased body is naturally obtained. The density also has a coarse and dense distribution, and there is a drawback that it is difficult to obtain a desired size and shape in the sintered body obtained through the subsequent sintering step due to the difference in shrinkage rate during sintering.

In order to solve the above-mentioned drawbacks, it has been attempted to raise the temperature of mixing and kneading, lengthen the time, and increase the energy applied during mixing and kneading to enhance the dispersibility.
Dispersion does not proceed beyond a certain dispersion rate, but conversely thermal degradation of the organic polymer compound progresses. In addition, a method of increasing the dispersibility between organic polymer compounds by adding a powder after kneading only the organic polymer compound has been studied,
A great effect cannot be exhibited in improving the dispersibility between the organic polymer compound and the powder. Further, mixing and kneading with only one kind of organic polymer compound has been considered, but either moldability or degreasing property must be sacrificed. On the other hand, as a surface treatment agent, using a silane-based, titanium-based, or chromium-based organometallic compound called a coupling agent, a method of improving the wettability between the powder surface and the polymer compound and improving the dispersibility is also proposed. However, since the metal component contained in the coupling agent becomes an impurity with respect to the metal powder and the ceramic powder, a fundamental solution has not been reached.

Therefore, a technical object of the present invention is to obtain a molding powder composed of an organic polymer compound and a metal powder or a ceramic powder, which is excellent in dispersibility, and achieves both molding property and degreasing property of the molded product. Another object of the present invention is to provide a method for producing a metal or ceramics sintered body, which can prevent deformation of the sintered body and obtain high dimensional accuracy.

[0009]

In order to solve the above-mentioned drawbacks of the conventional method for producing a metal or ceramics sintered body, the present inventor relates to metal powders, ceramics powders and organic polymer compounds, and injection molding. The present invention has been accomplished through intensive studies on the method and the extrusion molding method.

The method for producing a metal or ceramics sintered body of the present invention comprises mixing an organic binder obtained by mixing and kneading two or more kinds of organic polymer compounds, a metal powder or a ceramics powder and a plasticizer. The raw material mixed powder obtained as described above is mixed and kneaded, and then pulverized into pellets, the pellets are formed into a molded body by an injection molding method or an extrusion molding method, and then the molded body is degreased and sintered. To do. Further, the method for producing a metal or ceramics sintered body of the present invention uses a phthalic acid ester as a plasticizer, and the metal powder or the ceramic powder has a content of 0.3 to
It is characterized by mixing 3.0 wt%.

The metal or ceramic powder that can be used in the present invention is not particularly limited as long as it is a type that can be sintered and that can be applied to conventional powder metallurgy. In addition, various polymer compounds can be applied as the organic binder, and, for example, various polyolefins, various acrylic resins and waxes can be applied. Further, the phthalate ester as the plasticizer is phthalate di- 2-Ethylhexyl, dibutyl phthalate, dimethyl phthalate and the like can be used as appropriate, but are not limited thereto.

[0012]

The method for producing a metal or ceramics sintered body of the present invention is made in view of the characteristics of the organic polymer compound employed in the above-described series of steps.

That is, in order to mix and knead two or more kinds of organic polymer compounds with metal powder or ceramic powder, it is necessary to uniformly disperse a plurality of kinds of organic polymer compounds among the respective powders. As described above, it is extremely difficult to simultaneously mix the organic polymer compounds with each other and to knead the powder with high homogeneity at the same time.

However, according to the present invention, first, two or more kinds of organic polymer compounds are mixed and kneaded so that the macro can be regarded as a single kind of organic polymer compound, and then,
By mixing the metal powder or the ceramic powder with the plasticizer, the dispersibility associated with the mixing and kneading between the powder and the organic polymer compound is improved.

That is, since the plasticizer has the characteristics of lowering the elastic modulus and glass transition point of the organic polymer compound and adding flexibility, it is possible to mix the powder with the organic polymer compound. The fluidity at the interface between the polymer compound and the powder is increased to enhance the dispersibility.

Phthalates have a solubility parameter (SP value) of 8 to 9, and most organic polymer compounds selected in consideration of injection moldability, extrusion moldability and degreasing property have a solubility parameter of 8. Since they are close to each other, they have good compatibility and were selected as plasticizers.

