Experimental Study on Halbach Array-based Magnetic-field-assisted Shear Thickening Polishing of Zirconia Ceramics
Zirconia (ZrO2) ceramics are extensively utilized in aerospace, automotive, and biomedical sectors due to exceptional mechanical properties and favorable biocompatibility. However, inherent high hardness and brittleness pose significant challenges for conventional polishing tools in achieving effective surface removal. This study proposes a Halbach-array magnetic-field-assisted shear thickening polishing (HMSTP) method to achieve high-efficiency, low-damage, and low-cost precision polishing of ZrO2 ceramics. Magnetic-field rheological tests were conducted on magnetic shear thickening slurries prepared with carbonyl iron powder at different mass fractions. A slurry containing 4% carbonyl iron powder at a magnetic induction of 150 mT was selected as optimal, demonstrating the most pronounced synergistic enhancement between magnetorheological and shear thickening properties. The Halbach array magnetic field was designed comprising 11 magnets, characterized by a maximum magnetic induction of 192 mT and uniform central distribution. Experimental measurements confirmed an average magnetic induction of 150.2 mT, consistent with simulation. Polishing experiments revealed that increased polishing speed enhances shear rate and material removal rate (MRR), while excessive or insufficient polishing angle impairs slurry flow. Workpiece rotation ensures uniform force distribution but excessive rotation speed diverts slurry, weakening shear thickening. After 60 min of HMSTP, surface roughness (Ra) decreased from 601 nm to 11 nm, and MRR reached 7.26 μm/h. Compared to conventional shear thickening polishing without magnetic field, Ra was reduced by 85.6% and MRR increased by 1.33 times. The HMSTP method effectively improves surface quality and material removal rate of zirconia ceramics, achieving efficient, low-damage, and low-cost processing.