Characterization of a multilayer coating (Ni-P plus DLC) applied on PBF-LB AlSi10Mg components with complex geometries and lattice structures

AlSi10Mg alloy lattice structures produced by Powder Bed Fusion- Laser Beam (PBF-LB) technology show high specific strength and an optimal surface/volume ratio. However, in the as-built condition they are characterized by a high roughness that may worsen their performance. To address this issue, a multilayer coating consisting of (i) electroless Ni-9%P interlayer, to compensate surface defects and optimize the surface topography, and (ii) PA-CVD hydrogenated amorphous carbon (DLC a-C:H) topcoat was deposited. The features of the coated system were evaluated by: (i) optical profilometry, (ii) FEG-SEM/EDS observations, (iii) micro/nanoscale hardness tests, and (iv) scratch test. Based on the results, the main problems related to the deposition of the Ni-P + DLC multilayer coating on the PBF-LB AlSi10Mg critical components were identified, in order to optimize the whole post-printing cycle and guarantee adequate performance of the multilayer coating.