Further, the mixing ratio of the phthalic acid ester to the metal powder or the ceramic powder is 0.3 to 3.0.
wt% is desirable. If it is less than 0.3 wt%, the effect as a plasticizer does not sufficiently appear, while if it is more than 3.0 wt%, the melt viscosity of the organic polymer compound is remarkably reduced, resulting in deterioration of moldability and further molding. The plasticizer oozes out on the body surface, making industrial handling difficult.

[0018]

Next, the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view showing a ferrite sintered body obtained by a manufacturing method according to this embodiment of the present invention.

In FIG. 1, a ferrite sintered body 1 has a circular through hole 1b at the center, an outer diameter of 43 mm and an inner diameter of 2
Width 1.0m on the surface of a disk 1mm thick and 4.5mm thick
It has a structure in which five grooves 1a having a depth of 1.4 mm and a depth of 1.4 mm are located at intervals of 2.0 mm.

The method for manufacturing the ferrite sintered body shown in FIG. 1 will be described below.

Polypropylene 1 as an organic polymer compound
1.2 wt%, ethylene-vinyl acetate copolymer 33.3
wt%, polystyrene 33.3 wt%, and melting point 60
22.2 wt% of paraffin wax at 40 ° C is mixed, and then it is mixed with a 30 mm twin-screw extruder at 140 ° C and 50 rpm
After kneading, the mixture was pelletized using a rotary blade type pulverizer to obtain an admixture having a diameter of about 4 mm.

Fe ₂ O ₃ 49.5 as ceramic powder
mol%, NiO12.6mol%, ZnO32.2m
The starting raw material powder adjusted to ol% and CuO 5.7 mol% was mixed and crushed in water using a ball mill for 10 hours, then filtered and dried, and pre-fired and crushed to obtain Ni-Cu having an average particle size of 1 μm.
-Zn ferrite pre-fired powder was obtained.

Next, di-n-phthalate was added to 98.8 wt% of the above Ni-Cu-Zn ferrite pre-calcined powder.
Add 1.2 wt% of butyl and add 1 with a Henschel mixer.
The mixture was mixed at 20 rpm for 15 minutes to obtain a ferrite mixed powder.

9 wt% of the above-mentioned admixture was mixed with 91 wt% of the above-mentioned ferrite mixed powder, and the mixture was kneaded with a 30 mm biaxial kneading extruder at 140 ° C. and 50 rpm, and then pelletized using a rotary blade type pulverizer. A raw material for injection molding having a diameter of about 4 mm was obtained.

The above injection molding raw material is molded at a molding temperature of 160.
Introduced into a mold for injection molding having a cavity of a predetermined shape at ℃, filled and injection molded, then using a heating furnace with an internal volume of 4.2 liters, heating rate of 10 ℃ / hr in the atmosphere At 450 ° C., furnace cooling, degreasing, and further sintering in an air atmosphere at a sintering temperature of 1200 ° C. for 2 hours to obtain a ferrite sintered body shown in FIG.

When the dimensions of 50 ferrite sintered bodies obtained in the above series of steps were measured, the standard deviations of the outer diameter and the inner diameter were 0.010 and 0.005, respectively. Furthermore, the concentricity of the outer diameter with respect to the inner diameter is 0.03 on average.
It was 3 mm and the standard deviation was 0.003.

(Example 2) In the same steps as in Example 1,
The mixing amount of di-n-butyl phthalate with respect to the ferrite powder is 0, 0.1, 0.2, 0.3, 0.5, 1.0,
The injection molding raw materials were prepared at 2.0, 3.0, 4.0, and 5.0 wt% and then injection molded. The injection molding raw materials with a mixed amount of 5.0 wt% were melted at the time of molding. The viscosity was too low to mold. In addition, the mixing amount is 4.0 wt
%, The viscous liquid considered to be a plasticizer oozes out on the surface of the molded body.

The amount of the above-mentioned di-n-butyl phthalate mixed with the ferrite powder is 0, 0.1, 0.2, 0.
Ferrite obtained by degreasing and sintering an injection-molded article using the injection-molding raw material of 3, 0.5, 1.0, 2.0, 3.0, 4.0 wt% in the same manner as in Example 1. The dimension of the sintered body was measured. The standard deviations of the outer diameter and the inner diameter are shown in FIG.

