Fabrication of uniform core-shell structural calcium and titanium precipitation particles and enhanced electrorheological activities

A simple co-precipitation route was developed to synthesize uniform core-shell structured calcium and titanium precipitation (CTP) particles with ideal morphology and no aggregation. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and interface tension/contact angle (CA) measurement were utilized to characterize the components, structure, morphology, and wettability of the SiO2-CTP materials. The obtained core-shell structural SiO2-CTP particles were well dispersed spherical nanoparticles with a narrow size distribution. The electrorheological (ER) properties were studied by the shear stress under various electric fields. The SiO2 (2.3 wt%)-CTP ER fluid showed notable ER activity with a shear stress of about 109 kPa (at 5 kV mm(-1)), which outclassed the shear stress (65 kPa) of the CTP ER fluid. The ER properties of samples can be tuned by a few factors in the experimental process, such as the concentration of SiO2 particles and citric acid, pointing out the great potential for application of this route in bulk synthesis of many other types of ER materials.