A systematical study of the overall influence of carbon allotrope additives on performance, stability and redispersibility of magnetorheological fluids

Abstract

To this date many different additives have been used in order to stabilize the magnetorheological fluids or to enhance their performance, but their ranking in terms of the efficiency is still lacking. To design the efficient magnetorheological fluid it is necessary to analyse the overall effects of the additives on its complex behavior. In this study, carbon allotropes – fullerene powder, carbon nanotubes, graphene nanoplatelets – were added into the carbonyl iron-based magnetorheological fluids to examine their effect on stability and utility properties. The magnetorheological behavior of designed mixtures was investigated and obtained experimental data were numerically evaluated using the Robertson–Stiff model. While the fine fullerene powder acted as a gap-filler reinforcing field-induced structures, the other additives employed rather disrupted the microstructure during the shear. The role of the additives during the formation of field-induced structures was pointed out. The sedimentation stability was examined using Turbiscan analyzer as well as by direct observation method. Both approaches revealed that the carbon nanotubes possessed the highest stabilization effect. They also most effectively prevented packing the iron microparticles into a stiff sediment as was confirmed via redispersibility measurements.