Dispersion of silicon carbide whiskers and powders in aqueous and non-aqueous media

Abstract

The dispersion behaviour of two commercial SiC whisker samples and one SiC powder has been investigated in aqueous and non-aqueous media using equilibrium sediment density measurements. In water, the pH range 9–11.0 was identified as being optimum for the dispersion of the SiC materials. The colloidal stability of aqueous SiC suspensions was broadly consistent with their silica-like surface chemistry, although the SiC whiskers appeared to be more basic than the powder.

The dispersion behaviour of the SiC materials was found to be similar in a range of non-aqueous media. Formic acid was found to be the best intrinsic non-aqueous dispersion medium for the materials, although to obtain the best possible dispersion in non-aqueous media it was found necessary to use suitable dispersing agents.

On the basis of sedimentation density measurements, it was found to be possible to determine the aspect ratio of the whisker samples.