JPH1177635A - Production of hollow ceramic sintered object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly enhance yield at the time of production of a hollow ceramic sintered object. SOLUTION: A raw material powder is used to be formed into a square pillar by a handpress and isotropic pressure press is applied to this pillar. Next, the square pellar 11 is cut by green processing so as to form the same upper and lower shapes and the cut bonding surfaces are flatly ground to form planar bonding surfaces 14, 15. Further, recessed parts 16, 17 becoming a hollow part 3 are formed by green processing to obtain first and second ceramic molded objects 18, 19. By this method, the first and second ceramic molded objects 18, 19 bisected by a plane containing an axial line are obtained. Thereafter, ethanol is applied to the bonding surfaces of the first and second ceramic molded objects 18, 19 and both bonding surfaces 14, 15 are combined with each other to obtain a bonded object 22. Thereafter, the bonded object 22 is baked in a nitrogen atmosphere under normal pressure at 1700 deg.C for 4 hr to obtain a pipe being a hollow ceramic sintered object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a hollow ceramic sintered body by joining and sintering at least two ceramic molded bodies.

[0002]

2. Description of the Related Art Conventionally, a method of manufacturing a hollow ceramic sintered body by joining and sintering at least two ceramic molded bodies is disclosed in Japanese Patent Application Laid-Open No. Sho 64-33080.
The one disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, 1993 is known.

[0003] In other words, Japanese Patent Application Laid-Open No. Sho 64-33080 describes a pipe 30 composed of two components 31, 32 as shown in FIG. In order to manufacture the pipe 30, first, the constituent parts 31 and 32 are formed so that the difference in bulk density is 5 to 15%, and then the two are joined, and then a cold isostatic press (hereinafter referred to as "C").
IP ”), and then fired.

[0004]

However, according to the manufacturing method disclosed in JP-A-64-33080, since the density difference between the constituent parts 31 and 32 is 5 to 15%, the two constituent parts 31 and 32 are not combined. There was a possibility that cracks would occur during CIP after joining, cracks would occur during sintering, or even if sintering could be performed, the dimensions would not match.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for producing a hollow ceramic sintered body that significantly improves the yield when producing the hollow ceramic sintered body.

[0006]

Means for Solving the Problems, Embodiments of the Invention, and Effects of the Invention In order to solve the above-mentioned problems, a method of manufacturing a hollow ceramic sintered body according to the present invention comprises a hollow ceramic body communicating with at least one axis. In the method for producing a hollow ceramic sintered body having a portion, the ceramic molded body corresponding to each shape when the hollow ceramic sintered body is divided into two or more together with the hollow portion along a surface along the axis is formed by a density A molding step of molding so that the difference is within 5%, a joining step of joining the ceramic molded bodies manufactured in the molding step by isostatic pressing, and sintering the ceramic molded bodies joined in the joining step to form a hollow. And a sintering step of forming a ceramic sintered body.

The present invention is a method for manufacturing a hollow ceramic sintered body having at least one hollow portion communicating along at least one axis such that a hollow portion in the form of, for example, a pipe penetrates through the ceramic sintered body. In the present invention, first, a ceramic molded body corresponding to each shape when the target hollow ceramic sintered body is divided into two or more together with the hollow portion along the axis (molding step).

At this time, the density difference between the ceramic molded bodies is set to be within 5%. If the density difference exceeds this range, there is a possibility that cracks will occur during isostatic pressing in the joining step, cracks and cracks will occur during the sintering step, and dimensions will not match after sintering. These problems are more likely to occur because the ceramic sintered body to be manufactured in the present invention is hollow. That is, if the density difference between the ceramic molded bodies is within 5%, it is possible to prevent cracks during isostatic pressing, cracks and cracks during the sintering step, and mismatching of dimensions after sintering. Thereby, the yield at the time of manufacturing is improved.

In particular, in the present invention, for example, the ceramic molded body is not divided and formed along the axis, but divided along the axis to form the ceramic molded body. Therefore, for example, in the case of a member in which the hollow portion extends long along the axis, such as a pipe shape, the joining surface extends long, for example, compared with the case where the hollow portion is vertically divided along the axis, Since the force applied to the surface is dispersed, it is difficult to deform or break before and after firing.

