Differences of The Physical Properties between Graphitization Product and Carbonaceous Baking Products
Graphitization is the indispensable process during graphite electrode production. The purpose of graphitization is as follows:
1. Improve the electrical conductivity and thermal conductivity of the carbon materials.
2. Improve the thermal shock resistance and chemical stability of the carbon materials.
3. Make the carbon materials have the unctuosity and wearing quality.
4. Remove the impurities and improve the purity of carbon materials.
The main differences between graphitization products and carbonaceous products lie in:
A) The microstructure of carbonaceous products present 2D random layer structure arrangement, while the graphitization products belong to 3D ordered layered structure crystal.
B) The electrical and thermal conductivity of graphitization products are far better than the carbonaceous products.
C) During the graphitization process, the temperature can reach at least 2200℃, so part of impurities are gasified and then escaped. This leads to a low ash content.
D) The graphitization products own a lower hardness, it is more easily to cut and machining.
The specifications comparison between grpahitization and carbonaceous products can be seen in below forms:
We can see from the form, after the baking products being graphitized, the resistivity can be 4-5 times lower, the true density is enhanced by around 10%, the thermal conductivity is 10 times higher, coefficient of thermal expansion is reduced by 1 times, The oxidation start temperature increases, impurities vaporize and escape, and the mechanical strength decreases.
| Items |
Carbonaceous baking products |
Grpahitization products |
| Resistivity /μΩ·m | 30 ~ 60 | 5 ~ 12 |
| True density /g·cm-3 | 2.00 ~ 2.05 | 2.20 ~ 2.23 |
| Bulk density /g·cm-3 | 1.50 ~ 1.65 | 1.52 ~ 1.68 |
| Compressive strength /MPa | 25 ~ 40 | 16 ~ 30 |
| Porosity /% | 18 ~ 25 | 20 ~ 30 |
| Ash /% | ＜0.5 | ＜0.3 |
| Thermal conductivity /W·(m·K) -1 | 3.6 ~ 6.7（175 ~ 675℃） | 74.5（150 ~ 300℃） |
| CTE /K -1 |
（1.6 ~ 4.5）x 10-6 （20 ~ 500℃） |
（1.1 ~ 2.5）x 10-6 （20 ~ 600℃） |
| Oxidation start temperature/℃ | 450 ~ 500 | 600~ 700 |