Electrochemical magnetorheological finishing for hard-to-machine functional materials with nanometer-scaled surface roughness

WC-Co cemented carbide (WC-Co) is widely used in micro/nano-manufacturing owing to its excellent chemical stability, high-temperature resistance, and stiffness. Yet, its significant hardness and wear resistance make machining a challenging endeavor. In response, this study explores electrochemical magnetorheological finishing (ECMRF), a method combining magnetorheological finishing (MRF) and electrochemical mechanical polishing (ECMP). ECMRF demonstrates an encouraging increase in material removal rate (MRR), achieving up to 92.0 nm/min, compared to the 16.7 nm/min of conventional MRF. This improvement is largely due to a surface loosening effect on WC, facilitated by an oxide layer from surface electrooxidation. Furthermore, ECMRF shows a potential to enhance the convergence of surface roughness (Sa), at a rate significantly faster than traditional MRF. Post-polishing analyses indicate the WC workpiece remains chemically intact, without surface or subsurface damage. The process effectively reduces the Sa from 87.2 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.