To improve the thermal shock stability of magnesia-chrome bricks, we can start from the following aspects:

I. Optimizing raw materials and formula

Increasing the second solid content: adding pre-synthesized magnesia-chrome sand or magnesia-alumina spinel sand in the production process can improve the high temperature strength and thermal shock stability of bricks. For example, replacing part of magnesia-chrome spinel with magnesia-alumina spinel (MgO·Al₂O₃) can meet the requirements of thermal shock resistance and reduce the generation of hexavalent chromium harmful to the environment.

Controlling impurity content: reducing the content of SiO₂, CaO, Fe₂O₃ and other impurities in raw materials, while increasing the content of Cr₂O₃ and Al₂O₃, is helpful to improve the corrosion resistance and thermal shock stability of bricks.

Adding special additives: adding proper amount of ZrO₂, nano-Fe₂O₃, Al₂O₃ and other additives can significantly improve the thermal shock stability of magnesia-chrome bricks. For example, the addition of ZrO₂ can increase the fine cracks in the material, thus absorbing thermal stress and improving the thermal shock resistance.

II. Adjusting the production process

Increasing the firing temperature: In the firing process, increasing the firing temperature (such as above 1700℃) can promote the formation of secondary spinel, thus improving the high-temperature strength and thermal shock stability of bricks.

Controlling particle composition: increasing the critical particle size and reducing the fine powder content in chrome ore particles can effectively improve the thermal shock stability of magnesia-chrome bricks.

Using superfine powder technology: by adding superfine powder (such as the specific surface area of fine powder reaches 5 ~ 6 m/g), the amount of secondary spinel can be increased, thus improving the thermal shock resistance and corrosion resistance of brick.

III. Improving the structure and design of bricks

Increase the formation of secondary spinel: the amount and size of secondary spinel have an important influence on the high temperature performance and thermal shock resistance of magnesia-chrome bricks. By optimizing the raw material ratio and sintering process, the amount of secondary spinel can be increased, thus improving the thermal shock resistance of bricks.

Adopt composite structure: In some applications, brick with composite structure can be used, such as covering the surface of magnesia-chrome brick with a layer of material with better thermal shock resistance to reduce the direct impact of thermal shock on brick.

IV. Use of protective measures

Hanging kiln skin: In cement rotary kiln and other equipment, keeping the kiln skin intact can effectively protect magnesia-chrome bricks and reduce the impact of thermal shock.

Slow cooling: when the equipment is stopped, slow cooling is adopted to avoid thermal shock cracks caused by sudden cooling.

Through the above measures, the thermal shock stability of magnesia-chrome brick can be effectively improved, its service life can be prolonged, and the damage and maintenance cost caused by thermal shock can be reduced.