The commonly used carburant for cast iron is a carbonaceous material, the main component is carbon. Carbon materials mainly include graphite and amorphous carbon. Graphite is a hexagonal layered crystal. The carbon atoms in the graphite crystal are arranged in layers. The atoms in the same layer are separated by covalent bonds, which has a strong separation force; and the layers are polar bonds. Separation, its separation force is weak. Therefore, graphite is very easy to delaminate and the strength is extremely low. Because graphite crystals have such structural characteristics, they tend to grow into sheet-like structures when grown in molten iron. Amorphous carbon is also a hexagonal layered crystal, which is different from graphite in that the hexagonal arrangement is not perfect and the interval between layers is slightly larger.

According to the crystal structure of carbon in the carburizer, the carburizer can be divided into an amorphous state and a crystalline state. According to the form of carbon in the carburizing agent, it is divided into graphite carburizing agent and non-graphite carburizing agent. Graphite recarburizers mainly include graphite electrodes, graphite electrode scraps and debris, natural graphite pellets, microcrystalline graphite, etc. In addition, silicon carbide (SiC) has a hexagonal structure similar to graphite and is also classified as graphite recarburizer A special form. Non-graphite carburizing agents mainly include pitch coke, calcined petroleum coke, coke press, calcined anthracite, etc.

Principle of carbon increase

The carbon present in the carburizer in the elemental way has a coagulation temperature of 3727 ° C and cannot be coagulated at the temperature of the molten iron. Therefore, the carbon in the carburizer is mainly dissolved in the molten iron by dissolution and diffusion. When the wC of the molten iron is 2.1%, the graphite in the graphite carburant can be directly dissolved in the molten iron. The direct solution of non-graphite carbon does not exist at all, but as time goes by, the carbon gradually diffuses and dissolves in the molten iron. Therefore, regarding the carbon enhancement of synthetic iron casting by electric furnace smelting, the carbon increase rate of graphite carbon increase is significantly higher than that of non-graphite carbon increase agent.

Some materials show that the dissolution of carbon in the molten iron is affected by the layer-by-layer braking of the solid liquid surface. Comparing the results obtained with coke and coal particles with the results obtained with graphite, it was found that the diffusion and dissolution rate of graphite recarburizer in molten iron is significantly faster than that of coke and coal particles. An electron microscope was used to observe the locally dissolved samples of coke and coal particles. It was found that the sample surface formed a thin sticky gray layer, which was the main reason for its diffusion solubility in molten iron.

Selection of carburant

Regarding electric furnace smelting, the center of carbon-enhancing technology is the use of high-quality carbon-enhancing agents. With reference to the relevant materials, the selected carburant should have the following characteristics:

(1) Select a carburizing agent that has undergone high-temperature graphitization. As long as the carbon atoms have undergone high-temperature treatment, the ability of carbon atoms will change from the original disordered arrangement to the flake arrangement. Change.

(2) The sulfur content of good carburant is very low, wS <0.03% is an important indicator.

(3) The porosity of the carburizing agent is also very important for the carburizing effect and the carburizing agent absorption rate. Therefore, the high-temperature graphitized petroleum coke carburizing agent is more fragmented than the electrode graphite, and the carburizing effect is better.
The commonly used carburant for cast iron is a carbonaceous material, the main component is carbon. Carbon materials mainly include graphite and amorphous carbon. Graphite is a hexagonal layered crystal. The carbon atoms in the graphite crystal are arranged in layers. The atoms in the same layer are separated by covalent bonds, which has a strong separation force; and the layers are polar bonds. Separation, its separation force is weak. Therefore, graphite is very easy to delaminate and the strength is extremely low. Because graphite crystals have such structural characteristics, they tend to grow into sheet-like structures when grown in molten iron. Amorphous carbon is also a hexagonal layered crystal, which is different from graphite in that the hexagonal arrangement is not perfect and the interval between layers is slightly larger.

According to the crystal structure of carbon in the carburizer, the carburizer can be divided into an amorphous state and a crystalline state. According to the form of carbon in the carburizing agent, it is divided into graphite carburizing agent and non-graphite carburizing agent. Graphite recarburizers mainly include graphite electrodes, graphite electrode scraps and debris, natural graphite pellets, microcrystalline graphite, etc. In addition, silicon carbide (SiC) has a hexagonal structure similar to graphite and is also classified as graphite recarburizer A special form. Non-graphite carburizing agents mainly include pitch coke, calcined petroleum coke, coke press, calcined anthracite, etc.

Principle of carbon increase

The carbon present in the carburizer in the elemental way has a coagulation temperature of 3727 ° C and cannot be coagulated at the temperature of the molten iron. Therefore, the carbon in the carburizer is mainly dissolved in the molten iron by dissolution and diffusion. When the wC of the molten iron is 2.1%, the graphite in the graphite carburant can be directly dissolved in the molten iron. The direct solution of non-graphite carbon does not exist at all, but as time goes by, the carbon gradually diffuses and dissolves in the molten iron. Therefore, regarding the carbon enhancement of synthetic iron casting by electric furnace smelting, the carbon increase rate of graphite carbon increase is significantly higher than that of non-graphite carbon increase agent.

Some materials show that the dissolution of carbon in the molten iron is affected by the layer-by-layer braking of the solid liquid surface. Comparing the results obtained with coke and coal particles with the results obtained with graphite, it was found that the diffusion and dissolution rate of graphite recarburizer in molten iron is significantly faster than that of coke and coal particles. An electron microscope was used to observe the locally dissolved samples of coke and coal particles. It was found that the sample surface formed a thin sticky gray layer, which was the main reason for its diffusion solubility in molten iron.

Selection of carburant

Regarding electric furnace smelting, the center of carbon-enhancing technology is the use of high-quality carbon-enhancing agents. With reference to the relevant materials, the selected carburant should have the following characteristics:

(1) Select a carburizing agent that has undergone high-temperature graphitization. As long as the carbon atoms have undergone high-temperature treatment, the ability of carbon atoms will change from the original disordered arrangement to the flake arrangement. Change.

(2) The sulfur content of good carburant is very low, wS <0.03% is an important indicator.

(3) The porosity of the carburizing agent is also very important for the carburizing effect and the carburizing agent absorption rate. Therefore, the high-temperature graphitized petroleum coke carburizing agent is more fragmented than the electrode graphite, and the carburizing effect is better.

Hunan Xintan New Material Co., Ltd produces a recarburizer with low impurity content and high absorption rate. Among them, the annual sales of calcined petroleum coke and graphitized petroleum coke reach more than 20,000 US dollars.