RU2264982C1 - Composition for impregnation of the graphitized carbon products - Google Patents

Abstract

FIELD: by-product-coking industry; electrode industry; production of compositions for impregnation of graphitized carbon products.

SUBSTANCE: the invention is pertaining to the compositions for impregnation of graphitized carbon products and may be used in the by-product-coking industry and electrode industry. The impregnating composition of graphitized carbon products includes a coal-tar pitch and a plasticizer, in capacity of which use polymeric compounds of the benzene group (wastes of the by-product-coking process), at the following ratio of the components (in mass %): the coal-tar pitch - 94-96; polymeric compounds of the benzol group - the rest. The polymeric compounds of the benzol group have following composition(in mass %): substances insoluble in a toluene - 1.0-3.0; water - 0.05-0.10; ash - 0.10-0.15; aromatic hydrocarbons - the rest. Density of the graphitized carbon products impregnated with this composition after burning makes 1.78÷1.89 g/cm³; after graphitization - 1.85÷1,90 g/cm³, porosity - 19.2÷19.9 %, a mechanical strength - 26.5÷27.5 MPa. The invention also allows to improve production conditions due to reduction of the content of the carcinogenic substances in the peck.

EFFECT: the invention ensures an increased density of the graphitized carbon products impregnated with this composition by several percents, improved production conditions due to reduction of the carcinogenic substances share in the peck.

2 cl, 2 tbl

Description

The invention relates to the production of carbon-graphite materials and can be used in the coke and electrode industries.

It is known to use coal tar pitch for impregnating carbon-graphite products (Vyatkin S.E., Deev A.N., Nagorny V.G. et al. Nuclear graphite. M.: Atomizdat, 1967, 25-27 pp.). The specified pitch has the following characteristics:

softening temperature defined cube method in air, ° С 80-100 yield of volatiles,% no more than 68,0 ash, wt.% no more than 0.3 substance content insoluble in toluene, wt.%, 5.0-10.0 substance content insoluble in quinoline, wt.%, 3.0-5.0

However, the known coal tar pitch is mesophase and does not provide a high degree of impregnation process, which, in turn, negatively affects the mechanical strength and density of carbon-graphite products.

The closest in technical essence and the results that are achieved is the composition for the impregnation of carbon-graphite products (USSR Author's Certificate No. 1212941, IPC С 01 В 31/02, publ. 23.02.86) with the following ratio of components, wt.%:

high temperature pitch 60-90 coal oil rest

The proposed composition has the following characteristics:

- softening temperature, ° C (T _p ) 120-200 - yield of volatiles,% (V _r ) 31-50 - content of insoluble substances in toluene (α ₁ fraction), wt.% 40-60 - content of insoluble substances in quinoline (α-fraction), wt.% 0.2-1.5

However, the composition has a high viscosity, which in the case of impregnation of carbon-graphite materials only leads to partial pore densification. Therefore, the obtained carbon-graphite product has a low density and accordingly high porosity.

The basis of the invention is the task of developing a composition for the impregnation of carbon-graphite products, in which the combination of ingredients and their quantitative content will increase the density and reduce porosity by increasing the degree of impregnation of the workpieces.

The problem is solved in that the composition for impregnation of carbon-graphite products, including coal tar pitch and a plasticizer, according to the invention contains as a plasticizer polymers of the benzene compartment in the following ratio, wt.%:

coal tar pitch 94-96 benzene polymers rest

In this case, the polymers of the benzene compartment have the following composition, wt.%:

insoluble in toluene 1.0-3.0 water 0.05-0.10 ash 0.10-0.15 aromatic hydrocarbons rest

A causal relationship between the set of essential features of the claimed invention and the technical result that can be achieved is that, apparently, coal tar pitch and polymers of the benzene compartment form a homogeneous molecular solution and this increases the surface activity of the binder to the surface of the carbon blanks due to physico-chemical properties and, primarily, due to the intensification of diffusion processes. In turn, the intensity of penetration of coal tar pitch into pores and cracks increases, helping to improve the operational characteristics of carbon-graphite products.

