Formation Of Surface Oxide Film Research Articles

Investigation on Be, Mg, Ca, B, Ga, C, Si, and Ge atoms doped on Al (111) surface and their effect on oxygen adsorption: A first-principle calculation

Oxygen corrosion of the aluminum alloy has a substantial impact on the durability of engineering materials and equipment. To better understand how various alloy elements affect oxygen corrosion, we used first-principle DFT method to study the role of each given dopant atom (Be, Mg, Ca, B, Ga, C, Si, and Ge) in the formation of surface oxide film on the Al (111) surface, in the case replacing a surface Al atom. Our calculations show that the electron gain or loss abilities of these alloy elements differ from that of Al metal, with Be, B, C, and Si atoms tending to penetrate into the surface, Mg, Ca, and Ga atoms protruding, and Ge atom just embedded into the Al (111) surfaces. Additionally, the type of doping element at the Al (111) surface can greatly affect the O2 absorption, predicting that Ca-doped surface absorb the least amount of oxygen, followed by Si-doped surface, with Be-, Mg-, B-, Ga-, C-, and Ge-doped surfaces showing higher O2 absorption. Based on adsorption energy (Eads) and partial density of states (PDOS) analysis, we conclude that the doped Al (111) surfaces can make O2 adsorption different owing to the difference in electronic properties of the doping atoms. These insights draw a greater knowledge of the role of alloy elements in the oxygen corrosion of Al alloys, enabling guidance for designing more corrosion-resistant materials.

Surface Tension of GaInSnBiZn Liquid High-entropy Alloy

As an emerging alloy material, high-entropy alloy has potential applications that distinguish it from traditional alloys due to its special physicochemical properties. In this work, a low melting point GaInSnBiZn high-entropy alloy was designed based on Miedema model, and its surface tension was measured by the continuous pendant-drop method. The results show that the intrinsic surface tension of GaInSnBiZn high-entropy alloy at 80 °C is 545±5 mN/m, and the surface tension of the liquid alloy is significantly reduced by the formation of surface oxide film. The surface tension of GaInSnBiZn high-entropy alloy was analyzed by using theoretical models (Guggenheim model, GSM (general solution) model and Butler model), and the thermodynamic characteristics of the surface tension formation were further verified by combining with thermodynamic calculations, among which the calculated results of Butler model were in good agreement with the experimental data. Meanwhile, it is found that the surface concentration of Bi in the alloy is much larger than the nominal concentration of its bulk phase, which contributes the most to the surface tension of the alloy, however, it contributes the least to the entropy of the alloy formation in combination with the Butler model.

Characteristics of Dynamically Formed Oxide Films in Al–Zn Melt

The entrainment of surface oxide films in the melt leads to the formation of double oxide defects in the casting parts. Oxide/metal/oxide (OMO) sandwich technique is a method for physical simulation of the formation of surface oxide film. In this method, air bubbles are artificially introduced into the melt in order to trap two adjacent bubbles and extract the interface between them. In this study, to prepare OMO samples, air bubbles were blown with a pressure of 0.8 atm. into the mold filled with Al melt containing 3, 5 and 7 wt% of Zn. Using scanning electron microscopy and energy-dispersive X-ray spectroscopy, characteristics of dynamically formed oxide films such as morphology and film thickness were investigated. Results showed that in higher zinc content, more cracks appear on the oxide films. Thickness of the oxide films in Al–Zn alloys was estimated to be 95–1070 nm. According to the measurement performed on the folds, adding more than 3% zinc caused a reduction in the oxide film thickness. Thermodynamics suggests the presence of spinel phase along with aluminum oxide at 700 °C which is in agreement with energy-dispersive X-ray spectroscopy’s results. The presence of the spinel phase at the interface is the reason behind the reduction in the thickness of the oxide film.

A Research on the Surface Oxidation During Gas Carburization of Cr-Mo-Si Steels for the Automotive Transmission Gears

As global regulations of CO<sub>2</sub> emissions and fuel consumption efficiency become more strict, the automotive powertrain system has become more compact with lower lubrication viscosity. With the current trends in powertrain system improvement, the operating conditions of powertrain components such as gears are becoming more severe. As a result, it is increasingly important to improve the strength and durability of the materials used for the powertrain system by optimizing alloy design and heat treatment. Much research and development has focused on improving components by heat treatment, and especially carburization. Also, many different alloy concepts, such as Fe-Cr-Mo or Fe-Cr-Ni systems have been proposed for automotive components. Among various approaches, Cr and Si , and solid solution hardening, are known to effectively increase hardenability. However, it has been reported in many works that the carburized case depth can also be reduced by increasing the Cr/Si content, due to oxide film formation. The mechanism of Cr/Si oxide film formation during carburization has not yet been clearly determined. In the present work, therefore, the mechanism of surface oxide film formation during carburization was examined. Also, the microstructure, composition and crystal structure of different oxides were examined and compared in detail.

