Effect of Surface Morphology of SLM Printed AlSi10Mg on Adhesion Strength of PUA/AlSi10Mg Interface

In this study, the effect of surface morphology of AlSi10Mg substrates printed by selective laser melting (SLM) on the adhesion strength of polyurethane acrylate (PUA) coatings was investigated. Compared with the mirror-like surfaces formed by mechanical polishing, AlSi10Mg surfaces with honeycomb-like or island-like nanostructures could be formed after alkali or acid etching. PUA was sprayed on the substrate surfaces as an insulation and passivation layer. The adhesion strength of PUA on AlSi10Mg was tested using the pull-off method. The results show that the adhesion strength of the polished samples was only 2.3 MPa, while the adhesion strength of PUA on the alkali/acid etched samples was higher than the tensile strength of PUA (about 15 MPa). The cross-sectional morphology of the PUA/AlSi10Mg interface shows that the nanostructures on the AlSi10Mg surfaces were well wetted and fully filled by PUA. This resulted in a larger contact area and effective mechanical interlocking, greatly improving the bonding strength of the PUA/AlSi10Mg interface. This one-step chemical treatment process can be an effective and efficient method to achieve uniformly improved adhesion between organic polymer coatings and metal substrates. It has great application prospects in additive manufacturing of structure–function integration components or systems with complex three-dimensional structures.