Investigation of HVOF-sprayed WC-based coatings on 3D-printed Al-Mg-Sc to improve corrosion and wear performance

A critical issue for the application of SLM-fabricated Al-Mg-Sc alloys in marine environments is their insufficiency of wear and corrosion resistance. In this study, two kinds of WC-based protective coatings, including WC-12Ni and WC-20Cr₃C₂-7Ni, were deposited onto the surface of a 3D-printed aluminum alloy matrix via HVOF spraying process to simultaneously improve the corrosion and wear resistance. To systematically investigate the correlation between thickness and performance, each coating was fabricated at three distinct thickness levels (100, 200, and 300 μm). The corrosion resistance of both coatings was evaluated through electrochemical analyses, specifically electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, whereas their wear resistance was quantified using ball-on-disc dry sliding wear tests. After identifying 200 μm as the optimal thickness for both coating series, the post-corrosion and post-wear microstructural evolution of the corresponding specimens was characterized using SEM, XRD, XPS, and 3D profilometry to study the underlying enhancement mechanisms for WC-Cr₃C₂-2 coating induced by Cr₃C₂ incorporation. The result reveals that the Cr₃C₂ addition improves corrosion resistance by simultaneously refining the WC grain structure during deposition and promoting denser passive layer formation. Meanwhile, the fine-grained structure and interphase cohesion in WC-Cr₃C₂-2 coating can inhibit particle dislodgement, thereby enhancing its wear resistance. In conclusion, this study additionally provides novel research approaches into the surface modification of high-strength Al-Mg-Sc alloys produced through SLM technique.