The field-dependent viscoelastic and transient responses of plate-like carbonyl iron particle based magnetorheological greases

The field-dependent viscoelastic and transient behaviours of plate-like-carbonyl-iron-particle-based magnetorheological greases are experimentally investigated in this study. The plate-like carbonyl-iron particles are made from spherical carbonyl-iron particles through a milling process using a rotary ball mill. Several samples of magnetorheological greases consisting of different weight percentages of plate-like carbonyl-iron particles are prepared. The surface microstructures and distributions of the plate-like carbonyl-iron particles in the grease are observed using various types of microscopic investigations. Subsequently, the viscoelastic and transient (dynamic) rheological properties of the plate-like carbonyl-iron particles are investigated using a commercial rheometer. The spherical carbonyl-iron particles are transformed into the flattened plate-like carbonyl-iron particles with a larger surface diameter. It is shown that the viscoelastic properties such as storage modulus and response time of the plate-like carbonyl-iron particles significantly depend on the shape and particle weight fraction. The findings reveal that the shape of the carbonyl-iron particles has a significant effect on the field-dependent behaviours. Thus, the results presented in this work provide very useful scientific contributions for devising appropriate applications utilizing the plate-like-carbonyl-iron-particle-based magnetorheological greases.