JPH08119749A - Method for defatting and sintering ceramic molded product or metal molded product - Google Patents

Abstract

PURPOSE: To obtain a method for defatting and sintering the ceramic molded product or metal molded product, giving the ceramic sintered compact or metal sintered compact excellent in dimension and accuracy, high in homogeneity, and little in the deterioration of various characteristics and irregularity. CONSTITUTION: The mixture of ceramic powder or metal power with a binder consisting mainly of a polymeric compound is injection-molded or extrusion- molded, and the molded product is defatted. Therein, the columnar molded products 1 are inserted into aluminum pipes 2, and the aluminum pipes 2 are rotatably sealed in a SiC pipe 3. While the SiC pipe 3 is rotated in a continuous oven having a continuous temperature gradient, the molded products 1 are defatted, and the warpage and deformation of the molded products are prevented by the sizing of the rotation. The stress deformation of the molded products by the thermal treatment is removed due to the continuous temperature gradient, and the uniformity of the amount of residual carbon due to the always changes in the surface contacting with a floor plate is removed. The molded product is sintered by the same method as the defatting method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to precision small parts for watches,
The present invention relates to a degreasing and sintering method for a compact formed of a mixture of a compact component having a complicated shape and a ceramic powder or a metal powder used as an electronic component such as an alumina product and a binder containing a polymer compound as a main component.

[0002]

2. Description of the Related Art In the process of manufacturing a sintered product of ceramics or metal by a powder metallurgy method, a method of obtaining a green compact before sintering by compression molding with a press machine or the like is widely used.

Since this is a method in which powder is usually pressed by a punch from the up and down direction, the production efficiency per unit time is lower than that of the extrusion molding method described later.

On the other hand, in the field of ceramic products centering on so-called engineering ceramics and the like, by adding 5 to 20% by weight of an organic binder to raw material powder, mixing and kneading, and then extrusion molding, a relatively complicated process is performed. Extrusion molding methods are used industrially because even shaped products can be produced efficiently.

Further, this technique has been applied to metal powders and the like with the development of mixing, kneading and extrusion molding techniques.

[0006]

However, since the binder used is thermoplastic, the molded body immediately after being extruded from the die is likely to be deformed. That is, since the magnitude of the frictional resistance with the flow path wall of the mold is different in each part of the cross-sectional shape, the flow velocity becomes non-uniform, and a warpage occurs in the extrusion direction of the extrusion-molded body, that is, the longitudinal direction. There's a problem.

Further, if it is rectified before being cooled and solidified, a molding strain remains, and in the case of a sintered product, due to the influence of the strain, the sintered body is warped and deformed, and various characteristics are deteriorated. There was a problem.

Further, when degreasing, the residual carbon amount entering from the binder is distributed between the contact surface and the upper surface of the floor plate, and the residual carbon amount increases on the contact surface of the floor plate. Therefore, in the subsequent sintering process, non-uniformity of the sintered body,
A decrease in sintering density and the like occurred, which also caused deterioration of various characteristics.

In order to solve the above-mentioned problems, an object of the present invention is to provide a ceramic sintered body or a metal sintered body which has less warpage and deformation, excellent dimensional accuracy, high homogeneity, and less deterioration in various characteristics. It is an object of the present invention to provide a degreasing and sintering method for the obtained ceramic molded body or metal molded body.

[0010]

Means for Solving the Problems A mixture of ceramic powder or metal powder and a binder containing a polymer compound as a main component is used to prepare a molded body by injection molding or extrusion molding, and then the molded body is degreased. At the time of degreasing, it is inserted into a cylindrical case and degreased while rotating in a furnace having a continuous temperature gradient. Sizing due to rotation that occurs at this time eliminates warpage and deformation. Further, the stress-strain at the time of molding is removed by the heat treatment with a continuous temperature gradient, and the contact surface with the floor plate is constantly changed, so that the distribution of the residual carbon amount can be eliminated.

By sintering in the same manner, it is possible to provide a sintered body having excellent dimensional accuracy and high homogeneity.

