Method for preparing high-strength high-density isotropic graphite material

Abstract

The invention provides a method for preparing a high-strength high-density isotropic graphite material. According to the method, pitch mesocarbon micro bead (MCMB) powder of which the D50 is larger than 20 micrometers, and the volatile content is less than 7 percent is taken as a raw material, and the high-strength high-density isotropic graphite material is prepared by adopting the self-sintering process that the raw material powder is added into an organic solvent of pitch, the solvent is removed, the powder is pressed, a green briquette is formed through isostatic compaction, roasting and carbonization are performed, and graphitization is performed. According to the method, an organic solvent method is utilized to disperse bitumastic cement, so as to realize the modification on MCMB powder with large size and low volatile matter, the original shapes and sizes of the MCMB particles are basically kept after modification, good self sinterability is realized, and the finally obtained graphite is fine and uniform in structure, high in density and excellent in mechanical property. The pitch of the dispersed and modified MCMB is distributed uniformly, the inner stress of the green briquette in the isostatic compaction step is more uniformly distributed, and balanced expansion and shrinkage in the working procedures of roasting and graphitization are realized, and therefore, a product is not liable to crack, and the yield reaches not less than 90 percent.

Description

technical field [0001] The invention relates to a preparation method of a graphite material, in particular to a preparation method of an isotropic graphite material using pitch mesophase carbon microspheres as raw materials. Background technique [0002] Isotropic graphite has the characteristics of small specific gravity, high mechanical strength, good electrical and thermal conductivity and high temperature resistance, and is widely used. In the EDM precision mold processing (precision forging mold, precision parts, engineering plastic mold, etc.) industry, fine-structure and ultra-fine-structure isotropic graphite are often used as tool electrodes; Crystalline silicon furnaces use fine-structure isotropic graphite components as the thermal field; high-temperature gas-cooled reactors in the nuclear industry require a large number of large-scale isotropic graphite materials as deceleration materials and reflective materials, such as graphite core bricks and hot gas pipes fo...

AI Technical Summary

Problems solved by technology

At present, the raw materials used in the self-sintering method include raw petroleum coke powder, insoluble pitch powder, and pitch mesophase carbon microspheres (MCMB for short), among which MCMB is a more commonly used self-sintering raw material. And pre-oxidation modification treatment to obtain MCMB that meets the requirements of the self-sintering process, which complicates the original simple process and increases the cost, so it is not possible for large-scale production

[0004] At present, the cost of industrially produced MCMB is low and the raw materials are easy to obtain, but the particle size is relatively coarse, D50 is above 20 μm, and the volatile content is very low, less than 7%, so the self-sintering property is poor. Using this MCMB for direct molding and heat treatment, The resulting product does not perform well

Adding asphalt to increase the volatile content to improve its self-sintering property is currently the most commonly used method, but it is difficult to make the asphalt Uniform mixing with pitch mesophase carbon microspheres leads to poor performance of the prepared isotropic graphite material