Thermal shock damage of ceramic materials includes: thermalCracking and peeling under direct impact; instantaneous rupture under thermal shock. On this basis, two viewpoints are put forward on the evaluation theory of special thermal shock resistance of brittle ceramic materials. The first one is based on thermoelasticity theory. It is said that the original strength of the material cannot resist the thermal stress caused by thermal shock, resulting in "thermal shock fracture" of the material. This 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 elastic modulus, viscosity and thermal radiation coefficient, and have high thermal shock fracture ability. In addition, in order to improve the actual thermal shock resistance of ceramic materials, the heat capacity and density of the material can be appropriately reduced.
Another theory based on the concept of fracture mechanics in concrete, that is, the thermoelastic strain energy of the material can crack to nucleate and propagate as well as the new energy required to the surface for cracks to form and initiate Expansion, causing thermal shock damage to the material. According to this theory, materials with good thermal shock resistance should have higher elastic modulus and lower strength. By this approach, it can be seen that the above requirements are completely opposite to the ability of high thermal shock rupture. In addition, the actual fracture performance of ceramic materials can be improved and the actual fracture toughness of the material can be improved, which is obviously helpful in improving the damage capability of the material. In addition, having a certain number of micro-cracks is very helpful in improving the thermal shock damage performance. For example: in ceramics with a porosity between 10% and 20% density, the formation of thermal expansion cracks usually suffers from pore resistance, passivation cracks and The presence of pores can help reduce stress concentrations.
As a zirconia ceramic material, it has the characteristics of high temperature mechanical properties, high melting point, chemical stability and thermal stability. Therefore, it is often used under high temperature conditions, so its thermal shock performance is also a key indicator of its performance. Many zirconia have very special properties, such as: zirconia exists in a single material and in the form of square and cubic three crystals. It has its special phase change characteristics and can be used for so many functions. Mingrui Ceramics is also improving its thermal expansion. behavior to enhance its thermal shock performance.