Comparative Example 1 For comparison, the same mixing ratio as in Example 1, that is, 90 wt% of Ni-Cu-Zn ferrite pre-calcined powder, 1.0 wt.
%, Ethylene-vinyl acetate copolymer 3.0 wt%, polystyrene 3.0 wt%, paraffin wax 2.0 wt% having a melting point of 60 ° C., and di-n-butyl phthalate 1.0.
wt%, and then 1 with a 30 mm twin-screw kneading extruder
After kneading under the conditions of 40 ° C. and 50 rpm, the mixture was pelletized using a rotary blade type pulverizer to obtain a raw material for injection molding having a diameter of about 4 mm. Further, a ferrite sintered body 50 obtained by injection molding, degreasing, and sintering in the same manner as in Example 1
Individual dimension measurements were made. The results are shown in Table 1.

(Comparative Example 2) The same mixing ratio as in Example 1, that is, 90 wt% of Ni-Cu-Zn ferrite pre-calcined powder.
%, Polypropylene 1.0 wt%, ethylene-
Vinyl acetate copolymer 3.0 wt%, polystyrene 3.0
2.0 wt% paraffin wax with a melting point of 60%
%, And 1.0 wt% of di-n-butyl phthalate are mixed, and then, with a 30 mm twin-screw kneading extruder, 160 ° C., 50
After kneading under the conditions of rpm, the mixture was pelletized using a rotary blade type pulverizer to obtain a raw material for injection molding having a diameter of about 4 mm. Further, in the same manner as in Example 1, 50 ferrite sintered bodies obtained by injection molding, degreasing and sintering were measured. The results are shown in Table 1.

(Comparative Example 3) A mixing ratio similar to that of Example 1, that is, 90 wt% of Ni-Cu-Zn ferrite pre-calcined powder.
%, Polypropylene 1.0 wt%, ethylene-
Vinyl acetate copolymer 3.0 wt%, polystyrene 3.0
2.0 wt% paraffin wax with a melting point of 60%
%, And 1.0 wt% of di-n-butyl phthalate are mixed, and then 140 ° C. and 50 with a 30 mm twin-screw kneading extruder.
After kneading twice under the condition of rpm, the mixture was pelletized using a rotary blade type pulverizer to obtain a raw material for injection molding having a diameter of about 4 mm. Further, in the same manner as in Example 1, 50 ferrite sintered bodies obtained by injection molding, degreasing and sintering were measured. The results are shown in Table 1.

(Comparative Example 4) Further, for comparison, the same mixing ratio as in Example 1 was used, and polypropylene 10.0 wt.
%, Ethylene-vinyl acetate copolymer 30.0 wt%, polystyrene 30.0 wt%, paraffin wax having a melting point of 60 ° C. 20.0 wt%, and di-n-butyl phthalate 10.0 wt% are mixed, and then 30 mm After kneading with a twin-screw kneading extruder at 140 ° C. and 50 rpm, the mixture was pelletized with a rotary blade type pulverizer to obtain an admixture having a diameter of about 4 mm, and Ni-Cu-Zn ferrite pre-calcined powder 90.0 wt
% After mixing 10.0% by weight of the above-mentioned admixture with 30%
m Kneading with a twin-screw kneading extruder at 140 ° C. and 50 rpm, then pelletizing with a rotary blade type crusher, diameter of about 4 m
m raw material for injection molding was obtained. Further, in the same manner as in Example 1, 50 ferrite sintered bodies obtained by injection molding, degreasing and sintering were measured. The results are shown in Table 1.
Shown in.

[0033]

[Table 1]

As shown in Table 1, the dimensional accuracy of the ferrite sintered body according to the present invention was high, and the effectiveness of the present invention was confirmed.

(Embodiment 3) FIG. 3 is a perspective view showing an iron-cobalt sintered body obtained by the manufacturing method according to this embodiment of the present invention.

In FIG. 3, the iron-cobalt sintered body 2 is
One side of the cross section is 8.0 mm, the other side is 3.0 mm, the thickness is 1.0 mm, and the length is 50 mm.

The method of manufacturing the iron-cobalt sintered body shown in FIG. 3 will be described below.

