Research Progress of Layered Ceramics and Layered Refractories

The development of modern industrial technology has put forward to higher requirementson steel strength, toughness and processing perfor-mance for steel materials. In particular, iron and steel products gradually realize functionalization as excellent structural materials. Refractories are important supporting materials for high-temperature metallurgical industry, especially for the efficiency and quality of high quality steel smelting. The basic properties of refractories, such as thermal conductivity, corrosion resistance, thermal shock resistance and erosion wear resistance, are interacted with each other. The traditional preparation process of refractories can't realize the best performance of each property for refractory products. The low thermal conductivity refractories can prevent decreasing rapidly of the molten steel temperature, thus, reducing heat loss, so as to reduce energy consumption. However, the thermal stress in the high-temperature zone and the low-temperature zone is quite diffe-rent, and the shear stress between the two zones can easily lead to the cracking and damage of the refractory. The high thermal conductivity refractories can alleviate the damage of temperature difference stress to refractory products. The temperature reduction of thermal surface of refractory materials can also form slag-skin attachments to protect refractory products. Meanwhile, the chemical erosion rate of alkali metals will be significantly reduced. Especially for traditional carbon-containing refractories, although the presence of carbon components improves the thermal shock resistance of the refractories, the oxidation of carbon in high-temperature smelting leads to the formation of porous structure in the refractories reducing the strength of the material. Then, the refractories are eroded and permeated by molten slag effecting the content of carbon in steel. The researchers mainly optimized the performance of refractories by improving the composition and structure of refractories and adding or in situ generating ceramic protection phase. However, the optimization effect is still single, which can't achieve good unity of structure and function. Therefore, it is necessary to develop new type refractories with well-matched of structure and function, such as thermal shock resistance, anti-erosion and non-pollution. As a kind of bionic design, the fine structure of laminated composites ensures its excellent comprehensive performance. Although there are many methods to prepare laminated composites, there are some technical limitations. The technology of powder compaction and sequential casting cannot guarantee the uniformity of interface or interface layer, and the design of interlayer interface is limited. Centrifugal deposition and electrophoretic deposition are highly dependent on the characteristics of raw materials, which is not conducive to the structural design of refractories. Although 3D printing has been widely concerned, it has high requirements for equipment, especially for rapid prototyping of raw materials, and it has a lot shortcomings for ceramic materials. By contrast, the tape casting has flexible operation, good adaptable for raw material and convenient post processing for green tapes. Therefore, the researches on layered ceramics and refractories are often based on this. This paper reviews the preparation technology of layered ceramic composites and the influence of different preparation methods and layered structures on their fracture strength and fracture toughness. The application of layered structure in the study of refractories and its influence on the thermal shock resistance and corrosion resistance of refractories are introduced. The key problems and the future development direction of layered refractories are proposed. © 2019, Materials Review Magazine. All right reserved.