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WO1987007256A1 - Glass ceramics - Google Patents

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Publication number
WO1987007256A1
WO1987007256A1 PCT/GB1987/000352 GB8700352W WO8707256A1 WO 1987007256 A1 WO1987007256 A1 WO 1987007256A1 GB 8700352 W GB8700352 W GB 8700352W WO 8707256 A1 WO8707256 A1 WO 8707256A1
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WO
WIPO (PCT)
Prior art keywords
glass
glass ceramic
minutes
hour
mole
Prior art date
Application number
PCT/GB1987/000352
Other languages
French (fr)
Inventor
Peter Finlay James
Original Assignee
The University Of Sheffield
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The University Of Sheffield filed Critical The University Of Sheffield
Publication of WO1987007256A1 publication Critical patent/WO1987007256A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0036—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and a divalent metal oxide as main constituents
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0054—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing PbO, SnO2, B2O3

Definitions

  • This invention relates to glass ceramics and has for
  • Y 4 one object the production of a machineable glass ceramic that also has other good characteristics, such as hardness, chemical durability and biocompatibility.
  • a glass ceramic is formed from a batch mix having the composition range (in mole %) :-
  • the AI2O3 promotes internal crystal nucleation by leading to precipitation of AlP0 4 crystals during heat treatment (to be described presently). Too little AI2O3 and the glass will not crystallise internally, i.e. will not form a glass ceramic; too much AI2O3 and the glass formation, i.e. melting, is mo e difficult.
  • the AlP0 4 crystals act as heterogeneous crystal nucleation sites for the major crystal phase, which is in the form of needle-like crystals and has yet to be identified.
  • the Si ( _>2 (and/or B2O3) and Ti ⁇ 2 (and/or Zr0 ) appear to be essential to promote ease of glass formation and internal nucleation. They may have a role similar to the "mixed nucleating agents" used in some silicate based glass ceramics. There may be a complex interaction between Si0 2 , Ti ⁇ 2 and AI2O3 to promote nucleation of AIPO4. followed by the major crystal phase. For glass ceramics with particularly good machineability the batch mix has the composition range (in mole %):-
  • Na 2 O, K 2 0, Li 2 0, MgO, BaO and ZnO to aid melting of the glass, possibly by reducing the liquidus temperature and modifying viscosity of the melt, and/or modify the final properties of the glass ceramic.
  • the batch After the batch has been well mixed it is usually sintered at a temperature between 1100°C and 1250°C for approximately 20 minutes. It is then melted at suitable temperatures, depending on the exact composition of the glass, ranging from 1250°C to 1550°C, and conversion of the glass into a glass ceramic is effected by a 'nucleation' heat treatment at an appropriate temperature within the range from 550°C to 760°C for a period of up to 6 hours (but usually not greater than 2.5 hours), with a further 'growth' or 'crystallisation' heat treatment at an appropriate temperature within the range from 760°C to 950°C for a period of up to 3 hours (but usually not greater than 30 minutes).
  • the batch chemicals used in the preparation were SLR grade Calcium tetrahydrogen i- or tho phosphate CaH4(PO_i) 2 ,H2 0 ' ⁇ i0 2.
  • the batch was sintered at 1200°C for 30 minutes in an alumina or platinum rhodium crucible, then melting was carried out at 1450°C in an electric furnace for 1 hour.
  • the glass melt was cast into a block which was crushed and remelted at 1450°C for 1 hour.
  • Finally the glass was cast in a preheated steel mould and transferred to an annealing furnace at 600°C, held for 1 hour and allowed to cool to room temperature.
  • the remelting technique ensured that the glass block (approximately 4 cm x 4 cm x 10 cm in dimensions) was homogeneous, clear and bubble free.
  • the melting time could be reduced to approximately 30 minutes, or less.
  • the glass block was converted into a glass ceramic by a simple two stage heat treatment schedule.
  • This heating schedule converted the slightly purple glass (this colouration was probably caused by the presence of the Ti ⁇ 2) to a poly crystalline glass ceramic, which was white and opaque in appearance.
  • This glass ceramic is some properties of this glass ceramic:
  • Vicker's hardness 492 (kg/mm 2 )
  • Breaking strength (modulus of rupture determined by beam bending): 89 (MNm ⁇ 2)
  • Machinability good, (with a conventional drilling machine a thickness of 1 mm can be drilled through within 2- 3 seconds)
  • the batch materials were the same as specified in Example A.
  • the batch was sintered at 1200°C for 30 minutes, then the glass was melted at 1420°C for 1 hour. It was then cast, crushed and remelted at 1420°C for 1 hour, before final casting into a steel mould.
  • the glass ceramic could be expected to resist resorption or exhibit only very slow resorption, but a controlled micro ⁇ tructure of pores could be introduced into the glass during melting using gas bubbles, so that a highly porous glass ceramic could then be produced by the heat treatment to provide a resorbable bioceramic.
  • Technological and engineering applications may be found in electrical engineering and electronics, e.g. as glass ceramic to metal seals in a range of devices, in insulating, in preformed circuitry for electronics, and as substrates for microelectronics.
  • the machineability and capability of being highly polished suggest possible uses in the arts and crafts industries, e.g., worked into intricate shapes or engraved as in the production of cameos in the lapidary field.
  • the polished material is similar in appearance to ivory and thus could be used to produce ornamental pieces, decorative tiles, or even piano keys.
  • the material could also be coloured by incorporating small quantities of metal ions in the composition.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Compositions (AREA)

