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Artigo IPEN-doc 30179

Study of the effect of nanosecond laser texturing on the corrosion behavior of Ti6Al4V and Ti6Al4V parts produced by powder bed fusion

2023 - QUEIROZ, FERNANDA M.; RIBEIRO, GLEICY de L.X.; CASTRO, RENATO S. de; SANTOS, ROGERIO G. dos; VIEIRA, ALEXANDRE; TERADA, MAYSA; BUGARIN, ALINE de F.S.; ROSSI, WAGNER de; COSTA, ISOLDA

Combining metallic additive manufacturing with laser texturing could be an alternative in obtaining parts with functional hydrophilic surfaces, which improves osteointegration. Careful study of the corrosion behavior of the surfaces obtained is necessary, because the evolution of this phenomenon can influence the osteointegration of the implant, causing the release of metal ions in the body and even the rejection of the component. This study compared the corrosion behavior of laser texturing Ti6Al4V components with components manufactured using laser power bed fusion of the same alloy followed by laser texturing. Their microstructure, roughness, wettability, and electrochemical behavior were analyzed, and different morphologies and microtopographies were observed comparing both samples. The electrochemical tests obtained indicate that Ti6Al4V showed higher corrosion resistance than L-PBF Ti6Al4V after laser texturing. The results suggest that laser texturing can encourage cell proliferation and osseointegration on the surface of Ti6Al4V biomedical implants.

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Artigo IPEN-doc 30180

Dysprosium optogalvanic spectroscopy in a hollow cathode lamp

2023 - SANTOS, JHONATHA R. dos; BUENO, PATRICIA; JAKUTIS, JONAS; VICTOR, ALESSANDRO R.; BARRETA, LUIZ F.N.; SBAMPATO, MARIA E.; NERI, JOSE W.; SILVEIRA, CARLOS A.B.; RODRIGUES, NICOLAU A.S.; DESTRO, MARCELO G.

This work presents data obtained from optogalvanic spectroscopy (OGS) of dysprosium (Dy) using a commercial hollow cathode lamp. Combining laser beams from two tunable dye lasers, it was possible to identify 13 electronic transitions from excited states of the atom not observed or registered in published papers and the NIST database; these lines were observed between 555–575 nm and 585–615 nm. The study of 13 two-step transitions found in this work complement the available data for the Dy which may support other research or any work using this atom.

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Artigo IPEN-doc 30178

Photoelectrochemical conversion of glycerol aqueous solution to value-added chemicals using Bi2Fe4O9 as a photoanode

2023 - SILVA, BRUNO L. da; CARMINATI, SAULO A.; SOUZA, MATHEUS B.C.; SOARES, LEONARDO C.; LONGO, CLAUDIA; FERNANDEZ, PABLO S.; NOGUEIRA, ANA F.

A low-cost, stable and non-toxic Bi2Fe4O9 (BFO) photoanode was used for the first time to promote glycerol aqueous solution photoelectrochemical conversion to hydrogen and value-added chemicals. Photoelectrochemical measurements were performed under AM1.5G irradiation using a three-electrode cell. The best performance was achieved in alkaline medium, where four distinct glycerol oxidation products were detected (glycerate, formate, glycolate and lactate). In neutral medium, no oxidation products were detected. In acidic medium, we observed an improved selectivity, with only glyceraldehyde and dihydroxyacetone as oxidation products. Our results show that the electron–hole recombination, which restricts the efficiency of glycerol conversion, is one of the main shortcomings of BFO. However, its high open circuit potential (OCP) value and several other desirable properties for a good photoelectrocatalyst make it a material worth further research.

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Artigo IPEN-doc 30177

Impact of He+N2 concentration on self-modulated laser wakefield acceleration driven by pulses of a few TW

2023 - MOLDONADO, EDISON P.; SAMAD, RICARDO E.; ZUFFI, ARMANDO V.F.; SANTOS, JHONATHA R. dos; VIEIRA JUNIOR, NILSON D.

Laser wakefield electron acceleration with ionization injection has rarely been studied in the low-power, selfmodulated case. We performed simulations of such regimes using a mixture of He and N2 gases and driven by laser pulses with peak powers around 1 TW. Analyses show the generation of electron bunches with an average energy of up to 70 MeV, an energy spread as low as 18%, and an emittance as good as a fraction of a mm mrad. The obtained electron beam parameters lead to several trade-offs as a function of N2 concentration, allowing for many different designs.