Portugaliae
Electrochimica Acta

DBS corrosion resistance effect on MS immersed in a 0.25 mol/L sulphuric acid (H2SO4) solution has been evaluated at room temperature, using WL method, from which CR and IE(%) were obtained. The corrosion IE% increased with higher inhibitor concentrations. The CR decreased with higher DBS concentrations, since it blocked the MS active site, forming a protective film on its surface, which was confirmed by electrochemical studies and surface analysis techniques, such as FTIR and SEM. EDAX was used to analyze the elements present on the MS surface, after its immersion in 0.25 mol/L H2SO4, without and with DBD. The MS surface smoothness and roughness (polished and corroded) and the inhibitor have been evaluated by SEM and AFM. Keywords: AFM, corrosion, DBS inhibitor, H2SO4, MS, SEM and WL.

In continuation of our previously published work entitled Mechanical and Corrosion Behavior of Inconel 718 Nickel-Based Super Alloy Doped with Graphene Nanoplatelets, the present study investigated the tribological performance of modified IN 718 doped with GrNs. Friction and wear properties were analised using an advance universal tribometer, while surface mophologies were studied by SEM. The modified SA tribological properties validation was done in relative comparison to those of pure IN 718. Mechanical properties with higher , younger modulus values, better morphologies, higher AWI, lower SWR and µ values were noted on the modified IN 718. Nonetheless, an increase in the load proved to affect the tribological oxide layer properties of both pure and modified IN 718. Keywords: pure and modified IN 718, GrNs, frictional wear, tribology and SEM.

DESs, as new-generation room temperature ILs, are very promising to perform anodic processing of different metals and alloys. We report Ni-Cu alloy (45 wt.% Ni) anodic treatment in a DES, ethaline, for the first time. It is shown that the anodic dissolution originated the formation of sparingly soluble Ni and Cu chloride salts in the near-electrode layer. Ni-Cu alloy anodic treatment in ethaline resulted in changed patterns of the metallic surface morphology. Depending on the applied electrode E, star like crystallites, with sharply pointed shapes and thorns, may appear on the anodically etched surface, and surface morphology smoothing was observed, in some cases. The Ni-Cu alloy anodic processing in ethaline, which dramatically changed its surface morphology, contributed to a considerable increase in the electrocatalytic activity towards HER in an alkaline medium. Considering favorable environmental aspects of DES use and marked improvement in electrocatalytic properties, this treatment can be further used to develop high-efficient, eco-friendly and relatively inexpensive electrocatalysts methods for water electrolysis within H2 energy concept. Keywords: Ni-Cu alloy, anodic processing, ethaline, hydrogen production electrocatalysis.

Welding has been an incredibly important process used to join metals in several industrial applications, such as manufacturing, construction, automotive and aerospace sectors. It has been reported that welded joints sometimes exhibit poor corrosion resistance, due to the changes in the weld surface or HAZ chemical composition, residual stress and metallurgical structure. Therefore, there is a need to enhance welds corrosion resistance and microstructure properties through PWHT. In this study, PWHTs effect on the corrosion and microstructure properties of two MSs, SAE 1015 and 1010, which were fused by electric metal arc welding, was examined. The MS samples, with different chemical compositions, were cut to the desired dimensions, separately welded and, thereafter, subjected to PWHT, at 650, 750, 850 and 950 ºC, for 1 h. The corrosion and microstructure properties of the PWHT MS samples immersed in 3.5 wt.% NaCl were then investigated, using PDP and SEM, respectively. For the PWHT SAE 1015 and 1010 MS samples, the lowest CR values were 34.240 and 35.793 mm/year, at 650 ºC, while the highest were 90.16 and 60.10 mm/year, at 950 ºC, respectively. For the AW SAE 1015 and 1010 MS samples, the CR values were 107.54 and 118.09 mm/year, respectively. The SEM images revealed smaller grain sizes and boundaries and less porosity for PWHT MS samples at 650 ºC than for those at 950 ºC. Therefore, the first ones are recommended for advanced industrial applications. Keywords: AW MS, corrosion, microstructure, MS SAE 1015 and 1010, PWHT and welding.

Due to its highest gravimetric energy density, H2 has been regarded as the preferred clean-energy carrier, with potentially environmentally-friendly production through the solar-assisted WS. Since human activities generate enormous amounts of WW, H2 production from this new resource has gained attention as an emergent technology. This paper addresses the most relevant and current aspects of H2 production from WWEL, and electricity generation from RES. In this sense, the state of art of H2 production, especially from WS, is presented here, as well as the main approaches to electricity generation from RES, with the greatest potential for viability. A new approach on this matter, which is part of the work that is being developed by the authors of this study, was also herein presented. Keywords: WW, water, electrolysis, H2 and RES.