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US4960738A
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Mullite-alumina composite sintered body and process for producing the same
Assignee: Kureha Corp
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Filing: 1988-10-25
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Granted: 1990-10-02
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Expires: 2008-10-25
Abstract
Abstract A mullite-alumina composite sintered body composed of from 75 wt % to 85 wt % Al 2 O 3 balance SiO 2 , consisting of two crystalline phases, mullite and α-phase alumina, and being free from glass phase, wherein both of the average diameters of mullite grains and α-phase alumina grains are not more than 1.0 μm, the content of grains having the longitudinal-length of not less than 2.5 μm is 1% or less in the observation of a cross section of said sintered body, and the porosity of said sintered body is 1% or less. The sintered body of the present invention is produced by a process comprising the steps of preparing a starting powdery material composed of from 75 wt % to 85 wt % Al 2 O 3 balance SiO 2 and containing amorphous phase from 65 wt % to 90 wt %, wherein each particle of said starting powdery material contains both Al 2 O 3 and SiO 2 , and sintering said starting powdery material at a temperature in the range from 1500° C. to 1650° C. The sintered body of the present invention has a high bending strength exceeding 500 MPa at room temperature.
Inventors
- 👤 Saburo Hori
- 👤 Ryuichi Kurita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:24
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/622; C04B35/64; C04B35/01; C04B35/10; C04B35/111; C04B35/16; C04B35/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
A mullite-alumina composite sintered body comprising 77 to 85 wt % Al 2 O 3 , the balance being SiO 2 , the sintered body having two crystalline phases of mullite and α-phase alumina and being free from any glass phase, the average diameters of mullite grains and α-phase alumina grains being not more than 1.0 μm, the content of grains having a longitudinal length of not less than 2.5 μm being 1% or less upon observation of a crosssection of the sintered body, and the porosity of the sintered body being 1% or less.
Claim 2
Dependent Claim
95 words
A mullite-alumina composite sintered body comprising 77 to 85 wt % Al 2 O 3 , the balance being SiO 2 , the sintered body having two crystalline phases of mullite and α-phase alumina and being free from any glass phase, the average diameters of mullite grains and α-phase alumina grains being not more than 1.0 μm, the content of grains having a longitudinal length of not less than 2.5 μm being 1% or less upon observation of a crosssection of the sintered body, and the porosity of the sintered body being 1% or less.
Claim 3
Dependent Claim
27 words
The mullite-alumina composite sintered body of claim 1 consisting essentially of 77 to 85 wt % Al 2 O 3 , the balance being SiO 2 .
Claim 4
Dependent Claim
72 words
A process for producing a mullite-alumina composite sintered body, comprising preparing a starting powdery material comprising 77 to 85 wt % Al 2 O 3 , the balance being SiO 2 , the powdery material containing 65 to 90 wt % amorphous phase and each particle thereof containing both Al 2 O 3 and SiO 2 ; and sintering the starting powdery material at a temperature of 1500° C. to 1650° C.
Claim 5
Dependent Claim
72 words
A process for producing a mullite-alumina composite sintered body, comprising preparing a starting powdery material comprising 77 to 85 wt % Al 2 O 3 , the balance being SiO 2 , the powdery material containing 65 to 90 wt % amorphous phase and each particle thereof containing both Al 2 O 3 and SiO 2 ; and sintering the starting powdery material at a temperature of 1500° C. to 1650° C.
Claim 6
Dependent Claim
42 words
The process for producing a mullite-alumina composite sintered body of claim 3, where the starting powdery material further comprises crystallographically 0 to 10 wt % mullite; and 10 to 35 wt % gamma-phase or delta-phase alumina, in addition to the amorphous phase.
Claim 7
Dependent Claim
42 words
The process for producing a mullite-alumina composite sintered body of claim 3, wherein the starting powdery material comprises spherical particles having the average particle diameter of 30 to 100 nm and a specific surface area of 20 to 70 m 2 /g.
Claim 8
Dependent Claim
64 words
The process for producing a mullite-alumina composite sintered body of claim 3, further comprising producing the starting powdery material by blowing a vapor mixture of AlCl 3 and SiCl 4 into a combustion gas; oxidizing the vapor mixture in a high temperature vapor phase; and cooling the starting powdery material from 1500° C. to 900° C. at a cooling rate exceeding 5×10 3 °C./sec.
Claim 9
Dependent Claim
32 words
The process for producing a mullite-alumina composite sintered body of claim 6, wherein the vapor phase oxidation of the mixture is conducted at a maximum temperature of 1800° C. to 2100° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-10-01 | 1994-04-02 | 1994-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-01 | 1998-04-02 | 1998-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-01 | 2002-04-02 | 2002-10-02 | $7700.00 | Window Closed / Lapsed |