Glass Ceramic Having A Quartz Solid Solution Phase
Quartz solid solution glass ceramics 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 comprising a quartz solid solution phase, which comprises the following components
Component
wt.-%
SiO 2
37.0 to 50.0
Al 2 O 3
25.0 to 39.0
MgO
5.0 to 15.0
ZrO 2
13.5 to 19.0.
2 . Glass ceramic according to claim 1 , which comprises 38.0 to 49.0 wt.-% SiO 2 .
3 . Glass ceramic according to claim 1 , which comprises 26.0 to 38.0 wt.-% Al 2 O 3 .
4 . Glass ceramic according to claim 1 , which comprises 6.0 to 14.0 wt.-% MgO.
5 . Glass ceramic according to claim 1 , which comprises 14.0 to 18.0 wt.-% ZrO 2 .
6 . Glass ceramic according to claim 1 , which comprises at least one of the additional following components:
Component
wt.-%
Li 2 O
0 to 1.0
Na 2 O
0 to 1.0
K 2 O
0 to 1.0
CaO
0 to 2.5
SrO
0 to 4.0
ZnO
0 to 15.0
B 2 O 3
0 to 1.0.
7 . Glass ceramic according to claim 1 , which comprises the quartz solid solution phase as main crystal phase.
8 . Glass ceramic according to claim 1 , which comprises a high-quartz solid solution phase, a low-quartz solid solution phase or a mixture thereof.
9 . Glass ceramic according to claim 8 , which comprises the high-quartz solid solution phase in a higher amount than the low-quartz solid solution phase and which comprises the high-quartz solid solution phase as main crystal phase.
10 . Glass ceramic according to claim 8 , which comprises the low-quartz solid solution phase in a higher amount than the high-quartz solid solution phase and which comprises the low-quartz solid solution phase as main crystal phase.
11 . Glass ceramic according to claim 1 , which comprises zirconium oxide as a crystal phase.
12 . Starting glass, which comprises the components of the glass ceramic according to claim 1 .
13 . Starting glass according to claim 12 , which comprises nuclei for the crystallization of the quartz solid solution phase.
14 . Glass ceramic according to claim 1 , wherein the glass ceramic is present in the form of a powder, a blank or a dental restoration.
15 . Process for preparing the starting glass with nuclei according to claim 13 , in which
(a) the starting glass is subjected to a heat treatment at a temperature of from 750 to 870° C. for a period of 5 to 120 min.
16 . Process for preparing the glass ceramic according to claim 1 , in which a starting glass
comprising the following components
Component
wt.-%
SiO 2
37.0 to 50.0
Al 2 O 3
25.0 to 39.0
MgO
5.0 to 15.0
ZrO 2
13.5 to 19.0.
is subjected to at least one heat treatment at a temperature of from 850 to 1200° C.
17 . Process according to claim 16 , in which
(b) the starting glass is subjected to a heat treatment at a temperature of from 850 to 1000° C. for a period of 20 to 600 min, to form the glass ceramic with a higher amount of high-quartz solid solution phase.
18 . Process according to claim 16 , in which
(c) the starting glass is subjected to a heat treatment at a temperature of from 1000 to 1200° C. for a period of 10 to 240 min, to form the glass ceramic with a higher amount of low-quartz solid solution phase.
19 . Method of using the glass ceramic according to claim 1 comprising forming the class ceramic into a dental material or a dental restoration.
20 . Method of using the glass ceramic according to claim 19 , comprising machining a shape of the desired dental restoration into a bridge, inlay, onlay, veneer, abutment, partial crown, crown or facet.
21 . Method of using the glass ceramic according to claim 19 , wherein the glass ceramic comprises higher amount of high-quartz solid solution phase and is shaped to the dental restoration by machining using a a CAD/CAM process.
22 . Glass ceramic according to claim 2 , which comprises 38.5 to 48.0 wt.-% SiO 2 .
23 . Glass ceramic according to claim 3 , which comprises 27.0 to 37.0 wt.-% Al 2 O 3 .
24 . Glass ceramic according to claim 4 , which comprises 7.0 to 13.5 wt-% MgO.
25 . Glass ceramic according to claim 11 , wherein the zirconium oxide crystal phase comprises tetragonal zirconium oxide crystal phase.
26 . Starting glass according to claim 12 , wherein the starting glass is present in the form of a powder, a blank or a dental restoration.
27 . Process for preparing the starting glass with nuclei according to claim 15 , in which
(a) the starting glass is subjected to a heat treatment at a temperature of from 770 to 850° C. for a period of 5 to 60 min.
28 . Process according to claim 17 , in which
(b) the starting glass is subjected to a heat treatment at a temperature of from 890 to 980° C. for a period of 30 to 180 min, to form the glass ceramic with a higher amount of high-quartz solid solution phase.
29 . Process according to claim 28 , in which
(b) the starting glass is subjected to a heat treatment at a temperature of from 890 to 980° C. for a period of 30 to 90 min, to form the glass ceramic with a higher amount of high-quartz solid solution phase.