The claimed ratio of components is necessary and sufficient to achieve the task.

The increase in coal tar pitch in the composition for impregnation of more than 96 wt.% Entails an increase in the viscosity of the claimed composition, which, in turn, leads to a decrease in the density of carbon-graphite products and increase their porosity, and a decrease in its fraction below 94 wt.% Increases the yield of volatile substances , which also entails an increase in porosity and a decrease in density. This reduces the ability of the pitch to give coke residue, which leads to a deterioration in the mechanical strength of carbon-graphite products.

The proposed composition for impregnation of carbon products has the following characteristics:

softening temperature, ° C (T _p ) 55-60 yield of volatiles,% (V _r ) no more than 68 insoluble matter in toluene (α ₁ fraction), wt.% not less than 17 insoluble matter in quinoline (α ₂ fractions), wt.% no more than 3.0

Impregnation of carbon products is as follows.

To 1000 l of coal tar pitch with the following characteristics: softening point 62-65 ° C; volatiles yield 68%; substances insoluble in toluene, 20% and substances insoluble in quinoline, 3.0%, add benzene separation polymers and mix for 1 hour at 160-170 ° C. The resulting composition in a laboratory autoclave with a capacity of 1 liter is impregnated with calcined electrode blanks with a diameter of 60 mm and a length of 130 mm, prepared from industrial blanks of one batch of pressing and firing, with a density of 1.60 g / cm ³ and porosity of 21.1%.

The impregnated preforms are subjected to heat treatment in muffle furnaces at 1000 ° C for 402 hours and then graphitization in electric furnaces at a temperature of 2500-3000 ° C for 50 hours.

In accordance with the method described above, impregnating compositions were prepared, the ratio of components and characteristics of which are shown in table 1.

Table 1 Composition for impregnation The content of components, wt.% Composition characteristics Coal tar pitch plasticizer T _p , ° C V _r ,% fraction content, wt.% coal oil polymers benzene. branches α ₁ fractions α ₂ fractions prototype 80 twenty - 130 fifty fifty 1 claimed 1 98 - 2 60 68 twenty 3 2 96 - 4 57 68 twenty 3 3 94 - 6 55 68 twenty 3 4 92 - 8 48 75 twenty 3

The test results of the impregnated laboratory samples are shown in table 2.

table 2 Composition for impregnation After firing After graphitization coke residue from pitch,% apparent density, g / cm ³ apparent density, g / cm ³ porosity,% mechanical strength, MPa prototype 49.5 1.72 1.71 23.0 23.0 claimed 1 53.7 1.80 1.85 19,4 27.0 2 54.0 1.85 1.88 19.2 27.5 3 54.8 1.89 1.90 19.2 28.7 4 50.1 1.78 1.85 19.9 26.5

As a result of the tests, it was found that the samples obtained using the claimed composition for impregnation (options 2 and 3) have a higher density and lower porosity.

In addition, by increasing the coke residue after firing, the mechanical strength of the products is significantly increased. The proposed composition for the impregnation of carbon-graphite products is characterized by a low content of substances insoluble in toluene, this allows you to increase the frequency of use for impregnation and makes it possible to reduce the sticking of the impregnating material on the surface of the workpieces. When using the proposed composition for the impregnation of carbon-graphite products, the sanitary conditions of production are improved, namely, the carcinogenicity of the pitch is reduced by reducing the content of 3,4-benzpyrene in the pitch.

Claims (2)

1. The composition for the impregnation of carbon-graphite products, including coal tar pitch and plasticizer, characterized in that the plasticizer used is benzene, in the following ratio, wt.%: Coal tar pitch 94-96 Polymers of the benzene compartment Rest 2. The composition for impregnation of carbon-graphite products according to claim 1, characterized in that the polymers of the benzene compartment have the following composition, wt.%: Toluene Insoluble Substances 1.0-3.0 Water 0.05-0.10 Ash 0.10-0.15 Aromatic hydrocarbons Rest