[0010] Further, since the joint surface is widened by dividing the surface along the axis line as in the present invention, cracks during the isostatic pressing and cracks and cracks during the sintering process are generated. In addition, mismatching of dimensions after sintering can be more suitably prevented. In addition, it is preferable to adopt a flat surface as the surface along the axis line, since it is easy to divide the surface, but it is also possible to adopt a slightly curved surface or a surface that is bent in the middle. In particular, if the surface along the axis is a plane including the axis, the divided hollow portions have the same shape, so that cracks occur during isostatic pressing, cracks and cracks during the sintering process In addition, there is an advantage that the mismatch of dimensions after sintering can be more preferably prevented, and the shape of the ceramic molded body is simplified, and the workability thereof is improved.

In the forming step, in order to keep the density difference between the ceramic molded bodies within 5%, for example, one coarse ceramic molded body is formed and each ceramic molded body is obtained from the coarse ceramic molded body. Is also good. In this case, since the density of each ceramic molded body matches the original coarse ceramic molded body, the difference in density can be made substantially zero. Alternatively, in forming each ceramic molded body,
The ceramic composition may be subjected to molding / raw processing after obtaining the relationship between the press pressure and the density at the time of molding by isostatic pressing, injection molding, extrusion molding or the like. Of these, CIP
Molding with an isotropic pressure press such as that described above is preferred in that the density can be easily controlled and the equipment cost and molding cost are not increased as compared with injection molding or the like. Incidentally, the density of the molded body can be measured using a known method, but in the case of a complicated shape, for example, a fixed amount is coated on the molded body using an insoluble resin or rubber having a known density,
In this state, it is preferable to measure the density using the Archimedes method.

Subsequently, the ceramic molded bodies are subjected to isotropic pressure.
Joining by pressing (joining step). Isostatic pressing pressure
The force value depends on the density of the ceramic compact after joining during the molding process.
So that it is larger than the density of the obtained ceramic compact
Set forth in For example, the molding process is performed at 1.5 t / cm^TwoCI of
P, 1.5 to 10 t / cm in the bonding step ^Two
Is preferably performed. In addition, the ceramic after joining
Before sintering (for instance,
In such a case, the density increases.
The pressure value is determined so that it is not too long (in the above example, for example,
1.5-2t / cm^Two).

In this joining step, it is preferable that before joining by isostatic pressing, the joining surfaces of the respective ceramic molded bodies are matched, and at least the joining surfaces are sealed with latex or the like. This is because when the isotropic pressure press is performed, pressure is applied in a pressurized medium, but this pressurized medium does not enter the mating surface. The latex or the like may be removed by hand before firing, or may be removed at a temperature lower than the firing temperature or at a temperature that does not adversely affect the material (for example, 450
℃ oven).

In the joining step, before joining by isostatic pressing, a volatile liquid may be applied to the joining surface of each ceramic molded body and wetted, and then the joining surfaces may be joined. Alternatively, after the joining surfaces of the respective ceramic molded bodies are joined, a volatile liquid may be poured into the joining surfaces. In any case, since the joining surfaces are joined with a small force, the handling is easy in performing the isostatic pressing. Here, as the volatile liquid, for example, ethanol,
Methanol, acetone and the like can be mentioned. Further, after the joining surfaces of the respective ceramic molded bodies are joined, the co-base slurry may be poured into the joining surfaces. In this case, even if there is a gap in the mating surface, the mating surface can be filled with the slurry. Here, examples of the co-base slurry include those obtained by dispersing a ceramic component of a ceramic molded body in a volatile liquid.

[0015] The shape of the joining surface between the ceramic molded bodies is not particularly limited.
For example, the surface to be bonded can be easily formed by surface grinding or milling, which is preferable. Finally, the joined ceramic molded body is sintered to form a hollow ceramic sintered body (sintering step). The firing temperature at this time is appropriately determined according to the ceramic material used.

As described above, according to the method for manufacturing a hollow ceramic sintered body of the present invention, by dividing the sintered body along a plane along the axis, the manufacturing operation is easy, and breakage or the like in each operation process can be achieved. Can be prevented. Also, since there is no risk of cracking during the isostatic pressing in the joining step, cracking during the sintering step, or dimensions mismatching after sintering, when manufacturing a hollow ceramic sintered body, Has an effect that the yield is significantly improved. Furthermore, since large parts, long parts, or complicated-shaped parts are difficult to be raw-processed, cost reduction, yield, and dimensional accuracy can be improved by applying the manufacturing method of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The embodiments of the present invention are not limited to the following examples at all, and it goes without saying that various embodiments can be adopted as long as they belong to the technical scope of the present invention. (Embodiment 1) FIG. 1 is an explanatory view showing a method of manufacturing a hollow ceramic sintered body, and FIG. 2 is a perspective view of a pipe which is an embodiment of the hollow ceramic sintered body.

