Challenges and Mitigation Strategies for Chromium-Free Electroless Nickel Plating on as-Printed ABS Surfaces Manufactured by 3D Printing

The metallization of complex 3D-printed polymer components presents distinct challenges, especially when attempting to replace environmentally harmful chromium-based processes with chromium-free alternatives. This study investigates the application of chromium-free electroless nickel (EN) coatings on intricate as-printed acrylonitrile butadiene styrene (ABS) parts produced by fused deposition modeling (FDM) without sanding or other mechanical surface preparation. While traditional chromium-based activation effectively enhances adhesion, it raises significant environmental concerns, leading to the exploration of palladium chloride-based activators. However, coating as-printed parts without prior surface sanding introduces several significant challenges. Pronounced layer lines, surface roughness, and recessed geometries limit the uniform penetration and effectiveness of activation solutions, resulting in weak mechanical interlocking and low surface energy. Consequently, adhesion remains poor, as evidenced by consistent 0B ratings in ASTM D3359 cross-hatch tests. Surface analyses using EDX, FTIR, and SEM confirmed that nickel deposition occurs but also revealed persistent issues, including delamination, peeling, and non-uniform coatings, particularly in recessed or intricate areas. These results demonstrate that chromium-free activation alone is insufficient to achieve robust and durable metallization on native 3D-printed surfaces without sanding. Although future research may improve outcomes through advanced surface modification techniques and process optimization, significant challenges remain in achieving uniform, reliable coatings while maintaining environmentally sustainable practices.