Surface Defect Mitigation of Additively Manufactured Parts Using Surfactant-Mediated Electroless Nickel Coatings

The emergence of defects during the early production phases of ferrous-alloy additively manufactured (AM) parts poses a serious threat to their versatility and adversely impacts their overall mechanical performance in industries ranging from aerospace engineering to medicine. Lack of fusion and gas entrapment during the manufacturing stages leads to increased surface roughness and porosities in the finished part. In this study, the efficacy of employing electroless nickel–boron (Ni-B) deposition to fill and level simulated AM defects was evaluated. The approach to levelling was inspired by the electrochemical deposition techniques used to fill vias in the electronics industry that (to some extent) resemble the size and shape of AM-type defects. This work investigated the use of surfactants to attenuate surface roughness in electroless nickel coatings, thereby achieving the preferential inhibition of the coating thickness on the surface and promoting the filling of the simulated defects. A cationic surfactant molecule, CTAB (cetyltrimethyl ammonium bromide), and a nonpolar surfactant, PEG (polyethylene glycol), at different concentrations were tested using a Ni-B electrolyte for the levelling study. It was found that the use of electroless Ni-B to fill simulated defects on ferrous alloys was strongly influenced by the concentration and nature of the surfactant. The highest levelling percentages were obtained for the heavy-molecular-weight PEG-mediated coatings at 1.2 g/L. The results suggest that electroless Ni-B deposition could be a novel and facile approach to filling defects in ferrous-based AM parts

Mixed-phase titania foams via 3D-printing for pharmaceutical degradation

The continuing accumulation of organic micropollutants, particularly pharmaceuticals, in water is now considered an urgent threat to human health and the environment. Although the photocatalytic degradation of these compounds using slurries of photoactive nanoparticles has been proven to be highly effective at laboratory scale, this technology has not been implemented in industry due to cost and safety concerns. Here, 3D printed titania foams which are nanoparticle-free, mechanically robust and photoactive, are presented for the first time as a viable alternative to slurries for the photocatalytic degradation of pharmaceuticals. By optimizing the resin used to 3D print highly porous gyroid structures and the subsequent sintering conditions, it was possible to obtain a pure titania foam with a high anatase content, leading to the high photoactivity observed. Using carbamazepine, the pharmaceutical most found in waterways around the world, as a model pollutant, the 3D printed foams were tested in a recirculating flow reactor, with a quantum yield and electrical energy per order of 7.6 × 10−3 and 67.6 kW h m−3, respectively, outperforming literature results for titania nanoparticle slurries. These results, along with the reproducibility afforded by 3D printing methods, shows a clear pathway for photocatalysts to be implemented in practice, helping to solve an urgent health problem while addressing the risk of nanoparticulate release in the environment

OXIDAÇÃO ELETROQUÍMICA DOS CORANTES REATIVOS PRETO 5 E AZUL 19 UTILIZANDO UM ELETRODO DE DIAMANTE DOPADO COM BORO NÃO COMERCIAL

We have studied the treatment of Reactive Black 5 (RP5) and Blue 19 (RA19), which are respectively azo and anthraquinone textile dyes, by electrochemical oxidation using a non commercial boron doped diamond electrode supported on titanium metallic with a relation between B and C equal to 15,000 ppm. Pt was used as counter electrode and Ag/AgCl(sat) was the reference electrode. The variables investigated to optimize the degradation were support electrolyte concentration (0.05, 0.1 and 0.2 mol L-1 of K2SO4), temperature (25, 35 and 45 ºC) and pH (2.5 and 10) by applying a current density of 75 mA cm-2. Total decolorization was observed in all electrochemical conditions studied. The highest rates of mineralization and chromatographic area removal were attained at high support electrolyte concentration due to the increase of conductivity, which caused more generation of hydroxyl radicals. RP5 was degraded at lower electrolysis time than RA19 with smaller requirement of electric charge. The mineralization rate increased in acid medium and at higher temperature since the increase in temperature favors the generation reactions of persulfate. These conditions led to the highest levels of current efficiencies and lower energy consumed

Antifungal Properties of High Efficient W/WO3 Electrodes Acting under UV-Vis and Visible Light and Chloride Medium

<div><p>The present work investigates the use of W/WO3 electrodes prepared by electrochemical anodization applied in the photoelectrocatalytic disinfection of Candida parapsilosis using ultraviolet-visible (UV-Vis) and visible irradiation. The core objective of this work lies in describing a novel approach involving the use of chloride as supporting electrolyte, aiming at achieving a faster inactivation and towards understanding its behavior in water containing high chloride content. The best experimental conditions were found to be at pH 7.0 and 0.1 mol L-1 NaCl when the photoelectrode was biased at 1.5 V (vs. Ag/AgCl) illuminated by both UV-Vis and visible light. It is suggested that charges photogenerated on the electrode surface give rise preferably to HO•, known to be powerful oxidant that causes the total inactivation of the microorganism (1 min of treatment) while engendering around 84% of mineralization of organic matter released from the cell damage following 120 min of treatment.</p></div