Experimental investigation on magnetorheological shear thickening polishing characteristics for SiC substrate

Silicon carbide (SiC) substrates are widely used in semiconductor and photoelectric applications due to excellent electrical and chemical properties. However, due to its inherent hard-brittle properties and chemical inertness , traditional polishing processes are facing great challenges to obtain excellent surface and subsurface quality for the SiC substrates. In this work, a novel polishing process i.e. magnetorheological shear thickening polishing (MRSTP) was proposed to explore the feasibility for the polishing of the SiC substrates. The MRSTP experiments were conducted using multiple magnetic-pole-coupled tools. The magnetic field characteristics of the polishing area were investigated via finite element simulation and actual measurements. The magnetic-pole-coupled tool was capable of generating high magnetic induction strength in the polishing area. The MRSTP medium was designed and prepared. The media were formed magnetic brushes by the excited magnetic field. The MRSTP experiments were conducted to investigate the effects of processing parameters on the polished surface roughness. The optimum process parameters were determined as the spindle rotational speed of 700 rpm, the feed rate of 600 mm/min, the work gap of 0.5 mm and MRSTP media CIPs particle size of 100 μm. The surface roughness of the workpieces was improved from initial 1.414 μm to 27.6 nm. It is verified that the MRSTP is the feasible ultraprecision polishing process for the SiC substrates.