Multilevel Structure of Reinforcing Silica and Carbon

Published

June 1, 2000

Author(s)

D W. Schaefer, T Rieker, M M. Agamalian, J S. Lin, Daniel A. Fischer, S Sukumaran, C I. Chen, G Beaucage, C Herd, J Ivie

Abstract

We study the structure of colloidal silica and carbon on length scales from 0.25 -1<10⁷ using x-ray, neutron and light scattering. These materials consist of primary particles of the order of 100 , aggregated into micrometer-sized aggregates that in turn are agglomerated into 100 m agglomerates. We show that the primary particles in precipitated silica are composed of highly defective amorphous silica with little intermediate-range order. On the next level of morphology, primary particles arise by a two-stage nucleation process in which primordial nuclei briefly aggregate into rough particles that subsequently smooth out to become the seeds for the primaries. The primaries aggregate to strongly-bonded clusters by a complex process involving kinetic growth, mechanical disintegration and restructuring. Finally, the aggregates cluster into porous, non-fractal agglomerates that can be broken down to the strongly bonded aggregates by shear. We find similar structure in pelletized carbon blacks. In this case we show a linear scaling relation between the primary and aggregate sizes. We attribute the scaling to mechanical processing that deforms the fractal aggregates down to the maximum size able to withstand the compaction stress.

Citation

Journal of Applied Crystallography

Volume

33

Issue

No. 1

Pub Type

Journals

Keywords

carbon, colloidal silica, microstructure, porous materials, SAXS

Citation

Schaefer, D. , Rieker, T. , Agamalian, M. , Lin, J. , Fischer, D. , Sukumaran, S. , Chen, C. , Beaucage, G. , Herd, C. and Ivie, J. (2000), Multilevel Structure of Reinforcing Silica and Carbon, Journal of Applied Crystallography (Accessed April 25, 2024)