In this embodiment, the following molding step, joining step,
This is an example in which the pipe 1 shown in FIG. 2 is manufactured through a sintering process. This pipe 1 has a pipe-shaped hollow portion 3 that is bent at substantially a right angle inside a rectangular parallelepiped ceramic sintered body 2. Things. Both ends of the hollow portion 3 are open to the adjacent flat surfaces 2 a and 2 b of the ceramic sintered body 2. [1] forming step _{First, α-Si 3 N 4,} Y 2 O 3, AlN, each powder of Al ₂ O _3, a weight ratio of 88: 6: 3: to obtain a slurry by wet mixing by 3. The slurry was dried and granulated for spray pressing by spray drying to obtain a powder. This powder is placed in a press mold (not shown) and hand pressed (for example, 100
kg / cm ² ), a prism (coarse ceramic molded body) 11 shown in FIG. 1A was formed.

Thereafter, the prism 11 is vacuum-packed and covered with a polyurethane bag, and has a strength that facilitates raw processing.
An isotropic pressure press (for example, 1.5 t / cm ² ) was applied. Next, as shown in FIG. 1B, the prism 11 was cut by raw processing so that the upper and lower portions had the same shape, and first and second coarse ceramic divided bodies 12 and 13 were obtained.

Next, as shown in FIG. 1 (c), the joint surfaces of the first and second coarse ceramic divided bodies 12 and 13 are ground by using, for example, a surface grinding machine for raw processing to obtain a planar shape. Are formed. Further, the concave portions 16 and 17 serving as the hollow portions 3 were formed by raw processing using a milling machine to obtain first and second ceramic molded bodies 18 and 19. Thereby, the first and second ceramic molded bodies 18 and 19 divided into two along the axis of the hollow portion 3 along the axis, more specifically, the plane including the axis are obtained.

That is, the first and second ceramic molded bodies 1
8 and 19 show that the pipe 1 to be manufactured is
Are shapes corresponding to the respective shapes when divided into two by a plane including the axis of. Note that the first and second ceramic molded bodies 18,
19 is a result of raw processing of the crude ceramic molded body 11, so that the difference in density between the two is almost zero and within 5%. [2] Joining Step Ethanol is applied to the joining surface 14 of the first ceramic molded body 18 and the joining surface 15 of the second ceramic molded body 19 to wet them, and as shown in FIG. 15 were combined to obtain a joined body 22. By applying ethanol in this way and joining the joining surfaces 14 and 15, the joining was already performed with a weak force.

The joined surfaces 14 and 15 are referred to as a mating surface 23. The positioning of the mating surface 23 is performed by making the outer dimensions of both the ceramic molded bodies 18 and 19 accurate so that a high precision can be obtained. And can be. Next, a co-base slurry in which a powder having the same composition as the above-mentioned molded body was suspended in ethanol was poured into the mating surface 23 of the joined body 22. The gap between the mating surfaces 23 was filled by pouring the co-base ground slurry in this manner.

Subsequently, after evaporating the ethanol sufficiently,
Latex was applied to the entire surface of the joined body 22 and dried.
This latex is used for the first and second ceramic moldings 1.
This is to follow the contraction of 8 and 19 and prevent the intrusion of the pressurized medium when performing the CIP described later.

Note that the rubber band 2 is not shifted or separated from the two ceramic molded bodies 18 and 19 until the joining is integrated.
It can be fixed auxiliary by 1 or the like. Subsequently, the bonded body 22 coated with the latex was subjected to CIP at a pressure of 4 t / cm ² . Thereafter, the bonded body 22 was baked in a furnace at 450 ° C., which is lower than the calcination temperature, to remove latex. [3] Sintering Step The bonded body 22 subjected to the CIP is placed in a nitrogen atmosphere at normal pressure for 17 minutes.
Firing was performed at 00 ° C. for 4 hours to obtain a hollow ceramic sintered body, pipe 1 in FIG.

