KONTROLLVERFAHREN FUER DEN PHASENZUSTAND VON MATERIALIEN IN PROZESSEN MIT EINER KRISTALLISATION AUS DER SCHMELZE UND EINRICHTUNG ZU DESSEN DURCHFUEHRUNG

摘要

The phase condition of a material is controlled during its crystallisation from a melt, where the radiation emitted by the material is picked up by a photo-optical system, in which the amplitude/frequency spectrum of the electric output signals is monitored; the presence of a low frequency component (k) in the spectrum indicates the existence of the molten state. When component (k) is detected, the photo-optical system is pref. moved towards the solid phase and is locked when the component disappears at the liq. solid interface. The pref. appts. uses one or two photo-receivers mounted on a trolley which can be moved in two horizontal directions above the interface. The output of the photo-receiver is fed to an amplitude/frequency analyser providing signals which actuate a stepper motor driving the trolley. The frequency of component (k) is pref. 0.5-30 Hz. Used for the zone melting of metals or semiconductors growth of monocrystals; drawing profiled parts from a melt, and other uses. One example is the zone melting of Al.