Abstract

A machineable glass ceramic that also has other good characteristics, such as hardness, chemical durability and biocompatibility, is formed from a batch mix having the composition range (in mole %): Al2O3: 1.5 to 15.0; CaO: 22.0 to 55.0; P2O5: 28.0 to 65.0; SiO2 (and/or B2O3): up to 15.0; TiO2 (and/or ZrO2): up to 10.0. Up to 15 mole % may be added of any one or more of Na2O, K2O, Li2O, MgO, BaO and ZnO, to aid melting of the glass. Specific manufacturing stages and two specific batch mixes are given, and a wide range of uses is suggested.

Description

___ϊ CERAMICS
This invention relates to glass ceramics and has for
Y 4 one object the production of a machineable glass ceramic that also has other good characteristics, such as hardness, chemical durability and biocompatibility.
According to the present invention, a glass ceramic is formed from a batch mix having the composition range (in mole %) :-
A1203 1.5 to 15.0
CaO 22.0 to 55.0
Figure imgf000003_0001
Siθ2 (and/or B2O3) up to 15.0
Ti02 (and/or Z1.O2) up to 10.0
The AI2O3 promotes internal crystal nucleation by leading to precipitation of AlP04 crystals during heat treatment (to be described presently). Too little AI2O3 and the glass will not crystallise internally, i.e. will not form a glass ceramic; too much AI2O3 and the glass formation, i.e. melting, is mo e difficult. The AlP04 crystals act as heterogeneous crystal nucleation sites for the major crystal phase, which is in the form of needle-like crystals and has yet to be identified.
^ The Si(_>2 (and/or B2O3) and Tiθ2 (and/or Zr0 ) appear to be essential to promote ease of glass formation and internal nucleation. They may have a role similar to the "mixed nucleating agents" used in some silicate based glass ceramics. There may be a complex interaction between Si02, Tiθ2 and AI2O3 to promote nucleation of AIPO4. followed by the major crystal phase. For glass ceramics with particularly good machineability the batch mix has the composition range (in mole %):-
Figure imgf000004_0001
CaO 36.0 to 50.0
P205 33.0 to 45.0
Siθ2 1*5 t0 10'0
Ti02 1.5 to 9.0
Up to a total of 15 mole % may be added of any one or more of the following additives:-
Na2O, K20, Li20, MgO, BaO and ZnO, to aid melting of the glass, possibly by reducing the liquidus temperature and modifying viscosity of the melt, and/or modify the final properties of the glass ceramic.
After the batch has been well mixed it is usually sintered at a temperature between 1100°C and 1250°C for approximately 20 minutes. It is then melted at suitable temperatures, depending on the exact composition of the glass, ranging from 1250°C to 1550°C, and conversion of the glass into a glass ceramic is effected by a 'nucleation' heat treatment at an appropriate temperature within the range from 550°C to 760°C for a period of up to 6 hours (but usually not greater than 2.5 hours), with a further 'growth' or 'crystallisation' heat treatment at an appropriate temperature within the range from 760°C to 950°C for a period of up to 3 hours (but usually not greater than 30 minutes).
Specific examples are as follows:- Example & Al θ37.4%, CaO 40.2%, P2Os 39.1%, Si0 7.8% and Ti02 5.5% (in mole %)
The batch chemicals used in the preparation were SLR grade Calcium tetrahydrogen i- or tho phosphate CaH4(PO_i)2,H20' τi02. CaCc-3, Al(0H)3 and high purity silica quartz sand.
The batch was sintered at 1200°C for 30 minutes in an alumina or platinum rhodium crucible, then melting was carried out at 1450°C in an electric furnace for 1 hour. The glass melt was cast into a block which was crushed and remelted at 1450°C for 1 hour. Finally the glass was cast in a preheated steel mould and transferred to an annealing furnace at 600°C, held for 1 hour and allowed to cool to room temperature. The remelting technique ensured that the glass block (approximately 4 cm x 4 cm x 10 cm in dimensions) was homogeneous, clear and bubble free.
