JPH06122553A - Production of graphite material having low sputtering ratio - Google Patents

Abstract

PURPOSE:To obtain a highly densified graphite material having high thermal conductivity and low sputtering ratio by blending a carbon material such as coke or pitch with a boron composition such as B4C and heat-treating at high temperature. CONSTITUTION:Coke or pitch of raw material for use is blended with B4C powder to give mixed powder having a fixed particle size, which is molded under constant pressure, then heated to a high temperature and burnt at a fixed temperature. The burnt material is further heated, retained at a fixed temperature of 2,000 deg.C or higher and graphitized. Current is directly injected to the graphitized material and constant pressure is applied to the graphitized material while maintaining the heating temperature to carry out ultrahigh- temperature plastic processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a high forming density (high densification) obtained by adding a boron component such as B ₄ C to a carbon raw material such as coke or pitch and heat-treating at a high temperature. The present invention also relates to a method for producing a graphite material having high thermal conductivity. The produced graphite material is used as a low-sputtering armor tile material used in the first wall of a nuclear fusion reactor, and as a reaction tube material used in a chemical reaction device, and is used in the nuclear industry or the chemical industry. It is expected to be used in the industrial field.

[0002]

2. Description of the Related Art Prior to the filing of the present application, it is effective to produce a graphite material by adding a boron component to a graphite raw material for the purpose of improving and improving the sputtering characteristics and oxidation resistance of the graphite material. Was already known in. However, when a boron component is added to the graphite raw material, the obtained graphite material has low sputter characteristics, but its thermal and mechanical properties deteriorate, and in particular, the thermal conductivity decreases. there were. Therefore, a new technique for improving and improving the thermal conductivity and the like of the graphite material obtained by adding a boron component to the graphite material has been desired.

[0003]

The graphite material obtained by adding the boron component to the graphite raw material has the advantages that it has a low sputtering rate for high temperature plasma and that its oxidation resistance is improved. However, the following problems also occur.

(1) Addition of a boron component to the graphite raw material lowers the thermal conductivity, and as a result, the temperature of the boron-added graphite material rises when it is heated by plasma, and the sputter rate increases accordingly. (2) Mechanical and electrical characteristics are deteriorated, and (3) Manufacturing cost is increased.

[0005]

In order to solve the above problems (1), (2) and (3), graphite added with a boron component is utilized by utilizing the ultra-high temperature plasticity characteristic of graphite. It is necessary to densify.

That is, the low sputter rate graphite material of the present invention is manufactured by the method described below.

B ₄ C in the coke or pitch of the raw material used
A kneaded product of a certain particle size obtained by kneading powder is molded by applying a certain pressure, then heated at a high temperature and baked at a certain temperature,
After further heating and holding at a constant temperature of 2,000 ° C or higher for graphitization, this graphitized product is directly heated by electric current, and a constant pressure is applied while maintaining this heating temperature for ultra-high temperature plastic working. As a result, a low-sputtering graphite material that promotes densification and high thermal conductivity of a graphitized product to which B ₄ C is added is obtained.

The raw materials used, the respective processing steps, etc. will be described in detail below.

(A) Raw material coke Coal-based calcined pitch coke (commercial product) Pitch Coal-based pitch (commercial product) B ₄ C powder B ¹¹ ₄ C powder (commercial product) (B) Kneading, blending After kneading the coke and the pitch, they are pulverized into powder having an average particle size of about 20 μm. The B ₄ C powder is mixed with 100 crushed powder of coke and pitch to a boron concentration of up to 10 wt% according to the purpose of the final product.

(C) Molding The molding pressure is 800 kg / cm ² and the maximum is about 10 minutes.

(D) Calcining Using a hot air forced circulation type calcining furnace by heating heavy oil, the temperature is raised from room temperature to about 850 ° C. and kept for up to 24 hours.

(E) Graphitization Graphitization is carried out by holding the fired product obtained in the above step (d) at 2,000 ° C. for 1 hour.

(F) Densification The graphite block obtained in the above step (e) is treated at 2,500 ° C.
Processed by direct current heating type hot press at the above temperature,
The density is set to 1.9 kg / cm ² or more. As shown in FIG. 1, the energization heating is performed by setting a graphitized product 3 as a workpiece on a lower punch 2 in a press chamber 1 and lowering an upper punch 4 to move the workpiece between upper and lower punches. Ultra high temperature plastic working is carried out by applying a current between both punches at the same time as pressurizing the work piece and directly heating the work piece by heating to maintain it at 2,500 ° C.

[0014]

[Example] 0 (comparative example) with respect to coke used as a raw material,
After blending and kneading 5 and 10 wt% of B ₄ C powder,
The powder was pulverized to obtain a powder having an average particle size of about 20 μm. Molding was performed by applying a molding pressure of 800 kg / cm ² to the obtained pulverized powder for a maximum of 10 minutes. This molded product was heated from room temperature to about 850 ° C. in a hot air forced circulation type baking furnace by heating heavy oil, and then held and baked for up to 24 hours.

The fired product obtained was held at 2,000 ° C. for 1 hour for graphitization. After that, the graphitized block was processed by a direct current heating hot press at a temperature of 2,500 ° C. or higher to have a density of 1.9 kg / cm ² or higher. Boron component obtained using the above method,
The dimensions and density of the graphite material base material added with 0 wt% (comparative example), 5 wt% and 10 wt% are shown below.

[0016] Furthermore, the mechanical, thermal and electrical characteristics measured using test pieces cut out from each of the above graphite base materials are shown in Table 1.
The results are shown in Tables 2 and 3.

[0017]

[Table 1]

[Table 2]

[Table 3] According to these tables, the graphite material added with the boron component manufactured according to the present invention, in comparison with the high density, high thermal conductivity graphite of the comparative example without addition of the boron component, despite the addition of a large amount of the boron component, Then, no deterioration is observed in its mechanical, thermal and electrical properties.

[0018]

According to the present invention, it is possible to produce a low-sputtering graphite material. Therefore, by using this material as the first wall armor of the fusion reactor, the operation efficiency of the fusion reactor is further improved. Will be improved. Further, since the graphite material produced according to the present invention has oxidation resistance, it can be used as a material for internal furnace structure in a high temperature gas furnace.

[Brief description of drawings]

FIG. 1 is a diagram showing that the graphitized block in the present invention is subjected to pressure processing by a direct current heating type hot press to increase the density.

[Explanation of symbols]

 1 Press room 2 Lower punch 3 Graphitized product 4 Upper punch

Claims (1)

[Claims] 1. B _{4 in} the coke or pitch of the raw material used
A kneaded product of C particle size and a certain particle size was molded by applying a certain pressure, then heated at a high temperature to be fired at a certain temperature, and further heated and kept at a constant temperature of 2,000 ° C. or higher for graphitization. After that, the graphitized product is directly heated by electric current, and a constant pressure is applied to the graphitized product while maintaining the heating temperature to perform ultra-high temperature plastic working, whereby the graphitized product containing B ₄ C is densified and has high thermal conductivity. Method for producing low-sputtering graphite material that promotes high temperature.