Formation Of Passive Oxide Film Research Articles

Advancement of technology towards high-performance non-aqueous aluminum-ion batteries

Al-ion batteries (AIBs) have been identified as one of the most hopeful energy storage systems after Li-ion batteries on account for the ultrahigh volumetric capacity, high safety and low cost from the rich abundance of Al. Nonetheless, some inevitable shortcomings, such as the formation of passive oxide film, hydrogen side reactions and anode corrosion, finally limit the large-scale application of aqueous AIBs. The nonaqueous AIBs have been considered as one of most hopeful alternatives for high-powered electrochemical energy storage devices. Nonetheless, various technical and scientific obstacles should be resolved because nonaqueous AIBs are still nascent. Some significant efforts have aimed to resolve these issues towards large-scale applications, and some important advancement has been made. In the present review, we mainly intended to offer an overview of non-aqueous AIBs systems, and we comprehensively reviewed the recent research advancement of the cathode materials, anode materials electrolyte and collectors as well as the fundamental understanding of the functional mechanisms. In addition, we have also analyzed several technical challenges and summarized the strategies used for overcoming the challenges in improving the electrochemical properties, including morphology control, surface engineering, doping and construction of composite electrodes as well as the charge storage mechanisms of the materials with different crystal structures. At last, future research orientation and development prospect of the AIBs are proposed.

Quantitative Determination of Calcium Hydroxide by Using Near-Infrared Spectroscopy

Calcium hydroxide (CH) is a by-product from hydration reaction of cement along with calcium silicate hydrate (C-S-H) gel. It helps to protect the steel reinforcements in concrete structures from corrosion process due to carbonation. The presence of calcium hydroxide provides a basic environment (pH˃10) that induces the formation of passive oxide film and keeps steel structures from corrosion. The detection and quantification of calcium hydroxide in concrete structures are important to understand the nature and state of the steel structures in concretes. In this research work, the variation of calcium hydroxide to calcium silicate ratios in cement were measured by using near-infrared spectroscopy (NIR). The first overtone of the OH groups in calcium hydroxide absorbs at 7082 cm-1 and this absorption peak can be used as a quantitative measure of calcium hydroxide in samples. Correlation plot between second derivative absorbance intensity at 7082 cm-1 with different mixtures of calcium hydroxide in calcium silicate base. The amount of calcium hydroxide in calcium silicate base was established. This calibration plot was used as basis for determining calcium hydroxide content in unknown concrete samples. Concrete samples for the quantitative determination of calcium hydroxide were prepared from standard cement samples and cement samples with or without pozzolan along with various water to cement ratios. The results show that all samples analyzed in this work contain calcium hydroxide in varying amounts. This variation reflects the composition of the cement and concrete samples.

Electrodeposition of Ni(OH)2 reinforced polyaniline coating for corrosion protection of 304 stainless steel

In the present paper, polyaniline (PANI) coating was electropolymerized in the presence of phosphoric acid with subsequent deposition of Ni(OH)2 particles. The Ni(OH)2 reinforced PANI coating significantly enhances the corrosion resistance of 304 stainless steel (304SS) in comparison with the pristine PANI coating. The galvanostatically deposited Ni(OH)2 particles fill the pores of the pristine PANI coating and improves the coatings hydrophobicity which decreases the diffusion of aggressive media. Importantly, the Rp values of Ni(OH)2 reinforced PANI coating is much higher than that of pristine PANI coating and the Ni(OH)2 reinforced PANI coating presents a long-term anti-corrosive ability (360 h) in 3.5 wt% NaCl solution. The prolonged corrosion protection of Ni(OH)2 reinforced PANI coating is attributed to the improved physical barrier as well as the facile formation of passive oxide film that sustain the anodic protection of the coating.

The influence of current collector corrosion on the performance of electrochemical capacitors

This paper discusses the effect of current collector (stainless steel 316L) corrosion on the performance of electrochemical capacitors operated in aqueous electrolytes. This topic seems to be often neglected in scientific research. The studied electrolytes were 1 M H2SO4, 1 M KI, 1 M Na2SO4, 1 M KOH and 6 M KOH. The corrosion process was investigated by means of selected direct and alternating current techniques. The surface of the current collectors as well as the corrosion products were characterised using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Stainless steel 316L in alkaline solutions is characterised by the lowest values of corrosion potentials whereas the potentials in acidic media become the most noble. Our studies show that corrosion potentials increase with decreasing pH value. This phenomenon can be explained with the formation of passive oxide films on the stainless steel current collectors. The passive oxide films are usually thicker and more porous in alkaline solutions than that in the other electrolytes. The processes occurring at the electrode/electrolyte interfaces strongly influence the working parameters of electrochemical capacitors such as voltage, working potentials of single electrodes, self-discharge as well as the internal resistance and cycling stability.

