Glass-ceramic articles with increased resistance to fracture and methods for making the same
A glass-ceramic article having one or more crystalline phases; a residual glass phase; a compressive stress layer extending from a first surface to a depth of compression (DOC); a maximum central tension greater than 70 MPa; a stored tensile energy greater than 22 J/m 2 ; a fracture toughness greater than 1.0 MPa√m; and a haze less than 0.2.
1 . A method of forming a glass-ceramic article, the method comprising:
heating a glass composition to a nucleation temperature (T N ) to create a nucleated crystallizable glass composition;
heating the nucleated crystallizable glass composition to a crystallization temperature (T c ), wherein the crystallization temperature is in a range from 720° C. to 800° C.; and
maintaining the crystallization temperature for a predetermined period of time (t c ) to produce the glass-ceramic article,
wherein the glass-ceramic article comprises:
a residual glass phase that is less than or equal to 50 wt % of the glass-ceramic article;
a fracture toughness greater than 1.0 MPa√m; and
a haze less than 0.2,
wherein a composition of the glass-ceramic article, based on 100 mol % of the glass-ceramic article, comprises:
greater than or equal to 1.7 mol % ZrO 2 ;
from 65 mol % to 72 mol % SiO 2 ;
from 0 mol % to 6 mol % Al 2 O 3 ;
from 20 mol % to 32 mol % Li 2 O;
from 0 mol % to 2 mol % B 2 O 3 ;
from 0 mol % to 2 mol % Na 2 O; and
from 0 mol % to 2 mol % K 2 O,
wherein the glass-ceramic article comprises a molar ratio Li 2 O (mol %)/R 2 O (mol %) from greater than or equal to 0.85 to less than or equal to 1.00, where R 2 O is a total amount of Li 2 O, Na 2 O, and K 2 O.
2 . The method of claim 1 , further comprising: maintaining the nucleation temperature for a predetermined period of time to produce the nucleated crystallizable glass composition, wherein the period of time for maintaining the nucleation temperature is in a range from 1 minute to 6 hours.
3 . The method of claim 1 , further comprising:
heating the nucleated crystallizable glass composition to an intermediate temperature, wherein the intermediate temperature is greater than the nucleation temperature and less than the crystallization temperature, and maintaining the intermediate temperature for a predetermined period of time; and
heating the nucleated crystallizable glass composition from the intermediate temperature to the crystallization temperature.
4 . The method of claim 3 , wherein a heating rate for heating the nucleated crystallizable glass composition from the nucleation temperature to the intermediate temperature is different than the heating rate for heating the nucleated crystallizable glass composition from the intermediate temperature to the crystallization temperature.
5 . The method of claim 1 , further comprising:
subjecting the glass-ceramic article to an ion-exchange treatment to create a compressive stress layer extending from a first surface of the glass-ceramic article to a depth of compression (DOC), wherein after the ion-exchange treatment the glass-ceramic article has a maximum central tension greater than 70 MPa and a stored tensile energy greater than 22 J/m 2 .
6 . The method of claim 1 , wherein the nucleation temperature is in a range from 550° C. to 650° C., and wherein the heating to the nucleation temperature comprises heating from room temperature to the nucleation temperature at a heating rate in a range from 0.01° C./min to 50° C./min.
7 . The method of claim 1 , and wherein the predetermined period of time for maintaining the crystallization temperature is in a range from 1 minute to 4 hours.
8 . The method of claim 1 , wherein the heating to the crystallization temperature comprises heating from the nucleation temperature to the crystallization temperature at a heating rate in a range from 0.01° C./min to 50° C./min.
9 . The method of claim 1 , further comprising:
in a first cooling stage, cooling the glass-ceramic article from the crystallization temperature to a first temperature at a first cooling rate; and
in a second cooling stage, cooling the glass-ceramic article from the first temperature to a second temperature at a second cooling rate,
wherein the first cooling rate is slower than the second cooling rate.
10 . The method of claim 1 , further comprising:
in a first cooling stage, cooling the glass-ceramic article from the crystallization temperature to a first temperature at a first cooling rate;
in an intermediate cooling stage, cooling the glass-ceramic article from the first temperature to a second temperature at a second cooling rate;
in a second cooling stage, cooling the glass-ceramic article from the second temperature to a third temperature at a third cooling rate,
wherein (i) the first cooling rate is slower than the second cooling rate and the third cooling rate and (ii) the second cooling rate is slower than the third cooling rate.
11 . The method of claim 1 , wherein the glass-ceramic article comprises from greater than or equal to 1.7 mol % to less than or equal to 4.5 mol % ZrO 2 .
12 . The method of claim 1 , wherein the glass-ceramic article comprises greater than or equal to 24 mol % Li 2 O.
13 . The method of claim 1 , wherein the glass-ceramic article comprises from greater than or equal to 24 mol % to less than or equal to 32 mol % Li 2 O.
14 . The method of claim 1 , wherein the molar ratio Li 2 O (mol %)/R 2 O (mol %) is greater than or equal to 0.95.
15 . The method of claim 1 , wherein the molar ratio Li 2 O (mol %)/R 2 O (mol %) is from greater than or equal to 0.95 to less than or equal to 0.99.
16 . The method of claim 1 , wherein the glass-ceramic article comprises from 0.7 mol % to 2.2 mol % P 2 O 5 .
17 . The method of claim 1 , wherein the glass-ceramic article comprises a Young's modulus greater than 95 GPa.
18 . The method of claim 1 , wherein the glass-ceramic article comprises a crystal phase comprising lithium disilicate, petalite, or combinations thereof.