JPS5849485B2 - graphite sintering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sintering high density, high strength graphite (carbon).

Conventionally, to make graphite by sintering, petroleum coke, pitch coke, anthracite, carpon crack, and other aggregates are used as aggregates, pitch is mixed with this, and the mixture is kneaded at a temperature above the softening point of pitch. After that, preliminary sintering and main sintering are performed, but since the pitch of a binder with a low softening point and low fixed carbon, which is used in conventional sintering, has a high volatile content, the sintered body contains a lot of volatile matter. It contains pores and therefore cannot be sintered to high density and high strength.

As a method of increasing the sintered density, the pores are filled by repeating pressure impregnation and sintering of the pitch again, but this is time consuming and has many drawbacks.

In view of this point, the present invention does not use binder pitch or
Even if only a small amount is used, it can be easily sintered to a high density, and is characterized by the addition of a boron-containing chelate compound as a sintering accelerator.

Sintering is carried out by a current sintering method in which electricity is passed (including discharge) between raw material powders, and any sintering method using high frequency heating, heating in a furnace, etc. can be used.

According to the former electric current sintering method, the sintering strength is increased because the powders are purified by electric current and the activated powders are diffused and bonded together, and as is well known, amorphous carbon is graphitized by electric current sintering. It is known that a homogeneous molded body can be obtained, and sintering and graphitization can be performed simultaneously in one step.

Further, even in the furnace heating sintering method, the steps of primary sintering and secondary sintering are increased, but active sintering can be performed by mixing a boron-containing chelate compound as described above, and the sintering effect is improved.

Since the binder is not added to the sintered powder or is added in a small amount compared to the conventional method, the volatile content is reduced and the sintered density is increased.The powders are strongly diffused and bonded, resulting in mechanically high-strength graphite. A molded body is obtained.

As described above, the present invention uses ordinary aggregates such as coke,
By sintering without adding a binder or adding a small amount of binder to reduce the volatile content, it is possible to obtain graphite with high density and high strength, which was not possible with conventional methods.

Various organic chelate compounds can be used to promote sintering when added in small amounts, but borides are most effective, such as acetylaceto boride chelate, propylene diamine borate chelate, and the like.

Next, to explain the present invention using an example, coke 30
0 mesh aggregate with 2wt% tar (softening temperature 200℃)
) and 3 wt % of acetylacetoboride chelate were added and mixed, and the mixture was filled in a carbon mold, and sintered by applying electricity using pressure and current-carrying electrodes.

Current current is 220 A/crA, pressurization is 45
Sintering was carried out at 0 kg/crA.

The density of the sintered body was 2.36 f/i, and the compressive strength was 2.1 tons/d, which was nearly twice as strong as the conventional one.

As described above, since the present invention performs sintering by adding a boron-containing chelate compound, sintering can be performed without adding a binder such as pitch, or even if it is added, it can be done in a small amount, and the volatile content can be reduced. The boron-containing chelate compound can be easily sintered by the sintering promoting effect of the boron-containing chelate compound, and the sintered body can be graphitized to easily obtain high-density, high-strength, and high-quality graphite.

As mentioned above, the strength is nearly twice that of the conventional one.

If the amount of the boron-containing chelate compound added is less than 1%, the effect will be low and the addition of the binder will have to be increased, and if the amount of the boron-containing chelate compound added is too large, the characteristics of the sintered graphite will deteriorate. Since the amount changes, it is sufficient to add 10 wt% at most.

Claims (1)

[Claims] 1. A graphite sintering method characterized by mixing aggregates such as petroleum coke and pitch coke with a boron-containing chelate compound as a sintering accelerator, and converting the mixture into graphite by pressurizing and heating.