High strength glass-ceramics having petalite and lithium silicate structures
In embodiments, a precursor glass composition comprises from about 55 wt. % to about 80 wt. % SiO 2 ; from about 2 wt. % to about 20 wt. % Al 2 O 3 ; from about 5 wt. % to about 20 wt. % Li 2 O; greater than 0 wt % to about 3 wt. % Na 2 O; a non-zero amount of P 2 O 5 less than or equal to 4 wt. %; and from about 0.2 wt. % to about 15 wt. % ZrO 2 . In embodiments, ZrO 2 (wt. %)+P 2 O 5 (wt. %) is greater than 3. When the precursor glass composition is converted to a glass-ceramic article, the glass-ceramic article may include grains having a longest dimension of less than 100 nm.
1. An electronic device covering, comprising:
a microstructure of randomly-oriented interlocked crystals;
20 to 60 wt % lithium silicate crystalline phase;
20 to 70 wt % petalite crystalline phase;
a fracture toughness of 1 MPa·m 1/2 or greater;
a ring-on-ring strength of at least 300 MPa.
2. The covering of claim 1 , wherein crystals of the lithium silicate crystalline phase are orthorhombic.
3. The covering of claim 1 , wherein crystals of the lithium silicate crystalline phase comprise a tabular shape.
4. The covering of claim 1 , wherein crystals of the lithium silicate crystalline phase comprise a lath-like shape.
5. The covering of claim 1 , wherein the lithium silicate crystalline phase is a lithium disilicate crystalline phase.
6. The covering of claim 1 , wherein the lithium silicate crystalline phase is a lithium metasilicate crystalline phase.
7. The covering of claim 1 , wherein the petalite crystalline phase comprises fine-grained crystals having a longest dimension of 100 nm or less.
8. The covering of claim 1 , wherein crystals of the petalite crystalline phase are monoclinic.
9. The covering of claim 1 , wherein crystals of the petalite crystalline phase comprise a three-dimensional layered framework.
10. The covering of claim 1 , further comprising a thickness from 200 micrometers to 2 mm.
11. The covering of claim 1 , further comprising, in wt %:
Na 2 O: 0-5%;
K 2 O: 0-4%;
B 2 O 3 : 0-10%;
P 2 O 5 : 0.5-6%; and
ZrO 2 : 0.2-15%.
12. The covering of claim 11 , wherein: Na 2 O from 0-2%; K 2 O from 0-2%; P 2 O 5 from 1.5-2.5%; and ZrO 2 from 2-4%.
13. The covering of claim 11 , wherein the sum of the weight percentage of P 2 O 5 and ZrO 2 is greater than or equal to 4 wt %.
14. The covering of claim 11 , further comprising:
Li 2 O in an amount of 5-20 wt %;
SiO 2 in an amount of 55-80 wt %;
Al 2 O 3 in an amount of 2-20 wt %.
15. The covering of claim 14 , further comprising, Li 2 O in an amount of 5-14 wt %; SiO 2 in an amount of 69-80 wt %; Al 2 O 3 in an amount of 2-9 wt %.
16. The covering of claim 1 , further comprising a Vickers hardness of about 600 kgf/mm 2 or greater.
17. The covering of claim 1 , further comprising a transmittance of at least 85% for light in a wavelength range from 400 nm to 1,000 nm at a thickness of 1 mm.
18. The covering of claim 1 , further comprising 5 to 10 wt % residual glass.
19. The covering of claim 1 , wherein crystals of the petalite crystalline phase are of 50 to 100 nm grain size.
20. An electronic device comprising the covering of claim 1 .