Influence of material design on thermal shock resistance of monolithic refractories

In high-temperature industrial applications, monolithic refractories play a vital role. This type of material not only has to withstand extremely high temperatures, but also must maintain structural integrity and performance stability during drastic temperature changes, especially in terms of thermal shock resistance. Material design is a key link in improving the thermal shock resistance of unshaped refractory materials. Its impact is far-reaching and complex, involving many aspects.

First of all, the selection of ingredients is the basis of material design and directly affects the thermal shock resistance of monomorphous refractory materials. Aluminum oxide (Al2O3) has become one of the main components of amorphous refractory materials due to its high melting point, high hardness and excellent chemical stability. Research shows that adjusting the content and crystal form of Al2O3 can significantly affect the thermal expansion coefficient, thermal conductivity and elastic modulus of the material, thereby directly affecting its thermal shock resistance. In addition, the selection of raw materials such as silicon and magnesia also needs to be comprehensively considered based on specific application scenarios to achieve the best thermal shock resistance effect.

The control of microstructure is one of the key factors that determine material properties. For unshaped refractory materials, microstructural characteristics such as grain size, porosity and pore distribution have an important impact on their thermal shock resistance. By optimizing the sintering process, such as adjusting the sintering temperature, holding time and atmosphere conditions, the growth of grains can be effectively controlled, forming a uniform and fine grain structure, reducing internal defects, thereby improving the toughness and crack resistance of the material. At the same time, an appropriate amount of porosity can alleviate thermal stress, because the pores can serve as channels for stress release and reduce the concentration of thermal stress caused by temperature changes.

The introduction of additives can also significantly improve the thermal shock resistance of monolithic refractory materials. For example, nanoparticles, due to their high specific surface area and activity, can form nanoscale interface structures in materials, thereby enhancing the overall strength of the material. Ceramic fiber can improve the toughness of the material and reduce the damage to the material caused by thermal stress. In addition, some special additives, such as zirconium oxide (ZrO2), due to their phase change toughening effect, can undergo phase change at high temperatures and absorb thermal stress, thereby further improving the thermal shock resistance of the material.

Composite material design is another effective way to improve the thermal shock resistance of unshaped refractory materials. By carefully selecting the materials of the matrix and reinforcement to achieve a good match of thermal expansion coefficients, the thermal stress at the interface can be effectively reduced and the thermal shock resistance of the composite material enhanced. For example, combining aluminum oxide with zirconia can form a composite material with excellent thermal shock resistance. At the same time, the use of fiber reinforcement technology, such as adding steel fibers or refractory fibers to refractory castables, can significantly improve the toughness and crack resistance of the material, and further enhance its thermal shock resistance.