Search

Most existing methods for additive manufacturing (AM) of metals are inherently limited to ~20–50 μm resolution, which makes them untenable for generating complex 3D-printed metallic structures with smaller features. We developed a lithography-based process to create complex 3D nano-architected metals with ~100 nm resolution. We first synthesize hybrid organic–inorganic materials that contain Ni clusters to produce a metal-rich photoresist, then use two-photon lithography to sculpt 3D polymer scaffolds, and pyrolyze them to volatilize the organics, which produces a >90 wt% Ni-containing architecture. We demonstrate nanolattices with octet geometries, 2 μm unit cells and 300–400-nm diameter beams made of 20-nm grained nanocrystalline, nanoporous Ni. Nanomechanical experiments reveal their specific strength to be 2.1–7.2 MPa g−1 cm3, which is comparable to lattice architectures fabricated using existing metal AM processes. This work demonstrates an efficient pathway to 3D-print micro-architected and nano-architected metals with sub-micron resolution., Most current methods for additive manufacturing of complex metallic 3D structures are limited to a resolution of 20–50 µm. Here, the authors developed a lithography-based process to produce 3D nanoporous nickel nanolattices with octet geometries and a resolution of 100 nm.

International audience; The behaviour of the 6% aluminium-magnesium alloy (AM60) surface in zirconium or titanium fluoride aqueous acid solutions was studied. X-ray photoelectron spectroscopy was used to investigate modifications in the surface chemistry with respect to the composition of the surface treatment solution. The surface film is composed of magnesium hydroxide and hydroxyfluoride, zirconium oxide, oxyhydroxide or oxyfluoride, titanium oxide and structural and adsorbed water. Optimal parameters leading to the formation of a zirconium- or titanium-rich film were determined. A mechanism is proposed for the formation of zirconium- or titanium-based films.

International audience; The behaviour of the 6% Al magnesium alloy AM60 in aqueous acid fluoride solutions was studied in situ by electrochemical techniques and the surface chemistry of the resulting film was examined by monochromatized XPS. The evolution of the corrosion potential and cyclic voltammograms showed that the aggressiveness of the solutions is mainly driven by their fluoride concentration, the pH having almost no detectable influence. The more concentrated and acidic fluoride solutions led to a higher degree of fluoride coverage of the surface. The surface film is composed of magnesium hydroxide and hydroxyfluoride Mg(OH)2−xFx which approaches MgF2 with increasing fluoride concentration in the film. The parameters governing the film evolution and their relation to surface reactions are discussed.

International audience; Electrochemical rest potential and cyclic voltametry were used to investigate the behaviour of the 6% Al magnesium alloy AM60 in various zirconium or titanium fluoride aqueous acid solutions. These solutions have a wide range of aggressiveness with respect to AM60 due largely to fluoride concentration and in some cases to their highly acidic nature. The morphology and composition of the resulting film have been determined by Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDX). The film nucleation is promoted by a pH increase due to water reduction and is thus more likely to occur on the cathodic parts of the surface. Correlatively, film formation on the anodic primary solid solution occurred in only one solution.

NH4[VO3] reacts with aqueous polysulfide solutions in the presence of 4,4′-bipyridine to yield the tetranuclear anion [V4S20O4]6– which contains four bipyramids connected via a zigzag S42– bridge.