If the glass was stirred by a platinum stirrer during the final melting, the melting time could be reduced to approximately 30 minutes, or less.
Next the glass block was converted into a glass ceramic by a simple two stage heat treatment schedule. First the glass was held at a nucleation temperature of 700°C for 1 hour. The temperature was then raised at 10°C/min. (although the heating rate was not critical) to the crystal growth (crystallisation) temperature, in this case 850°C, and held for 12 minutes, before cooling finally to room temperature. This heating schedule converted the slightly purple glass (this colouration was probably caused by the presence of the Tiθ2) to a poly crystalline glass ceramic, which was white and opaque in appearance. The following are some properties of this glass ceramic:
Degree of crystallinity: 75% by volume.
Density: 2.65 grams per cm3.
Vicker's hardness: 492 (kg/mm2)
Breaking strength (modulus of rupture determined by beam bending): 89 (MNm~2)
Machinability: good, (with a conventional drilling machine a thickness of 1 mm can be drilled through within 2- 3 seconds)
Thermal expansion: (Temperature range)
12.6 x 10-6/<_legree (20°C -185°C)
9.2 x 10-6/degree (185°C - 650°C)
Example j5
Al2°3 7.0%, CaO 41.0%, P2O5 41.0%, Siθ2 4.5%, Tiθ2 4.5% and Na202.0%. (in mole %)
The batch materials were the same as specified in Example A. The batch was sintered at 1200°C for 30 minutes, then the glass was melted at 1420°C for 1 hour. It was then cast, crushed and remelted at 1420°C for 1 hour, before final casting into a steel mould.
The other details of the melting and final heat treatment were similar to those given in Example A.
A heat treatment at 680°C for 40 minutes and 760°C for 20 minutes converted the glass into a white glass-ceramic.
The machinability and other properties of this glass ceramic were similar to those given for Example A.
Some tissue culture experiments have been performed and these indicate that glass ceramics produced in accordance with the invention are biocompatible, which is perhaps not surprising in view of the high calcium and phosphate contents.
Accordingly, possible applications and areas of potention exploitation are in dentistry, e.g., as an implant material for augmentaton of the alveolar ridge and for the preparation of ceramic crowns, in orthopaedics for bone replacemenmt or repair with prosthetic devices and other implants, and as coatings for orthopaedic appliances.
In the dense solid form the glass ceramic could be expected to resist resorption or exhibit only very slow resorption, but a controlled microεtructure of pores could be introduced into the glass during melting using gas bubbles, so that a highly porous glass ceramic could then be produced by the heat treatment to provide a resorbable bioceramic.
Technological and engineering applications may be found in electrical engineering and electronics, e.g. as glass ceramic to metal seals in a range of devices, in insulating, in preformed circuitry for electronics, and as substrates for microelectronics.
The machineability and capability of being highly polished suggest possible uses in the arts and crafts industries, e.g., worked into intricate shapes or engraved as in the production of cameos in the lapidary field. The polished material is similar in appearance to ivory and thus could be used to produce ornamental pieces, decorative tiles, or even piano keys. The material could also be coloured by incorporating small quantities of metal ions in the composition.

