Alumina ceramic has its thermal conductivity, which is related to its chemical composition, microstructure, density and sintering process. In a certain range, through a specific method to increase the thermal conductivity of alumina ceramic materials, will improve its heat conduction, heat convection, heat radiation capabilities, the preparation of alumina ceramic materials with strong absorption of heat, high storage, strong heat dissipation and high thermal conductivity, can further expand the application of alumina ceramic material.

In order to improve the thermal conductivity of alumina ceramic materials, it is necessary to improve the purity of alumina ceramic materials, try not to add or add admixtures, but in order to improve the density of ceramic materials and control the grain size, then it is necessary to add a certain amount of admixtures.

Thermal conductivity of alumina ceramics: Material - thermal conductivity (W/mk) Alumina ceramics - 29.3 beryllium oxide ceramics - 196.8; The thermal conductivity can reach 30W/M*K, and the thermal conductivity of boron nitride and aluminum nitride can reach 100-200W/M*K.

The thermal conductivity of alumina ceramics is about 30, and alumina ceramics have good conductivity, mechanical strength and high temperature resistance. Its thermal conductivity varies greatly with the change of temperature.

Thermal properties

The thermal properties of alumina ceramics are also one of its excellent properties. Thermal properties refer to the ability of a substance to transfer heat, generally measured by the coefficient of thermal conductivity. The heat transfer coefficient is the ratio of heat transfer per unit area in unit time to the temperature gradient, and the unit is W/(m·K).

The thermal conductivity of alumina ceramics is about 20-30 W/(m·K). Compared with metal, its heat conductivity is smaller, but in the same volume, because the density of alumina ceramics is smaller than that of metal, its heat capacity is also smaller, so it can also withstand higher temperatures. In addition, the coefficient of thermal expansion of alumina ceramics is also very small, which makes it able to withstand thermal stress at high temperatures and is not easy to crack.

The internal structure of alumina ceramic materials has a complex influence on its thermal conductivity, and there are many internal heat transfer modes according to different situations. For example, the thermal conductivity of interconnected pores in the internal structure of alumina ceramic materials is higher than that of closed pores. The higher the closed porosity, the lower the thermal conductivity. The addition of other components may change the internal structure of alumina ceramics during the firing process and affect the properties of alumina ceramics. In some cases, measures are chosen to change the internal structure of alumina ceramics to meet specific functional needs. The porosity connectivity, the size of the raw material particle size, and the appearance of internal defects such as micro-cracks will have a significant impact on the thermal conductivity of the material.

Application prospect

Because of the unique comprehensive properties of alumina ceramics, it has a wide range of application prospects in many fields. For example, in the aspect of high temperature heating elements, alumina ceramics can be used to make heating elements, and its heat conduction performance can effectively control the temperature distribution of components; In terms of mechanical seals, alumina ceramics can be used to make bearings and sealing rings, and its high hardness and low wear properties can effectively extend the service life of seals; In terms of optical devices, alumina ceramics can be used to make flasher for high-pressure sodium lamps, and its high strength and high temperature stability can ensure the long-term stability of the device.