White, opaque β-spodumene/rutile glass-ceramic articles and methods for making the same
Crystallizable glasses, glass-ceramics, IXable glass-ceramics, and IX glass-ceramics are disclosed. The glass-ceramics exhibit β-spodumene ss as the predominant crystalline phase. These glasses and glass-ceramics, in mole %, include: 62-75 Si O 2 ; 10.5-17 Al 2 O 3 ; 5-13 Li 2 O; 0-4 ZnO; 0-8 MgO; 2-5 TiO 2 ; 0-4 B 2 O 3 ; 0-5 Na 2 O; 0-4 K 2 O; 0-2 ZrO 2 ; 0-7 P 2 O 5 ; 0-0.3 Fe 2 O 3 ; 0-2 MnOx; and 0.05-0.2 SnO 2 . Additionally, these glasses and glass-ceramics exhibit the following criteria: a. a ratio: [ Li 2 O + Na 2 O + K 2 O + MgO + ZnO ] [ Al 2 O 3 + B 2 O 3 ] between 0.7 to 1.5; b. a ratio: [ TiO 2 + SnO 2 ] [ SiO 2 + B 2 O 3 ] greater than 0.04. Furthermore, the glass-ceramics exhibit an opacity ≧about 85% over the wavelength range of 400-700 nm for an about 0.8 mm thickness and colors an observer angle of 10° and a CIE illuminant F02 determined with specular reflectance included of a* between −3 and +3, b* between −6 and +6, and L* between 88 and 97.
1. An IX, β-spodumene glass-ceramic comprising:
a. a nominal composition, in mole percent (mole %), comprises:
i. 67-74 SiO 2 ;
ii. 11-15 Al 2 O 3 ;
iii. 5.5-9 Li 2 O;
iv. 0.5-2 ZnO;
v. 2-4.5 MgO;
vi. 3-4.5 TiO 2 ;
vii. 0-2.2 B 2 O 3 ;
viii. 0-1 Na 2 O;
ix. 0-1K 2 O;
x. 0-1 ZrO 2 ;
xi. 0-4% P2O5
xii. 0-0.1 Fe 2 O 3 ;
xiii. 0-1.5 MnOx; and
xiv. 0.08-0.16 SnO 2 ;
b. a ratio:
[
Li
2
O
+
Na
2
O
+
K
2
O
+
MgO
+
ZnO
]
[
Al
2
O
3
+
B
2
O
3
]
between 0.7 to 1.5;
c. a ratio:
[
TiO
2
+
SnO
2
]
[
SiO
2
+
B
2
O
3
]
greater than about 0.04;
d. one or more β-spodumene solid solutions comprising:
i. at least about 70 wt % of the crystalline phases of the glass-ceramic and
ii. one or more Li 2 O:Al 2 O 3 :SiO 2 ratios between about 1:1:4.5-1:1:8;
e. at least one Ti-containing crystalline phase comprising:
i. about 2.5-8 wt % of the crystalline phases of the glass-ceramic,
ii. an acicular morphology exhibiting a length≧about 50 nm, and
iii. rutile;
f. an opacity comprising ≧about 85% over the wavelength range of 400-700 nm for an about 0.8 mm thickness;
g. a depth of layer (DOL)≧about 2% of an overall thickness of an article of the IX, β-spodumene glass-ceramic and a compressive stress (σ s ) in at least a portion of a surface of the article of at least about 300 MPa; and
h. optionally, one or more crystalline phase comprising:
i. up to about 10 wt % of the crystalline phases of the glass-ceramic and
ii. a spinel structure.
2. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the ratio:
[
Li
2
O
+
Na
2
O
+
K
2
O
+
MgO
+
ZnO
]
[
Al
2
O
3
+
B
2
O
3
]
comprises between about 0.75-1.05 or between about 0.85-1.
3. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the at least one Ti-containing crystalline phase further comprises any one of anatase, a magnesium titanate, and an aluminum titanate; or further comprising mixtures of rutile and two or more of anatase, a magnesium titanate, and an aluminum titanate.
4. The IX, β-spodumene glass-ceramic according to claim 1 , further comprising cordierite or mixtures of rutile, cordierite, and one or more of anatase, a magnesium titanate, and an aluminum titanate.
5. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the at least one Ti-containing crystalline phase comprises rutile comprising about 2-6 wt % of the crystalline phases of the glass-ceramic.
6. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the one or more β-spodumene solid solutions comprise at least about 75 wt % of the crystalline phases of the glass-ceramic.
7. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the optional one or more crystalline phase comprises:
i. about 1-10 wt % of the crystalline phases of the glass-ceramic and
ii. a Zn-containing spinel structure.
8. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the IX, β-spodumene glass-ceramic exhibits one or more of:
a. a fracture toughness of greater than about 0.8 MPa·m 1/2 ; or
b. MOR of greater than 40,000 psi; or
c. a dielectric constant determined over a frequency between about 15 MHz-3.0 GHz at about 25° C. of less than about 10; or
d. a loss tangent determined over a frequency between about 15 MHz-3.0 GHz at about 25° C. of less of less than 0.02; or
e. a depth of layer (DOL)≧about 40 μm in at least a portion of a surface of an article of the IX, β-spodumene glass-ceramic having a 2 mm overall thickness; or
f. a compressive stress (σ s ) of at least about 500 MPa in at least a portion of a surface of an article of the IX, β-spodumene glass-ceramic having a 2 mm overall thickness; or
g. any combination of two or more of the preceding.
9. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the glass-ceramic comprises at least a portion of at least one of an electronic devices or a portable computing device.
10. The IX, β-spodumene glass-ceramic according to claim 1 , wherein the glass-ceramic comprises a color presented in CIELAB color space coordinates for an observer angle of 10° and a CIE illuminant F02 determined from reflectance spectra measurements using a spectrophotometer with specular reflectance included comprising:
h. CIE a* between −3 and +3;
i. CIE b* between −6 and +6; and
j. CIE L* between 88 and 97.
11. A process for making a glass-ceramic having β-spodumene as the predominant crystalline phase, the process comprising:
a. heating a crystallizable glass at a rate of about 1-10° C./min to a nucleation temperature (Tn) between about 700° C.-810° C.;
b. maintaining the crystallizable glass at the nucleation temperature (Tn) for between about 15-120 minutes to produce a nucleated crystallizable glass;
c. heating the nucleated crystallizable glass at a rate of about 1° C.-10° C./min to a crystallization temperature (Tc) between about 850° C.-1250° C.;
d. maintaining the nucleated crystallizable glass at the crystallization temperature (Tc) for between about 15-240 minutes to produce a glass-ceramic having one or more β-spodumene solid solutions as the predominant crystalline phase; and
e. cooling the glass-ceramic to about room temperature,
i. wherein, in mole percent (mole %), the crystallizable glass comprises:
(1.) 62-75 SiO 2 ;
(2.) 10.5-17 Al 2 O 3 ;
(3.) 5-13 Li 2 O;
(4.) 0-4 ZnO;
(5.) 0-8 MgO;
(6.) 2-5 TiO 2 ;
(7.) 0-4 B 2 O 3 ;
(8.) 0-5 Na 2 O;
(9.) 0-4 K 2 O;
(10.) 0-2 ZrO 2 ;
(11.) 0-7 P 2 O 5
(12.) 0-0.3 Fe 2 O 3 ;
(13.) 0-2 MnOx; and
(14.) 0.05-0.20 SnO 2 ;
(15.) a ratio:
[
Li
2
O
+
Na
2
O
+
K
2
O
+
MgO
+
ZnO
]
[
Al
2
O
3
+
B
2
O
3
]
comprises between 0.7 to 1.5;
(16.) a ratio:
[
TiO
2
+
SnO
2
]
[
SiO
2
+
B
2
O
3
]
comprises greater than 0.04; and
ii. wherein the glass-ceramic comprising:
(1.) β-spodumene solid solutions comprising:
(a.) at least about 70 wt % of the crystalline phases of the glass-ceramic and
(b.) a Li 2 O:Al 2 O 3 :SiO 2 ratio between about 1:1:4.5-1:1:8;
(2.) a Ti-containing crystalline phase comprising about 2.5-8 wt % the crystalline phases of the glass-ceramic and rutile;
(3.) an opacity comprising≧about 85% over the wavelength range of 400-700 nm for an about 0 8 mm thickness; and
(4.) optionally, one or more crystalline phase comprising:
(a.) about 1-10 wt % of the crystalline phases of the glass-ceramic and
(b.) a spinel structure.
12. The process according to claim 11 , wherein, in mole percent (mole %), the crystallizable glass comprises:
i. 67-74 SiO 2 ;
ii. 11-15 Al 2 O 3 ;
iii. 5.5-9 Li 2 O;
iv. 0.5-2 ZnO;
v. 2-4.5 MgO;
vi. 3-4.5 TiO 2 ;
vii. 0-2.2 B 2 O 3 ;
viii. 0-1 Na 2 O;
ix. 0-1K 2 O;
x. 0-1 ZrO 2 ;
xi. 0-4 P 2 O 5
xii. 0-0.1Fe 2 O 3 ;
xiii. 0-1.5 MnOx; and
xiv. 0.08-0.16 SnO 2 .