Corona discharge assisted polishing with composite abrasives for silicon nitride bioceramics: Material removal modeling, surface morphology and wettability

ABSTRACT Bioceramics are widely used in orthopedic and dental implants, where surface morphology and wettability are critical for osseointegration and bone healing. This paper proposes a novel corona discharge-assisted polishing (CDAP) method using composite abrasives, which is integrated into a CNC machine tool to generate in-situ corona discharge during polishing. This method simultaneously generates micro/nano-scale grooves and pits on the surface and improves its hydrophilicity. The electrohydrodynamic characteristics of the corona discharge ionic wind were revealed through tests and simulations, with an error of less than 4%. Three-dimensional surface morphology and roughness were simulated with a relative error of less than 2.6%, comprehensively considering the pad’s stress-strain behavior, multi-scale contact mechanics, nanoindentation data, and the Bresenham algorithm. Experimental and simulation results indicate that the effects of process parameters are directional for both surface roughness and contact angles. Feed speed has the greatest impact on both roughness and contact angle, with contribution ratios of 75.96% and 50.68%, respectively. Applied voltage contributes 23.85% to the contact angle. A minimum contact angle of 37.5° was achieved at a voltage of 11 kV. This work offers a potential, efficient, and environmentally friendly solution for the surface treatment of bioceramics, as well as a multi-scale, multi-field coupling perspective for an in-depth understanding of surface formation and wettability regulation. The lack of biocompatibility evaluation and the insufficient intensity of corona discharge are limitations of this work, which will be addressed in future research.