Corrosion behavior of aluminum in molten hydrated salt phase change materials for thermal energy storage

The corrosion behavior of aluminum 1060 in hydrated salt phase change materials (PCM) melts comprised of Na2HPO4·12H2O - Na2SO4·10H2O was investigated through electrochemical tests as a function of pH. The pH of PCM medium was adjusted by adding H2SO4 or NaOH. Electrochemical impedance spectroscopy reveals the existence of concentration difference layer at aluminum/PCM interface ascribed to the adsorption of PCM species and the formation of aluminum oxides. The observed anodic branch of DC polarization exhibits potential independence which is ascribed to the formation of surface oxide film and the accumulation of hydrogen molecules inside surface pores. The oxide film formed at neutral condition is characterized as the most compact and corrosion resistant while as the environmental pH shifts away from 7 the oxides/aluminum dissolution is accelerated and more aluminum 1060 substrate is exposed.

(Keynote) Recent Progress in Nanoscale Understanding of Surface Oxide Film Formation, Properties and Breakdown on Metals and Alloys Using in Situ and Ex Situ Characterization Methods

After a short historical introduction in recognition to the pioneering work of Masahiro Seo, recent advances in the understanding at the nanoscale of the formation, properties and breakdown of oxide films on metals and alloys will be presented, with emphasis on data obtained using advanced in situ and ex situ surface analytical techniques such as Scanning Tunneling Microscopy (STM), Scanning Tunneling Spectroscopy (STS),Current-Sensing Atomic Force Microscopy (CS-AFM), X-ray Photoelectron Spectroscopy (XPS), and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), combined with electrochemical measurements, and complemented by atomistic modelling with Density Functional Theory (DFT). The following topics will be addressed: Nanostructured oxide layers formed by controlled thermal oxidation of copper single crystal surfacesPassive oxide films for corrosion protection of metals and alloys: crystallinity, oxide/metal epitaxy, effects of time of polarization on oxide crystallinity, compositional heterogeneity of surface oxides (in the case of stainless steel)Role of surface oxide defects in passivity breakdown and initiation of localized corrosion, investigated with high resolutionOxide layers deposited by ALD (Atomic Layer Deposition) for corrosion protection, and as model systems for the study of conversion-deconversion mechanisms in Li-ion batteriesAtomistic modelling of oxide layers on metals using density functional theory (DFT)

Erratum: “Grain boundary diffusivity of Ni in Au thin films and the associated degradation in electrical contact resistance due to surface oxide film formation” [J. Appl. Phys. 113, 114906 (2013)

Erratum: “Grain boundary diffusivity of Ni in Au thin films and the associated degradation in electrical contact resistance due to surface oxide film formation” [J. Appl. Phys. <b>113</b>, 114906 (2013)

Grain boundary diffusivity of Ni in Au thin films and the associated degradation in electrical contact resistance due to surface oxide film formation

The low temperature diffusion from a nickel strike layer through varying thickness films of gold, a common electrical contact overlayer, was characterized and correlated to changes in electrical contact resistance (ECR). The diffusivity of Ni in Au was determined by the surface accumulation method (type C kinetics) for Au film thicknesses of 280 and 994 nm at an annealing temperature of 150 °C over a 32 day period. X-ray photoelectron spectroscopy (XPS) was used to determine the rate of Ni surface accumulation. The average product of grain boundary width and diffusivity for Ni in polycrystalline Au was calculated to be δbDb≅2.0 × 10−22cm3s using the Hwang-Balluffi model, and δbDb≅2.5×10−22cm3s using the Ma-Balluffi model. ECR measurements were made in parallel to surface accumulation measurements, revealing a correlation between ECR and Ni-O surface concentration; ECR values for both film thicknesses increased by 1 to 2 orders of magnitude at saturation coverage. Film cross-sections were extracted using focused ion beam milling and analyzed via scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy after 32 days of annealing, enabling a direct observation of the composition and thickness of the accumulated Ni-O layer, which was approximately 3 nm thick.

알루미늄합금 재료의 산화막 형성이 피로거동에 미치는 영향

본 논문에서는 알루미늄 7075-T6 재료의 부식 기간별 표면 산화막 형성이 피로거동에 미치는 영향에 대해 연구하였다. 사용된 알루미늄 재료는 부식에 대한 부동태화 현상으로 부식저항 특성이 높은 금속으로 알려져 있다. 알루미늄 합금은 다른 재료에 비해 가볍고 강한 재료 특성 때문에 항공기 부품 산업과 같은 다양한 산업분야에서 널리 사용되고 있다. 때문에 부식에 대한 재료의 피로거동 특성과 부식에 대한 부동태화 특성에 대한 연구가 요구된다. 4절점 회전 굽힘 시험기를 사용하여 부식 기간별 재료의 피로거동 특성을 확인하였고, 표면 거칠기를 측정하여 부식 기간별 알루미늄 재료의 표면 부식 정도를 평가하였다. 또한 전자주사현미경을 통해 파단면 분석 및 재료 표면에 형성된 산화막을 측정하였다. 실험결과 초기 부식 4주 동안은 부식이 활발히 진행되어 피로수명은 크게 감소하고 표면 거칠기는 증가하였다. 하지만 4주 이후부터 재료의 부동태화 현상으로 부식 반응이 둔화되는 경향을 보였다. 전자주사현미경을 통한 분석에서도 표면 산화막의 성장이 4주 이후부터 둔화되어 재료 표면의 산화막이 보호층 역할을 하여 더 이상의 부식진행을 방지한다는 결론은 얻었다.

EQCN study of anodic dissolution and surface oxide film formation at Au in the presence of Cl − or Br − ions: A model process for corrosion studies

The anodic dissolution of an Au electrode and associated thin-layer oxide film formation in aq. H 2SO 4 in the presence of Cl − or Br − ions at various concentrations provides a model process for metal corrosion. In the present work such processes were investigated using cyclic voltammetry and chronoamperometry, with complementary nanogravimetry measurements using the EQCN. The results clearly indicate that in 0.5 M H 2SO 4 electrolyte, containing 1 mM Br − or Cl −, Au dissolves over the potential range 1.0 – 1.45 V(RHE) through a 3e oxidation process involving Au complex-ion formation that can be followed in situ by means of UV spectroscopy. The linear relationship between mass changes and reciprocal square-root of sweep-rate and between anodic currents in cyclic voltammetry at ca. 1.20 V for Br − (1.39 V for Cl −) and square-root of sweep-rate/or electrode rotation rate indicated quantitatively that the dissolution process is diffusion-controlled. It was interesting to find that electrode rotation in the presence of Cl − ions has little effect on the anodic formation of surface oxide, while, on the contrary, with Br − ions present, currents for oxide film reduction are not observed at rotation rates > ca. 400 rpm.

変色した銅箔表面の解析

Tarnished copper foil was investigated before surface treatment. Its surface color changed to band strips (streaks) of soft reddish-brown, dark blue, purple, dark blue, and soft reddish-brown. Its surface morphology was related to the color change. Actually, this surface oxide film formation caused the color change. Surfaces of all samples were composed of CuO and Cu2O. The fractions of these oxides differed. The soft reddish-brown out-end sample has the lowest CuO content ; all other samples show almost identical CuO contents. The oxygen contents of the out-end sample show the lowest value. Its degree of oxidation was the lowest of all samples. The out-end and center samples show an almost constant CuO content region. In contrast, the CuO content of the middle of the samples decreased gradually with increasing depth from the surface. The color samples, out-ends, and center samples have similar depth profiles of CuO contents, but they have different surface contents of CuO. However, the other color samples, the middle two samples, show almost identical CuO depth profiles and contents. Therefore, it is concluded that the main factor of color change is the CuO depth profile.

Investigation of surface oxidation of low carbon sheet steel during its treatment with Nd:Glass pulsed laser

The surfaces of hot-rolled and cold-rolled samples of low carbon mild steel have been treated by Nd:Glass laser. The temperature conditions at the surface have been characterised via a numerical simulation. The thermal conductivity equation has been solved for the one-dimensional case. In the model developed for numerical simulation the change in absorption coefficient during the laser treatment due to the formation of surface oxide film has been considered. The temperature gradients during the laser pulse and following the cooling stage have been estimated. It has been found that the maximum temperature reached at the end of the laser pulse on the samples’ surface is 1814 °C, and this relatively high temperature causes oxidation of both samples and surface melting of the cold-rolled specimen. The thickness of the formed oxide film has been evaluated via the developed model for numerical simulation to be 77 nm. Some important parameters of the grown oxide film namely: phase composition; lattice imperfections; and residual macro-stresses have been estimated via X-ray asymmetric grazing incidence beam methods. It has been revealed that the oxide film has a layered macrostructure built up by two mono-phase layers namely Fe 3O 4 and FeO, from which the former is the top and the latter the bottom layer. The comparison between the broadening of the corresponding diffraction lines shows that the FeO layer formed on the cold-rolled steel has a higher concentration of lattice imperfections than the one grown on the hot-rolled specimen. For the top Fe 3O 4 layers formed on both steels the relation between the peaks broadening is the reverse. It has also been revealed that the grown laser-assisted oxide films contain tensile residual macro-stresses.

