The main indicators affecting the quality of graphite electrode are thermal expansion coefficient, resistivity, strength and bulk density, which are good
Bad directly affects the use of graphite electrodes in steel making‘
Thermal expansion coefficient refers to the expansion degree of graphite electrode after heating. The lower the thermal expansion coefficient of raw material, the same process
The smaller the thermal expansion coefficient of the graphite electrode prepared under the conditions. The main factor affecting the conductivity of graphite electrode is resistivity,
The smaller it is, the greater the current density allowed to pass. Using modified asphalt with higher softening point as binder is better than using softening point
The graphite electrode produced by pitch with lower point has higher strength. The density of graphite electrode is related to the type of raw materials used, which is related to the
The particle size composition of the material is related to the amount of the binder and the process parameters. At the same time, the density is in a certain range
The mechanical and thermodynamic properties of the graphite electrode were affected to some extent. Graphite, graphite electrode, graphite products, graphite processing, graphite mold

In terms of various indicators (table 3.10, table 3.11 and table 3.12), domestic needle coke CTE and D. And P
It is lower than that of Shuidao needle coke, and the domestic needle coke has fewer bar shaped particles such as needle shaped particles after crushing. From the appearance, Shuidao needle
The shaped coke is silver gray and shiny, with obvious grain trend. Jinzhou needle coke is black and shiny, and some coke grains are bright
Obviously, no obvious grain trend can be seen in the rest of the coke, and the acicular property is not very developed. From the microstructure (Fig. 3.3 and
Figure 3.4) and K values also confirm this.
There are two factors affecting the performance of needle coke, one is the raw oil, and the other is the process conditions during coking. Production needle
The feedstock oil of coke is high in aromatics (condensed ring macromolecular hydrocarbons are not included), low in asphaltene, sulfur, nitrogen and metal impurities
High quality residual oil with low quality. The formation, growth or fusion of mesophase spheroids of different feedstock oils have various results,
The molecular nature of raw materials and the resulting microstructure play a decisive role in the nature of coke. Coking process conditions, such as:
Temperature, pressure, circulation ratio, flow rate and water injection rate also have great influence on the structure and properties of coke. Group of feed oil
The variation range of composition and properties is quite wide, while the variation range of parameters such as coking process conditions is usually kept narrow. yes
The raw oil and coking process conditions of the needle coke of Shuidao petroleum system in Japan are not clear, which is not conducive to the comprehensive analysis of coke properties
It can have a certain impact. The properties of the feed oil and coking process conditions of the two kinds of needle coke are different, and the needle coke thus produced has different properties
I can make a difference. In this experiment, Jinzhou needle coke was used as raw material, and because Jinzhou needle coke belongs to the oil system, water island oil was used
Needle coke was used for comparison.
The true density of coke is an industrial index to identify the crystallinity of graphite in coke samples,
The density and arrangement regularity of the basic particles can be explained. The true density of Shuidao needle coke is higher than that of Jinzhou needle
The true density of the shaped coke is high. The true density of graphitized coke is affected not only by the coke itself, but also by the temperature and medium during graphitization
Qualitative and temporal influences.
The pores between the particles are affected by the shape of the particles, that is, the pores accumulated between the particles due to the large aspect ratio of the particles
From table 3.1l, we can see that the aspect ratio of Shuidao petroleum needle coke is larger than that of Jinzhou needle coke, which indicates that Jinzhou needle coke
The internal pores of the coke are large.
In industrial production, CTE is the main index to measure the quality of needle coke and graphite electrode. It can be seen from table 3.12
It can be seen that the CTE of Shuidao needle coke is lower than that of Jinzhou needle coke. The CTE of needle coke is closely related to its microstructure.
The microstructure of needle coke is mainly fibrous (the fiber is divided into fine fiber and coarse fiber), and also contains
There are various transitional structures and mosaic structures in different quantities. Under the optical microscope, it has a fibrous structure with a layered array inside
The lamellae of the row are parallel to the fiber direction. The fiber structure of oil-based needle coke is fine, and the structure of Jinzhou needle coke is fine fiber
There are many structures. From the perspective of microstructure, very straight and few curved fine fiber structures are beneficial to reduce CTE. coke
The average aspect ratio of particles can not only explain the appearance of calcined coke, but also has a certain correlation with the CTE of coke.
The large average K value and the small CTE are related to the structure of coke. The K value of calcined coke particles mainly depends on
The size and orientation of coke fiber. The results in table 3.12 show that the strength of Shuidao needle coke is lower than that of Jinzhou needle coke