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Ultraprecision Machining of Si3N4 Ceramics with Shear-Thickening Polishing

Shear-thickening polishing (STP) technology was used on ultraprecision machining of Si3N4 ceramics. The STP slurry with diamond abrasives was prepared for STP process and its rheological property was studied. The polishing performance of Si3N4 ceramics with STP was analyzed. Results show that STP slurry with diamond abrasives exhibits non-Newtonian power-law fluid characteristics with shear-thickening effect. As using STP slurry with abrasive particle size of 0.2 μm, the material removal rate changed from 4.22 to 4.05 μm/h after 60 mins ́ polishing; and decreased from 3.88 to 3.75 μm/h after 120 mins ́ polishing. The average surface roughness reduced from Ra 107.2 to Ra 6.5 nm after 120 mins ́ polishing.