Glass, some oxides and salts all share the characteristic that they are electrical and heat insulators at ambient temperature and become conductive at high temperature. They may therefore be re-heated and melted using the induction heating method. This method of heating is attracting increased attention due to its int rinsic qualities:
Exceptional energy efficiency,
Control simplicity,
Good thermal homogeneity in the pot (absence of hot spots and presence of a cold dome),
No wearing parts.
In comparison with metals, glass and similar materials offer far greater resistivity (104 to 106). The resulting behavior in respect to induction is original, the consequences of which are:
The ability to melt in a skull crucible (forming of an insulating wall of the same composition),
Requirement of pre-heating in order to attain a sufficiently low resistivity
The use of operating frequencies and dimensions different to those used for metals
Requirement of extremely flexible power supplies to match the impedance to the variations in the glass resistivity (MOSFET transistors generators of
CELES MP or
CELES Hi Power MP product ranges)
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The direct coil technique is a method of fusion, which has thanks to its possibility to melt in a skull crucible an extremely high efficiency and reduced inertia. It could be used for many materials such as glass, salts and oxides.