Investigation on sedimentation, magnetization, and polishing characteristics for magnetorheological shear thickening polishing fluids

Magnetorheological shear thickening polishing (MRSTP) has garnered significant attention in the field of ultra-precision polishing. However, current studies have primarily concentrated on the rheological properties of MRSTP fluids (MRSTPFs) and their application in polishing planar workpieces. The study investigated the sedimentation behavior, magnetization property of MRSTPFs, and their polishing performance on ring-shaped silicon carbide ceramic. The MRSTPFs were prepared by blending diamond particles, carbonyl iron particles, and a carrier fluid consisting of polyethylene glycol 200 and silicon dioxide. MRSTPFs with higher concentration of carrier fluid exhibited superior resistance to sedimentation. Specifically, the MRSTPFs with carrier fluid concentrations of 15 % and 20 % showed sedimentation ratios of 4 % and 2 %, respectively, after 49 days. The magnetic hysteresis loop of MRSTPFs revealed excellent magnetic stability and minimal hysteresis loss. The coercive force, remanence, and saturation magnetization were 6 Oe, 0.16 emu/g, and 43 emu/g, respectively. Furthermore, polishing experiments were conducted on ring-shaped silicon carbide ceramic using various polishing parameters, including feed rate, tool rotation speed, diamond particle size, and working gap. Under the optimal polishing parameters, the surface roughness was significantly reduced from 767 nm to 37 nm, indicating a remarkable improvement in surface quality. This study provides valuable insights into the fundamental characteristics of the MRSTPFs and highlights their significant potential for applications in ultra-precision polishing.