EP0172382A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Mullite-Beta Spodumene Composite Ceramic
Assignee: General Electric Co
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Filing: 1985-07-10
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Granted: —
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Expires: 2005-07-10
Abstract
Abstract Method for producing a polycrystalline body comprised of from about 50% by weight to about 95% by weight of crystalline mullite and from about 5% by weight to about 50% by weight of crystalline beta spodumene, said body having a density greater than 85% of its theoretical density.
Inventors
- 👤 James David Hodge
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 16:31
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/18; C04B35/19
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
230 words
A process for producing a polycrystalline body comprised of from about 50% by weight to about 95% by weight of crystalline mullite phase and from about 5% by weight to about 50% by weight of crystalline beta spodumene phase which comprises providing a mixture comprised of mullite and/or beta spodumene and/or A1 2 0 3 and/or Si0 2 and/or a precursor for Li 2 O, said mixture having a composition required to produce said polycrystalline body, shaping said mixture into a compact, sintering said compact at a temperature ranging from greater than 1423°C to about 1500°C at which sufficient liquid phase is generated to liquid phase sinter the compact and produce a densified body having a density greater than about 85% of the theoretical density of said body, said sintering temperature having no significant deleterious effect on said compact or body, said sintered body containing said mullite phase and a glassy phase of beta spodumene, nucleation-annealing said sintered body at a temperature ranging from about 600°C to about 800°C to nucleate said glassy beta spodumene phase, crystallization-annealing the resulting nucleated body at a temperature ranging from about 1200°C to below the temperature at which liquid forms in said body to produce said polycrystalline body, said sintering, said nucleation-annealing and said crystallization-annealing being carried out in an atmosphere or vacuum which has no significant deleterious effect on said compact or body.
Claim 2
Dependent Claim
230 words
A process for producing a polycrystalline body comprised of from about 50% by weight to about 95% by weight of crystalline mullite phase and from about 5% by weight to about 50% by weight of crystalline beta spodumene phase which comprises providing a mixture comprised of mullite and/or beta spodumene and/or A1 2 0 3 and/or Si0 2 and/or a precursor for Li 2 O, said mixture having a composition required to produce said polycrystalline body, shaping said mixture into a compact, sintering said compact at a temperature ranging from greater than 1423°C to about 1500°C at which sufficient liquid phase is generated to liquid phase sinter the compact and produce a densified body having a density greater than about 85% of the theoretical density of said body, said sintering temperature having no significant deleterious effect on said compact or body, said sintered body containing said mullite phase and a glassy phase of beta spodumene, nucleation-annealing said sintered body at a temperature ranging from about 600°C to about 800°C to nucleate said glassy beta spodumene phase, crystallization-annealing the resulting nucleated body at a temperature ranging from about 1200°C to below the temperature at which liquid forms in said body to produce said polycrystalline body, said sintering, said nucleation-annealing and said crystallization-annealing being carried out in an atmosphere or vacuum which has no significant deleterious effect on said compact or body.
Claim 3
Dependent Claim
19 words
The process according to claim 1 wherein said nucleation-annealing temperature ranges from about 650 0 C to about 750°C.
Claim 4
Dependent Claim
25 words
The process according to claim 1 wherein said atmosphere is selected from the group consisting of air, hydrogen, wet hydrogen, nitrogen, argon and mixtures thereof.
Claim 5
Dependent Claim
16 words
The process according to claim 1 wherein said compact is in the form of a tape.
Claim 6
Dependent Claim
41 words
The process according to claim 1 wherein said polycrystalline body is comprised of from about 60% by weight to about 70% by weight of said mullite and from about 30% by weight to about 40% by weight of said beta spodumene.
Claim 7
Dependent Claim
29 words
The process according to claim 1 wherein said polycrystalline body is comprised of about 37% by weight of said beta spodumene and about 63% by weight of said mullite.
Claim 8
Dependent Claim
69 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body and crystalline beta spodumene in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, said body having a density greater than about 85% of the theoretical density of said body.
Claim 9
Dependent Claim
69 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body and crystalline beta spodumene in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, said body having a density greater than about 85% of the theoretical density of said body.
Claim 10
Dependent Claim
12 words
The polycrystalline body of claim 7 in the form of a sheet.
