Currently, the common methods to reduce the high-temperature erosion of magnesia-carbon bricks can be summarized as follows:
1. Using High-Quality, Stable Materials
Select stable, high-quality materials to enhance erosion resistance, thermal shock resistance, and structural spalling resistance.
Use high-purity and premium fused magnesia, which features large grains, high density, low chemical activity, and excellent erosion resistance. It also resists self-destructive reactions with carbon at high temperatures, thereby suppressing slag erosion on MgO particles.
Increase MgO content while reducing impurities, especially limiting SiO₂ content, to minimize silicate phases in the structure. This reduces high-temperature side reactions, such as the reaction between SiO₂ and graphite, preventing carbon oxidation.
Improve the crystallinity of MgO to prevent grain boundaries from transforming into liquid phases at high temperatures, thus stopping slag penetration into magnesia-carbon bricks. Similarly, increasing the purity of graphite can enhance slag resistance. Higher-purity graphite improves thermal shock resistance and high-temperature flexural strength. Typically, graphite with more than 95% carbon content is used. Higher purity results in fewer silicate phases, which reduces decarburization reactions and the formation of low-melting phases in the presence of alkaline slag.
Add appropriate amounts of antioxidants and select high-quality thermosetting binders to improve the high-temperature performance of magnesia-carbon bricks.
2. Optimizing Slag Composition
Increase MgO content in the slag to saturation levels to minimize the dissolution of MgO. As MgO is an alkaline oxide, increasing slag alkalinity reduces the chemical reaction between slag and magnesia, thereby mitigating chemical erosion.
Reduce FeO and other elements in the slag that may react chemically to limit oxidation of MgO and graphite
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3. Adopting External Protective Measures
Form a protective layer on the surface of magnesia-carbon bricks to prevent contact with slag, thereby inhibiting the physical penetration and chemical erosion of molten steel/slag into the refractory. Techniques like slag splashing can protect the furnace.
Utilize external fields, such as electric fields, magnetic fields, or ultrasonic fields, to protect magnesia-carbon bricks. Among these, the cathodic protection method using external electric fields is a novel technology for combating high-temperature erosion by molten steel/slag, which has garnered significant attention from researchers in recent years.
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