Rheology of magnetorheological shear thickening polishing fluids with micro diamond abrasive particles

Abstract

Magnetorheological shear thickening polishing (MRSTP) has the dual effect of shear thickening and magnetization enhancement, thereby enhancing polishing efficiency. MRSTP fluids (MRSTPFs) were prepared using polyethylene glycol (PEG), silicon dioxide (SiO2), carbonyl iron particles (CIPs), and diamond micro-abrasive particles. MRSTPFs containing diamond particles of various sizes were prepared for rheological tests. A rheological hypothesis was proposed regarding the development of CIPs chains and the ability to aggregate PEG and SiO2. Rheological tests results indicated that each sample exhibited shear thickening and magnetization enhancement effects under the magnetic field and shear rate. The shear thickening effect decreased with increasing magnetic flux density, while the overall viscosity and shear stress increased. As the magnetic flux density increased from 0 mT to 112 mT, the thickening ratio of MRSTPFs containing 3 μm diamond particles decreased from 18.94 to 1.37, but the peak viscosity increased from 5.208 Pa·s to 3639 Pa·s. The thickening ratios of MRSTPFs with different abrasive sizes showed a slight variation from 0.11 to 1.76 at the same magnetic flux density of 22 mT, 45 mT, 68 mT, 90 mT, and 112 mT, respectively. It demonstrated that the diamond particle size did not have a significant effect on the rheological properties of MRSTPFs. The correctness of the hypothesis was confirmed. The storage modulus of MRSTPFs exceeded the loss modulus at non-zero magnetic flux density, indicating that the MRSTPFs had become semi-solid. The microscopic mechanism showed that the rheological characteristics were determined by the evolution of the chain structure of CIPs and the binding ability of PEG to SiO2. This study provided valuable insights into exploring mechanisms of MRSTPFs and demonstrating the potential application of MRSTP.