Due to the complex structure and poor working environment, lightweight insulation bricks have many factors that affect their insulation effects. Moreover, various factors influence each other and are related to each other, making it difficult to conduct accurate analysis and research. However, among the many influencing factors, the composition and structure of the material, the porosity and the characteristics of the pores, the bulk density, and the temperature are the main factors.
(1) The composition and structure of the material
The chemical mineral composition and crystal structure of the material are the primary factors affecting the thermal conductivity of lightweight insulating bricks. In general, the more complex the crystal structure of the lightweight insulation brick, the smaller the thermal conductivity. The solid phase of the material can be simply divided into a crystalline phase and a glass phase. When atoms (ions) transmit kinetic energy from atoms with higher kinetic energy (electrons) to other atoms (ions) with lower kinetic energy due to vibration and collision, and atoms (ions) in the glass phase are disorderly arranged, the resistance encountered is higher than the orderly arranged crystal phase. Therefore, the glass phase has a lower thermal conductivity than the crystalline phase. However, when the temperature rises to a certain extent, the viscosity of the glass phase decreases, the resistance of the atoms (ion) decreases, and the thermal conductivity of the glass phase increases. The crystal phase is opposite. When the temperature rises, the kinetic energy of the atom (ion) increases, the vibration increases, and the free path is shortened, and the thermal conductivity decreases. In the internal structure of lightweight insulating bricks, the solid phase is separated by many pores of different sizes, which cannot form a continuous solid phase transfer of heat, and the gas phase heat transfer replaces most of the solid phase heat transfer, so the thermal conductivity Very low.
In this period we mainly introduce light weight insulation bricks’ composition and structure. Hope this can bring help to furnace builders. Next period we will introduce porosity of light insulation bricks and characteristics of pores.Please stay tuned.
