The properties of magnesia-zirconium refractories

 Y₂O₃ can stabilize ZrO₂, the thermal expansion coefficient of pure monoclinic ZrO₂ is small, but the thermal expansion coefficient is anisotropic; the thermal expansion coefficient of cubic ZrO₂ is related to temperature, the higher the temperature, the greater the thermal expansion coefficient, thermal expansion will generate thermal stress, which will affect the material The thermal shock resistance. At the same time, when Y₂O₃ is corroded by slag, it can form Y₂O₃-CaO-SiO₂ eutectic and MgAl₂O4 spinel. Compared with the Y₂O₃-CaO-SiO₂-Al₂O3 eutectic formed when the magnesia-zirconium refractory product without Y₂O₃ is eroded by slag, its eutectic temperature is higher, and it can consume part of SiO₂, reduce the viscosity of slag, and effectively hinder melting.

The continued infiltration of slag improves the slag resistance. prepared MgO-ZrO₂-Y₂O₃ composite material by co-precipitation method and studied its mechanical properties. The results show that the introduction of Y₂O₃ into the MgO-ZrO₂ system can improve the stability of the magnesium-zirconium material, and Y₂O₃ can stabilize the c-ZrO₂ phase and inhibit the formation of the m-ZrO₂ phase. Compared with MgO-ZrO₂ composite material, MgO-ZrO₂-Y₂O₃ composite material has increased hardness and decreased fracture toughness. Wang Chun used fused magnesia, dicalcium fused magnesia, fused magnesia zirconium clinker, monoclinic ZrO₂, desiliconized ZrO₂, high calcium magnesium calcium clinker and Y₂O₃ as refractory raw materials, and studied the effects of additives CaO and Y₂O₃ on MgO- The influence of ZrO₂ brick performance.

The results show that when the addition amount of Y₂O₃ is 1% (w), the apparent porosity of the magnesia-zirconium brick is the lowest (11.6%), the bulk density is the highest (3.33g·cm-3), the air permeability is the smallest (0.27μm2), and the high temperature. The maximum flexural strength (4.3MPa). With the increase of Y₂O₃ addition, the apparent porosity increases, the volume density decreases, the air permeability increases, and the high temperature flexural strength decreases. Compared with the magnesia-zirconium brick without Y₂O₃, when Y₂O₃ is 1%(w), its slag erosion resistance index decreases significantly (from 20 to 11); with the increase of Y₂O₃ addition, the slag erosion resistance index does not change much (The average is 8).

When the content (w) of Y₂O₃ is 2%, the compressive strength at room temperature reaches the maximum; when the content of Y₂O₃ (w) exceeds 2%, the segregation of Y₂O₃ causes a large number of cracks in the product, and the compressive strength at room temperature gradually decreases. Therefore, Y₂O₃ can promote the sintering of MgO-ZrO₂ materials, improve the microstructure of the material, and improve the mechanical properties of the material. It can partially stabilize the zirconia and reduce the surface cracking of the material, but too high content will have an adverse effect.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.

Article Source:The properties of magnesia-zirconium refractories

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