The furnace lining material produced by dry tapping manufacturers, commonly known as "furnace lining material", is suitable for coreless medium frequency induction furnaces in steel mills, foundries, and metal manufacturing. High temperature resistant lining materials are required for tapping. The main raw material of the material belongs to quartz matrix, and its chemical property is acidic. Based on the high-purity microcrystalline quartz matrix, some fused silica, high temperature resistant binder, anti quenching and anti heating stabilizer, anti-seepage agent, anti cracking agent, and imported composite micro powder materials are added, which has the disadvantage of improving the expansion of the furnace lining, and there is no crack when the furnace is cold.
The furnace lining material based on quartz sand materials has high purity of raw materials, reasonable material ratio, enhanced resistance to molten iron corrosion, strong resistance to extreme cold and heat, high softness, strong impact resistance, high load softening temperature, high high temperature compressive strength, high high temperature bending strength, and good slag resistance, especially suitable for intermittent operation of large medium frequency induction furnaces.
1. Permeation failure of molten iron
The molten iron penetrates along the pores of the carbon brick into the interior of the carbon brick, dissolving the binder in the carbon brick, and then corroding the carbon particles in the carbon brick, damaging the compactness of the carbon brick structure and reducing the strength of the carbon brick. The molten iron infiltrates into the carbon brick and undergoes a chemical reaction with the carbon brick, generating brittle substances such as FexC -. After the formation of this substance, volume expansion occurs in the pores of the carbon brick, causing the pores of the carbon brick to become brittle and rupture, Forming a brittle layer on the hot surface of carbon bricks.
2. Circulation of molten iron in the furnace
The circulation of molten iron intensifies the erosion and erosion of the brittle layer on the surface of carbon bricks by molten iron, causing the carbon bricks to become thinner, the depth of the dead iron layer to be shallower, and the flow velocity in the central area of the furnace hearth slows down. The circulation on the side walls of the furnace hearth strengthens, and the carbon bricks on the side walls of the furnace hearth are strongly eroded and eroded by flowing slag iron, thereby reducing the life of the furnace lining.
3. Corrosion of carbon bricks by alkali metals and zinc
Thermodynamic calculations by dry material manufacturers indicate that when the heat transfer performance of carbon bricks is poor, there is a large temperature difference between the hot and cold surfaces. The temperature difference and thermal stress inside the carbon bricks are large, inducing cracks in the carbon bricks. Pure alkali metal vapor continuously flows and diffuses towards the low-temperature zone of the carbon bricks through the microcracks, and microcracks are the cause of ring cracks. If the alkali metal vapor enters the microcracks of carbon bricks and reaches a temperature of 800 ° C, it will liquefy in the microcracks and react with the silicon aluminum ash content of the carbon bricks, causing a volume expansion of 30% of the ash content, exacerbating the propagation of microcracks in the carbon bricks and forming cracks. Calculations have shown that only after the enrichment and liquefaction of alkali metal vapor can it interact with CO to form activated carbon deposition within the cracks. This reaction continues to occur, causing continuous expansion and compression of carbon brick cracks. The cracks in the carbon brick continue to expand, ultimately splitting the carbon brick to form annular cracks. Improving the thermal conductivity of the carbon brick is an effective means to prevent annular cracks.
