The selection of furnace lining materials largely determines the lifespan of intermediate frequency furnaces. Currently, improving the lifespan of intermediate frequency furnaces is also a key focus of intermediate frequency furnace manufacturers, which has great significance for customers to save costs and investment. Do you know how to choose refractory materials for furnace lining? Below, the editor will take you to take a look:
Medium frequency furnace, sufficient fire resistance
The basic factor determining the fire resistance of refractory materials is the chemical mineral composition and distribution of the material. Various impurities, especially those with strong flux effects, can seriously reduce the fire resistance of the product. The fire resistance of refractory materials refers to the Celsius temperature at which the conical specimen of refractory materials can resist high temperature without softening and melting under no load. Simply put, fire resistance refers to the ability of refractory materials to resist high temperatures without melting under no load. Fire resistance is the basis for determining whether a material can be used as a refractory material. According to the International Organization for Standardization, inorganic non-metallic materials with a fire resistance of over 1500 ℃ are considered refractory materials. Therefore, the main way to improve the refractoriness of refractory materials is to take appropriate measures to ensure and improve the purity of raw materials.
When smelting in a medium frequency furnace, the high temperature of molten steel can reach 1700 ° C and that of molten iron can reach over 1500 ° C. Therefore, the selection of furnace lining materials that can meet the melting temperature needs to be based on the melting temperature of the melted metal.
2、 Good chemical stability
Slag erosion is a common form of damage to refractory materials in use, such as the lining of intermediate frequency furnace, the working lining of ladle, and the lining of cupola from the lower part of the furnace stack to the hearth, which are mostly caused by this effect. In practical use, about 59% of the damage is caused by erosion of slag. Slag resistance is the ability of refractory materials to resist slag erosion and erosion at high temperatures.
When selecting refractory materials, it is recommended to choose refractory materials with similar chemical composition to slag, in order to reduce the reaction strength at their interfaces. For example, when smelting high manganese steel, alkaline refractory materials should be used as the lining material; Alternatively, changing the composition of the slag as much as possible to bring it closer to the composition of the refractory material used is also a way to improve the slag resistance of the refractory material.
3、 Good thermal shock resistance
Refractory materials are often subjected to rapid changes in environmental temperature during use. For example, during intermediate frequency furnace melting, changes in furnace temperature during charging, tapping, or operation, as well as rapid changes in temperature and pressure during the pouring process of the ladle, can lead to cracks, peeling, and even collapse of the furnace lining and ladle lining. This destructive effect limits the heating and cooling rates of the furnace lining, ladle lining, and furnace, limits the strengthening of furnace operation, and is one of the main reasons for the rapid damage of the furnace lining and ladle lining.
4、 Fixed high-temperature strength
The high-temperature compressive strength of refractory materials refers to the pressure that the material can withstand per unit area under high temperature conditions above 1000 ℃ to 2000 ℃, expressed in N/m2. The compressive strength of refractory materials generally varies significantly with increasing temperature. When the temperature starts from constant temperature, it decreases linearly with increasing temperature. Afterwards, some materials continued to decrease with increasing temperature; When the temperature rises to a certain range, it increases with the temperature and reaches a higher value at a certain temperature, followed by a sharp decrease.
During the melting process of the intermediate frequency furnace, the lining wall of the furnace must withstand the impact force of the metal burden, the static pressure of the metal liquid, the force of electromagnetic stirring of the metal liquid movement, temperature difference stress, and other effects. Therefore, the selection of furnace lining materials should have a certain high-temperature compressive strength, not crack under the action of multiple forces, and be resistant to erosion. The high-temperature strength of furnace lining materials is directly related to the hardness of the particles that make up the refractory material, and the bonding strength between particles and the porosity of the refractory matrix also affect the wear resistance. The wear resistance of the same material decreases with increasing temperature.
5、 The thermal conductivity should be small, and the conductivity should be low
During the melting process of an intermediate frequency furnace, there is a large temperature difference between the inside and outside of the furnace wall, with about 10% to 15% of the heat dissipated outward through the furnace wall. To reduce heat loss and increase heat rate, the furnace lining material must have low heat conductivity. The lining material should have low conductivity and should not contain magnetic induction materials, especially during the lining tying process, it is not allowed to include metals or substances with strong conductivity in it.
6、 Adapt to environmental requirements
The use of furnace lining materials does not release substances that are toxic, harmful, or polluting to the human body, and the waste after use cannot cause harm to the environment.
7、 High cost-effectiveness
Select materials with high cost-effectiveness based on the materials and requirements melted. It can save costs and also use suitable and safe lining materials. Luoyang Yuhua is a manufacturer's direct sales, with many years of production qualifications. It not only has the above performance, but also has a better price and high cost-effectiveness.
Through the above description, we believe that you also have a certain understanding of the choice of furnace lining. Good furnace lining materials must have high fire resistance, good chemical stability, good heat shock resistance, resistance to rapid changes in temperature, and do not crack or peel off; There are also requirements such as low thermal conductivity, low conductivity, and adaptability to environmental requirements. When choosing an intermediate frequency furnace in the future, it can be used as a reference.
