Kanoite glass-ceramics
A compositional range of manganese aluminosilicate glass-ceramics with high durability, and methods for making the same, are described herein. The glass-ceramics can be used in conjunction with electronic devices, such as in protective exteriors for such devices. The glass-ceramics can be characterized as having ring-on-ring strengths of at least 300 MPa and fracture toughnesses of at least 1.5 MPa·m 1/2 .
1. An article comprising:
a glass-ceramic composition comprising:
25-45 mol % MnO,
>0 mol % MgO,
15-25 mol % Al 2 O 3 , and
35-50 mol % SiO 2 , wherein the glass-ceramic composition comprises a plurality of grains having a major silicate phase, the major silicate phase having a kanoite crystal structure and composition (Mn,Mg) 2 Si 2 O 6 .
2. The article of claim 1 , wherein the article comprises the glass-ceramic composition.
3. The article of claim 1 , wherein the article comprises a consumer device, and the glass-ceramic composition is a part of the consumer device.
4. The article of claim 1 , wherein the article comprises a consumer electronic device, and the glass ceramic composition forms a protective exterior over at least a part of the consumer electronic device.
5. The article of claim 1 , wherein the glass-ceramic composition comprises at least 50 to 100% by volume of the plurality of grains having the kanoite crystal structure.
6. The article of claim 1 , wherein each of the plurality of grains has a grain size of up to 50 μm.
7. The article of claim 1 , wherein the glass-ceramic composition further comprises 0.1-15 mol % MgO.
8. The article of claim 1 , wherein the glass-ceramic composition further comprises less than 5 mol % TiO 2 .
9. The article of claim 1 , wherein the glass-ceramic composition further comprises one or more ingredients selected from the group consisting of 0.1-5 mol % Li 2 O, 0.1-6 mol % Na 2 O, and 0.1-6 mol % Y 2 O 3 .
10. The article of claim 1 , wherein the glass-ceramic composition has a ring-on-ring strength of at least 300 MPa.
11. The article of claim 1 , wherein the glass-ceramic composition has a fracture toughness of at least 1.5 MPa·m 1/2 .
12. A method of making a composition, the process comprising:
providing a precursor composition comprising:
25-45 mol % MnO,
>0 mol % MgO,
15-25 mol % Al 2 O 3 , and
35-50 mol % SiO 2 ;
heat treating the precursor by subjecting the precursor to a temperature in the range 700-950° C. to form a glass-ceramic composition wherein the glass-ceramic composition comprises a plurality of grains having a major silicate phase, the major silicate phase having a kanoite crystal structure and composition (Mn,Mg) 2 Si 2 O 6 .
13. The method of claim 12 , wherein the heat treating comprises:
subjecting the precursor, in order, to:
a nucleation temperature in the range 700-775° C. for 0.5 to 6 hours, and
a crystallization temperature in the range 850-950° C. for 0.5 to 6 hours.
14. The method of claim 12 , wherein the heat treatment is carried out in an inert atmosphere.
15. The method of claim 12 , wherein the glass-ceramic composition comprises at least 50% by volume of the plurality of grains with kanoite crystal structure, and wherein each of the plurality of grains has a grain size of up to 50 μm.
16. The method of claim 12 , wherein each of the plurality of grains has a grain size of 0.2 μm to 50 μm.
17. The method of claim 12 , wherein the glass-ceramic composition further comprises less than 5 mol % TiO 2 .
18. The method of claim 12 , wherein the glass-ceramic composition further comprises one or more ingredients selected from the group consisting of 0.1-5 mol % Li 2 O, 0.1-6 mol % Na 2 O, and 0.1-6 mol % Y 2 O 3 .
19. The method of claim 12 , wherein the glass-ceramic composition has a ring-on-ring strength of at least 300 MPa.
20. The method of claim 12 , wherein the glass-ceramic composition has a fracture toughness of at least 1.5 MPa·m 1/2 .
21. A glass-ceramic composition comprising:
25-45 mol % MnO,
>0 mol % MgO,
15-25 mol % Al 2 O 3 , and
35-50 mol % SiO 2 , wherein the glass-ceramic composition comprises a plurality of grains having a major silicate phase, the major silicate phase having a kanoite crystal structure and composition (Mn,Mg) 2 Si 2 O 6 .
22. The composition of claim 21 , wherein the glass-ceramic composition comprises at least 50 to 100% by volume of the plurality of grains having the kanoite crystal structure.
23. The composition of claim 22 , wherein each of the plurality of grains has a grain size of up to 50 μm.
24. The composition of claim 21 , wherein the glass-ceramic composition further comprises 0.1-15 mol % MgO.
25. The composition of claim 21 , wherein the glass-ceramic composition further comprises less than 5 mol % TiO 2 .
26. The composition of claim 21 , wherein the glass-ceramic composition further comprises one or more ingredients selected from the group consisting of 0.1-5 mol % Li 2 O, 0.1-6 mol % Na 2 O, and 0.1-6 mol % Y 2 O 3 .
27. The composition of claim 21 , wherein the glass-ceramic composition has a ring-on-ring strength of at least 300 MPa.
28. The composition of claim 21 , wherein the glass-ceramic composition has a fracture toughness of at least 1.5 MPa·m 1/2 .