JP2766753B2 - Manufacturing method of low sputter graphite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, by heat treatment at a high temperature with the addition of boron components B ₄ C or the like to a carbon raw material such as coke or pitch, is highly molded density (high densification), 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 for the first wall of a fusion reactor and as a material for a reaction tube used in a chemical reactor, such as the nuclear industry or the chemical industry. Its use is expected in industrial fields.

[0002]

Prior to the filing of the present application, it was effective to produce a graphite material by adding a boron component to a graphite raw material for the purpose of improving and improving sputter characteristics and oxidation resistance of the graphite material. Was already known in However, when a boron component is added to a graphite raw material, the obtained graphite material has low spattering properties, but its thermal and mechanical properties are deteriorated, and in particular, the thermal conductivity is lowered. 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]

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

(1) The addition of a boron component to a graphite raw material lowers the thermal conductivity. As a result, the temperature of the boron-added graphite material rises during plasma heating, and the sputter rate increases accordingly. (2) The mechanical and electrical characteristics are degraded, and (3) the manufacturing cost is increased.

[0005]

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

That is, the graphite material having a low sputtering rate according to the present invention is manufactured by the following method.

In the coke or pitch of the raw material used, B ₄ C
A kneaded product of a certain particle size obtained by kneading the powder is molded by applying a certain pressure, then heated to a high temperature and baked at a certain temperature,
After further heating and holding at a constant temperature of 2,000 ° C. or more to graphitize, this graphitized product is directly heated by current, and a constant pressure is applied while maintaining this heating temperature to perform ultra-high temperature plastic working. Thus, a low-sputtered graphite material which promotes densification and high thermal conductivity of a graphitized product to which B ₄ C has been added is obtained.

The raw materials used, each processing step, and the like are specifically described as follows.

[0009] (b) Materials used coke coal calcined pitch coke (commercial product) pitch coal based pitch (commercial product) B ₄ C powder B ¹¹ ₄ C powder (commercial product) (ii) kneading, blending predetermined amounts After kneading the coke and the pitch, they are pulverized into a powder having an average particle size of about 20 μm. B ₄ C powder is mixed with the pulverized powder 100 of coke and pitch to a maximum boron concentration of 10 wt% according to the purpose of the final product.

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

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

(E) Graphitization The calcined product obtained in the above step (d) is kept at 2,000 ° C. for 1 hour for graphitization.

(F) Densification The graphite block obtained in the above step (e) is heated at 2,500 ° C.
At the above temperature, it is processed by a direct current heating type hot press,
The density is set to 1.9 kg / cm ² or more. As shown in FIG. 1, the electric 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 the upper and lower punches. At the same time, a current is passed between the punches, and the workpiece is directly heated by heating and maintained at 2,500 ° C. to perform ultra-high temperature plastic working.

[0014]

[Examples] 0 (comparative example) for coke used as raw material,
After blending and kneading 5 and 10 wt% of B ₄ C powder,
By pulverizing, a powder having an average particle size of about 20 μm was obtained. A molding pressure of 800 kg / cm ² was applied to the obtained crushed powder for a maximum of 10 minutes to perform molding. This molded product was heated from normal temperature to about 850 ° C. in a hot air forced circulation type baking furnace by heating with heavy oil, and then calcined for a maximum of 24 hours.

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

[0016] Further, the mechanical, thermal and electrical properties measured using a test piece cut from each of the above graphite material 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 to which the boron component was added according to the present invention was compared with the high-density, high-thermal-conductivity graphite of the comparative example in which the boron component was not added, although a large amount of the boron component was added. Thus, no deterioration is observed in its mechanical, thermal and electrical properties.

[0018]

According to the present invention, it has become possible to produce a low-sputtered graphite material. By using this material as the first wall armor of a fusion reactor, the operation efficiency of the fusion reactor can be further improved. Will be improved. Further, the graphite material produced according to the present invention has oxidation resistance, so that it can be used as a structural material in a high-temperature gas furnace.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing that a 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)

(57) [Claims] 1. A B ₄ in the coke or pitch of raw materials used
A kneaded product having a certain particle size obtained by kneading C powder was molded by applying a certain pressure, and then heated at a high temperature, baked at a certain temperature, and further heated and kept at a certain temperature of 2,000 ° C. or more to be graphitized. Later, the graphitized product is directly heated by electric current, and a constant pressure is applied while maintaining the heating temperature to perform ultra-high-temperature plastic working, thereby densifying the B ₄ C-added graphitized product and achieving high thermal conductivity. Of low sputtered graphite materials that promotes