ftb graphite electrode
ftb graphite electrode
The quality index of graphite electrode and the way to deal with it
The main indicators reflecting the quality and performance of graphite electrode are: bulk density db, electrical resistivity ρ, flexural strength &;, elastic modulus E, thermal expansion coefficient &; and ash content A%. According to the differences in these indicators and the differences in raw materials and manufacturing processes, the graphite electrode is divided into ordinary power graphite electrode (RP) and high power graphite electrode (HP) in the national standard (YB/T 4088/89/90-2000) , Ultra-high power graphite electrode (UHP) three kinds. After that, the graphite electrode manufacturer added high-density graphite electrode (HD) and quasi-super-high graphite electrode (SHP) according to user needs. On the basis of national standards, each company has its own corporate standards, and customers also put forward their own quality standards when placing orders. The volume density is the ratio of the mass of the graphite electrode sample to its volume. The unit is g/cm3. The larger the volume density, the denser the electrode. It is positively related to the strength and oxidation resistance. Generally speaking, the larger the volume density of the same type of electrode, the greater the density of the electrode. The resistivity is also lower. Ways to increase bulk density are: adjust the formula, increase the amount of small-grain materials and powders, use coke with high true density, use pitch with high coking value, and increase the number of dipping. Resistivity is a parameter to measure the conductivity of the electrode. It refers to a property of the resistance of the conductor to the current when the current passes through the conductor. The value is equal to the resistance value of a conductor with a length of 1m and a cross-sectional area of 1m² under certain temperature conditions. , Unit μ&;&;m. The lower the resistivity, the better the conductivity of the electrode in use and the lower the consumption.
The ways to reduce the resistivity are: use high-quality raw materials, increase the volume density of the product, and increase the graphitization temperature. Flexural strength is a parameter that characterizes the mechanical properties of graphite materials. It is also called flexural strength. It refers to the ultimate resistance when the external force is perpendicular to the axis of the object and the object is first bent to the moment of breaking after being subjected to the external force. The unit is MPa. The strength of graphite material is significantly different from other metals and non-metals. Its strength increases with the increase of temperature, reaching the highest at 2000-2500 ℃, which is 1.8-2 times that of normal temperature, and then decreases. High-strength electrodes and connectors are not easy to break during use. The way to improve the flexural strength is to reduce the particle size of the coke in the formula, increase the strength of the carbon raw materials, increase the volume density of the product, and reduce the internal defects of the product. Elastic modulus is an important aspect of mechanical properties. It is an index to measure the elastic deformation ability of a material. It refers to the ratio of stress to strain within the elastic deformation range of the material, and the unit is GPa. The greater the modulus of elasticity, the greater the stress required to produce a certain elastic deformation. Simply put, the greater the modulus of elasticity, the more brittle the material, and the smaller the modulus of elasticity, the more flexible the material.
The level of elastic modulus has a comprehensive effect on the use of electrodes. The higher the bulk density of the product, the more compact it is, and the greater the elastic modulus, but the worse the thermal vibration resistance of the product, the more likely it is to crack and break. In production, the modulus of elasticity that is more suitable for the use requirements is often grasped through the adjustment of the formula size and the volume density of the product. The coefficient of thermal expansion refers to the measurement of the degree of expansion of a material after being heated, that is, when the temperature rises by 1°C, the expansion ratio constant of a unit of solid material sample in a certain direction is called the coefficient of linear expansion along that direction. 1&;10-6/℃. Unless otherwise specified, the thermal expansion coefficient refers to the linear expansion coefficient. The axial and radial linear expansion coefficients of graphite electrodes are very different, and the radial direction is 0.8-1 times larger than the axial direction. The thermal expansion coefficient in the graphite electrode quality index Refers to the axial thermal expansion coefficient.
The thermal expansion coefficient of graphite electrode is a very important thermal parameter. The lower the value, the stronger the thermal stability of the product and the higher the oxidation resistance. The performance reflects the less breakage and lower consumption in use. Ways to reduce the coefficient of thermal expansion: Mainly determined by the inherent properties of the raw materials to use good quality raw materials, use a larger particle size formula or increase the amount of large particles (but it will reduce the density and strength of the product). Ash content refers to the content of other solid elements in the product except carbon graphite. The ash content in the graphite electrode is mainly affected by the ash content of the raw materials used, and the ash content of petroleum coke needle coke is relatively low.
Therefore, the ash content of the graphite electrode generally does not exceed 0.5%, and the ash content within 1% has no significant effect on steelmaking, but the impurity elements in the ash will reduce the oxidation resistance of the electrode. The thermal vibration resistance factor is a parameter that characterizes the thermal vibration resistance. The thermal vibration resistance is a characteristic of the material itself. It expresses the performance of withstanding rapid cold and rapid heat. In other words, it is the material in a certain temperature gradient. The resistance to fragmentation is a very important comprehensive factor that affects the use of electrodes. K&;&; Thermal shock resistance factor, w/m; &;&;&; Tensile strength, MPa; E&;&; Elastic modulus, MPa; &;&;&; Thermal conductivity, w/m&;k ;&;&;&; Thermal expansion coefficient, 1/KK is a relative value, the larger the value, the stronger the thermal vibration resistance. The K value of the graphite electrode has a high correlation with its performance in the electric arc furnace, that is, a higher K value corresponds to a lower fragmentation and fracture of the electrode.
Company introduction: CGM Carbon is a leading group company focusing on the production and operation of carbon metallurgical material products, in accordance with industrial standards and customer requirements, providing fast quotations, reliable quality, competitive price products and delivery services as quickly as possible . It was founded in 1992 in Zhengzhou in the east of China. In order to play a greater role in the entire production and supply chain, we work closely with our customers. With more than 20 years of professional experience and expertise in the carbon metallurgy industry, the company is committed to research and development, and provides a series of high-quality, innovative, and cost-effective carbon and metallurgical products and solutions. At present, the main products are graphite electrode, electrode paste, forged petroleum coke and refractory materials. The product line includes carbon materials, graphite materials, refractory materials and water treatment materials. Annual output of 200,000 tons of electrode paste, 50,000 tons of graphite electrode, 250,000 tons of calcined coke, 20,000 tons of refractory materials, etc. As a leading supplier of carbon metallurgical materials in China, CGM, as a pilot enterprise under the Belt and Road Initiative, seizes development opportunities, exports first-class carbon and metallurgical products to the world as its mission, and vigorously explores overseas markets. Our products have been exported to Asia, Africa, the Middle East, South America and many other countries and regions, enjoying a good reputation. CGM (Our company specializes in the production and sales of electrode products: electrode paste, graphite electrode, etc.)