High strength machinable glass-ceramics
AssigneeCorning Incorporated
InventorGeorge Halsey Beall
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Abstract
In one aspect the invention is directed to a machinable glass-ceramic having a high degree of crystallinity (greater than 50 Vol. %), high mechanical strength (MOR>150 MPa) In accordance with the invention, the machinable glass-ceramics described herein consists essentially of, in weight percent, 35-55% SiO2, 6-18% Al2O3, 12-27% MgO, 3-12% F, 5-25% SrO, 0-20% BaO and 1-7% K2O. The machinable glass-ceramics of the invention have a dielectric constant of <8 (typically being in the range of 6-8) at 25° C. and 1 KHz; a loss tangent of <0.002 at 25° C. and 1 MHz; a CTE in the range of 80-120×10−7/° C. in the temperature range of 25-300° C.; a Poisson's ration of approximately 0.25; and a porosity of 0%.
Claims9
A machinable glass-ceramic consisting essentially of, in weight
- percent on a oxide basis, 35-55% SiO2, 6-18% Al2O3, 12-27% MgO, 5-25% SrO, 0-20% BaO, 1-7% K2O and 3-12% F, a colorant consisting of FeO+Fe2O3 in an amount in the range of >3% to 20%;
- wherein said machinable glass-ceramic has greater than 50 Vol. % crystalline phase and less than 50 Vol. % glass phase, and a mechanical strength greater than 150 MPa;
- and
- wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica.
A black colored machinable glass-ceramic consisting essentially of, in weight percent, 35-55′% SiO2, 7-13% Al2O3, 13-20% MgO, 3-12% F, 6-20% SrO, 0-20% BaO and 1-7% K2O, and 7-20% FeO+Fe2O3.
Dependencies are inferred from the claim text.