Carburant Diffusion Dissolution Rate Was Significantly Faster
Many types of Carburant, can be used as cast iron Carburant is also a lot of material, but the quality of great disparity, the price difference is also great, to ensure the quality of casting under the premise of the product should be based on the characteristics and quality requirements, Choose to increase Carburant.
Many types of Carburants, according to the use of most factories, only briefly introduced two commonly used Carburant:
1. Artificial graphite
In the commonly used Carburant, artificial graphite is the best quality Carburant.
The main raw material for making artificial graphite is powdered high-quality calcined petroleum coke, in which a small amount of other auxiliary materials are added. After the raw materials are pressed and shaped, and then treated at 2500 to 3000 ° C in a non-oxidizing atmosphere to be graphitized. After high temperature treatment, ash, sulfur, gas content are significantly reduced. Because of its production processes and longer production cycle, so the price is higher.
Foundry commonly used artificial graphite Carburant, mostly graphite electrode manufacturing when the chip, waste electrodes and graphite blocks and other recycling materials.
2. petroleum coke
Petroleum coke is currently widely used as a Carburant.
Petroleum coke is a by-product of refined crude oil. Crude oil through atmospheric distillation or vacuum distillation of the oil residue and oil asphalt, can be used as the raw material for the manufacture of petroleum coke, and then after the coke to get raw petroleum coke. Raw oil coke in the high content of impurities, can not be directly used as Carburant, must first be calcined. The calcination of petroleum coke is to remove sulfur, moisture and volatiles. The raw petroleum coke in the 1200 ~ 1350 ℃ calcined, can make it a basic pure carbon.
Carbon is present in the form of simple carbon, the melting temperature is 3727 ℃, can not melt at the temperature of molten iron. Therefore, the carbon in the carbon is mainly dissolved in molten iron by dissolving and diffusing in two ways. 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 increased 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 rate of graphite carbonizer in iron liquid was much faster than that of coke and coal particles. The partially dissolved coke and coal particles were observed by electron microscopy. 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.
Adding Carburant to join the method, in the synthesis of cast iron, the addition of a large amount of Carburant, in the electric furnace before or during the melting furnace can join, and scrap at the same time to join, with the addition of silicon carbide. Which involves the late amount of smelting, play a pretreatment, increase the role of graphite core, then you must add low nitrogen content of the carburant, the amount of the best not too much, not more than 0.2%, to avoid coarse graphite. The last to add Carburant, the ideal hot metal temperature of 1500 degrees or so, add a clean liquid in the clean liquid surface, a few minutes later, the temperature can be baked properly, do not ignore the liquid surface does not absorb the residual Carburant, because it is baked Hot metal impact mixing process, you can also play a role in nurturing.