Surface modification of 316 stainless steel with platinum for the application of bipolar plates in high performance proton exchange membrane fuel cells

316 stainless steel has been regarded as one of the promising candidates to replace graphite for bipolar plate application. However, the relatively high electrical resistance caused by the formation of passive oxide film and the insufficient corrosion resistance in long-term operation are two main concerns of 316 stainless steel bipolar plates. Low temperature active screen plasma alloying technology shows the ability to reduce electrical resistance and enhance corrosion resistance of 316 stainless steel bipolar plates to some extent, but still can not satisfy the Department of Energy (DOE) requirements. In this paper, active screen plasma co-alloying treatments with nitrogen and platinum are conducted to modify the surface of 316 stainless steel. The surface morphology, phase constitute, chemical composition and layer structure of treated 316 stainless steel are fully studied. A dense, columnar structured and single phase Pt3Fe deposition layer is produced on the surface of 316 stainless steel after treatments. Thanks to the excellent electrical conductivity and corrosion resistance of Pt3Fe, the surface electrical conductivity and corrosion resistance are greatly enhanced and satisfies the DOE requirements, contributing to the significant improvement of single cell performances.

Microstructure and corrosion resistance of molybdenum and aluminum coatings thermally sprayed on 7075-T6 aluminum alloy

Pitting corrosion upon 7075-T6 high strength aluminum alloy, often associated with cathodic intermetallic particles decreases its fatigue life by a factor of about 6 to 8. In order to improve the corrosion resistance of this alloy, arc spray coatings of molybdenum and aluminum are applied. The open circuit potential and potentiodynamic polarization measurements made in 3.5% NaCl naturally aerated solution reveal that the molybdenum coating, which has an excellent hardness, shifts the 7075-T6 corrosion potential (Ecorr) to noble values and increases slightly the corrosion current density (icorr). On the contrary, when the aluminum coating alloy is applied, both Ecorr and icorr are shifted to better values. The increase of icorr of the alloy when molybdenum coating is applied can be attributed to the high porosity present into the coating. On the other hand, microstructure observations of the aluminum coating reveal a small porosity, which helps the formation of passive oxide film that protects the coating against a further corrosion.

Influence of the applied potential and pH on the steady-state behavior of the iron oxide

Numerous studies on the formation of passive oxide films on metals have been made, all aiming to understand and quantify how the thickness of the oxide film depends on the electrolyte solution's pH and on the applied potential. A one dimensional electrochemical model is presented considering the passive film on a rotating disk electrode (RDE) in contact with electrolyte solutions with the pH in the interval [8.4–11.2]. The mobile species in the oxide are oxygen vacancies, iron interstitials Fe2+, Fe3+ and iron vacancies. Reactions at the interfaces involving the defects in the oxide are combined with equations providing species and potential distributions, both in the oxide film and in the electrolyte solution. This approach offers new ways to link the film–solution interface with locally changing electrolyte composition. The passive film is described in terms of mass balance equations together with Poisson's equation. The results of our numerical simulations based on the finite element method show that Fe3+ interstitials and oxygen vacancies are the species responsible for the transport of mass in the oxide. These results are discussed and compared with experimental data and other numerical results.

Performance of Nickel-Coated Manganese Steel in High-Chloride Low-Sulphate Seawater Environments

This work investigated the service performance of nickel-coated manganese steel in both normal high-chloride (clean) and low-sulphate high-chloride (polluted) seawater environments (typical offshore oil and gas production environments). Structural manganese steels coated with nickel together with the control were tested for corrosion characteristics using the weight loss method. It was found that the nickel coat was able to resist corrosion overtime via spontaneous formation of passive oxide films at ambient temperatures. Analysis of resulting corrosion rates underscored the viability of nickel coating at inhibiting severe corrosion owing to the harsh chloride- and sulphate-containing seawater typical of the oil and gas production environments.

Coupled acidification and ultrasound with iron enhances nitrate reduction

Contaminated soils, especially when pollutant concentrations are high, pose potentially serious threats to surface and groundwater quality, when there are spills, discharges, or leaking storage tanks. For in situ remediation of nitrate in groundwater, the use of zero-valent iron (Fe 0) is suggested. The formation of passivating scales on Fe 0 over time may limit the long-term reduction potential of Fe 0. The aim of this study was to investigate the effect of ultrasound and pH on the destruction of passive oxide film. Batch tests were conducted in a specially designed protocol using ultrasound, and changing iron (commercial iron powder of micro-scale grain size) loading and pH. The results showed deactivation of the degradation process by Fe 0 with combined ultrasound/iron system and with ultrasound alone. However, the degradation rate increases with decrease in pH. The degradation rate was 45% for pH 2 and 20% for pH 4. The combination of iron, acidification, and ultrasound showed excellent degradation efficiency, and the degradation rate was 99%. Acidification could destroy passive oxide film and activate iron, thus, hastening the reaction between Fe 0 and nitrate. Ultrasound was helpful in destroying or preventing the formation of passive oxide film under acidification.

Biomaterial optimization in total disc arthroplasty.

