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Rheological Properties of Concentrated, Nonaqueous Silicon Nitride Suspensions
Author(s) -
Bergström Lennart
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.tb08074.x
Subject(s) - volume fraction , materials science , rheology , viscoelasticity , shear thinning , dispersant , silicon nitride , particle (ecology) , particle size , adsorption , viscosity , composite material , chemical engineering , shear (geology) , volume (thermodynamics) , polymer , particle size distribution , mineralogy , layer (electronics) , chemistry , dispersion (optics) , thermodynamics , organic chemistry , oceanography , physics , engineering , optics , geology
The rheological properties of nonaqueous silicon nitride powder suspensions have been investigated using steady shear and viscoelastic measurements. The polymeric dispersant, Hypermer KD‐3, adsorbed strongly on the powder surfaces, and colloidally stable, fluid suspensions up to a volume fraction of φ= 0.50 could be prepared. The concentrated suspensions all displayed a shear thinning behavior which could be modeled using the high shear form of the Cross equation. The viscoelastic response at high concentrations was dominated by particle interactions, probably due to interpenetration of the adsorbed polymer layers, and a thickness of the adsorbed Hypermer KD‐3 layer, Δ∼10 nm, was estimated. The volume fraction dependences of the high shear viscosity of three different silicon nitride powders were compared and the differences, analyzed by using a modified Krieger‐Dougherty model, were related to effective volume effects and the physical characteristics of the powders. The significantly lower maximum volume fraction, φ m = 0.47, of the SN E‐10 powder was referred to the narrow particle size distribution and the possibility of an unfavorable particle morphology.