Glass ceramic with SiO2 as the main crystalline phase
Glass ceramics having SiO 2 as main crystal phase and precursors thereof are described which are characterized by very good mechanical and optical properties and in particular can be used as restoration material in dentistry.
1. Glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
Al 2 O 3
0 to 10.0
and comprises SiO 2 as main crystal phase and comprises 5.0 to 50.0 wt.-% SiO 2 as crystal phase.
2. Glass ceramic according to claim 1 , which comprises 60.0 to 90.0 wt.-% SiO 2 .
3. Glass ceramic according to claim 1 , which comprises 2.8 to 9.0 wt.-% Li 2 O.
4. Glass ceramic according to claim 1 , which comprises 0 to 13.0 further alkali metal oxide Me I 2 O.
5. Glass ceramic according to claim 1 , which comprises 0 to 11.0 wt.-% oxide of divalent elements Me II O.
6. Glass ceramic according to claim 1 , which comprises 0 to 10.0 wt.-% oxide of trivalent elements Me III 2 O 3 .
7. Glass ceramic according to claim 1 , which comprises 0 to 21.0 wt.-% further oxide of tetravalent elements Me IV O 2 .
8. Glass ceramic according to claim 1 , which comprises 0 to 7.0 wt.-% P 2 O 5 .
9. Glass ceramic according to claim 1 , which comprises 0 to 6.0 wt.-% further oxide of pentavalent elements Me V 2 O 5 .
10. Glass ceramic according to claim 1 , which comprises 0 to 6.0 wt.-% oxide of hexavalent elements Me VI O 3 .
11. Glass ceramic according to claim 1 , which comprises 0 to 5.0 wt.-% fluorine.
12. Glass ceramic according to claim 1 , which comprises at least one of the following components in the specified amounts:
Component
wt.-%
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
Me I 2 O
0 to 13.0
Me II O
0 to 11.0
Me III 2 O 3
0 to 10.0
Me IV O 2
0 to 21.0
P 2 O 5
0 to 7.0
Me V 2 O 5
0 to 6.0
Me VI O 3
0 to 6.0
fluorine
0 to 5.0.
13. Glass ceramic according to claim 1 , which comprises low quartz, cristobalite or a mixture thereof as main crystal phase.
14. Glass ceramic according to claim 1 , which comprises lithium phosphate and/or lithium silicate as further crystal phase.
15. Glass ceramic according to claim 1 , wherein the glass ceramic is present in the form of a powder, a frit, a blank or a dental restoration.
16. Glass ceramic according to claim 13 , which comprises low quartz as main crystal phase.
17. Glass ceramic according to claim 1 , which comprises 10.0 to 30.0 wt.-% SiO 2 as crystal phase.
18. Glass ceramic according to claim 4 , wherein Me I 2 O is selected from Na 2 O, K 2 O, Rb 2 O and/or Cs 2 O.
19. Glass ceramic according to claim 5 , wherein Me II O is selected from MgO, CaO, SrO and/or ZnO.
20. Glass ceramic according to claim 6 , wherein Me 111 2 0 3 is selected from Al 2 O 3 , B 2 O 3 , Y 2 O 3 , La 2 O 3 , Ga 2 O 3 and/or In 2 O 3 .
21. Glass ceramic according to claim 7 , wherein Me IV O 2 is selected from ZrO 2 , GeO 2 , CeO 2 , TiO 2 and/or SnO 2 .
22. Glass ceramic according to claim 9 , wherein Me V 2 O 5 is selected from V 2 O 5 , Ta 2 O 5 and/or Nb 2 O 5 .
23. Glass ceramic according to claim 10 , wherein Me VI O 3 is selected from WO 3 and/or MoO 3 .
24. Glass ceramic according to claim 1 , which comprises at least one of the following components in the specified amounts:
Component
wt. %
SiO 2
70.0 to 83.0
Li 2 O
5.0 to 9.0
Me I 2 O
1.0 to 13.0
Me II O
1.0 to 7.0
Me III 2 O 3
2.0 to 9.0
Me IV O 2
0 to 21.0
P 2 O 5
1.0 to 6.5
Me V 2 O 5
0 to 5.0
Me VI O 3
0 to 6.0
fluorine
0 to 1.0.
25. Glass ceramic according to claim 1 , which comprises 5.0 to 50.0 wt.-% low quartz, cristobalite or mixtures thereof as crystal phase.
26. Method for the preparation of the glass ceramic according to claim 1 , comprising subjecting a starting glass comprising 58.0 to 92.0 wt.-% SiO 2 , 2.0 to 10.0 wt.-% Li 2 O and 0 to 10.0 wt.-% Al 2 O 3 to at least one heat treatment at a temperature of from 700 to 950° C.
27. Method according to claim 26 , in which
(a′) melt of the starting glass is shaped to form a glass blank, and
(b′) the glass blank is subjected to a heat treatment at a temperature of 700 to 900° C.
28. Method for the preparation of a glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
Al 2 O 3
0 to 10.0
and comprises SiO 2 as main crystal phase, in which
(a) powder of a starting glass comprising 58.0 to 92.0 wt.-% SiO 2 , 2.0 to 10.0 wt.-% Li 2 O and 0 to 10.0 wt.-% Al 2 O 3 , optionally after the addition of further components, is pressed to form a powder compact, and
(b) the powder compact is subjected to a heat treatment at a temperature of 700 to 950° C.
29. Method for the preparation of a dental restoration comprising shaping a glass ceramic, which comprises the following components
Component
wt.-%
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
and comprises SiO 2 as main crystal phase, into the desired dental restoration by pressing, sintering or milling.
30. Method according to claim 29 , wherein the dental restoration comprises a bridge, inlay, onlay, veneer, abutment, partial crown, crown or facet.
31. Glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
Al 2 O 3
0 to 10.0
and comprises SiO 2 as main crystal phase and comprises 5.0 to 30.0 wt.-% lithium disilicate as further crystal phase.
32. Method for the preparation of a glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
Al 2 O 3
0 to 10.0
and comprises SiO 2 as main crystal phase, which comprises subjecting a starting glass comprising 58.0 to 92.0 wt.-% SiO 2 , 2.0 to 10.0 wt.-% Li 2 O and 0 to 10.0 wt.-% Al 2 O 3 to at least one heat treatment at a temperature of from 700 to 950° C. for a period of 5 to 40 min.
33. Method for the preparation of a dental restoration comprising shaping a glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
and comprises SiO 2 as main crystal phase, into the desired dental restoration by pressing, sintering or milling, wherein said milling is carried out as part of a CAD/CAM method.
34. Method for the preparation of a dental restoration comprising shaping a glass ceramic, which comprises the following components
Component
wt. %
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
and comprises SiO 2 as main crystal phase, into the desired dental restoration by milling.