Quantitative surface roughness analysis of selective masking electrochemical polishing in additive manufactured lattices using a novel X-ray computed tomography based method

Additive manufacturing (AM) has enabled the fabrication of complex lattice structures with unique mechanical properties, making them valuable for applications in biomedical and aerospace industries. However, the inherent surface roughness of as-built AM parts can adversely affect mechanical performance and corrosion resistance, particularly in complex structures like lattices. This study investigates the effectiveness of electrochemical polishing (ECP) strategies using an eco-friendly electrolyte, consisting of 1 mol/L NaCl in ethylene glycol with 20% ethanol, applying selective area masking and varying treatment durations on surface roughness reduction in Ti5553 lattice structures. A novel developed methodology based on X-ray computed tomography (XCT) was employed to quantify roughness parameters across central and edge struts, providing a detailed analysis of roughness evolution by different ECP strategies. Results reveal that ECP with masking enhances surface smoothness in internal struts while minimizing over-polishing in external ones, thereby achieving more uniform material removal across the lattice structure. The proposed eco-friendly approach achieved roughness reductions of up to 57% in central regions, reaching the minimum R_a values between 1.89 µm and 1.73 µm in central and edge areas, while maintaining the geometric integrity of the lattice structure. This study demonstrates the potential of the developed XCT-based roughness analysis for accurately assessing post-processing effects on complex AM structures and provides insights into optimizing ECP techniques for improved surface quality in lattice geometries.