The dispersion behavior of Si-C-N nanopowders in organic liquids

The dispersion behavior of laser synthesized Si-C-N nanopowders in 15 pure organic liquids has been studied through particle size analysis and sedimen tation test. The Van der Waals potential energy of interaction between the particles and organic liquid molecules, i.e. V-A, is estimated. The results are correlated with the surface composition of powders and the chemical an d physical characteristics of the organic liquids. Poor dispersions are fou nd in nonpolar hydrocarbons, whereas in polar organic liquids, the dispersi ty and stability depend on the functional group, dielectric constant and ca rbochain length of the organic liquids. After some of the organic groups on the powder surfaces are eliminated by heat-treatment, the dispersity is de creased. The V-A Of the dispersions can be adequately used to predicate the stability of the nonpolar hydrocarbon dispersions. However, in polar organ ic liquids, the contribution coming from the electric double layers and sol vation layers should also be considered. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.