Magnetorheological elastomers (MREs) are widely used in vibration control due to their excellent magneto-controlled mechanical properties. In this research, polyurethane-based MRE polishing pads were prepared and used for the polishing of single-crystal SiC to investigate the magneto-controlled mechanical properties, the magneto-polishing effect, and the mechanism of action thereof. The results show that the pre-structuring process is affected by parameters such as mass fraction and particle size of magnetic particles in MREs and curing magnetic field strength, different chain strings that demonstrate different magnetorheological effects are formed. The greater the mass fraction of magnetic particles and curing magnetic field strength, the more the MREs exhibit magnetorheological effects, especially so when the magnetic particles size of 3 μ m. A series of 90 min polishing experiments on single-crystal SiC with original surface roughness ( R _a ) 80 nm were conducted using an MRE pad. The results indicate that with the increase of polishing magnetic field strengths, the shear modulus of MRE polishing pads increases, the material removal rate (MRR) of the polishing process increases and R _a decreases. As the magnetic field strength is increased from 0 mT to 335 mT, the shear modulus is increased from 1.392 MPa to 1.825 MPa (an increase of 31.1%), while MRR is increased from 706.3 nm h ⁻¹ to 835.3 nm h ⁻¹ (an increase of 18.3%), R _a is decreased from 19.92 nm to 3.62 nm (an improvement in surface quality of 81.8%). The results show that the increase of the polishing magnetic field strengths changes the material modulus of the MRE polishing pads, which cause the decreases in the compressive and shear elastic deformation of the abrasive grains on the elastic substrate. This increases the positive pressure of the abrasive grains on the SiC wafer, which enhances the material-removal ability of the SiC wafer, thereby improving the surface quality of the wafer.

A water-based high catalytic activity magnetorheological chemical finishing fluid (HCAMRCFF) was prepared and modified to enhance the chemical action strength in magnetorheological chemical finishing (MRCF) for single-crystal SiC. The fluid consisted of ferroferric oxide (Fe₃O₄) and chromium (Cr), deionized water (DW), polyethylene glycol (PEG) and oleic acid, and hydrogen peroxide (H₂O₂) as the composite catalyst particles, base carrier liquid, surfactants, and oxidant, respectively. HCAMRCFFs with different component concentrations were used to modify via evaluating their catalytic activity. Moreover, the MRCF experiments on SiC were conducted using the prepared HCAMRCFFs. The results show that the catalytic activity increases with an increase in the oxidant concentration. Furthermore, composite catalysts and composite surfactants can significantly improve their catalytic activity. The catalytic activity also increases with an increase in the concentration of composite catalysts. In the composite catalysts, increasing the Cr concentration can significantly enhance the catalytic performance. Composite surfactants can exert the relative superiority to enhance the catalytic activity. Compared with the unmodified finishing fluid, the catalytic activity of modified HCAMRCFF increases by 65.4%; the material removal rate (MRR) of SiC increases by 72.5% up to 635.621 nmh⁻¹, and a surface with a roughness of 0.33 nm is obtained.