GLASS CERAMIC WITH QUARTZ SOLID SOLUTION PHASE

Abstract

Quartz solid solution glass ceramics and precursors thereof are described, which are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

Claims

1. A glass ceramic, which comprises the following components TABLE-US-00011 Component Wt.-% SiO.sub.2 54.1 to 67.0 Li.sub.2O 13.1 to 18.5 K.sub.2O 0.1 to 2.0 Al.sub.2O.sub.3 1.6 to 4.0 P.sub.2O.sub.5 4.1 to 6.5 ZrO.sub.2 7.0 to 13.5 and comprises at least one quartz solid solution phase.

2. The glass ceramic according to claim 1, which comprises at least two different quartz solid solution phases.

3. The glass ceramic according to claim 1, which comprises at least one and preferably at least one stoichiometric or non-stoichiometric aluminosilicate crystal phase (s).

4. The glass ceramic according to claim 1, which comprises 57.0 to 66.5 wt.-% SiO.sub.2.

5. The glass ceramic according to claim 1, which comprises 13.3 to 18.0 wt.-% Li.sub.2O.

6. The glass ceramic according to claim 1, which comprises 0.5 to 1.7 wt.-% K.sub.2O.

7. The glass ceramic according to claim 1, which comprises 2.0 to 3.8 wt.-% Al.sub.2O.sub.3.

8. The glass ceramic according to claim 2, which comprises 4.3 to 6.0 wt.-% P.sub.2O.sub.5.

9. The glass ceramic according to claim 1, which comprises 7.2 to 13.0 wt.-% Zro.sub.2.

10. The glass ceramic according to claim 1, which comprises 1.0 to 8.0 wt.-% oxide of monovalent elements Me.sub.2.sup.IO selected from the group of Na.sub.2O, Rb.sub.2O, CS.sub.2O and mixtures thereof.

11. The glass ceramic according to claim 1, which comprises 0.05 to 5.0 wt.-% oxide of divalent elements Me.sup.IIO selected from the group of Cao, MgO, Sro, Zno, and mixtures thereof.

12. The glass ceramic according to claim 1, which comprises 0 to 5.0 wt.-% oxide of trivalent elements Me.sub.2.sup.IIIO.sub.3 selected from the group of B.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, Ga.sub.2O.sub.3, In.sub.2O.sub.3, and mixtures thereof.

13. The glass ceramic according to claim 1, which comprises SiO.sub.2 and Li.sub.2O in a molar ratio in the range of 1.5 to 6.0.

14. The glass ceramic according to claim 1, which comprises lithium disilicate or lithium metasilicate as main crystal phase.

15. The glass ceramic according to claim 1, which comprises at least 20 wt.-%, lithium disilicate crystals.

16. The glass ceramic according to claim 1, which comprises 0.2 to 28 wt.-% of quartz solid solution.

17. A starting glass comprising the components of the glass ceramic according to claim 1.

18. The starting glass according to claim 17, which comprises nuclei for the crystallization of quartz solid solution phase and nuclei for the crystallization of lithium disilicate or lithium-metasilicate.

19. The glass ceramic according to claim 1, wherein the glass ceramic is in the form of a powder, a granulate, a blank or a dental restoration.

20. A process for producing the glass ceramic according to claim 1, in which a starting glass in particulate form, is subjected to at least one heat treatment in the range from 600 to 1000? C.

21. (canceled)

22. (canceled)

23. A process for producing a dental restoration selected from a bridge, inlay, onlay, veneer, abutment, partial crown, crown or facet, in which the glass ceramic according to claim 1 is given the shape of the desired dental restoration by pressing or machining.

Description

EXAMPLES

Examples 1 to 9Composition and Crystal Phases

[0079] A total of 9 glasses and glass ceramics according to the invention with the composition given in Table I were produced by melting of corresponding starting glasses and subsequent heat treatment for controlled crystallization.

[0080] The heat treatments applied are also given in Table I. The following meanings apply [0081] T.sub.g Glass transition temperature, determined by DSC [0082] T.sub.Kb and t.sub.kb Applied temperature and time for nucleation of the starting glass. [0083] T.sub.c and t.sub.c Applied temperature and time for crystallization

[0084] For this purpose, the starting glasses were first melted from usual raw materials in a platinum-rhodium crucible at 1500 to 1700? C.

