The crystal structure of C in the recarburizer can be divided into an amorphous structure and a crystal structure. According to the form of C in the recarburizer, it can be divided into a graphite recarburizer and a non-graphite recarburizer.
Graphite recarburizers generally have non-graphite recarburizers that break the original atomic structure of the recarburizer at high temperature and then recombine the covalent bonds of the atoms. The graphitized recarburizer forms a layered hexagonal crystal structure.
Moreover, the C in the recarburizer is mainly dissolved in the molten iron by dissolution and diffusion, and the graphite in the graphite recarburizer can be directly dissolved in the molten iron. The direct dissolution of non-graphite recarburizers basically does not exist, but over time, C gradually diffuses and dissolves in the molten iron.
The dissolution of C in molten iron is controlled by the mass transfer of C in the liquid boundary layer on the surface of the solid particles. There is a very thin layer of viscous gray matter on the surface of the recarburizer. This layer of gray matter is very resistant to high temperatures and is also an important factor affecting the diffusion rate. In the graphitization process, the higher the temperature, the more this layer of gray matter will be removed, which can accelerate the diffusion. speed.
After experiments, it is found that the higher the degree of graphitization, the faster the diffusion and direct melting. The ordinary graphitization recarburizer is graphitized at 2600 degrees, and the fast-melting recarburizer is heated in order to achieve complete graphitization and remove the gray matter layer on the surface. Graphitization is performed at a high temperature of 3200 degrees.
In order to make the fine-tuning time of carbon for foundry enterprises shorter and easier to operate, the quick-melting recarburizer is equipped with a quick-melting agent to speed up the melting and absorption. After the molten iron is melted and slag removed in the electric furnace, it can be added to the surface of the molten iron for about 1 minute. Completely melted.