Investigation of the Addition of (NaPO3)6 to Al2O3 Ceramic Coatings Prepared on AlSi10Mg Selective Laser Melted Components via Micro-Arc Oxidation

Al2O3 ceramic coatings were prepared on the surface of AlSi10Mg selective laser-melted components via micro-arc oxidation. The microstructure and corrosion property of the coatings were investigated. Scanning-electron microscopy results indicated that the number of craters on the coatings' surface increased with selective laser-melted energy density. The surface of the coatings became smooth with an increase in (NaPO3)(6) content, and the number of craters decreased. X-ray diffraction and x-ray photoelectron spectroscopy results showed that the coatings were composed of gamma-Al2O3 and alpha-Al2O3. In particular, gamma-Al2O3 content increased and alpha-Al2O3 appeared, surface roughness decreased from 2.22 mu m to 1.21 mu m. Meanwhile, corrosion current density decreased from 3.46e(-006) to 9.71e(-007) A cm(-2) and the corrosion depth decreased from 4.62e(-04) to 1.09e(-05) mm/year. The morphologies of the coatings were influenced by the diameter of keyholes. The small keyholes were enclosed, and the inside of large keyholes formed micro-arc oxidation coatings. The addition of (NaPO3)(6) increased the threshold value for obtaining consistent coatings.

Automated summary

Al2O3 ceramic coatings prepared via micro-arc oxidation on AlSi10Mg selective laser-melted components showed that energy density and (NaPO3)(6) content have significant effects on the microstructure and corrosion properties of the coatings. Changes in coating composition, surface roughness, and corrosion resistance were observed with the increase in energy density and (NaPO3)(6) content.