JPH05221719A - Production of isotropic high density carbonaceous material - Google Patents

Abstract

PURPOSE:To easily and inexpensively obtain an isotropic high density carbonaceous material having a void in shape close to the product shape by filling a sinterable carbonaceous power in a rubber mold while leaving the void and by filling a non-sinterable material into the void, CIP molding and sintering. CONSTITUTION:The sinterable carbonaceous powder is filled into the cylindrical rubber mold with bottom, in which a core is temporarily placed. Next, the core is removed to form the void and the non-sinterable material is filled in the void. By removing the non-sinterable material after executing CIP molding and sintering or graphitizing in this state, the isotropic high density carbonaceous material having a void in shape close to the product shape is obtained. As a result, a process to finish to a desired product shape by mechanically working such as cutting or machining is simplified and the generation of large quantity of working scraps is prevented. Sintering and graphatizing are also executed after removing the non-sinterable material after CIP molding.

Description

Detailed Description of the Invention

The present invention relates to a method for producing an isotropic high density carbon material. More specifically, it relates to a method for producing an isotropic high-density carbon material having cavities close to the product shape.

[0002]

2. Description of the Related Art Isotropic high-density carbon materials are used in many fields such as hot zone members for semiconductor manufacturing, sealing materials, bearings, and graphite crucibles. These products use conventional sinterable carbonaceous powder for corner blocks and cylinder blocks.
Generally, an isotropic high-density carbon material block after IP (Cold Isostatic Press) molding and firing or further graphitization is finished into a desired product shape by machining such as cutting and cutting. However, it takes a lot of man-hours to cut out these carbon products from the isotropic high-density carbon material block by machining, and at the same time, the expensive material block becomes a large amount of processing waste, so it is necessary to process as much as possible. Measures have been taken to reduce the number.

For example, in Japanese Patent Publication No. 2-20402,
A hydrostatic pressure molding die has been proposed in which the outer die is a split die having a plurality of divided surfaces in the direction of pressure transmission, but the structure is complicated and the applicable range is generally limited. Therefore, in the isotropic high-density carbon product, CIP molding has also been performed by using a rubber mold having a shape similar to the product shape and allowing for volume shrinkage in the manufacturing process. However, since a rubber mold having a complicated shape is expensive and the rubber mold is likely to contract uniformly during CIP molding, there is a problem that deformation of the molded body or firing cracking due to the deformation is likely to occur.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a carbon material product having a hollow or complex shape with a molded product having a similar shape to the product shape in order to reduce processing waste such as cutting as much as possible. C
It is an object of the present invention to provide a method for producing an isotropic high-density carbon material, which comprises using an IP rubber mold to form a molded body without deformation or firing cracking due to deformation.

[0005]

The present inventors have conducted various studies to solve these problems, and have completed the present invention. That is, according to the present invention, (1) CIP molding is performed in a state where a cavities are left in advance in a rubber mold and sinterable carbonaceous powder is filled therein, and the cavities are filled with non-sinterable powder. A method for producing an isotropic high-density carbon material, characterized by removing non-sinterable powder after firing or further graphitization,

(2) The method for producing an isotropic high-density carbon material according to the above (1), characterized in that after the CIP molding, the non-sinterable powder is removed, followed by firing and graphitization.

(3) A core is temporarily placed in advance in a rubber mold to fill it with sinterable carbonaceous powder and then the core is removed to form a cavity. ) Or the method for producing the isotropic high-density carbon material according to the above (2).

The present invention will be described in detail below. The sinterable carbonaceous powder used in the present invention includes pitch coke, calcined coke such as petroleum coke, uncalcined raw coke which is an intermediate product thereof, and further contains natural graphite, carbon black and the like as main components. A finely pulverized product of carbonaceous raw material that is secondarily pulverized by heating and kneading it with a binder such as coal tar, coal tar pitch, or petroleum pitch, or an uncalcined raw material that can be sintered without the addition of a binder. It is a fine powder such as coke and carbon micro beads.

