Brake performance of core–shell structured carbonyl iron/silica based magnetorheological suspension

• Silica coated magnetic particle was fabricated as magnetorheological (MR) material.
• Small-sized MR brake of disc-type was specially designed.
• MR fluid based on silica coated particles exhibited improved tracking accuracy.

Chemically stable core–shell structured magnetic particles were synthesized by coating soft-magnetic carbonyl iron (CI) microspheres with silica through a sol–gel reaction, and applied as magnetorheological (MR) materials for a specially designed small-sized MR brake. The dynamic yield stress of the MR suspension containing the synthesized particles was also measured using a rotational rheometer under an applied magnetic field. The performance characteristics of the MR brake, including field dependent torque, hysteresis, time and torque tracking control responses were examined. The results showed that with the exception of the settling time, the other response times were faster than those of the pristine CI based MR fluid.