Alliedsignal Inc.

Philip D DuBois

Timothy J Barder

Silica microspheres formed by hydrolysis of a silica precursor having a mean diameter in the range of about 0.1 to 10 .mu.m are provided with a thin surface layer, often a monolayer, of a metal to provide the appearance of a solid particle of the metal as its oxide. The microspheres are contacted with an aqueous or alcoholic solution of a metal compound to deposit the surface layer.

Process for coating silica spheres

A process for producing highly uniform microspheres of silica having an average diameter of 0.1-10 .mu.m from the hydrolysis of a silica precursor, such as tetraalkoxysilanes, which is characterized by employing precursor solutions and feed rates which initially yield a two-phase reaction mixture.

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Lisle, IL, United States of America

Philip D DuBois