Quasi-Dry Electrochemical Mechanical Polishing Method of Additively Manufactured Parts

Selective laser melting (SLM) of TC4 titanium alloy inevitably introduces surface defects including spheroidized particles, adhered powders, and microcracks, resulting in high roughness and poor flatness that prevent direct service. Electrochemical polishing (ECP) is suitable for complex curved surfaces, yet conventional immersion ECP consumes substantial acidic electrolytes, leading to waste and pollution. To overcome this, we propose a quasi-dry electrochemical mechanical polishing (Q-DECMP) method. Millimeter-scale abrasives serve as carriers, and an ethylene glycol-based NaCl electrolyte is coated onto the abrasive surfaces at an electrolyte-to-abrasive mass ratio of 1:20, existing only as a trace liquid film instead of immersing the workpiece. Owing to their high viscosity and capillary forces, a stable conductive liquid film forms on the abrasives. Since the abrasive size (2 mm) is larger than the microscopic peak-valley height of the SLM surface, the film-covered abrasives preferentially dissolve the peaks while the valleys remain unattacked, achieving selective leveling. Experiments performed at 200 V, 1 m/s linear velocity, and 6.5 mm interelectrode gap for 40 min show that Ra decreases from 6.89 to 0.77 μm (88.8% reduction) and material removal rate reaches 612.5 μg/min, outperforming pure mechanical polishing (Ra 4.98 μm, MRR 220 μg/min). With minimal electrolyte usage, this method reduces electrolyte consumption compared with conventional immersion electrochemical polishing, enabling efficient and low-loss finishing.