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Aqueous Dispersion and Slip Casting of Boron Carbide Powder: Effect of pH and Oxygen Content
Author(s) -
Williams P. Douglas,
Hawn David D.
Publication year - 1991
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1991.tb07147.x
Subject(s) - boric acid , boron carbide , boron , aqueous solution , zeta potential , materials science , oxygen , viscosity , dispersion (optics) , inorganic chemistry , adsorption , chemical engineering , chemistry , metallurgy , composite material , organic chemistry , physics , engineering , nanoparticle , optics , nanotechnology
The effect of pH and oxygen content on the zeta potential, viscosity, and casting performance of fine (>3 μm) boron carbide powder is presented. X‐ray photoelectron spectroscopy of the powder revealed a surface layer of adsorbed water and oxides of boron and carbon. The soluble boric acid impurity was removed by washing the powder with water or alcohols. Electrophoresis indicated that the B 4 C surface was negatively charged in water above pH 1, but the presence of dissolved boric acid suppressed the zeta potential at high pH. Stable, low‐viscosity dispersions of >30 vol% solids were prepared and slip cast at pH >6, but boric acid was destabilizing for dispersions prepared above pH 7. The green density of slip‐cast parts was more reproducible and about 3% to 5% higher for washed powders than for high‐oxygen‐content powders.