RU2064471C1 - Method for preparation of the press powder for carbon articles - Google Patents

Abstract

FIELD: carbon construction materials. SUBSTANCE: preparation of the carbon construction materials, widely useful in manufacturing the parts of the electrovacuum devices in the electronics and other technics field, includes a method of preparing the press powder for the above-said articles. The method consists in preparing a filler by its mixing with a binder followed by shaping the mixture, its thermal treatment with a subsequent fine crushing of the pitch-coke composition with adding therein 5-15% of the graphitized fraction coke - 0.09 mm. EFFECT: improved physico-chemical characteristics of the carbon articles. 1 tbl

Description

 The invention relates to methods for manufacturing structural carbon materials, and more particularly to methods for preparing a press powder for the production of these materials. Carbon structural materials are widely used for the manufacture of parts of vacuum devices, in electronic and other fields of technology.

 A known composition for producing carbon materials [1] having the following wt. content of components: non-calcined coke fraction 0.3-0.8 mm 11-13 non-calcined coke fraction less than 0.2 mm 46-48, calcined coke fraction 0.3-0.8 mm 17-20 coal tar pitch 21-23. The resulting mixture is pressed, calcined, graphitized to obtain a material with high physical and mechanical characteristics. The disadvantage of this composition is the large shrinkage during firing, leading to the formation of cracks in the products and their destruction.

 Closest to the invention is a method of preparing a press powder for carbon products [2] The essence of the method is as follows. Petroleum coke fractions of less than 0.09 mm are mixed with 28-30 wt. coal tar pitch, the resulting mixture is molded, heat treated and crushed. The resulting pitch is added to the resulting finely ground filler, mixed, cooled and ground again. Then, from the obtained press powder, the workpieces are pressed on a hydraulic press, calcined and graphitized. The material obtained in this way is also capable of cracking with unstable characteristics in terms of density, electrical resistance, and others.

 The present invention eliminates the above disadvantages, improves the physicomechanical characteristics of the material due to a sharp decrease in shrinkage processes during firing or generally eliminate shrinkage during firing. The introduction of graphitized coke into the mixture of powders contributes due to the positive coefficient of linear thermal expansion of graphitized coke particles together with the shrinkage of mixtures of calcined or non-calcined particles with a binder to bring the shrinkage of the product to zero or eliminate it altogether.

As graphitized coke, waste from production is used in gravity furnaces with a moisture content of not more than 0.9-1.0% sulfur and more than 0.05%
The introduction of graphitized coke less than 5% wt. does not affect its positive effect indicated above in connection with the small contribution of these particles to the overall coefficient of linear expansion.

 Exceeding the content of additives of graphitized coke above 15% weight. leads to a decrease in mechanical strength, an increase in electrical resistivity and porosity, the strength of materials and products by reducing the activity of interaction of particles with a coal binder.

An example of a specific implementation: petroleum coke is crushed and crushed to particles with a size of less than 0.09 mm (at least 90%) mixed with medium-temperature coal tar pitch (t softening 67 ^o C) in an amount of 25 wt. at a temperature of 120-150 ^o C. The obtained coke-pitch composition is molded in the form of blocks (500x400x500 mm) at a pressure of 35 kgf / cm ² .

The molded blocks are fired in a 20 chamber kiln with a final temperature of 1200 ± 25 ^o .

The calcined billets are crushed on a jaw, and then on a hammer mill and then on a vibratory mill to obtain a fraction of less than 0.09 mm ≥ 80%
In a fine grinding add graphitized coke fraction of 0.09 mm in an amount of 5 wt.

Then the press powder is mixed with the remaining amount of pitch, the resulting composition is pressed into 1152x210 mm blanks at a pressure of 49 MPa. The formed preforms are fired with a final temperature of 1200 ± 25 ^{° C.} and then graphitized.

 The preforms thus obtained were used to obtain samples for testing the physical and mechanical properties.

 The remaining examples, performed in accordance with example 1 with a change in the content of graphitized coke, as well as the properties of graphite obtained by the proposed method, are summarized in a table for comparison. The properties of graphite obtained by the prototype method are given in the same table.

 As can be seen from the table, the proposed method for producing a press powder allows to increase the main technical characteristics of the obtained material and products from it.

Claims (1)

 A method of preparing a press powder for producing carbon products, including the preparation of a coke filler, mixing it with a pitch binder, molding the mixture, heat treatment and fine grinding the resulting composition, characterized in that graphite coke fraction of 0.09 mm is introduced into the coke-pitch fine grinding composition in the following the ratio of components, wt. Fine coke cake composition 85-95
Graphite coke fractions -0.09 mm 5-15

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