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US4744831A
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Hollow inorganic spheres and methods for making such spheres
Assignee: 3M Co
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Filing: 1984-07-30
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Granted: 1988-05-17
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Expires: 2004-07-30
Abstract
Abstract Novel hollow inorganic spheres are prepared by (1) tumbling together a mixture comprising (a) solidifiable liquid globules that comprise a fugitive organic binder material and a source of volatile void-forming agent and (b) a mass of free-flowing inorganic sinterable parting agent particles that are at least partially absorbed into the globules during the tumbling action; (2) providing conditions under which hollow spheres form in which the sphere walls contain the sinterable particles; and (3) firing the spheres to remove the binder material and sinter the parting agent particles to form shape-retaining spheres having sintered inorganic walls.
Inventors
- 👤 Warren R. Beck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:36
CPC Classifications
E; E21; E21B; E21B43/00; E21B43/25; E21B43/26; E21B43/267; B; B22; B22F; B22F1/00; B22F1/06; B22F1/065; B22F1/0655; C; C04; C04B; C04B38/00; C04B38/009; C09; C09K; C09K8/00; C09K8/60; C09K8/80; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
59 words
A free-flowing mass of hollow spheres which individually comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space, the exterior wall of the individual spheres being at least about 1/3 millimeter thick and comprising inorganic particulate material selected from metals, metalloids, metal oxides and metal salts sintered together to provide a rigid shape-retaining structure.
Claim 2
Dependent Claim
59 words
A free-flowing mass of hollow spheres which individually comprise a solidified seamless spherical exterior wall that defines and encloses a central interior space, the exterior wall of the individual spheres being at least about 1/3 millimeter thick and comprising inorganic particulate material selected from metals, metalloids, metal oxides and metal salts sintered together to provide a rigid shape-retaining structure.
Claim 3
Dependent Claim
20 words
Hollow spheres of claim 1 wherein the inorganic material is selected from aluminum silicate, alumina, magnetite, silica, spinels and zirconia.
Claim 4
Dependent Claim
21 words
Hollow spheres of claim 1 wherein the inorganic material includes metallic components selected from copper, nickel, iron, silicon, aluminum and zirconium.
Claim 5
Dependent Claim
24 words
Hollow spheres of claim 1 which have been impregnated with an inorganic-containing material and heated to incorporate the additional inorganic material in the spheres.
Claim 6
Independent Claim
189 words
A method for forming hollow inorganic spheres comprising (A) tumbling together and thoroughly mixing (1) solidifiable liquid globules comprising a thermally fugitive organic binder material and a source of void-forming agent adapted to evolve as a gas and convert the liquid globules to a hollow condition and (2) a mass of minute discrete free-flowing inorganic heat-sinterable parting agent particles selected from metals, metalloids, metal oxides and metal salts that are wetted by, and at least partially absorbed into, the liquid globules during the tumbling action; sufficient parting agent particles being present so that any portion of liquid globules uncovered by parting agent particles tumble against discrete unabsorbed parting agent particles; (B) providing conditions during the tumbling action, and tumbling for a sufficient time, for the void-forming agent to evolve as a gas and form a central interior space within the liquid globules and for the thus-hollowed liquid globules to solidify; (C) collecting the converted globules after they have solidified to a shape-retaining condition; and (D) firing the hollow spheres to first burn out the organic binder, and to then sinter the parting agent particles to form hollow shape-retaining spheres.
Claim 7
Independent Claim
189 words
A method for forming hollow inorganic spheres comprising (A) tumbling together and thoroughly mixing (1) solidifiable liquid globules comprising a thermally fugitive organic binder material and a source of void-forming agent adapted to evolve as a gas and convert the liquid globules to a hollow condition and (2) a mass of minute discrete free-flowing inorganic heat-sinterable parting agent particles selected from metals, metalloids, metal oxides and metal salts that are wetted by, and at least partially absorbed into, the liquid globules during the tumbling action; sufficient parting agent particles being present so that any portion of liquid globules uncovered by parting agent particles tumble against discrete unabsorbed parting agent particles; (B) providing conditions during the tumbling action, and tumbling for a sufficient time, for the void-forming agent to evolve as a gas and form a central interior space within the liquid globules and for the thus-hollowed liquid globules to solidify; (C) collecting the converted globules after they have solidified to a shape-retaining condition; and (D) firing the hollow spheres to first burn out the organic binder, and to then sinter the parting agent particles to form hollow shape-retaining spheres.
Claim 8
Dependent Claim
15 words
A method of claim 5 in which the fugitive organic binder material comprises corn starch.
Claim 9
Dependent Claim
22 words
A method of claim 1 comprising impregnating the sintered spheres completed in Step D with an inorganic-containing matrial and re-firing the spheres.
Claim 10
Dependent Claim
19 words
Spheres of claim 1 in which the exterior wall of the spheres is at least about 2/3 millimeter thick.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |