Alumina surface modification of silicon nitride for colloidal processing

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1995.tb08611.x· OSTI ID:105997

Luther, E P; Lange, F F; Pearson, D S ^[1]

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1. Univ. of California, Santa Barbara, CA (United States). Materials Dept.

Two different methods are used to coat silicon nitride particles with an alumina precursor to make Si{sub 3}N{sub 4} behave like Al{sub 2}O{sub 3} in aqueous slurries. The first method involves the precipitation of an aluminum hydroxycarbonate from dissolve Al(NO{sub 3}){sub 3} during the decomposition of urea. In the second method, dry silicon nitride powder is reacted with aluminum tri-sec-butoxide in hexane at room temperature. Both methods produce a coated powder in which the electrophoretic and rheological properties of aqueous slurries mimic those of alumina. When salt is added to slurries consisting of coated Si{sub 3}N{sub 4} powder, all rheological evidence suggests the presence of a short-range repulsive potential that produces a weakly attractive particle network similar to that previously reported for Al{sub 2}O{sub 3} powder. Although electrophoretic and rheological data showed that the coated powder behaved like Al{sub 2}O{sub 3}, consolidation data indicated that slurries of coated powder with added salt did not pack to high density. In addition, these bodies were not plastic as found for bodies consolidated from dispersed and salt-added Al{sub 2}O{sub 3} slurries.

• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 105997
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 8 Vol. 78; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRATES
ALUMINIUM OXIDES
BULK DENSITY
CARBONATES
COATINGS
COMPACTING
ELECTROPHORESIS
ORGANOMETALLIC COMPOUNDS
PLASTICITY
POWDERS
RHEOLOGY
SILICON NITRIDES
SLURRIES
SURFACE COATING