Claims
- 1. A glass-ceramic comprising miserite as a predominant crystal phase, the glass-ceramic having a composition comprising in weight percent: 40-68% SiO.sub.2, 12-35% CaO, 8-20% CaF.sub.2, 4-10.5% K.sub.2 O, 0-5% Al.sub.2 O.sub.3, 0-5% B.sub.2 O.sub.3, 0-15% P.sub.2 O.sub.5, 0-4% R.sub.2 O.sub.3, wherein R represents Y.sup.3+ and rare earth metals in the lanthanide series, and 0-5% of optional constituents selected from the group consisting of MgO, SrO, BaO, Na.sub.2 O, Nb.sub.2 O.sub.5, ZrO.sub.2, and ZnO, and 0-10% of optional constituents selected from the group consisting of Nb.sub.2 O.sub.5 and TiO.sub.2, and 0-2% Li.sub.2 O as an optional constituent.
- 2. The glass-ceramic of claim 1, wherein the composition most preferably comprises in weight percent: 42-65% SiO.sub.2, 12-25% CaO, 12-16% CaF.sub.2, 5-9% K.sub.2 O, 0-2% Al.sub.2 O.sub.3, 0-4% B.sub.2 O.sub.3, 0-8% P.sub.2 O.sub.5, 0-3% R.sub.2 O.sub.3, where R represents Y.sup.3+ and rare earth metals in the lanthanide series.
- 3. The glass-ceramic of claim 1, wherein the glass-ceramic has a modulus of rupture greater than 25,000 psi (175 MPa).
- 4. The glass-ceramic of claim 1, wherein the glass-ceramic has a modulus of rupture as high as 34,000 psi (235 MPa).
- 5. The glass-ceramic of claim 1, wherein the glass-ceramic has a fracture toughness greater than 3.5 MPa.sqroot.m.
- 6. The glass-ceramic of claim 1, wherein the glass-ceramic has a cristobalite secondary crystal phase.
- 7. The glass-ceramic of claim 1, wherein the glass-ceramic has a xonotlite secondary crystal phase.
- 8. The glass-ceramic of claim 1, wherein the glass-ceramic has a fluorite secondary crystal phase.
- 9. The glass-ceramic of claim 1, wherein the glass-ceramic has a fluorapatite secondary crystal phase.
- 10. A glass-ceramic comprising a microstructure of randomly-oriented, interlocked miserite crystals.
- 11. The glass-ceramic of claim 10, wherein the miserite crystals have a length of about 10 microns and a diameter of about 1 micron.
- 12. The glass-ceramic of claim 10, wherein the miserite crystals have a rod-like crystal morphology.
- 13. A glass-ceramic comprising a miserite predominant crystal phase and a fluorapatite secondary crystal phase.
- 14. The glass-ceramic of claim 13, wherein the glass-ceramic is used as a biomaterial.
- 15. A method of producing a glass-ceramic having a predominant crystal phase of miserite, said method comprising:
- a) melting a glass having a composition, as calculated in weight % on an oxide basis, comprising 40-68% SiO.sub.2, 12-35% CaO, 8-20% CaF.sub.2, 4-10.5% K.sub.2 O, 0-5% Al.sub.2 O.sub.3, 0-5% B.sub.2 O.sub.3, 0-15% P.sub.2 O.sub.5, 0-4% R.sub.2 O.sub.3, wherein R represents Y.sup.3+ and rare earth metals in the lanthanide series, and 0-5% of optional constituents selected from the group consisting of MgO, SrO, BaO, Na.sub.2 O, Nb.sub.2 O.sub.5, ZrO.sub.2, and ZnO, and 0-10% of optional constituents selected from the group consisting of Nb.sub.2 O.sub.5 and TiO.sub.2, and 0-2% Li.sub.2 O as an optional constituent;
- b) making a glass frit and shaping a glass article of desired configuration therefrom; and,
- c) exposing the glass article to a thermal treatment to produce a miserite crystal phase.
- 16. A method according to claim 15, wherein the melting step is carried out at a temperature ranging from 1475.degree. C. to 1500.degree. C. for a time ranging from 4 to 6 hours.
- 17. A method according to claim 15, wherein the thermal treatment is at a temperature of about 1000.degree. C. for about 4 hours.
- 18. A glass ceramic according to the process of claim 15.
- 19. A method according to claim 15, wherein the glass article is shaped according to a method selected from the group consisting of extrusion, slip casting, isostatic pressing, tape casting and spray drying.
- 20. A method for producing a glass-ceramic article containing miserite as the predominant crystal phase comprising the steps of:
- a) melting a batch for a glass having a composition comprising in weight percent: 40-68% SiO.sub.2, 12-35% CaO, 8-20% CaF.sub.2, 4-10.5% K.sub.2 O, 0-5% Al.sub.2 O.sub.3, 0-5% B.sub.2 O.sub.3, 0-15% P.sub.2 O.sub.5, 0-4% R.sub.2 O.sub.3, wherein R represents Y.sup.3+ and rare earth metals in the lanthanide series, and 0-5% of optional constituents selected from the group consisting of MgO, SrO, BaO, Na.sub.2 O, Nb.sub.2 O.sub.5, ZrO.sub.2, and ZnO, and 0-10% of optional constituents selected from the group consisting of Nb.sub.2 O.sub.5 and TiO.sub.2 and 0-2% Li.sub.2 O as an optional constituent;
- b) cooling the glass to a temperature at least below the transformation range thereof and simultaneously forming a glass article therefrom of a desired configuration;
- c) exposing the glass article to a temperature between about 800-1000.degree. C. for a period of time sufficient to cause development of miserite crystals as a predominant crystal phase to form a glass-ceramic; and,
- d) cooling the glass-ceramic to room temperature.
- 21. A method according to claim 20 wherein said glass body is initially exposed to a temperature in the range of about 600-800.degree. C. for a period of time sufficient to develop a nucleated glass body, and thereafter the nucleated glass body is exposed to a temperature in the range of about 900-1000.degree. C. for a period of time sufficient to cause the growth of crystals.
- 22. A method according to claim 21 wherein the period of time sufficient to develop the nucleated glass body is about 2 hours.
- 23. A method according to claim 21 wherein the period of time sufficient to grow crystals is about 4 hours.
- 24. A glass-ceramic formed according to the process of claim 20.
Parent Case Info
This application is a provision of Ser. No. 60/082,127 filed Apr. 16, 1998.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 076 692 |
Jun 1986 |
EPX |
Non-Patent Literature Citations (3)
Entry |
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George H. Beall, Chain Silicate Glass-Ceramics, Journal of Non-Crystalline Solids 129 (1991) pp. 163-173. |
S. Likitvanichkul et al., Effect of Fluorine Content on Crystallization of Canasite Glass-Ceramics, Journal of Materials Science 30 (1995) pp. 6151-6155. |