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Title: Method for producing small hollow spheres

Abstract

A method for producing small hollow spheres of glass having an outer diameter ranging from about 100.mu. to about 500.mu. with a substantially uniform wall thickness in the range of about 0.5-20.mu.. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions. In one embodiment, one of the temperature regions is lower than both the preceeding region and the subsequent region. One region utilizes a temperature of at least 200.degree. C. higher than the melting point of the glass-forming material in the solution and, for example, may be at least 3 times higher than the temperature of the preceeding region. In addition, there is a sharp temperature gradient between these regions. As each droplet of solution passes through a first region it forms into a gel membrane having a spherical shape and encapsulates the rest of the drop retained in the elastic outer surface and the water entrapped within diffuses rapidly through the thin gel membrane which causes more of the glass-forming material to go out of solution and is incorporated into the gel membrane causing it to grow in size and become hollow. thus produced hollow glassmore » sphere has a sphericity, concentricity, and wall uniformity of better than 5%. The sphere is capable of retaining material of up to at least 100 atmospheres therein over long periods of time. In one embodiment.« less

Inventors:
 [1];  [2];  [3]
  1. (Danville, CA)
  2. (San Ramon, CA)
  3. (Spring Valley, OH)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
863834
Patent Number(s):
4257799
Assignee:
United States of America as represented by United States (Washington, DC) LLNL
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; producing; hollow; spheres; glass; outer; diameter; ranging; 100; 500; substantially; uniform; wall; thickness; range; 5-20; involves; introducing; aqueous; droplets; glass-forming; solution; vertical; drop; oven; furnace; varying; temperature; regions; embodiment; preceeding; region; subsequent; utilizes; 200; degree; melting; material; example; times; addition; sharp; gradient; droplet; passes; forms; membrane; spherical; shape; encapsulates; retained; elastic; surface; water; entrapped; diffuses; rapidly; causes; incorporated; causing; grow; size; produced; sphere; sphericity; concentricity; uniformity; capable; retaining; atmospheres; therein; periods; time; spherical shape; hollow spheres; wall thickness; temperature gradient; method involves; outer surface; substantially uniform; hollow glass; outer diameter; produced hollow; forming material; uniform wall; method involve; hollow sphere; solution pass; /65/264/376/501/

Citation Formats

Rosencwaig, Allen, Koo, Jackson C., and Dressler, John L. Method for producing small hollow spheres. United States: N. p., 1981. Web.
Rosencwaig, Allen, Koo, Jackson C., & Dressler, John L. Method for producing small hollow spheres. United States.
Rosencwaig, Allen, Koo, Jackson C., and Dressler, John L. Thu . "Method for producing small hollow spheres". United States. https://www.osti.gov/servlets/purl/863834.
@article{osti_863834,
title = {Method for producing small hollow spheres},
author = {Rosencwaig, Allen and Koo, Jackson C. and Dressler, John L.},
abstractNote = {A method for producing small hollow spheres of glass having an outer diameter ranging from about 100.mu. to about 500.mu. with a substantially uniform wall thickness in the range of about 0.5-20.mu.. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions. In one embodiment, one of the temperature regions is lower than both the preceeding region and the subsequent region. One region utilizes a temperature of at least 200.degree. C. higher than the melting point of the glass-forming material in the solution and, for example, may be at least 3 times higher than the temperature of the preceeding region. In addition, there is a sharp temperature gradient between these regions. As each droplet of solution passes through a first region it forms into a gel membrane having a spherical shape and encapsulates the rest of the drop retained in the elastic outer surface and the water entrapped within diffuses rapidly through the thin gel membrane which causes more of the glass-forming material to go out of solution and is incorporated into the gel membrane causing it to grow in size and become hollow. thus produced hollow glass sphere has a sphericity, concentricity, and wall uniformity of better than 5%. The sphere is capable of retaining material of up to at least 100 atmospheres therein over long periods of time. In one embodiment.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1981},
month = {1}
}

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