How long can a graphite crucible withstand prolonged exposure to high temperatures

How long can a graphite crucible withstand prolonged exposure to high temperatures? How can a graphite crucible operate stably at high temperatures for an extended period? This depends on the physical properties of graphite.

Graphite possesses the following physical properties: high temperature resistance. Graphite has a high melting point, reaching 3850 degrees in vacuum, and sublimates at a temperature of 2200 degrees under low pressure. Unlike general materials, when the temperature rises, the graphite crucible not only does not soften but its strength actually increases. At 2500 degrees, the tensile strength of graphite doubles. Graphite exhibits exceptional thermal shock resistance due to its anisotropic thermal expansion, which results in a small macroscopic expansion coefficient. In the case of sudden temperature changes, the volume change of graphite is also minimal. Coupled with its good thermal conductivity, graphite demonstrates excellent thermal shock resistance.

Based on the above two points, graphite components should be able to operate stably at high temperatures for an extended period. We understand that everything has its lifespan, and graphite crucibles are no exception. During their lifespan, it's crucial to pay attention to usage methods. Next, let's discuss how to extend the lifespan of graphite crucibles. Firstly, graphite crucibles can be directly heated, but they should not be cooled immediately after heating. Use crucible tongs to remove them and avoid placing them on a cold metal surface to prevent cracking due to rapid cooling. Secondly, because the bottom of the crucible is small, it needs to be placed on a graphite pad or a mud triangle when being heated.