Wire Arc Additive Manufacturing (WAAM) surfaces exhibit heterogeneous microstructures and oxide layers which might influence coating deposition and interfacial properties. The influence of electrophoretic deposition chemistry on coating structure, coating architecture, and electrical properties of WAAM-fabricated nickel-based superalloys still lacks sufficient understanding. In this study, conventional electrophoretic deposition (EPD) and sol-gel derived electrophoretic deposition techniques were employed for ZnO coating deposition on WAAM-fabricated Inconel 625 superalloys. ZnO coatings were deposited at 10 V for 1 min and then subjected to heat treatment at 600°C for 1 h. The structural and morphological properties of ZnO coatings were studied using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy while the electrical properties were studied using a Wheatstone bridge circuit. The crystalline nature of ZnO coatings was observed for both conventional and sol-gel derived EPD routes; however, differences in coating structure and compactness were observed. Conventional EPD route exhibited a coating porosity of 14.2 ± 1.5% and coating thickness of 1.4 ± 0.2 µm while sol-gel derived EPD route exhibited a coating porosity of 3.8 ± 0.6% and coating thickness of 0.92 ± 0.18 µm. The Zn/(Ni + Cr) ratio was observed to increase from 0.62 to 3.23, indicating better coating coverage for sol-gel derived EPD route coatings. The conductivity of Inconel 625 was observed to reduce by 10.5% for conventional electrophoretic deposition route coatings and 7.2% for sol-gel electrophoretic deposition route coatings. The suspension chemistry was observed to influence coating compactness, coating structure and interfacial electrical properties of WAAM-fabricated Inconel 625 superalloys. Sol-gel derived EPD route coatings exhibited better homogeneity and electrical stability for ZnO coatings.
Doruk Gürkan (2026) studied this question.