As the organic polymer compound, 30.2 wt% of butyl methacrylate-butyl acrylate copolymer, 36.1 wt% of high-density polyethylene, and 33.7 wt% of ethylene-vinyl acetate copolymer were mixed, and then 30 mm 2 After kneading with a shaft kneading extruder at 130 ° C. and 50 rpm,
The mixture was pelletized using a rotary blade type pulverizer to obtain an admixture having a diameter of about 4 mm.

Fe50 wt% and Co50 as metal powders
An ingot having a composition of wt% was melted and an iron-cobalt powder having an average particle diameter of 9 μm was obtained by a water atomizing method.

Then, the above-mentioned iron-cobalt powder 99.
Add 0.8 wt% of di-2-ethylhexyl phthalate to 2 wt%, and use a Henschel mixer for 120 r
The mixture was mixed at pm for 15 minutes to obtain an iron-cobalt mixed powder.

91.7w of the above-mentioned iron-cobalt mixed powder
30 m after mixing 8.3 wt% of the admixture with t%
m After kneading with a twin-screw kneading extruder at 130 ° C. and 50 rpm, pelletizing with a rotary blade type crusher, diameter of about 4 m
A raw material for extrusion molding of m was obtained.

The above-mentioned extrusion molding raw material is molded at a molding temperature of 1
After extrusion molding at 30 ° C. through an extrusion molding die having a predetermined opening, a heating furnace having an internal volume of 4.2 liters was used, while flowing 0.5 liter / min of argon, from room temperature to 10 ° C. / It was heated to 550 ° C at a heating rate of hr, heated to 550 ° C and held for 5 hours, then rapidly cooled to degrease, further heated to 1200 ° C at 400 ° C / hr and held for 2 hours to sinter, and then the length was reduced to 50 mm. Figure 3 by cutting
The iron-cobalt sintered body shown in was obtained.

The dimension of 50 iron-cobalt sintered bodies obtained by the above-mentioned series of steps was measured and found to be 8.0 mm.
And the standard deviation of 3.0 mm part is 0.029,
It was 0.011. Further, the parallelism of the 8.0 mm portions facing each other was 0.043 mm on average and 0.009 in standard deviation.

Example 4 In the same steps as in Example 3, the mixing amount of di-2-ethylhexyl phthalate with respect to the iron-cobalt powder was 0, 0.1, 0.2, 0.3, 0.5. ,
A raw material for extrusion molding was prepared as 1.0, 2.0, 3.0, 4.0, 5.0 wt%, and then extrusion molding was performed. In the raw material for use, a viscous liquid considered to be a plasticizer oozes out on the surface of the molded body.

The amount of di-2-ethylhexyl phthalate mixed with the iron-cobalt powder was 0, 0.1, 0.
2, 0.3, 0.5, 1.0, 2.0, 3.0, 4.
The extrusion-molded body obtained by using the extrusion-molding raw material at 0 and 5.0 wt% was degreased and sintered in the same manner as in Example 3, and the dimension of the obtained iron-cobalt sintered body was measured.
The standard deviations of the 8.0 mm portion and the 3.0 mm portion are shown in FIG.

Comparative Example 5 For comparison, the same mixing ratio as in Example 3, ie, iron-cobalt powder 91.0 wt%
On the other hand, 2.5 wt% of butyl methacrylate-butyl acrylate copolymer, 3.0 wt% of high density polyethylene, 2.8 wt% of ethylene-vinyl acetate copolymer and 0.7 wt% of di-2-ethylhexyl phthalate. After mixing and then kneading with a 30 mm biaxial kneading extruder under the conditions of 130 ° C. and 50 rpm, the mixture was pelletized using a rotary blade type pulverizer to obtain an extrusion molding raw material having a diameter of about 4 mm. Further, the dimensions of 50 iron-cobalt sintered bodies obtained by extrusion molding, degreasing, and sintering were measured in the same manner as in Example 3. The results are shown in Table 2.

