Effect of corroded plate-like iron particles on the rheological properties of magnetorheological elastomer

Abstract

Prior studies have shown that the storage modulus and MR effect of MR materials were mainly determined by the performance of magnetic particles. However, there is still doubt for its utilization in a long-term operation under various external loads and conditions. In MREs, even though the magnetic particles are embedded in an elastomeric matrix and not exposed to the air, corrosion agents however such as moisture and oxygen can penetrate the structure phase and alter their properties. This corrosion phenomenon can significantly affect the performance of MRE devices. In this work, the effect of corroded plate-like carbonyl iron particles (CIPs) on the properties of magnetorheological elastomer (MRE) is investigated. The CIPs are corroded via accelerated corrosion test in various concentrations of diluted hydrochloric acid; particularly 0.5, 1.0 and 1.5 vol.% HCl. The morphology of non-corroded and corroded plate-like CIPs are characterized via SEM prior to fabrication of MREs. The rheological properties of MREs are tested using a rheometer under varying applied currents and frequencies. The results from SEM images show that the sample of non-corroded plate-like CIPs has a smooth surface structure while the corroded plate-like CIPs looked rougher on its surface structure. The storage modulus of MRE is increased with the increased of frequencies but decreased with MRE containing higher corrosion rates. Similarly, the MR effect are decreased from 90.6% for MRE containing of non-corroded plate-like CIP, to 87%, 81.8%, and 71.8%, respectively with increasing of corrosion rate plate-like CIPs in MRE. The obtained results demonstrate that higher purity of the CIPs, the greater the impact on storage modulus and MR effect of MRE. Hence, significant finding of this research is related to the purity of CIPs that play an important role to ensure the continuous reliable performance of MRE devices for long-term applications.