SU1286513A1 - Method of firing fine-grained carbon-containing workpieces - Google Patents

Abstract

The invention relates to methods for firing fine-grained carbon-containing blanks based on non-calcined petroleum coke and coal tar pitch and allows to increase and stabilize the physicomechanical characteristics over the section of the blanks. The mixture consisting of unhealed petroleum coke

Description

The invention relates to the process of firing fine-grained carbon-containing blanks, used after graphitization as a structural material, operating under conditions of high temperatures, sealing elements, crystallizers, antifriction parts and in other areas of technology,

The purpose of the invention is to stabilize and enhance the physicomechanical characteristics over the section of the blanks.

The method is carried out as follows.

Example 1. A mixture consisting of KNPS brand uncalcined petroleum coke (GOST 22898-78) 62% by mass and medium temperature coal tar pitch A (GOST 10200-83) 38% by mass is mixed for 30 minutes at Then the mass is discharged, cooled to room temperature, crushed and dispersed in a vibrating mill to a particle size of less than 0.09 mm. The resulting powder is pressed in a closed matrix with a specific pressure of 500 kgf / cm in the form of blanks with a diameter of 250 mm and a height of 120 mm or 0.80 x 120 mm, or 0 320x x120 mm. Pressed, blanks are loaded into an electric furnace. At the bottom of the chamber, a layer of transfer material consisting of coke breeze is pre-filled (GOST 1125510

f5

5 mm from the side surface of the bogie. The blanks are cooled with the furnace, the discharge is carried out at a temperature not exceeding 60 ° C.

The ratio of the exposure time to the smallest size of the workpiece with a pressure of 0.3 h / min.

The graphitization of the sintered billet is carried out at 2600 ° C in identical fishing vessels in industrial furnaces of the graph. Temperature rise rate 50 ° С / h. Graphite coke with a particle size of 5-10 mm.

Technological parameters and properties of graphite blanks are presented in the table.

Examples 2-9 are carried out in accordance with Example 1, changing the size of the workpiece, the temperature of the isothermal lane, and the ratio of the lining time to the smallest girth of the workpiece, the values of which are listed in the table together with

physicomechanical characteristics of graphitized blanks.

thirty

The table shows that the use of the proposed method (in comparison with the prototype) makes it possible to reduce the variation in the limit of compressive strength, porosity and electrical resistivity by 1.5 times,

75) with particle sizes from 0.2 to 5 mm, according to the flexural strength in

A preform is placed on this layer with a distance of at least 25 mm from the furnace wall and covered with coke breeze between the workpiece and the walls. The next one is installed on the bottom blank, and the layer of interstitial material between the blanks was 45-50 mm, etc. The top blank is filled with coke breeze with a layer thickness of 150-200 mm,

The firing process was carried out according to the following temperature regime:

From 20 to 200 ° C

Exposure at 200 ° C

From 200 to 600 ° C

From 600 to

From 800 to 1100 ° C

Exposure at 1100 ° C

The firing mode is carried out with a thermocouple type XA installed in the middle part of the working chamber at a distance of

S / h

36 ° C / h

4 ° C / h

6 ° C / h

10 h

5 mm from the side surface of the workpiece. The blanks are cooled with the furnace, the unloading is carried out at a temperature not exceeding 60 ° C.

The ratio of holding time to the smallest size of the workpiece is 0.3 h / min.

Graphitization of baked blanks was carried out at 2600 ° C under identical conditions in industrial graphitization furnaces. Temperature rise rate 50 ° С / h. The transfer material is graphite coke with a particle size of 5-10 mm.

Technological parameters and properties of graphite blanks are presented in the table.

Examples 2-9 are carried out in accordance with example 1, changing the dimensions of the workpiece, the temperature of the isothermal lane and the ratio of lag time to the smallest dimension of the workpiece, the values of which are presented in the table together with

physical and mechanical characteristics of graphite blanks.

thirty

The table shows that the use of the proposed method (compared to the prototype) allows to reduce the variation in compressive strength, porosity and electrical resistivity by 1.5 times, and

  by flexural strength in

2.7 times with a significant (1.5-2 times) improvement of the physical and mechanical characteristics of graphite.

Claims (1)

Invention Formula The method of firing fine-grained carbon-containing blanks based on oil non-calcined coke and coal tar pitch in protective medium up to 1000-1200 ° C with intermediate temperature exposures, characterized in that, in order to stabilize and improve the physicomechanical characteristics of the section of the blanks, firing is carried out using isothermal exposure in the temperature range of 170-250 ° C with a duration ranging from 0.2 to 0.5 h / mm of the smallest overall size of the blanks, P smer 0 250 km Scatter of values in relation to the relation to the ekachen.