Accession Number:

AD0260982

Title:

SILICA MICROBUBBLES

Descriptive Note:

Corporate Author:

EMERSON AND CUMING INC CANTON MASS

Personal Author(s):

Report Date:

1960-12-01

Pagination or Media Count:

1.0

Abstract:

Glass microbubbles 0.150 to 0.020 mm diameter, having a bulk density of 0.25 gcc and a true density of 0.50 gcc have been greatly improved by decreasing the alkali content and also by making them of vitreous silica. The improvements consist of marked decrease in moisture adsorption, enhanced electrical properties, and great increase in maximum use temperature. An acid leaching technique applied to the commercially available 18 alkali Eccospheres of Emerson Cuming, Inc. re uces the alkali content to 6 and increases the maxim m use temperature from 500 to 800 C. Formation from pure silica by a direct high temperature process to give a vitreous silica bubble retains the useful characteristics of the low-melting-alkali-glass bubble with the desirable properties of vitreous silica - low to negligible moisture adsorption, outstanding dielectric properties even at high temperature, and a safe use temperature for most applications of 1300 C. The feasibility of the direct process has been briefly demonstrated on pilot plant scale at 2 lbhr rate. Work on bonding the high temperature product into structural shapes is described. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE