Plasma Electrolytic Polishing Techniques for Metal Surface Enhancement

Plasma electrolytic polishing (PEP) is an advanced surface‐finishing method that employs controlled electrical discharges in an electrolytic bath to generate a gaseous plasma envelope at the metal–electrolyte interface. Within this envelope, material removal occurs through a combined action of micro‐arcing, electrochemical dissolution and thermal effects, yielding exceptionally smooth surfaces with minimal mechanical stress. The absence of abrasive contact and the use of benign aqueous solutions confer ecological and economic advantages over conventional mechanical or acid‐based electrochemical polishing. Recent technological refinements have focused on waveform modulation, multi‐stage processing and inline metrology to enhance process stability, control removal rates and tailor surface topography. PEP has demonstrated particular utility for near-net‐shape components produced by additive manufacturing or wire electrical discharge machining, where geometrical complexity renders traditional finishing techniques impractical. Applications span aerospace superalloys, stainless biomaterials, medical implants and internal pipe surfaces, reflecting its global significance for corrosion resistance, fatigue life extension and fluid‐dynamic performance. Ongoing research integrates multiphysics simulation with experimental metrology to predict roughness evolution and optimise processing parameters across diverse alloys and geometries.

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Plasma Electrolytic Polishing Techniques for Metal Surface Enhancement publication trend

The graph below shows the total number of articles in plasma electrolytic polishing techniques for metal surface enhancement across all publications each year (not limited to Nature Index journals).

Technical terms

Plasma electrolytic polishing (PEP): A finishing technique that uses high-voltage electrical discharges in an electrolyte to form a plasma layer, enabling material removal and surface smoothening without abrasive contact.

Electrolyte: An aqueous solution containing ions that conducts current and fosters plasma formation at the workpiece surface under applied voltage.

Near-net fabrication: Manufacturing processes that produce components close to their final geometry, minimising subsequent machining or finishing requirements.

Surface roughness (Ra, Sa, Sz): Quantitative metrics describing average or peak‐to‐valley deviations of a surface’s profile, used to assess the quality of polished finishes.

Unipolar-polarisation waveform: A voltage modulation strategy combining pulsed unipolar peaks with constant potential to balance high removal rates and fine surface quality.

References

1. Enhanced surface finishing of selective laser melted 17-4PH steel by a novel two-step electrolyte plasma polishing process. Materials Today Communications (2025).
2. Pulsed Unipolar-Polarisation Plasma Electrolytic Polishing of Ni-Based Superalloys: A Proof of Conception. Chinese Journal of Mechanical Engineering (2024).
3. Mechanism and technological opportunity of plasma electrolytic polishing of metals and alloys surfaces. Applied Surface Science Advances (2020).
4. Process Understanding of Plasma Electrolytic Polishing through Multiphysics Simulation and Inline Metrology. Micromachines (2019).
5. Electrolytic Plasma Polishing of Pipe Inner Surfaces. Metals (2017).
6. Plasma Electrolytic Polishing—An Ecological Way for Increased Corrosion Resistance in Austenitic Stainless Steels. Materials (2022).