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 sedimentation test. The Van der Waals potential energy of interaction between the particles and organic liquid molecules, i.e. VA, is estimated. The results are correlated with the surface composition of powders and the chemical and physical characteristics of the organic liquids. Poor dispersions are found in nonpolar hydrocarbons, whereas in polar organic liquids, the dispersity and stability depend on the functional group, dielectric constant and carbochain length of the organic liquids. After some of the organic groups on the powder surfaces are eliminated by heat-treatment, the dispersity is decreased. The VA of the dispersions can be adequately used to predicate the stability of the nonpolar hydrocarbon dispersions. However, in polar organic liquids, the contribution coming from the electric double layers and solvation layers should also be considered.