(US-based black metallurgical industry standard, YB / T 192-2001 carbon steel with Carburant) and cast iron with Carburant, and some other added materials are also useful to Carburant , Such as brake pads with additives, for friction materials. Carbonizers are added to the steel, iron and carbon increased raw materials. High-quality Carburant is essential for the production of high-quality steel auxiliary additives.
Sunshine casting material quality Carburant
There are many kinds of raw materials to increase the Carburant, the production process is also different. Not the market that the use of graphite powder by compression molding, this production methods need to add too much binder molding, carbon content generally less than the requirements of high-quality Carburant. After the suppression of graphite powder, because it is solid block, no porous structure, so the absorption rate and absorption rate is not as calcined, roasting molding of Carburant. High-quality Carburant generally refers to the graphitization of the Carburant, in high temperature conditions, the arrangement of carbon atoms in the micro-morphology of graphite, so called the graphitization. Graphitization can reduce the content of magazines in the carbon, increase the carbon content of carbonizers and reduce the sulfur content.
The use of carbonizers in the casting can significantly increase the amount of scrap, reduce the amount of pig iron or no pig iron. At present, the vast majority of carbonizers are suitable for electric furnace smelting, there are a small part of the absorption rate is particularly fast carbonizer for cupola. Electric furnace smelting of the feeding method, the Carburant should be with the scrap and other materials into the inside together, the addition of small doses can be added to the surface of the molten iron. But to avoid large quantities of molten iron to feed, in order to prevent excessive oxidation and the effect of carbon is not obvious and the cast carbon content is not enough. The addition of Carburant, according to the ratio of other raw materials and carbon content to be set. Different types of cast iron, according to the need to choose different types of Carburant. The characteristics of the Carburant itself choose pure carbon-containing graphitizing substances, reduce excess impurities in pig iron, the choice of Carburant can reduce the cost of casting production.
First, the choice of Carburant
The same time as the above-
1. Classification of Carbon
Cast iron commonly used carbonizer is a carbonaceous material, the main component is carbon. Carbonaceous materials are mainly graphite and amorphous carbon. Graphite is a hexagonal lamellar crystal. The carbon atoms in the graphite crystal are arranged in a layered form, and the cohesive bonds are covalently bonded in the same layer of atoms. The bonding force is strong, while the layer and the layer are polar bonds Combined, the combination of weak. Therefore, the graphite is easily delaminated, the strength is extremely low. Since the graphite crystal has such a structural feature, it is easy to grow into a sheet-like structure when it is grown in the molten iron. Amorphous carbon is also hexagonal lamellar crystal , and graphite is different from the hexagonal arrangement is not complete, slightly larger interval between layers.
According to carbon crystal in the carbon structure, Carburant can be divided into amorphous and crystalline state. According to the carbon in the presence of carbon in the form, divided into graphite carbon and non-graphite Carburant. In addition, silicon carbide (SiC) has a hexagonal structure similar to that of graphite, and is also classified as a graphite-carbonized agent. The graphite carbon (SiC) has a hexagonal structure similar to that of graphite. A special form. Non-graphite Carburant mainly asphalt coke, calcined petroleum coke, coke pressed material, calcined anthracite and so on.
2. Carbon principle
Carbon melting agent in the form of carbon in the form of quality, melting temperature of 3727 ℃, can not melt at the temperature of molten iron, so carbon in the carbon by dissolving and diffusion in two ways dissolved in molten iron. When the wc = 1.0% of the molten iron, the graphite in the graphite can be dissolved directly in the molten iron. Rather than the direct phenomenon of graphite carbon does not exist, but with the passage of time, carbon in the molten iron gradually spread and dissolved. Therefore, for the furnace smelting synthetic cast iron by carbon, the use of graphite by carbon to increase the carbon speed was significantly higher than non-graphite Carburant.
It is shown that the dissolution of carbon in the molten iron is affected by the liquid boundary layer of the solid particles. The results obtained with coke and coal particles were compared with those obtained by graphite. It was found that the diffusion and dissolution rate of graphite carbonizer in iron liquid was much faster than that of coke and coal particles. Electron microscopy was used to observe the partially dissolved coke and coal particles. It was found that a thin layer of viscous gray layer was formed on the surface of the sample, which was the main reason for its diffusion solubility in molten iron.