Glass manufacturing – Processes – Self-supporting particle making
Patent
1979-07-26
1981-03-24
Lindsay, Jr., Robert L.
Glass manufacturing
Processes
Self-supporting particle making
65 22, 106 40V, 264 43, C03B 304
Patent
active
042577993
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 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.
REFERENCES:
patent: 3717486 (1973-02-01), Fukumoto et al.
patent: 4017290 (1977-04-01), Budrick et al.
patent: 4133854 (1979-01-01), Hendricks
Laser Fusion Hollow Microspheres by Liquid-Droplet Method; Rosencwaig et al., 6-5-1978; preprint UCRL 81421.
Dressler John L.
Koo Jackson C.
Rosencwaig Allen
Besha Richard G.
Carnahan L. E.
Gaither Roger S.
Lindsay, Jr. Robert L.
The United States of America as represented by the United States
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