Study of the electrochemical behaviour of the 7075 aluminum alloy in the presence of sodium oxalate

The formation of oxide layers on aluminum and its alloys has a protective function. Protective oxide layers may be formed by various processes and may be promoted in the presence of chemical compounds present at the metal/water interface. In the present work, the electrochemical behavior of aluminum alloy 7075 in the presence of aqueous oxalate solutions in the concentration range between 10–80 mM was studied by open circuit potential, polarization and ac impedance measurements. It was found that the oxalate ions present in the solutions promoted passivation of the specimens surface. The passivation was attributed to the formation of a resistive oxide layer which was thicker than the corresponding layer formed in distilled water. This finding was confirmed by XPS measurements. Since the interaction between the anionic species, such as the oxalate ions, with the metal and or oxide surfaces seem to play an important role, the influence of the duration of immersion and of the concentration of the aqueous oxalate solutions on the surface oxide film formation was investigated. It was found that in a treatment process in which both the immersion time and the oxalate concentration were increased, a thicker, more resistive film was formed. In the treatment process of the aluminum alloy specimens with oxalate, the effect of the oxalate concentration on the electrical properties of the surface layer formed during the immersion in the oxalate solutions (increase of oxide resistance upon increasing oxalate concentration) was revealed when testing solutions of the same concentration (10 mM) in sodium oxalate were used for conducting electrochemical measurements, regardless of the composition of the treating solutions. The apparently low resistivity observed when the treating and testing solutions had the same, high, oxalate concentration (resulting in solutions of high conductivity) was attributed to the porous structure of the surface oxide layer.

Interface between steel rebar and concrete, studied by electromechanical pull-out testing

The interface between concrete and steel rebar was evaluated by electromechanical pull-out testing, which involved measuring the shear bond strength and contact electrical resistivity of each sample. The bond strength was increased by steel rebar surface treatment (acetone, water, ozone or sand blasting, with ozone being most effective and acetone being least effective), polymer addition to concrete (methylcellulose or latex), increase in water/cement ratio of concrete (particularly from 0.45 to 0.50), and decrease in curing age (particularly from 14 to 7 days). The origins of these effects are rebar cleansing for acetone treatment, rebar surface oxide film formation for water and ozone treatments, rebar surface roughening for sand blasting, polymer interface layer formation for polymer addition, and decreased interfacial void content for water/cement ratio increase and for curing age decrease.

Decrease of Deuterium Permeation Rate through Austenitic Stainless Steel Facing Molten Li17-Pb83 Alloy with Formation of Surface Oxide Film

(1994). Decrease of Deuterium Permeation Rate through Austenitic Stainless Steel Facing Molten Li17-Pb83 Alloy with Formation of Surface Oxide Film. Journal of Nuclear Science and Technology: Vol. 31, No. 6, pp. 617-619.

Decrease of Deuterium Permeation Rate through Austenitic Stainless Steel Facing Molten Li17-Pb83 Alloy with Formation of Surface Oxide Film.

Decrease of Deuterium Permeation Rate through Austenitic Stainless Steel Facing Molten Li17-Pb83 Alloy with Formation of Surface Oxide Film.

Surface and bulk processes at oxidized iridium electrodes—I. Monolayer stage and transition to reversible multilayer oxide film behaviour

Because of the facility with which multilayer hydrous oxide films are formed electrochemically at Ir, the true monolayer stage of surface oxide film formation has not been studied without complications from multilayer growth and associated redox processes. This paper reports the behaviour and properties of the monolayer surface oxide film that can be formed on Ir electrodes under well controlled conditions, together with some aspects of upd of H at Ir. Information on the monolayer oxide is of interest in relation to (a) the surface oxidation behaviour of Ir in comparison with that of other noble metals, especially Ru, and (b) to the development (Part II) of multilayer oxide films exhibiting reversible oxidation/reduction behaviour, when the metal is subjected to anodic/cathodic potentiodynamic cycling.