The pipe 1 had no cracks or dimensional differences. This pipe 1 had sufficient strength as a blast furnace part or an iron manufacturing plant part. As described above, in the present embodiment, the first ceramic molded bodies 18, 1 divided into two by the plane including the axis of the hollow portion 3.
Since the pipe 9 is used and joined at both joining surfaces 14 and 15 and fired to produce the pipe 1, there is an advantage that not only the yield is good but also the production is easy.

The periphery of the open end of the hollow portion 3 of the pipe 1 may be appropriately processed according to the members to be connected. This processing can be performed in a raw state or after firing. [Other Embodiments] Hollow ceramic sintered bodies as shown in FIGS. 3 to 6 can be manufactured in the same manner as in the above embodiment. (Example 2) That is, as shown in FIG. 3, when manufacturing a hollow ceramic sintered body 31 having a rectangular prism bent at a right angle, the shape of each ceramic molded body is similarly bent. And cut along a plane a including the axis of the hollow portion 32 to obtain 2
It may correspond to the divided shape. In addition, you may divide | segment further along an axis (for example, four divisions etc.). Embodiment 3 As shown in FIG. 4, when manufacturing the hollow ceramic sintered body 41 of Embodiment 3 in which the cylinder is bent at a right angle, the shape of each ceramic molded body is similarly bent. The shape may correspond to a shape that is cut by a plane b including the axis of the hollow portion 42 and divided into two. In addition, you may divide | segment further along an axis (for example, four divisions etc.). (Embodiment 4) As shown in FIG. 5, when manufacturing a hollow ceramic sintered body 51 having a cylindrical hollow portion 52 having a large internal diameter in a rectangular parallelepiped, the shape of each ceramic molded body is as follows. The hollow portion 52 may be cut along a plane c including the axis thereof to correspond to a shape divided into two. In addition, you may divide | segment further along an axis (for example, four divisions etc.). (Embodiment 5) As shown in FIG. 6, when manufacturing a pipe-shaped hollow ceramic sintered body 11 having a cylindrical hollow portion 62 having a large internal diameter, the shape of each ceramic molded body is as follows. The hollow portion 62 may be cut along a plane d including the axis to correspond to a shape divided into two. In addition, you may divide | segment further along an axis (for example, four divisions etc.).

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a method for manufacturing a hollow ceramic sintered body of Example 1.

FIG. 2 is a perspective view showing a hollow ceramic sintered body of Example 1.

FIG. 3 is a perspective view showing a hollow ceramic sintered body of Example 2.

FIG. 4 is a perspective view showing a hollow ceramic sintered body of Example 3.

FIG. 5 is a perspective view showing a hollow ceramic sintered body of Example 4.

FIG. 6 is a perspective view showing a hollow ceramic sintered body of Example 5.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pipe, 3, 32, 42, 52, 62 ... Hollow part, 11 ... Square pillar, 12 ... 2nd ceramic molding, 14, 15 ... Joining surface, 18 ... 1st ceramic molded body, 22 ... joined body, 23 ... mating surface, 31, 41, 51, 61 ... hollow ceramic sintered body

Claims (7)

[Claims] 1. A method of manufacturing a hollow ceramic sintered body having a hollow portion communicating along at least one axis, wherein the hollow ceramic sintered body is two or more together with the hollow portion on a surface along the axis. Forming a ceramic molded body corresponding to each shape when divided into a shape such that the difference in density is within 5%, and joining the ceramic molded bodies produced in the molding step by isotropic pressure pressing A sintering step of sintering the ceramic molded body joined in the joining step to form a hollow ceramic sintered body. 2. The method for producing a hollow ceramic sintered body according to claim 1, wherein in the forming step, a plane including the axis is used as a surface along the axis. 3. The hollow ceramic sintered body according to claim 1, wherein in the forming step, one coarse ceramic molded body is molded, and each ceramic molded body is obtained from the coarse ceramic molded body. How to make the body. 4. The method for producing a hollow ceramic sintered body according to claim 1, wherein the forming step is performed by using an isostatic press. 5. The method for producing a hollow ceramic sintered body according to claim 1, wherein in the forming step, green processing is performed after forming the ceramic molded body. 6. The method according to claim 1, wherein in the joining step, before the ceramic molded bodies are joined to each other by isostatic pressing, co-base slurry is poured into a joint surface between the ceramic molded bodies. The method for producing a hollow ceramic sintered body according to any one of the above. 7. The method for producing a hollow ceramic sintered body according to claim 1, wherein in the bonding step, a bonding surface between the ceramic molded bodies is planar.