graphite electrode hp uhp
Resistivity analysis of graphite electrode hp uhp
Most graphite products are used as conductive materials, so the higher the conductivity, the better, that is, the lower the specific resistance, the better. The lower the resistance, the greater the current density allowed to pass.
The factors that affect the specific resistance of the product are as follows:
1. The influence of raw materials: the better the conductivity of the raw materials, the higher the conductivity of the product. The conductivity of the raw material generally refers to the conductivity of the raw material after calcination. For example, the specific resistance of some petroleum coke after calcination is 600 ohms &; mm:/m, while the specific resistance of pitch coke after calcination at the same temperature is 600-700 ohms &; mm2/m. Therefore, if all pitch coke is used to produce graphitized electrodes, the specific resistance of the product will increase significantly, and the rate of superior grades (measured by the specific resistance) will decrease relatively. The used pitch coke is compared with graphite anode plate | graphite electrode hp uhp produced with 50% pitch coke and oil coke. The use of oil coke with high sulfur content also has a significant impact on the specific resistance of the finished product. For example, some products have been trial-produced with polysulfur coke with a sulfur content of 1 to 11% (analysis after calcination), and only 50% of this polysulfide coke is used in the formulation (the remaining half is 1/4 pitch Coke and 3/4 oil coke v calcined mixture).
2. The final heat treatment temperature of the product: whether it is the higher the baking or graphitization temperature, the lower the specific resistance of the product, but the reasons for the decrease in the specific resistance of the two are different. During the roasting process, the specific resistance of the product is reduced due to the discharge of volatiles, the coking of the binder and the continuous shrinkage of the product itself, while the reduction in the specific resistance of the graphitization process is the result of the conversion of amorphous carbon to graphite crystals.
3. Ingredients: the production of carbon products and electrode pastes, such as adding graphitized crushed, graphitized metallurgical coke or natural graphite with good conductivity, the conductivity of the product will be significantly improved.
4. Impregnation: After roasting, the impregnated product is roasted or graphitized, because the non-conductive pores are partially replaced by conductive carbon particles, and the specific resistance can be reduced to varying degrees.
Whether it is an extruded product or a molded product, the specific resistance of graphite anode plate | graphite electrode hp uhp must be measured with attention to the directionality of the sample. For extruded products, the specific resistance parallel to the extrusion direction is smaller than the specific resistance perpendicular to the extrusion direction, while the opposite is true for molded products.
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