[0085] In Examples 1 to 3, the melts of the starting glasses were poured into graphite or steel molds to produce glass monoliths. These glass monoliths were stress relieved and slowly cooled to room temperature. They were then subjected to a first heat treatment at temperature T.sub.Kb for a duration t.sub.kb for nucleation and then to another heat treatment at temperature T.sub.c for a duration t.sub.c for crystallization.

[0086] In Examples 4 to 9, glass frits, i.e. glass granulates, were produced by pouring the molten starting glasses into water. The glass frits were ground to a particle size of <45 ?m using ball or mortar mills and pressed into powder compacts using powder presses. The powder compacts were subjected optionally to a heat treatment at the temperature T.sub.kb for a duration of t.sub.kb, to a first heat treatment at temperature T.sub.c1 for a duration t.sub.c1 and a second heat treatment at temperature T.sub.c2 for a duration t.sub.c2 for nucleation and crystallization.

[0087] In the following table I means: [0088] QMK: Quartz solid solution phase [0089] SP: Spodumene (LiAlSi.sub.2O.sub.6)

TABLE-US-00010 TABLE I Example 1 2 3 Composition Wt.-% Wt.-% Wt.-% SiO.sub.2 62.5 65.0 66.1 Li.sub.2O 14.2 13.3 14.5 K.sub.2O 1.4 0.5 1.4 Al.sub.2O.sub.3 2.4 3.6 2.0 P.sub.2O.sub.5 5.4 4.5 5.8 ZrO.sub.2 10.1 13.0 7.2 MgO 3.0 0.1 0.5 B.sub.2O.sub.3 1.0 2.5 T.sub.g [? C.] 490 531 488 T.sub.Kb [? C] 510 550 510 t.sub.kb [min] 10 10 10 T.sub.C [? C.] 800 800 810 t.sub.C [min] 30 30 30 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 QMK QMK QMK:SP Example 4 5 6 7 Composition Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 59.0 60.0 62.0 63.0 Li.sub.2O 16.0 17.5 16.0 14.2 K.sub.2O 1.3 1.0 1.5 1.2 Al.sub.2O.sub.3 2.8 2.8 3.4 3.8 P.sub.2O.sub.5 5.6 6.0 5.9 5.8 ZrO.sub.2 10.0 9.5 10.5 11.5 MgO 0.1 1.5 0.2 0.4 B.sub.2O.sub.3 2.5 1.7 0.5 0.1 Y.sub.2O.sub.3 0.1 Ce.sub.2O.sub.3 1.0 V.sub.2O.sub.5 0.4 Er.sub.2O.sub.3 0.2 Tb.sub.4O.sub.7 1.0 T.sub.g [? C.] 488 475 499 524 T.sub.C1 [? C.] 750 750 750 750 t.sub.C1 [min] 5 5 5 5 T.sub.C2 [? C.] 880 880 880 880 t.sub.C2 [min] 10 10 10 10 Example 8 9 Composition Wt.-% Wt.-% SiO.sub.2 59.0 63.0 Li.sub.2O 16.0 14.2 K.sub.2O 1.3 1.2 Al.sub.2O.sub.3 2.8 3.8 P.sub.2O.sub.5 5.6 5.8 ZrO.sub.2 10.0 11.5 MgO 0.1 0.4 B.sub.2O.sub.3 2.5 0.1 Y.sub.2O.sub.3 0.1 Ce.sub.2O.sub.3 1.0 V.sub.2O.sub.5 0.4 Er.sub.2O.sub.3 0.2 Tb.sub.4O.sub.7 1.0 T.sub.g [? C.] 488 524 T.sub.Kb [? C.] 530 t.sub.kb [min] 30 T.sub.C1 [? C.] 670 730 t.sub.C1 [min] 120 60 T.sub.C2 [? C.] 800 860 t.sub.C2 [min] 60 60 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 QMK QMK Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.2SiO.sub.3