Thermal shock resistance represents the resistance of ceramic materials to temperature changes and is a comprehensive reflection of their thermal and mechanical properties.
Zirconia ceramic materials have the thermal properties of thermal stress and the mechanical properties of ceramic materials. Its geometric shape and the size of the environmental medium also affect the thermal stress of ceramic materials. Therefore, thermal shock resistance represents the resistance of ceramic materials to temperature changes and is a comprehensive reflection of their thermal and mechanical properties.
Thermal shock damage of ceramic materials includes cracking and peeling under the direct action of thermal shock and instantaneous rupture under the action of thermal shock. On this basis, two viewpoints are put forward for the evaluation theory of the special thermal shock resistance of brittle ceramic materials.
The first is based on the theory of thermoelasticity. It is said that the original strength of the material cannot withstand the thermal stress caused by thermal shock, resulting in the “thermal shock fracture” of the material. The theory believes that ceramic materials need to have a combination of thermal conductivity, high strength, low thermal expansion coefficient, Poisson’s ratio, and Young’s modulus of elasticity, viscosity, and thermal radiation coefficient, and have a high thermal shock fracture ability. In addition, in order to improve the actual thermal shock resistance of the ceramic material, the heat capacity and density of the material can be appropriately reduced.
Another theory is based on the concept of concrete fracture mechanics, that is, materials with thermoelastic strain energy can be broken into nuclei and spread to the surface of the new energy needed, cracks are formed and begin to expand, causing thermal shock damage to the material.
According to this theory, materials with good thermal shock resistance should meet higher elastic modulus and lower strength. Through this theory, it can be found that the above requirements are completely opposite to the ability of high thermal shock rupture.
We can improve the actual fracture toughness of the material by improving the actual fracture performance of the ceramic material, which is obviously helpful to improve the damage ability of the material. In addition, having a certain number of micro-cracks is also very helpful to improve the avoidance of thermal shock, for example, the porosity is between 10% and 20% of the density ceramics, the formation of thermal expansion cracks usually suffers from pore resistance, passivation cracks and pores. Presence can help reduce stress concentration.
Zirconia ceramic materials have the characteristics of high-temperature mechanical properties, high melting point, chemical stability, and thermal stability. Therefore, its use is often under high-temperature conditions, so its thermal shock performance is also a key indicator of its performance.
Zirconia has very special properties, such as special phase change characteristics, which can provide good thermal shock resistance. Mingrui Ceramics is also improving its thermal expansion behavior and strengthening its thermal shock performance. Welcome Inquiry!