Claims
- 1. A glass-ceramic comprising, as a predominant crystal phase, lithium disilicate (Li2O·2SiO2) having a crystal grain diameter (average) of 0.05 μm or below.
- 2. A glass-ceramic as defined in claim 1 wherein degree of crystallization of the lithium disilicate crystal phase is within a range from 3% to 20%.
- 3. A glass-ceramic as defined in claim 1 wherein Young's modulus (GPa)/specific gravity is 37 or over.
- 4. A glass-ceramic as defined in claim 1 comprising further at least one crystal phase selected from the group consisting of α-quartz (α-SiO2) and α-quartz solid solution (α-SiO2 solid solution), degree of crystallization of the α-quartz (α-SiO2) and the α-quartz solid solution (α-quartz solid solution) being within a range from 5% to 25% and a crystal grain diameter thereof (average) being 0.10 μm or below.
- 5. A glass-ceramic as defined in claim 1 comprising further at least one crystal phase selected from the group consisting of α-cristobalite (α-SiO2) and α-cristobalite solid solution (α-SiO2 solid solution), degree of crystallization of the α-cristobalite (α-SiO2) and α-cristobalite solid solution (α-SiO2 solid solution) being within a range from 2% to 10% and a crystal grain diameter thereof (average) being 0.10 μm or below.
- 6. A glass-ceramic as defined in claim 1 comprising, as predominant crystal phases, lithium disilicate (Li2O.2SiO2) and at least one crystal phase selected from the group consisting of α-quartz (α-SiO2), α-quartz solid solution (α-SiO2 solid solution), α-cristobalite (α-SiO2) and α-cristobalite solid solution (α-SiO2 solid solution).
- 7. A glass-ceramic as defined in claim 1 wherein crystal grains of the predominant crystal phase or phases are fine and substantially of a globular shape.
- 8. A glass-ceramic as defined in claim 1 which is substantially free of Na2O and PbO.
- 9. A glass-ceramic as defined in claim 1 which has a surface roughness Ra (arithmetic mean roughness) after polishing of 5.0 Å or below.
- 10. A glass-ceramic as defined in claim 1 which has a coefficient of thermal expansion within a range from +65×10−7/° C. to +130×10−7/° C. in a temperature range from −50° C. to +70° C.
- 11. A glass-ceramic as defined in claim 1 which has bending strength of 400 MPa or over.
- 12. A glass-ceramic as defined in claim 1 having a composition which comprises in weight percent:SiO2 70-77%Li2O 8-12%K2O 1-3%MgO 0-2%ZnO 0-2%P2O51.5-3%ZrO2 2-7%Al2O3 3-9%Sb2O3 + As2O3 0-2%.
- 13. A glass-ceramic as defined in claim 1 obtained by heat treating a base glass for nucleation under a temperature within a range from 500° C. to 600° C. for one to seven hours and further heat treating the glass for crystallization under a temperature within a range from 700° C. to 780° C. for one to twelve hours.
- 14. A glass-ceramic substrate for a light filter using a glass-ceramic as defined in claim 1.
- 15. A light filter provided by forming a multi-layer film on a glass-ceramic as defined in claim 1.
Priority Claims (3)
Number |
Date |
Country |
Kind |
10-94020 |
Mar 1998 |
JP |
|
10-125316 |
Apr 1998 |
JP |
|
10-351682 |
Dec 1998 |
JP |
|
Parent Case Info
This application is a continuation-in-part of Ser. No. 09/267,743, filed Mar. 15, 1999, now U.S. Pat. No. 6,174,827, which claims priority to Japanese Applications Serial No. 94020/1998 filed Mar. 23, 1998; Serial No. 125316/1998 filed Apr. 20, 1998 and Serial No. 351682/1998 filed Dec. 10, 1998.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
6174827 |
Goto et al. |
Jan 2001 |
B1 |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09/267743 |
Mar 1999 |
US |
Child |
09/593551 |
|
US |