Electrochemical Magnetorheological Finishing for Hard-to-Machine Functional Materials with Nanometer-Scaled Surface Roughness

Abstract

Abstract Tungsten carbide (WC) is a widely employed mold material in micro/nano-manufacture industry due to its exceptional attributes, including excellent chemical stability, high temperature resistance, and substantial stiffness. Nevertheless, its formidable hardness and wear resistance pose significant machining challenges. To realize high-quality and high-efficiency polishing, we introduce electrochemical magnetorheological finishing (ECMRF), which combins magnetorheological finishing (MRF) and electrochemical mechanical polishing (ECMP). Because the WC workpiece surface becomes loose rapidly due to the formation of an oxide layer through surface electrooxidation, ECMRF exhibits remarkable material removal rates (MRR) of up to 92.0 nm/min, nearly five times higher than that of conventional MRF (16.7 nm/min). Moreover, ECMRF accelerates the convergence rate of surface roughness (Sa) by a factor of 17 when compared to MRF. More importantly, chemical composition analysis reveals no surface or subsurface chemical damage after an simple additional MRF process, maintaining the pristine state of the WC workpiece. The final Sa is significantly reduced from 87.2 nm to 2.1 nm. This pioneering research underscores the prospect in polishing challenging materials and presents an innovative route to achieve highly efficient surface polishing with nanoscale roughness.