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Low Temp Furnace Model ITL-M-17701 13-07/20
FREEZING THE TIN CELL
Realisation of the Tin plateau is accomplished in a manner similar to those of Indium, Lead and Zinc with
the following exception.
Tin can supercool as much as 10°C. If the furnace were allowed to cool to the nucleation point, it would
probably not recover in time to realise the plateau.
Following melt, reduce the temperature of the furnace to a few tenths of a degree below the anticipated
freeze plateau temperature. Prior to supercool, and with the thermometer still in place, withdraw the cell in
its Inconel basket, from the furnace. Suspend the basket (with cell) in ambient air. Continue monitoring
until the temperature begins to rise. Return the cell to the furnace, remove the monitor thermometer and
replace with a quartz rod from ambient temperature. After 2 minutes remove the rod and replace the
thermometer. When the monitoring thermometer has shown no change for some minutes, the plateau has
been achieved.
A typical melt/freeze sequence is shown in Figure 17.
A useful hint
When first creating freezes use large under settings - typically 3 to 5°C BELOW the freeze plateau. The
result will be a shorter freeze time than ideal, but will engender confidence in establishing a plateau. Once
familiar with the procedure using coarse settings, on subsequent exercises bring the setting of the controller
closer to the known freeze temperature to increase the plateau length.
There follows later a tutorial about Fixed Points.
