Internal oxidation in dry and wet conditions for oxygen permeability of Fe–Ni alloys at 1150 and 1100 °C

The design of new austenitic alloys based on the Fe–Ni–Cr system requires knowledge of their oxygen permeability. Data are available for pure Fe and Ni but not for Fe–Ni alloys. Wagner’s model for internal oxidation is used to evaluate the oxygen permeability in Fe–Ni alloys. Internal oxidation of Fe–Ni–Cr alloys carried out at 1150 and 1100 °C in Rhines packs and H2/H2O mixtures is described. Internal oxidation produces zones of FeCr2O4 and Cr2O3 precipitates, according to parabolic kinetics. Permeabilities are deduced taking into account interfacial diffusion contributions. Oxygen permeability decreases with nickel addition in a non-ideal way, and oxygen permeability in nickel-rich alloys is independent of the studied environments. However, the oxygen permeability in iron at the highest temperature studied is increased in H2/H2O

Oxygen permeability of Fe-Ni-Cr alloys at 1100 and 1150 °C under carbon-free and carbon-containing gases

Wagner's model of internal oxidation allows the prediction of an alloy's critical concentration of oxide forming metal required to achieve a protective oxide scale at high temperatures. The model depends on oxygen permeability in the alloy, but this parameter has not been evaluated for the Fe-Ni system, and the influence of carbon-bearing gases is unknown. Oxygen permeability measurement by internal oxidation of Fe-Ni-Cr alloys, reacted at 1100 and 1150 8C is described. Exposures in Rhines packs and flowing CO-CO2 gas mixtures serve to assess the influence of carbon on oxygen permeability at the Fe-FeO equilibrium oxygen potential. Oxygen permeability in Fe-Ni increases with iron content in a non-ideal manner in both gas environments. Higher permeability is found in carbon bearing gases for iron-rich alloys, and the size of this effect increases with temperature

Two-Dimensional Hybrid Halide Perovskite as Electrode Materials for All-Solid-State Lithium Secondary Batteries Based on Sulfide Solid Electrolytes

An all-solid-state lithium secondary battery using two-dimensional hybrid halide perovskite (2D-HHP) (CH3(CH2)(2)NH3)(2)(CH3NH3)(2)Pb3Br10 as electrode materials and sulfide-based solid electrolyte is fabricated for the first time. Although large amounts of lithium-ion conductor have been mixed in the electrodes of the all-solid-state batteries based on sulfide solid electrolytes, the high lithium-ion coefficient of the 2D-HHP, around 10(-7) cm(2) s(-1), allowed the suitable operation of the batteries without the addition of any lithium-ion conductors into the electrodes. The lithium-ion diffusion in the electrode improves with the temperature, showing a better performance at 100 degrees C and keeping a low resistance between electrode/electrolyte interface of 13 Omega. The all-solid-state battery retains a reversible capacity of more than 242 mAh g(-1) for 30 cycles at 0.13 mA cm(-2) with a negligible capacity fade. The mechanism of the lithium storage into the 2D-HHP electrode material based on ex-situ XRD measurements at different stages of the discharge-charge processes is suggested, consisting of a three-step reaction: Li+ insertion/extraction, conversion, and alloying-dealloying reactions

Oxygen solubility and diffusivity in Fe-Ni alloys in carbon-free and carbon-containing gases at high temperature

Wagner’s model of internal oxidation allows the prediction of an alloy’s critical concentration of oxide forming metal required to achieve a protective oxide scale at high temperatures. The model depends on oxygen permeability, the product of oxygen solubility and diffusivity in the alloy, but these parameters have not been evaluated for the Fe-Ni system, and the influence of carbon-bearing gases is unknown.In this work, oxygen solubility and diffusivity have been measured for the Fe-Ni system at temperatures from 1000 to 1150 °C, under oxygen partial pressures corresponding to the Fe/FeO equilibrium in Rhines packs or by flowing CO/CO2 gas mixtures.Oxygen solubility was determined by equilibrating a series of binary austenitic Fe-Ni alloys achieving saturation, and then the oxygen concentration was measured using the inert gas fusion method. Thermodynamics of oxygen dissolution were obtained and oxygen dissolution in the Fe-Ni system was characterised using several solution models.Oxygen diffusivity was determined indirectly by internal oxidation of a series of Fe-Ni-Cr alloys. Kinetics of internal oxidation were used to obtain the oxygen permeability of Fe-Ni binaries using a modified Wagner’s model, which was corrected for internal oxide volume expansion and interfacial diffusion. Oxygen permeability data was coupled with solubility to calculate oxygen diffusivity in the Fe-Ni system. It was found that oxygen solubility was higher than previously published for the pure metals. Values in both conditions yielded the same results within measurement uncertainty, showing that carbon has no effect on oxygen solubility at the levels used. However, higher oxygen permeability was found in carbon bearing gases for iron-rich alloys, and this effect became more significant at higher temperatures. The dependence of oxygen solubility, diffusivity and permeability on Fe-Ni alloy composition is non-ideal in both gas environments. Wagner’s classical solution model and the amended version of the internal oxidation model were shown to represent the results well

Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.Fil: Berlanga, Isadora. Universidad de Chile; ChileFil: Etcheverry Berríos, Álvaro. Universidad de Chile; ChileFil: Mella, Andy. Universidad de Chile; ChileFil: Jullian, Domingo. Universidad de Chile; ChileFil: Gómez Andrade, Victoria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Chile; ChileFil: Aliaga-Alcalde, Núria. Institució Catalana de Recerca i Estudis Avancats; España. Universitat Autònoma de Barcelona; EspañaFil: Fuenzalida, Victor. Universidad de Chile; ChileFil: Flores, Marcos. Universidad de Chile; ChileFil: Soler, Monica. Universidad de Chile; Chil