Claim 11
Dependent Claim
62 words
A polycrystalline body comprised of crystalline mullite ranging from about 60% by weight to about 70% by weight of the total weight of the body, and crystalline beta spodumene ranging from about 30% by weight to about 40% by weight of the total weight of the body, said body having a density greater than 85% of the theoretical density of said body.
Claim 12
Dependent Claim
62 words
A polycrystalline body comprised of crystalline mullite ranging from about 60% by weight to about 70% by weight of the total weight of the body, and crystalline beta spodumene ranging from about 30% by weight to about 40% by weight of the total weight of the body, said body having a density greater than 85% of the theoretical density of said body.
Claim 13
Dependent Claim
12 words
The polycrystalline body of claim 9 in the form of a sheet.
Claim 14
Dependent Claim
36 words
A polycrystalline body comprised of about 63% by weight of polycrystalline mullite and about 37% by weight of polycrystalline beta spodumene, said body having a density greater than 85% of the theoretical density of said body.
Claim 15
Dependent Claim
36 words
A polycrystalline body comprised of about 63% by weight of polycrystalline mullite and about 37% by weight of polycrystalline beta spodumene, said body having a density greater than 85% of the theoretical density of said body.
Claim 16
Dependent Claim
13 words
The polycrystalline body of claim 11 wherein said density is greater than 90%.
Claim 17
Dependent Claim
122 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body, crystalline beta spodumene in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, a-Al203 phase ranging up to about 11% by weight of the total weight of the body and a glassy phase ranging from a detectable amount up to about 5% by volume of the total volume of said body, said body having a density greater than 85% of the theoretical density of said body, said body having a dielectric constant ranging from higher than 6 to lower than 7 at 300°K.
Claim 18
Dependent Claim
122 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body, crystalline beta spodumene in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, a-Al203 phase ranging up to about 11% by weight of the total weight of the body and a glassy phase ranging from a detectable amount up to about 5% by volume of the total volume of said body, said body having a density greater than 85% of the theoretical density of said body, said body having a dielectric constant ranging from higher than 6 to lower than 7 at 300°K.
Claim 19
Dependent Claim
122 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 60% by weight to about 70% by weight of the total weight of the body, crystalline beta spodumene in an amount ranging from about 30% by weight to about 40% by weight of the total weight of the body, a-Al203 phase ranging up to about 11% by weight of the total weight of the body and a glassy phase ranging from a detectable amount up to about 5% by volume of the total volume of said body, said body having a density greater than 85% of the theoretical density of said body, said body having a dielectric constant ranging from greater than 6 to lower than 7 at 300°K.
Claim 20
Dependent Claim
122 words
A polycrystalline body comprised of crystalline mullite in an amount ranging from about 60% by weight to about 70% by weight of the total weight of the body, crystalline beta spodumene in an amount ranging from about 30% by weight to about 40% by weight of the total weight of the body, a-Al203 phase ranging up to about 11% by weight of the total weight of the body and a glassy phase ranging from a detectable amount up to about 5% by volume of the total volume of said body, said body having a density greater than 85% of the theoretical density of said body, said body having a dielectric constant ranging from greater than 6 to lower than 7 at 300°K.
Claim 21
Dependent Claim
121 words
A polycrystalline body comprised of crystalline mullite phase in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body and crystalline beta spodumene phase in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, said mullite phase being comprised of from about 71.8 weight % to about 74.0 weight % A1 2 0 3 balance SiO 2 , said beta spodumene phase being comprised of from about 58.5 weight % to about 79.4 weight % SiO 2 balance Li 2 O·Al 2 O 3 , said body having a density greater than 85% of the theoretical density of said body.
Claim 22
Dependent Claim
121 words
A polycrystalline body comprised of crystalline mullite phase in an amount ranging from about 50% by weight to about 95% by weight of the total weight of the body and crystalline beta spodumene phase in an amount ranging from about 5% by weight to about 50% by weight of the total weight of the body, said mullite phase being comprised of from about 71.8 weight % to about 74.0 weight % A1 2 0 3 balance SiO 2 , said beta spodumene phase being comprised of from about 58.5 weight % to about 79.4 weight % SiO 2 balance Li 2 O·Al 2 O 3 , said body having a density greater than 85% of the theoretical density of said body.
References Cited (Backward Citations)
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