That is, according to the present invention, a pellet-like mixture obtained by mixing and kneading a ceramic powder or a metal powder and a binder containing a polymer compound as a main component is formed into a cylinder by an extrusion molding method or an injection molding method. Alternatively, after producing a cylindrical molded body, a small cylinder in which the molded body is inserted is inserted into a cylindrical case, the case is rotated, and the molded body itself is degreased while rotating. A degreasing method for a molded body or a metal molded body,
A pellet or a mixture obtained by mixing and kneading ceramic powder or metal powder with a binder containing a polymer compound as a main component is formed into a cylindrical or cylindrical molded body by an extrusion molding method or an injection molding method. After that, a small cylinder into which the molded body is inserted is inserted into a cylindrical case, the case is rotated, and the molded body itself is continuously sintered while being rotated, or a ceramic molded body or metal. A method for sintering a molded body, comprising the steps of degreasing and sintering a ceramic molded body or a metal molded body as described above and rotating the cylindrical case in which a plurality of small cylinders each having a molded body inserted in a cylinder are stacked. And degreasing and sintering while rotating the molded body, which is a method for degreasing and sintering a ceramic molded body or a metal molded body. When rotating the cylindrical case of, a plate for applying a rotational force to the case and moving it is placed on the cylindrical case in which a plurality of small cylinders each having a molded body inserted therein are stacked. A method for degreasing and sintering a ceramic molded body or a metal molded body, characterized in that the case is continuously rotated by sequentially sending out, and the molded body is degreased and sintered while being rotated.

[0013]

In the past, warping was generated by extrusion molding, and molding strain remained, which adversely affected the dimensional accuracy and various characteristics of the sintered body. Further, when degreasing the molded body, the binder is likely to evaporate from the upper surface of the molded body due to heating in the furnace, so the carbon of the binder also evaporates together with the binder at the same time as the binder evaporates, and The amount of residual carbon decreases. When the floor plate contact surface is in a fixed position and the contact surface with the fired body is fixed, the binder cannot evaporate from the fired body and is difficult to escape, so that carbon does not escape and the amount of residual carbon increases.
Therefore, during degreasing, a non-uniform distribution of residual carbon amount was generated between the contact surface and the top surface of the fired body, which was a major cause of non-uniformity of the sintered body and deterioration of various characteristics.

As shown in FIG. 1, a cylindrical product, which is a cylindrical product, is sealed at both ends and is inserted into a plurality of alumina tubes 2 each having a hole in the sealing portion, and is loaded on a SiC tube 3 so as to be rotatable. To be done. Similar to the alumina tube 2, a plurality of small holes are formed at both ends of the SiC tube 3 and are closed so that the molded body and the alumina tube 2 do not pop out.

As shown in FIG. 2, according to the present invention, a continuous furnace 4 provided with a continuous temperature gradient is prepared, a feed plate pushing body 7 is driven, and an alumina tube 2 in which a molded body is inserted is sealed with SiC.
The feed plate 6 is moved to the upper surface of the pipe 3, and the SiC pipe 3 is forcibly rotated and transferred into the continuous furnace 4. Since the SiC tube 3 rotates in the direction of the arrow 17 and moves forward, the molded product of the product is degreased by evaporating the binder while rotating. At the same time, the molding strain is removed by heating with a continuous temperature gradient, the rotation of the molded body itself causes the evaporation of the binder without warping, and the molded body is processed through the degreasing and firing steps as described above. Therefore, when fired, a fired body with extremely high homogeneity is obtained. And,
Further, the residual carbon amount is not uneven, and the warp and deformation of the molded body are corrected.

[0016]

Embodiments of the present invention will be described with reference to the drawings.

(Example 1) Fe50 wt as raw material powder
% -Co 50 wt% alloy is melted by high frequency heating in an argon gas atmosphere, and powder produced to have an average particle size of 10 μm by a water atomization method is used. 91 wt% of the alloy powder, ethylene / vinyl acetate copolymer (Vinyl acetate content 20 wt%) 5 wt%, paraffin wax with a melting point of 60 ° C. 3 wt%, dioctyl phthalate 1 wt%
After being kneaded for 30 minutes at 130 ° C. by a pressure kneader, pellets having a diameter of 2 mm and a length of about 4 mm were prepared.

This raw material was fed with a screw diameter of 30 mm and L / D
22, a cylinder temperature of 130 ° C., a feed rate of the molded body of 0.
5 mm diameter by extrusion machine at 5 m / min
Molding was performed into a shape having a length of 150 mm.