Comparative Example 6 The same mixing ratio as in Example 3, that is, 91.0 wt% of iron-cobalt powder to 2.5 wt% of butyl methacrylate-butyl acrylate copolymer.
%, High-density polyethylene 3.0 wt%, ethylene-vinyl acetate copolymer 2.8 wt%, and di-2-ethylhexyl phthalate 0.7 wt% are mixed, and then 150 ° C. with a 30 mm biaxial kneading extruder. After kneading under the condition of 50 rpm, pelletized using a rotary blade type crusher and diameter of about 4 m
A raw material for extrusion molding of m was obtained. Further, the dimensions of 50 iron-cobalt sintered bodies obtained by extrusion molding, degreasing, and sintering were measured in the same manner as in Example 3. The results are shown in Table 2.

Comparative Example 7 The same mixing ratio as in Example 3, that is, 91.0 wt% of iron-cobalt powder to 2.5 wt% of butyl methacrylate-butyl acrylate copolymer.
%, High-density polyethylene 3.0 wt%, ethylene-vinyl acetate copolymer 2.8 wt%, and di-2-ethylhexyl phthalate 0.7 wt% are mixed, and then 130 ° C. with a 30 mm biaxial kneading extruder. After kneading twice under the condition of 50 rpm, it was pelletized using a rotary blade type pulverizer to obtain an extrusion molding raw material having a diameter of about 4 mm. Furthermore, Example 3
The dimensions of 50 iron-cobalt sintered bodies obtained by extrusion molding, degreasing, and sintering were measured in the same manner as in.
The results are shown in Table 2.

(Comparative Example 8) Further, as a comparison, the same mixing ratio as in Example 3 was used, that is, 27.8 wt% of butyl methacrylate-butyl acrylate copolymer, 33.8 wt% of high-density polyethylene, and ethylene-vinyl acetate. Copolymer 3
1.1 wt% and 7.3 wt% of di-2-ethylhexyl phthalate were mixed and then kneaded with a 30 mm twin-screw kneading extruder at 130 ° C. and 50 rpm, and then pelletized using a rotary blade type pulverizer An admixture of about 4 mm was obtained, and the above admixture 9.
After mixing 0wt%, 130mm with a 30mm twin-screw kneading extruder
After kneading at 50 ° C. at 50 ° C., it was pelletized using a rotary blade type pulverizer to obtain an extrusion molding raw material having a diameter of about 4 mm.

Further, the dimensions of 50 iron-cobalt sintered bodies obtained by extrusion molding, degreasing, and sintering were measured in the same manner as in Example 3. The results are shown in Table 2.

[0051]

[Table 2]

As shown in Table 2, the dimensional accuracy of the iron-cobalt sintered body according to the present invention was high, and the effectiveness of the present invention was confirmed.

[0053]

As described above in detail, according to the method for producing a metal or ceramics sintered body of the present invention, 2
After mixing and kneading one or more kinds of organic polymer compounds, mixing with metal powder or ceramic powder mixed with a plasticizer,
Since the mixture is kneaded, it is possible to provide the raw material for molding with homogeneous dispersibility associated with mixing and kneading between the organic polymer compounds and between the organic polymer compounds and the powder,
Further, the homogeneity of the green compact density of the degreased body is enhanced, and a metal or ceramics sintered body having a desired shape with high dimensional accuracy can be manufactured by uniform sintering shrinkage, which is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a sectional view showing a ferrite sintered body obtained by a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a graph illustrating the results of Example 2 of the present invention.

FIG. 3 is a perspective view showing an iron-cobalt sintered body obtained by a manufacturing method according to Example 3 of the present invention.

FIG. 4 is a graph illustrating the results of Example 4 of the present invention.

[Explanation of symbols]

 1 Ferrite Sintered Body 1a Groove 1b Through Hole 2 Iron-Cobalt Sintered Body 3 Outer Diameter 4 Inner Diameter 5 8.0 mm Part 6 3.0 mm Part

Claims (2)

[Claims] 1. An organic binder obtained by mixing and kneading two or more kinds of organic polymer compounds, and a raw material mixed powder obtained by mixing metal powder or ceramic powder and a plasticizer are mixed and kneaded. After that, it is crushed into pellets, the pellets are molded by an injection molding method or an extrusion molding method, and then the molded body is degreased and sintered. 2. A phthalic acid ester is used as a plasticizer, and a phthalic acid ester is added to a metal powder or a ceramic powder in an amount of 0.
The method for producing a metal or ceramics sintered body according to claim 1, characterized in that 3 to 3.0 wt% is mixed.