Claims

1. A glass ceramic formed from a batch mix having the composition range (in mole %):-
A1203 1.5 to 15.0
CaO 22.0 to 55.0 p 2θ5 28.0 to 65.0
Siθ2 (and/or B2O3) up to 15.0
Ti02 (and/or Zrθ2) up to 10.0
2. A glass ceramic formed from a batch mix having the composition range (in mole %):-
AI2O3 4.5 to 9.5
CaO 36.0 to 50.0
P2θ5 33.0 to 45.0
Si02 1.5 to 10.0
Ti0 1.5 to 9.0
3. A glass ceramic as in Claim 1 or Claim 2, wherein up to a total of 15 mole % is added of any one or more of Na o, K20, Li 0, MgO, BaO and ZnO, to aid melting of the glass.
4. A glass ceramic as in any one of Claims 1 to 3 , wherein the batch after mixing is sintered at a temperature between lløøoc and 1250°C for approximately 20 minutes, then melted at a temperature ranging from 1250°C to 1550°C, and conversion of the glass into a glass ceramic is effected by a 'nucleation' heat treatment at an appropriate temperature within the range from 550°C to 760°C for a period of up to 6 hours with a further 'growth' or 'crystallisation' heat treatment at an appropriate temperature within the range from 760°C to 950°C for a period of up to 3 hours.
5. A glass ceramic as in Claim 4, wherein the period of 'nucleation' heat treatment is not greater than 2.5 hours and the period of 'growth' or 'crystallisation' heat treatment is not greater than 30 minutes.
6. A glass ceramic formed from a batch mix having the composition (in mole %)
Al2θ3 7.4%, CaO 40.2%, P2O539.1%, Siθ27.8% and Tiθ2 5.5%.
7. A glass ceramic as in Claim 6, wherein the batch after mixing is sintered at 1200°C for 30 minutes in an alumina or platinum rhodium crucible then melting is carried out at 1450°C in an electric furnace for 1 hour, the glass melt is cast into a block which is crushed and remelted at 1450°C for 1 hour, the glass is cast in a preheated steel mould and transferred to an annealing furnace at 600°C, held for 1 hour and allowed to cool to room temperature, and the glass block thus formed is converted into a glass ceramic by a two stage heat treatment schedule, in the first stage of which the glass is held at a nucleation temperature of 700°C for 1 hour, while in the second stage it is raised at 10°C/min. to 850°C and held for 12 minutes, before cooling finally to room temperature.
8. A glass ceramic formed from a batch mix having the composition (in mole %)
AI2O3 7.0%, CaO 41.0%, P2O5 41.0%, Siθ2 4.5%, Tiθ2 4.5% and Na 02.0%.
9. A glass ceramic as in Claim 8, wherein the batch after mixing is sintered at 1200°C for 30 minutes, then the - -
glass is melted at 1420°C for 1 hour, the glass melt is cast, crushed and remelted at 1420°C for 1 hour, before final casting into a steel mould, and the glass block thus formed is
heat treated at 680°C for 40 minutes and 760°C for 20 minutes, before cooling finally to room temperature.
PCT/GB1987/000352 1986-05-21 1987-05-21 Glass ceramics WO1987007256A1 (en)

