Molecular engineering of ceramics. [Silica gel]

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5923650

Martin, J E

We discussed some recent advances in the study of silica sol-gels, including the kinetics of growth of the sol beneath the gel point, the fractal structure of the sol and the observation of a spatial correlation length in undiluted gels. We attempted to connect these results to popular theories, but were not able to paint a definitive picture of the sol-gel transition. In part, this is due to the paucity of experimental data in this field. A few tentative conclusions can be drawn: (1) The static structure of the fractionated and unfractionated sol seems to be fairly well accounted for by the percolation model if swelling is taken into account. (2) The divergences of the average cluster mass and radius are stronger than predicted by the percolation model, and much stronger than the Flory-Stockmayer predictions. (3) The static structure observed in the undiluted, low-density silica gels are in reasonable agreement with either an equilibrium model, such as correlated percolation, or a kinetic growth model. Discrepancies exist in either case. 16 refs., 5 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5923650
• Report Number(s): SAND-87-2098C; CONF-870878-1; ON: DE88000174
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ADSORBENTS
CERAMICS
COLLOIDS
DISPERSIONS
GELATION
GELS
KINETICS
LIGHT SCATTERING
MASS
MOLECULAR STRUCTURE
MOLECULES
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
SCATTERING
SILICA GEL
SOL-GEL PROCESS
SOLS
SOLVENTS
SWELLING