In order to leave a cavity in the rubber mold of the present invention in advance, a core is temporarily placed in the mold in advance, the sinterable carbonaceous powder is filled, and then the core is removed. Form a cavity. What is the non-sinterable powder that fills the remaining cavity?
It is necessary that it does not become integrated with the product and does not contaminate the product quality in the process of firing or further graphitization, and it is selected from calcined coke such as pitch coke, petroleum coke, silica sand and the like. As they are, they are non-sinterable as they are, and by not incorporating a binder during filling, they can be easily removed without being fused to each other during firing or further graphitization. In addition, since the non-sinterable powder layer is isotropically compressed in conjunction with the sinterable carbonaceous powder during CIP molding, it is formed as if using a non-compressible metallic core or partition. The body is not deformed, and the molding of the crucible type has less shape deformation than the case of using the crucible type rubber mold because of the shape-retaining effect of the core.

As the core to be temporarily placed in advance in a rubber mold, a cardboard, metal, plastic, etc. are often used as long as they do not deform when the sinterable carbonaceous powder layer is filled. Although hollow (circular) cylinders, cylinders, etc. can be used, a taper is provided so that the core can be easily removed after filling the sinterable carbonaceous powder layer around these cores. Is desirable. The firing conditions are usually about 800 to 120.
A carbon material is obtained by firing at a temperature of 0 ° C. for about 20 days to 1 month. This is a so-called amorphous carbon material, but a crystalline isotropic graphite carbonaceous material can be obtained by further performing heat treatment at a temperature condition of about 2600 to 3200 ° C.

Next, the present invention will be described in detail with reference to an example of a hollow cylindrical molded body shown in the accompanying drawings. In the case of molding a hollow cylinder, a double cylinder type rubber mold with a bottom lid is generally used. In this case, however, the rubber mold having a complicated shape is expensive as described above and the CIP is used. Since the rubber mold tends to contract unevenly during molding, there is a problem that deformation of the molded body or firing cracks due to the deformation easily occur. On the other hand, in the present invention, a bottomed cylindrical rubber mold having the same outer diameter as the double cylindrical rubber mold is used. This determines the outer diameter of the hollow cylinder,
On the other hand, the inner diameter is determined by filling the hollow portion in the center with a non-sinterable powder layer as shown in FIG. In the central cavity, a core is temporarily placed in advance in a rubber mold and the sinterable carbonaceous powder layer is filled in the gap between the core and the surrounding rubber mold. Since the core is easily removed by gently removing the carbonaceous powder layer so that the carbonaceous powder layer does not collapse, the remaining cavity is filled with the non-sinterable powder. Then, after sealing the upper surface with a rubber lid, CIP molding, firing or further graphitizing, and then removing the non-sinterable powder,
It is possible to obtain a hollow cylindrical isotropic high-density carbon material with little deformation and extremely uniform physical properties.

FIG. 1 (b) shows another application example in which the cavity is effectively used. Two kinds of cores to be temporarily placed are combined and sintered carbonaceous powder and non-sintered are used. This is an example in which two or more types of isotropic high-density carbon materials are manufactured simultaneously by simultaneously forming a plurality of CIP molded bodies by arbitrarily combining cavities filled with the conductive powder. This case is for molding a hollow cylindrical body and a crucible body contained in it at the same time. It is for a silicon crucible holder (Czochralski method) used for semiconductor manufacturing, and a carbon heater for heating it. The material can be manufactured efficiently.

As described above, the non-sinterable powder powder layer functions as a core or a partition and isotropically compressed in association with the sinterable carbonaceous powder during CIP molding. The molded body does not deform as in the case of using a flexible core or partition, and the molded body does not deform due to the shape-retaining effect of the core compared to when a crucible type rubber mold is used. Few. Further, there is also an advantage that it is possible to easily change an arbitrary thickness without manufacturing a new rubber mold. In the present invention, it is preferable to fire the non-sinterable powder layer in the CIP molded body while leaving it from the viewpoint of preventing deformation of the molded body during firing, but if that is not possible, remove it before firing. Is also good.

[0014]

EXAMPLES Examples will be described below. Example 1 A cardboard hollow cylinder having an outer diameter of 150 mmΦ × 300 mm (height) is placed at the center of a bottomed rubber mold having an inner diameter of 250 mmΦ × 300 mm (height), and is placed between the cylinder and the rubber mold. In the formed annular space, 100 parts by weight of pitch coke having an average particle size of 5μ was mixed with 60 parts by weight of coal tar pitch (SP: 95 ° C) as a binder, and the mixture was heated and kneaded to form a paste, which was then secondary pulverized with an atomizer. Average particle size 15
After the sinterable carbonaceous powder having a thickness of μ was densely packed, the hollow cylinder was gently extracted.

An average particle size of 20 μm is left in the cavity left behind.
The non-sinterable calcinated pitch coke powder is packed with a dedicated jig while being compacted, the upper part of the rubber mold is sealed with a rubber lid, degassed, and the molding pressure is 1 T / cm with a CIP molding machine. CIP molding was performed under the conditions of ² . The obtained molded product was a cylindrical molded product having a flat outer surface. This was baked as it was in stuffing powder (pitch coke) to obtain a cylindrical fired body with little deformation. From this, the non-sinterable calcined pitch coke powder could be easily removed, and as a result, a hollow cylindrical fired body could be obtained.

Comparative Example 1 A tapered metal core having an outer diameter of 130 mmΦ × 300 mm (height) is arranged in the center of the rubber mold with a bottom of Example 1, and the core and the rubber mold are arranged between the core and the rubber mold. The formed annular space was densely filled with the same sinterable carbonaceous powder as that used in Example 1, and then the upper part of the rubber mold was sealed with a rubber lid while leaving the core, and degassed. CIP molding was performed with a CIP molding machine under a molding pressure of 1 T / cm ² . Both ends of the obtained molded product were inclined in the shape of an abacus, and when the product was directly baked in a stuffing powder (pitch coke), many cracks were generated on both ends.

(Comparative Example 2) Outer diameter is 250 mmΦ and inner diameter is 1
The same sinterable carbonaceous powder as that used in Example 1 was densely filled in the annular space portion of the rubber mold with a bottom having an annular space of 50 mmΦ and a height of 300 mm, and the rubber mold upper part was covered with a rubber lid. And then seal, degas and mold with CIP molding machine 1T /
CIP molding was performed under the condition of cm ² . The obtained hollow cylindrical molded body is uneven due to wrinkles on the inner surface,
When this was fired under the same conditions, many cracks were generated in the wrinkles.

[0018]

According to the present invention, CIP molding having a cavity close to the intended product shape such as a crucible shape or a hollow cylindrical body is possible without using an expensive rubber mold, and the resulting molded body is deformed. It has less effect and is less likely to cause firing cracks. Further, there is an effect that it is possible to easily change an arbitrary wall thickness and the like simply by replacing a core that is temporarily placed without manufacturing a new rubber mold.

[Brief description of drawings]

FIG. 1 shows CIP of a cylindrical carbon material by the method of the present invention.
FIG. 3 is a sectional elevation view and a plan view showing the shapes of a sinterable carbon raw material and a non-sinterable carbon raw material when forming.

FIG. 2 is a sectional elevation view and a plan view similar to FIG. 1 when the cylindrical and crucible-shaped carbon materials are simultaneously CIP-molded by the method of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Ogata 4-16-11 Tomigaoka, Tomiya-cho, Kurokawa-gun, Miyagi Prefecture

Claims (3)

[Claims] 1. A rubber mold is filled with sinterable carbonaceous powder leaving a cavity in advance, and the cavity is filled with non-sinterable powder for CIP molding, firing or A method for producing an isotropic high-density carbon material, further comprising removing non-sinterable powder after graphitization. 2. The method for producing an isotropic high-density carbon material according to claim 1, wherein the non-sinterable powder is removed after CIP molding, followed by firing and graphitization. 3. The method according to claim 1, wherein a core is temporarily placed in advance in a rubber mold to fill it with sinterable carbonaceous powder, and then the core is removed to form a cavity. The method for producing the isotropic high-density carbon material according to claim 2.