Abstract:
This research investigated the colloidal behavior of kaolinitic clay in aqueous
suspensions. The foundation of most current clay suspension behavior is based on early
studies conducted prior to the application of colloidal concepts in ceramic systems and
also when many of the colloidal theories were being developed. Technological advances
in colloid science and the application of the theories greatly enhance the interpretation of
the clay suspension behavior. Kaolinitic clay is the primary component responsible for
the colloidal behavior of in traditional ceramics because the clay accounts for over 90%
of the total surface area and active charge sites.
The impact of cations and anions on colloidal behavior, specifically the dispersion and
coagulation, of a whiteware suspension was examined using rheology and electrophoretic
mobility measurements. The results indicate the cations are responsible for coagulating
the suspension, including sodium, which has been labeled both a dispersant and a
coagulant. The anionic species are responsible for dispersing the clay suspension, but
zeta potential is an inaccurate measure of suspension stability.
The influence of chemistry changes via cation and anion additions observed in
suspensions are also detected in plastic bodies. The plasticity measured by the cohesion
stress decreases with increasing cation concentration. It is suggested that the magnitude
of the cohesion stress directly influences the formability and stress gradients established
duringdrying.
Description:
Advisory committee members: Paul Johnson, Alexis Clare, William Lacourse. Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Ceramics at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