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GB8612387 1986-05-21

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002102431A1 (en) * 2001-06-15 2002-12-27 Humboldt Universität Berlin Charite Universitätsklinikum (Ccm) Surface treated metallic implant and blasting material
WO2017067909A1 (en) 2015-10-19 2017-04-27 Vita Zahnfabrik H. Rauter Gmbh & Co. Kg Process for producing a workpiece with low translucency
CN109195927A (en) * 2016-05-27 2019-01-11 康宁股份有限公司 Bioactivity boron phosphate glass
US11236012B2 (en) 2018-03-28 2022-02-01 Corning Incorporated Boron phosphate glass-ceramics with low dielectric loss
US11274059B2 (en) 2017-11-28 2022-03-15 Corning Incorporated Bioactive glass compositions and dentin hypersensitivity remediation
US11384009B2 (en) 2017-11-28 2022-07-12 Corning Incorporated High liquidus viscosity bioactive glass
US11446410B2 (en) 2017-11-28 2022-09-20 Corning Incorporated Chemically strengthened bioactive glass-ceramics
US11814649B2 (en) 2016-05-27 2023-11-14 Corning Incorporated Lithium disilicate glass-ceramic compositions and methods thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4907850B2 (en) * 2003-06-11 2012-04-04 日本特殊陶業株式会社 Low-temperature fired dielectric ceramic composition and manufacturing method thereof
CN100406069C (en) * 2005-09-28 2008-07-30 中国科学院金属研究所 CaO-P2O5-NaO-TiO-Zro-biological glass ceramic and its production

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3241935A (en) * 1963-07-29 1966-03-22 Corning Glass Works Bone china and method of making it
US4202700A (en) * 1979-05-02 1980-05-13 The United States Of America As Represented By The United States Department Of Energy Glassy composition for hermetic seals
DE3500287A1 (en) * 1984-01-24 1985-08-01 VEB JENAer GLASWERK, DDR 6900 Jena PHOSPHATE GLASS CERAMICS
EP0175265A2 (en) * 1984-09-14 1986-03-26 Asahi Glass Company Ltd. Calcium phosphate type crystallizable glass

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3241935A (en) * 1963-07-29 1966-03-22 Corning Glass Works Bone china and method of making it
US4202700A (en) * 1979-05-02 1980-05-13 The United States Of America As Represented By The United States Department Of Energy Glassy composition for hermetic seals
DE3500287A1 (en) * 1984-01-24 1985-08-01 VEB JENAer GLASWERK, DDR 6900 Jena PHOSPHATE GLASS CERAMICS
EP0175265A2 (en) * 1984-09-14 1986-03-26 Asahi Glass Company Ltd. Calcium phosphate type crystallizable glass

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002102431A1 (en) * 2001-06-15 2002-12-27 Humboldt Universität Berlin Charite Universitätsklinikum (Ccm) Surface treated metallic implant and blasting material
WO2017067909A1 (en) 2015-10-19 2017-04-27 Vita Zahnfabrik H. Rauter Gmbh & Co. Kg Process for producing a workpiece with low translucency
AU2016342140B2 (en) * 2015-10-19 2020-09-10 Vita Zahnfabrik H. Rauter Gmbh & Co. Kg Process for producing a workpiece with low translucency
US11384002B2 (en) 2015-10-19 2022-07-12 Vita Zahnfabrik H. Rauter Gmbh & Co. Kg Process for producing a workpiece with low translucency
CN109195927A (en) * 2016-05-27 2019-01-11 康宁股份有限公司 Bioactivity boron phosphate glass
US11814649B2 (en) 2016-05-27 2023-11-14 Corning Incorporated Lithium disilicate glass-ceramic compositions and methods thereof
US11274059B2 (en) 2017-11-28 2022-03-15 Corning Incorporated Bioactive glass compositions and dentin hypersensitivity remediation
US11384009B2 (en) 2017-11-28 2022-07-12 Corning Incorporated High liquidus viscosity bioactive glass
US11446410B2 (en) 2017-11-28 2022-09-20 Corning Incorporated Chemically strengthened bioactive glass-ceramics
US11999653B2 (en) 2017-11-28 2024-06-04 Corning Incorporated High liquidus viscosity bioactive glass
US11236012B2 (en) 2018-03-28 2022-02-01 Corning Incorporated Boron phosphate glass-ceramics with low dielectric loss

Also Published As

Publication number Publication date
GB8800756D0 (en) 1988-02-17
GB2199028B (en) 1990-05-09
GB2199028A (en) 1988-06-29
GB8612387D0 (en) 1986-07-16

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