Dispersive action of octane for cobalt nano-particles

In order to prepare nano-grained WC–Co cemented carbides with high performance, the dispersion of cobalt nano-particles in octane was studied. Three fatty acids, 12-hydroxystearic acid, stearic acid and oleic acid, were used as surfactants to modify the cobalt nano-particles in octane. The adsorption behavior, surface characteristics, suspension stability and rheological behavior were investigated by chemical titration, FT-IR spectroscopy, UV–vis spectroscopy and rheometer, respectively. The results indicated that the cobalt nano-particles modified with 12-hydroxystearic acid achieved the best dispersion performance and suspension stabilization, and 12-hydroxystearic acid also exhibited the highest ability to reduce interparticle van der Waals potential energy. The adsorption of 12-hydroxystearic acid onto the surface of cobalt nano-particles is a chemical and physical process, but the adsorption of stearic acid or oleic acid is only a chemical one.

► HSA, SA and OA were used as the surfactants to modify the cobalt nano-particles.
► The dispersion performance and the stabilization of suspension were investigated.
► The HSA-modified cobalt nano-particles achieved the best performance.