The inserted state of this molded body is shown in FIG. That is, both ends having an inner diameter of 15 mm and a length of 200 mm are sealed, and the both ends are sealed. The lid is sealed with the product 1 in an alumina tube 2 having a small hole, and a spacer for preventing back and forth displacement is inserted. Put dozens into the SiC tube 3,
The both ends were fitted with lids, and small holes were provided in this lid to seal and fix both ends.

This is charged into a furnace 5 having a temperature gradient using the continuous furnace 4 shown in FIG. As described above, Si
The molded body enclosed in the C tube 3 together with the alumina tube is driven by the feed plate pushing body 7 so that the feed plate 6 for cylindrical rotation moves on the SiC pipe. Rotate due to the frictional force of the tube. That is, degreasing was performed while rotating the product by such a method.

Further, as shown in FIG. 2, the cylindrical rotary feed plate 6 and the SiC pipe 3 are separated from each other by providing the furnace floor with an inclination and installing the separation plate 8 thereon.

The rotation speed was about 3 minutes / time, and the heating rate was about 10 ° C./h, the temperature was raised to 500 ° C., and the heating was performed in an Ar gas atmosphere.

As a comparative example, the product was placed on an alumina plate as in the conventional case, and degreasing was performed in an Ar gas atmosphere under the above conditions.

Then, the respective degreased bodies which are the products of the present invention and the comparative example are placed in the same furnace, and 120
Sintering was performed under the conditions of 0 ° C. × 3 hours.

Next, the warpage of each of the sintered products, which are the products, was measured by the method shown in FIG. The warpage 9 of a columnar or cylindrical product was measured by fixing the product in the longitudinal direction at a position 60 mm to the left and right from the center of the sled, that is, at a position 120 mm.

The results are shown in Table 1. In this case, the amount of warpage was warped / 120 mm. Table 1 also shows the residual carbon amount and magnetic properties (B ₁₀₀ , H _c35 ).

[0027]

As is apparent from these results, the residual carbon content was reduced to 1/10, warpage and deformation were reduced, and a highly uniform metal sintered body with excellent dimensional accuracy was obtained, and various characteristics were obtained accordingly. Will also be good. It was found that by using the examples of the present invention, it is possible to produce a metal sintered body having excellent dimensional accuracy and magnetic properties as compared with the conventional method.

(Example 2) The mixture used as a raw material for molding was Pb (Mn _1/3 Sb _2/3 ) O ₃ having an average particle size of 0.5 μm.
Was prepared with the same conditions as in Example 1 above, using the PZT-based calcined powder containing as a third component and the binder composition shown in Example 1.

Using the same, an extrusion molding machine was used under the same conditions as shown in Example 1 above to obtain a diameter of 3 mm and a length of 150.
It was molded into a shape of mm.

Using the apparatus shown in FIG. 2 according to the present invention, the molded body was rotated at a rotation speed of about 3 minutes / cycle and the temperature rising rate was about 20 ° C./h.
The temperature was raised to 500 ° C. and degreasing was performed.

The degreased body was subjected to the method shown in FIG. 2 for 3 minutes /
Once, a sintered body was produced under the condition of 100 ° C./h and 1250 ° C. × 2 h.

The alumina tube 2 for product insertion during sintering is
After inserting the sample, both sides were covered with a lid to prevent evaporation of PbO, and the sample was sealed.

As Comparative Example 2 of the prior art, a compact of the same size was placed on an alumina floor plate, and the heating rate was about 20 ° C.
Degreasing is carried out by raising the temperature to 500 ° C at 1 / h, and then installing in a well-sealed alumina container with a tight seal, 1250 ° C x 2
Sintering was performed under the condition of h.

As Comparative Example 3, a degreased body produced by the degreasing method according to the present invention was used, and sintering was performed in the same manner as in Comparative Example 2 to produce a sample.

Next, these sintered bodies were cut to a length of 20 mm to form strip electrode sintered bodies having a pattern shown in FIG. 4 in order to evaluate homogeneity.

