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Improved Aqueous Dispersion of Silicon Nitride with Aminosilanes
Author(s) -
Buchta Michael A.,
Shih WeiHeng
Publication year - 1996
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.1151-2916.1996.tb08729.x
Subject(s) - silicon nitride , aqueous solution , nitride , materials science , dispersion (optics) , chemical engineering , isoelectric point , silicon , inorganic chemistry , chemistry , nanotechnology , metallurgy , layer (electronics) , organic chemistry , optics , physics , engineering , enzyme
The addition of a standard fiberglass surfactant, 3‐aminopropyltriethoxysilane (APS), improves whisker and powder dispersion of silicon nitride aqueous suspensions. Aqueous suspensions of APS‐coated silicon nitride have lower viscosities, increased consolidation, and higher dried green‐body densities compared to uncoated silicon nitride in suspensions with pH values ≤8. The APS coating shifts the isoelectric point (IEP) of silicon nitride to a more basic value, dependent on the concentration of APS coating. Suspension pH measurements indicate that APS extracts one hydrogen ion for each APS molecule either chemisorbed on the particle surface or dissolved in the solution. Optical microscopy reveals that dilute suspensions coated with APS at pH 10 are qualitatively more dispersed than uncoated silicon nitride at pH 7. Our results show increased dispersion of APS‐coated silicon nitride in acidic environments, with a 12% increase in green density under identical wetpressing conditions.