JPH0337108A - Isotropic carbon material - Google Patents

Abstract

PURPOSE:To obtain a carbon material having a high density and strength imparted thereto without using a binder by blending mesocarbon microbeads with a specific amount of scaly graphite, press forming the resultant blend using a rubber press and calcining the formed blend. CONSTITUTION:Mesocarbon microbeads having about 15mum average grain diameter in an amount of 100 pts. wt. is blended with 0.5-50 pts.wt. scaly graphite having <=44nun average grain diameter and the obtained blend is sufficiently mixed. The resultant mixture is formed by using a rubber press and calcined to afford an isotropic carbon material, which, as necessary, is further graphitized at >= about 2000 deg.C. Thereby, products having characteristics, such as wide ranges of heat conductivity and hardness, according to demand can be produced by using the aforementioned material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to carbon materials, particularly isotropic carbon materials.

[Prior art]

Carbon materials are used in electrical discharge machining electrodes, bearing seals, jigs, rocket nozzles, and nuclear power applications.

In particular, isotropic carbon materials have excellent practicality because the electrical discharge machining characteristics, sliding characteristics, machinability, etc. are uniform throughout the product.

Conventionally, isotropic carbon materials used for boat fishing usually have a molecular weight of 1200 to 1300
It is manufactured through a series of steps such as finely pulverizing coke fired at ℃, adding a binder such as pitch, mixing it, re-pulverizing it, molding it, and firing it.

However, when carbon materials mainly composed of petroleum coke and pitch coke are used, pitch coke must be impregnated in order to maintain high density and high strength physical properties, which makes them expensive and during molding. Since embossing was used, the resulting product was anisotropic, which was a practical problem.

[Problem to be solved by the invention]

From the above points of view, if mesocarbon microbeads are used, they can be molded, fired, and molded as they are without adding a binder.
It can be graphitized, and when molded using a rubber press, it has a bulk density of 1.90 g/cs3 or more and a bending strength of 900 kg/ell" or more, and
This is advantageous in that a high-strength, isotropic carbon material can be obtained. However, the carbon material obtained from mesocarbon microbeads alone has drawbacks such as low thermal conductivity and high hardness, which are not necessarily optimal for the purpose of use.

This invention was proposed in view of the above-mentioned conventional circumstances, and can be molded without using a binder, and
The purpose of this invention is to provide an isotropic carbon material that can be used to manufacture products with a wide range of characteristics such as thermal conductivity and hardness according to requirements.

[Means to solve the problem]

In order to achieve the above-mentioned object, this invention blends scale-like graphite into mesocarbon microbeads, pressure-forms them with a rubber press, fires them, and then graphitizes them as necessary.

[For production]

The mesocarbon microbeads have a viscous component represented by β-resin, and can be molded without using a special binder.

The mesocarbon microbeads used here have an average particle size of about 15 μm, and the scaly graphite used has an average particle size of 44 μm or less. 44μm
If it is more than that, the porosity will increase and the strength will decrease, which is disadvantageous. In addition, 0.5 to 50 parts by weight of scaly graphite is blended with respect to 100 parts by weight of mesocarbon microbeads.

If the blending ratio of graphite scales exceeds 50 parts by weight, cracking may occur during molding or firing, and even if such a phenomenon does not occur, various properties will deteriorate significantly, making it impossible to put it to practical use. On the other hand, if the amount of scaly graphite is 0.5 parts by weight or less, the characteristics due to the mesocarbon microbeads become large, and various characteristics cannot be changed, so that the purpose of the present invention cannot be avoided.

The above-mentioned mesocarbon microbeads and scale graphite are thoroughly mixed, for example, in a Henschel mixer or an omnimixer, and further, in order to obtain isotropy, they are molded and fired using a rubber press, and if necessary, 2000 ℃
If graphitization is performed at a temperature above, a high-density and high-strength isotropic carbon material can be obtained.

(Example) (Example 1) 10 parts by weight of mesocarbon microbeads with volatile content of 8.5% by weight and β-resin of 1.5% by weight were mixed with 10 parts by weight of scaly graphite having an average particle size of 10 μm, Mixing was performed for 20 minutes using an omnimixer. This is 1000 kg/cm
After isostatically forming the carbon material, it was calcined in an inert atmosphere at 1100°C and further graphitized at 2500°C to obtain an isotropic carbon material. The properties of the obtained carbon material are shown in Table 1.

(Example 2) 20 parts by weight of the scaly graphite of Example 1 was mixed with 100 parts by weight of the mesocarbon microbeads of Example 1.
Pressure molding was performed in the same manner as in , and graphitization was performed to obtain an isotropic carbon material.

Table 1 shows the properties of the obtained carbon material.

(Comparative Example) Using only the mesocarbon microbeads of Example 1, pressure molding, firing, and graphitization were performed under the same conditions as in Example 1 to obtain an isotropic carbon material.

From Table 1, the isotropic carbon material obtained by this invention is:
Compared to the case of mesocarbon microbeads alone (comparative example), it is now possible to have a wider range of properties such as specific resistance and thermal conductivity, and also has high strength with excellent thermal conductivity. It becomes an orientated carbon material.

〔Effect of the invention〕

As explained above, in this invention, scale-like graphite is mixed into mesocarbon microbeads, so by adjusting the amount of mixed graphite, the properties of the graphite can be changed as necessary. It has the advantage that it can be produced at a lower cost compared to other methods, and does not require procedures such as mixing and pulverization that are required when carbon materials mainly composed of petroleum coke or pinch coke are used.

Claims (1)

[Scope of Claims] [1] 100 parts by weight of mesocarbon microbeads are blended with 0.5 to 50 parts by weight of scaly graphite with an average particle size of 44 μm or less, pressure-molded using a rubber press, and then fired, as required. An isotropic carbon material that is characterized by graphitizing depending on the temperature.