Views: 0 Author: Site Editor Publish Time: 2025-09-29 Origin: Site
The main component of quartz crucible is silicon dioxide (SiO _ 2), which has a highly crystalline lattice structure and a uniform chemical composition, which makes the quartz crucible have a certain thermal conductivity. Its thermal conductivity is about 2.09 W/(m · K) at room temperature. Although this value is lower than that of metallic materials, it still belongs to a good level in non-metallic materials.
Factors affecting thermal conductivity
- Temperature: The thermal conductivity of quartz crucibles increases with increasing temperature. In the temperature range of 273-423 K, its thermal conductivity is linearly related to temperature. When the temperature increases further, especially at high temperatures, the change in thermal conductivity may be more pronounced.
- Humidity: After the quartz crucible absorbs moisture and becomes damp, the thermal conductivity will increase. Because the thermal conductivity of water is 0.5 W/(m · K), which is 20 times greater than the thermal conductivity of air at 0.029 W/(m · K), and the thermal conductivity of ice is 2.33 W/(m · K), this will further increase the thermal conductivity of the quartz crucible.
- Heat flow direction: When the heat flow is parallel to the fiber direction of the quartz crucible, the thermal insulation performance is weakened and the thermal conductivity is enhanced; while when the heat flow is perpendicular to the fiber direction, the heat resistance performance of the quartz crucible is better.
- Internal structure: Factors such as porosity and crystal structure inside quartz crucible can also affect its thermal conductivity. If there are many pores or defects inside the crucible, it will hinder the conduction of heat and reduce thermal conductivity.
The manifestation of thermal conductivity in applications
- Heating uniformity: The quartz crucible can transfer heat quickly and evenly, so that the sample is heated evenly, effectively avoiding the influence of the temperature layer on the sample. In high temperature experiments, this uniform heating effect can ensure the accuracy and reliability of the experiment.
- Temperature control: Using the high thermal conductivity of quartz crucibles, it is possible to estimate the temperature of the measurement area by measuring the temperature change of its surface, which is widely used in temperature monitoring and measurement in experimental and industrial production.
- Thermal stability: quartz crucibles have a small coefficient of thermal expansion and good thermal stability, making them less prone to cracking or deformation even during rapid heating or cooling. This allows quartz crucibles to maintain structural stability under complex temperature changes and extend their service life.
Comparison with other materials
- Compared to metal crucibles: Metal crucibles usually have higher thermal conductivity and can conduct heat faster. However, quartz crucibles have better chemical stability, are not easily corroded, and do not chemically react with the heated substance at high temperatures.
- Compared with porcelain crucibles: porcelain crucibles have lower thermal conductivity and poor thermal conductivity, but they are relatively inexpensive. Although quartz crucibles are more expensive, their excellent thermal conductivity and high temperature stability make them more advantageous in some experiments and industrial production that require higher heating.
Although the thermal conductivity of quartz crucibles is not as good as that of some metal materials, it performs well in non-metallic materials and can meet the needs of most high temperature experiments and industrial production. Its thermal conductivity is affected by many factors, and it needs to be selected and optimized according to specific conditions in practical applications.
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