Britannica
Sources used in this answer
How fast does a heated ring travel during zone melting?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
zone melting
Figure 1: Schematic representation of (A) normal freezing, (B) zone refining
In the context of zone melting, the heated ring travels along the rod very slowly, typically at a rate of a few centimeters per hour.1
More specifically, the freezing ratesāwhich correspond to the speed at which the molten zone movesādepend on the type of material being processed:
- Organic substances: Typical rates range from 0.1 to 2.0 cm/hr (0.04 to 0.8 in./hr).2
- Inorganic substances: Typical rates range from 0.5 to 30 cm/hr (0.2 to 12 in./hr).2
These slow speeds are necessary to maintain the desired liquid-solid equilibrium, allowing impurities to be effectively redistributed and concentrated in the liquid zone as it moves toward the end of the ingot.21