Knowledge gained through the clinical history of total joint replacement materials combined with the current promise of new biomaterials provides improved guidelines for biomaterial selection in total disc arthroplasty. The following will detail: 1) current biomaterials technology; 2) how current designs of total disc arthroplasty seek to optimize implant performance through judicious biomaterial selection; and 3) what technical obstacles and clinical concerns remain. Metals and polymers remain the central material components of state-of-the-art total joint arthroplasties. Polymers provide low friction surfaces for articulating bearings and some degree of shock absorption. Metals provide appropriate material properties such as high strength, ductility, fracture toughness, hardness, corrosion resistance, formability, and biocompatibility necessary for use in load-bearing roles required total disc replacement. There are three principal metal alloys used in orthopaedics and particularly in total joint replacement: 1) titanium based alloys; 2) cobalt based alloys; and 3) stainless steel alloys. Alloy specific differences in strength, ductility, and hardness generally determine which of these three alloys is used for a particular application or implant component. Current designs. Two examples of current lumbar (Charitè and Prodisc) and cervical (Bryan and Prestige) disc replacements are compared. The similarities and differences in the biomaterials used for each demonstrate prevailing consensus and some idea of how to best optimize implant performance through biomaterial selection. The primary factors governing total disc arthroplasty biomaterials are similar to those of all total joint arthroplasties: generation of wear debris is the primary source of implant degradation, and the subsequent tissue reaction to such debris is the primary factor limiting the longevity of joint replacement prostheses. Particulate debris generated by wear, fretting, or fragmentation induces the formation of an inflammatory reaction, which at a certain point promotes a foreign-body granulation tissue response that has the ability to invade the bone-implant interface. This commonly results in progressive, local bone loss that threatens the fixation of both cemented and cementless devices alike. All metal alloy implants corrode in vivo. When severe, the degradative process may reduce structural integrity of the implant, and the release of corrosion products is potentially toxic to the host. The corrosion resistance of implant alloys is primarily due to the formation of passive oxide films to prevent significant electrochemical dissolution from taking place. The result of this knowledge is a consensus of opinion as to which materials are best suited for use in current total disc arthroplasty designs, where most total disc replacement designs incorporate cobalt-chromium-molybdenum alloy endplates articulating internally on a relatively soft polymeric core and externally coated with titanium or titanium alloy for enhanced bone fixation.

Non-equilibrium point defect model for time-dependent passivation of metal surfaces

This work presents an improved point defect model for the time-dependent formation of passive oxide films on metal surfaces. Like previous point-defect models, the present model assumes that charged defects, or vacancies, carry current across the growing oxide film. However, we treat the vacancies explicitly as material species which participate in oxide formation and dissolution reactions formulated for arbitrary oxide stoichiometry. The model includes boundary conditions, based on jump mass balances from formal continuum mechanics, that relate vacancy fluxes to the interfacial reaction rates as well as the motion of the film boundaries. Thus, unlike previous models, this model treats the film growth process formally as a moving boundary problem. Casting the equations in dimensionless form yields the key dimensionless groups. The dependence of the film growth rate on these groups can be rationalized in simple physical terms. The predicted trends in film growth rate and current density agree qualitatively with experimental data for nickel passivation, although the model parameters have not been optimized to achieve good agreement with current density data. The model provides a starting point for incorporating better descriptions of interfacial reaction kinetics within boundary conditions based on rigorous continuum mechanics.

Cell design for in—situ X-ray scattering study of electrodes in transmission geometry

A novel electrochemical cell that permits in— situ X-ray scattering studies in transmission geometry for the examination of electrode/electrolyte interfaces is described. The advantages of this geometry over others used presently are discussed, and initial experimental results are reported on the electrochemical formation of passive oxide film on silver.

Kinetics of Formation of Passive Oxide Films on Corrosion‐Resistant Fe‐Cr Thin Films

The transient electrochemical behavior of chromium‐containing amorphous and amorphous/microcrystalline iron‐alloy thin films in near‐neutral solutions has been investigated and compared with the behavior of “bulk” amorphous and bulk crystalline specimens of comparable compositions. The films have been deposited onto Ebrite (Fe‐Cr) substrates by the ion‐plating technique. The transient current‐decay behavior upon application of a positive voltage step from the specimen rest potential is reported here. This voltage‐step technique has revealed several distinct regions in the behavior of current with time. Initially, there is an exponential decay region, with current relaxation time constant of 0.5–0.8 sec. Then follows another exponential decay with . The next region of current decay can be described by a power law: , with in the range of 0.6–0.7 for the ion‐plated films and the “bulk” amorphous Fe‐Cr alloy (Metglas 2826A), and 1.0 for the bulk polycrystalline alloy (Ebrite). Finally, there is a relatively slow exponential decay region with time constant of 200 sec to over 1000 sec for low and intermediate values of the voltage step, . For high values of , this region is approximately exponential over limited periods of time, with increasing monotonically from a few hundred seconds to over 6000 sec. The overall results strongly suggest that different mechanisms are operative at various intervals during the formation of the passive oxide layer.

金属表面における薄いアノード酸化皮膜成長過程の速度論的研究方法に対する寄与―ニッケル不働態皮膜成長の速度論

金属表面における薄いアノード酸化皮膜成長過程の速度論的研究方法に対する寄与―ニッケル不働態皮膜成長の速度論