As shown in FIG. 4, the piezoelectric ceramic cylinder 1
Six strip-shaped electrodes 11, 12, 13, 14, 15, 1 parallel to the length direction are arranged at positions that divide the circumference on the outer peripheral surface of 0 into 6 equal parts.
6 are formed, the strip electrodes are connected to each other, and polarization treatment is performed as two terminals.
3 and 15 are electrodes for common ground, and the remaining strip electrodes 1
The individual resonance frequencies of 2, 14 and 16 are measured by an impedance measuring machine, and the difference between the maximum value and the minimum value is Δfr,
The homogeneity of the sintered body was evaluated.

The results are shown in Table 2.

[0039]

From these results, it is clear that when the method according to the present invention is used during degreasing and sintering, variations in resonance frequency characteristics are reduced and a sintered body having excellent homogeneity can be produced.

[0041]

As described above in detail, a mixture of ceramic powder or metal powder and a binder containing a polymer compound as a main component is used to prepare a molded body by injection molding or extrusion molding, When degreasing the molded body, insert it into a cylindrical case and perform degreasing while rotating in a furnace that has a continuous temperature gradient to correct warpage and deformation by sizing due to rotation, and to continue. The stress-strain at the time of molding is removed by heat treatment with a general temperature gradient, and since the contact surface with the floor plate constantly changes, it is possible to eliminate the distribution of the residual carbon amount, and when the degreased body is sintered, excellent homogeneity is achieved. Moreover, it is possible to manufacture a sintered body having high dimensional accuracy with almost no warpage and deformation, improved various characteristics, and little deterioration or variation in various characteristics. Further, by performing sintering in the same manner while rotating a material that is sensitive to the sintering atmosphere, such as PbO, which accompanies evaporation, the influence of the ground plane, etc. is eliminated and a homogeneous sintered body can be produced.

[Brief description of drawings]

FIG. 1 is a sectional view of a container for degreasing and sintering according to the present invention.

FIG. 2 is a schematic configuration diagram of a degreasing and sintering furnace.

FIG. 3 is an explanatory diagram showing a method for measuring the amount of warpage of a sintered body.

FIG. 4 is an external view of a piezoelectric ceramic column, FIG. 4A is an external perspective view of the piezoelectric ceramic column, and FIG. 4B is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 1 Molded Product (Product) 2 Alumina Tube 3 SiC Tube 4 Continuous Furnace 5 In-furnace 6 Feed Plate 7 Feed Plate Pushing Body 8 Separation Plate 9 Sled 10 Piezoelectric Ceramic Cylinder 11, 13, 15 (for Common Earth) Strip Electrode 12, 14 , 16 Strip electrode 17 Arrow direction

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C04B 35/64 J

Claims (4)

[Claims] 1. A pellet-shaped mixture obtained by mixing and kneading a ceramic powder or a metal powder and a binder containing a polymer compound as a main component is formed into a cylinder or a column by an extrusion molding method or an injection molding method. After producing the molded body of, the small cylinder into which the molded body is inserted is inserted into a cylindrical case, the case is rotated, and the molded body itself is degreased while rotating, or a ceramic molded body, A method for degreasing a metal molded body. 2. A pellet-shaped mixture obtained by mixing and kneading a ceramic powder or a metal powder and a binder containing a polymer compound as a main component is formed into a cylinder or a cylinder by an extrusion molding method or an injection molding method. After producing the molded body, the small cylinder into which the molded body is inserted is inserted into a cylindrical case, the case is rotated, and the molded body itself is continuously sintered while being rotated. A method for sintering a ceramic compact or a metal compact. 3. A method for degreasing and sintering a ceramic molded body or a metal molded body according to claim 1,
A ceramic molded body or a metal molded body, characterized in that the cylindrical case, in which a plurality of small cylinders each having a molded body inserted therein are stacked, is rotated, and degreasing and sintering are performed while rotating the molded body. Degreasing and sintering methods. 4. When rotating the cylindrical case according to claim 3, a rotational force is applied to the case on the cylindrical case on which a plurality of small cylinders each having a molded body inserted therein are stacked. Degreasing of a ceramic molded body or a metal molded body, characterized in that the case is continuously rotated by sequentially feeding out a plate for giving and moving it, and degreasing and sintering are performed while rotating the molded body. And sintering method.