Back to results
US 4,140,645 AGranted
Glasses and glass-ceramics suitable for induction heating
AssigneeCorning Glass Works
InventorsGeorge H. Beall, Richard F. Reade
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeCorning Glass Works
InventorsGeorge H. Beall, Richard F. Reade
Estimating the term…
The instant invention relates to the production of glass and glass-ceramic compositions containing a ferrimagnetic crystal phase throughout which respond thermally to fields generated by induction coils. Magnetite (Fe.sub.3 O.sub.4) is the preferred ferrimagnetic crystal phase because of its high permeability and low resistivity (.about.10.sup.-4 ohm-cm) at room temperature as well as the relative low cost of iron when compared with other ferrimagnetic species. Two general composition areas are of interest: Na.sub.2 O and/or K.sub.2 O-FeO-B.sub.2 O.sub.3 -SiO.sub.2 and Li.sub.2 O-Al.sub.2 O.sub.3 -B.sub.2 O.sub.3 -SiO.sub.2. Where the coefficient of thermal expansion is sufficiently low to impart good thermal shock resistance, the compositions can be considered for top-of-stove cooking vessels.
A glass article which will demonstrate efficient and uniform heating when placed in an oscillatory magnetic field and containing magnetite crystals dispersed throughout the body thereof, said glass article having an overall composition, expressed in weight percent on the oxide basis as calculated from the batch, selected from the groups
A glass-ceramic article which will demonstrate efficient and uniform heating when placed in an oscillatory magnetic field, said article consisting essentially of crystals dispersed within a glassy matrix, said glass-ceramic article having an overall composition, expressed in weight percent on the oxide basis as calculated from the batch, selected from the groups
Dependencies are inferred from the claim text.