EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Additively manufactured (AM) porous metal and polymer materials were coated using thermal and plasma-enhanced (PE) Atomic Layer deposition (ALD). Structures were plates, lattice cells with a mesh size between 0.5 and 1.5 mm and random porous with a pore size between 1 and 2 mm. Applied AM methods were laser-beam powder-bed fusion (LB-PBF), material extrusion bonded by thermal reaction (MEX-TRB, fused deposition modelling, FDM) and material jet modelling with curing by ultraviolet light exposure (MJM-UV). The structures were printed from stainless steel 316L and titanium alloy Ti-6Al-7Nb powder, ULTEM 1010 biocompatible thermoplastic filament and MED610 acrylic resin (Stratasys Ltd.). Titanium oxide, zinc oxide and zirconium oxide coatings with a film thickness between 13 and 43 nm (measured on (100) silicon wafers) were applied on the structures by thermal and PE-ALD.
Film thickness, structure, chemical composition and homogeneity were characterized by numerous methods including stylus profilometry, atomic force microscopy (AFM), X-ray fluorescence (XRF), X-ray reflection and diffraction (XRR, XRD), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, Raman spectroscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).
The oxide coatings could be deposited on the surface and internal parts of 3D-printed substrates, on and in high aspect ratios and porous and mesh structures. However, delaminated coating fragments, and relatively high titanium and zinc concentration ranges suggests lower adhesion energies for coatings on the polymeric substrates. This could be explained by substrate dependent growth mechanisms, forming stronger chemical and weaker physical bonding and mixtures of both. Potential applications of these coatings are for example improvement of biological responses for implants or improved efficiency in fuel cells for power production.