Claims
- 1. .alpha.-Alumina consisting essentially of .alpha.-alumina single crystal particles characterized in that they are homogeneous containing no crystal seed inside said particles; have an octa- or higher polyhedral shape; have a D/H ratio of from 0.5 to 2, wherein D represents a maximum particle diameter parallel to a hexagonal lattice plane of a hexagonal close-packed lattice of said particles, and H represents a diameter perpendicular to said hexagonal lattice plane; have a number average particle diameter of more than 5 .mu.m and not more than 30 .mu.m; have a sodium content of less than 5 ppm in terms of Na.sub.2 O; have an alumina purity of not less than 99.90% by weight; and have a particle size distribution wherein a D90/D10 ratio is not more than 10, wherein D10 and D90 represent a cumulative 10% diameter and a cumulative 90% diameter, respectively, of a cumulative distribution depicted from the small diameter side.
- 2. .alpha.-Alumina as claimed in claim 1, wherein the D/H ratio is 1 to 2.
- 3. .alpha.-Alumina as claimed 1, wherein the D90/D10 ratio is 4 or less.
- 4. .alpha.-Alumina as in claim 1, characterized in that said .alpha.-alumina has an alumina purity of not less than 99.95% by weight.
Priority Claims (2)
Number |
Date |
Country |
Kind |
4-168385 |
Jun 1992 |
JPX |
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4-314052 |
Oct 1992 |
JPX |
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Parent Case Info
This is a Continuation of application Ser. No. 08/343,521 filed Feb. 2, 1995, which is a 371 of PCT/JP93/00738 filed Jul. 1, 1993, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0105025 |
Apr 1984 |
EPX |
0281265 |
Sep 1988 |
EPX |
WO 90 15777 |
Dec 1990 |
WOX |
Non-Patent Literature Citations (1)
Entry |
62th CATSJ Meeting Abstracts: No. 2D105 (with full English translation thereof), 1988, no month, by Ayame, et al. |
Continuations (1)
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Number |
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Parent |
343521 |
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