The thermal properties of refractories generally include thermal expansion and thermal conductivity.
1. Thermal expansion
The thermal expansion of the refers to the performance that the length and the volume of the recarburizer change with the increase in temperature during the heating process. The thermal expansion rate and the expansion coefficient are used to show that the value is equivalent to the change in the unit temperature. The ratio of the amount of expansion in a certain direction to the actual length before expansion in that direction. The standard GB/T7320-2000 "Test Method for Thermal Expansion of Refractory Products" stipulates that the thermal expansion rate is the relative change rate of the sample length from room temperature to the test temperature, expressed in %; the average thermal expansion coefficient is the temperature between room temperature and the test temperature for every 1℃ increase in temperature. The relative change rate of sample length, the unit is 10-6/℃.
The thermal expansion performance of materials will directly affect the tightness of the kiln's masonry length and the stability of the structure. In actual work, the baking system should be determined in accordance with the thermal expansion and the construction of the masonry to avoid excessive thermal expansion causing damage to the refractory.
2. Thermal conductivity
Thermal conductivity is also known as thermal conductivity, which indicates the heat flow rate per unit area of the material under a unit temperature gradient, indicated by λ. The thermal conductivity of materials is to consider the thermal insulation ability of the material in the application process. In thermal design, it is the basic data of thermal calculation.
The thermal conductivity of the material depends on the chemical composition of the material, the crystal structure and its reaction to the pore distribution and porosity of the material in the production and processing state. Generally speaking, for most materials in a certain temperature range, for a range of porosity, with the increase of porosity, the thermal conductivity decreases; and the thermal conductivity of products increases with the increase of bulk density. Big.
