LAUSR

Abstract Micro-arc oxidation (MAO) ceramic coatings were prepared on porous AlSi10Mg selective laser-melted components to improve their corrosion property. The microstructure and composition of the coatings at different processing times were characterized via scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. Results showed that the diameter of micro-pores increased with an extension of treatment time, the porosity of coatings decreased from 6.24% to 0.85%. Thickness increased from 4.45 ± 0.01 μm to 15.20 ± 0.01 μm and surface roughness increased from 0.76 ± 0.01 μm to 5.41 ± 0.01 μm with increasing processing time. Meanwhile, the coatings were mostly composed of γ-Al2O3 and trace amounts of α-Al2O3, Al2SiO5, AlPO4 and WO3, the content of α-Al2O3 was increased from 0.51% to 4.12%. Corrosion current density decreased from 2.213 e−5 A·cm−2 to 1.088 e−7 A·cm−2. The polarization resistances Rb were increased from 4.8 × 103 Ω·cm2 to 2.6 × 105 Ω·cm2. The long term EIS results show that Rb was 7.7 × 103 Ω·cm2 after 3 weeks immersion, which show that the MAO coatings could provide good protection on AlSi10Mg alloy. The gas holes and defects of the SLM components were treated via MAO to form uniform MAO coatings on the surface of a sample, expanding the application range of selective laser-melted components in corrosive environments.