Copper Corrosion in Irradiated Environments. the Influence of H202 on the Electrochemistry of Copper Dissolution in Hcl Electrolyte

1986 ◽  
Vol 84 ◽  
Author(s):  
W. H. Smyrl ◽  
R. T. Bell ◽  
R. T. Atanasoski ◽  
R. S. Glass
Keyword(s):  
Anodic Dissolution ◽  
Rotation Rate ◽  
Film Formation ◽  
Copper Surface ◽  
Open Circuit ◽  
Ring Electrode ◽  
Positive Direction ◽  
Rotation Rates ◽  
Copper Dissolution ◽  
Copper Disk

AbstractThe anodic dissolution of copper has been examined in deaerated, 0.1 M HCl aqueous solution in the presence of H202. Concentrations of H202 up to 0.2 M were studied at a rotating copper disk-platinum ring electrode. The open circuit potential (OCP) of copper was found to depend on both peroxide concentration and rotation rate. The OCP shifts towards more positive values with increasing H202 concentration (C) and decreasing rotation rate (ω). The dependence of OCP on (C/ω1/2) was the same s for oxygenated solutions reported earlier [1], at small values of (C/ω1/2). At higher values of (C/ω1/2), departure from the expected behavior was observed. The current- voltage curves for anodic dissolution of copper were also influenced by the presence of peroxide. The curves recorded with the potential scanned in the positive direction showed the expected 60 mV slope, but the reverse scans showed significant departures. At a given potential scan rate, hysteresis was observed which was larger for higher H202concentrations, lower rotation rates, and more positive anodic potential limits. Monitoring the cuprous ions at the outer Pt ring revealed that there was a complex set of events taking place at the copper surface, including film formation and the appear- ance of cupric ions.

Growth of passive oxide films on iron and titanium under non-stationary state

2018 ◽  
Vol 36 (1) ◽  
pp. 87-104 ◽  
Author(s):  
Toshiaki Ohtsuka
Keyword(s):  
Oxide Film ◽  
Stationary State ◽  
Ph Dependence ◽  
Ring Electrode ◽  
Constant Current ◽  
Oxide Growth ◽  
Potential Sweep ◽  
Constant Current Density ◽  
Positive Direction ◽  
Passive Oxides

AbstractGrowth of passive oxides on iron and titanium under the non-stationary state was studied during constant current density (CD) oxidation and potential sweep oxidation. Increase and decrease of the thickness of the passive oxide film were determined from the relation between dissolution and growth CDs. By using rotating Fe disc-Pt ring electrode, the CDs of the dissolution from the oxide to solution and the growth of the passive oxide on iron were simultaneously measured. From the ratio of the growth CD to the dissolution CD and the pH dependence of the growth CD, a possible mechanism was discussed. Next, the growth of passive oxides on iron in pH 8.4 borate solution and on titanium in 0.1 m sulfuric acid solution during the potential sweep oxidation was examined by using three-parameter ellipsometry. Oxide growth was initially delayed when the sweep in the positive direction was started, and then the oxide film linearly grew with the potential increase. It was found that the oxide growth rate influenced the properties of the oxide film. The electric field in the oxide film during the non-stationary growth was discussed, concerned with the CD of the oxide film formation.

scholarly journals The Formation of Sulfide Scales on Carbon Steel in Saturated H2S

2020 ◽  
Author(s):  
Noora Alqahtani ◽  
Jiahui Qi ◽  
Aboubakr M. Abdullah ◽  
Nicholas J. Laycock ◽  
Mary P. Ryan
Keyword(s):  
Carbon Steel ◽  
Corrosion Product ◽  
Film Formation ◽  
Open Circuit ◽  
Iron Surface ◽  
Ion Concentration ◽  
Bulk Solution ◽  
Formation Mechanisms ◽  
Structure Thickness ◽  
Circuit Technique

There are three contributing elements of corrosion of Carbon Steel in H₂ S environment: the effect of H2S on water chemistry; electrochemical reactions of the bare iron surface (both anodic and cathodic processes); and the formation and growth of corrosion product layers. The electrochemical reaction commonly contains three stages: first, the reactant transported from the solution (bulk) to the metal surface; then the transfer of the charge reaction on the surface, followed by the reaction product transported away from the iron surface to the bulk solution or the formation and development of the corrosion product which then can decrease the corrosion rate. Development of a robust corrosion model to predict the corrosion process in H2S requires a mechanistic understanding of all these elements. An experimental study was carried out to assess the corrosion of C-steel under open-circuit technique conditions and in solutions at several ranges of time and temperatures. The effect of film composition, morphology, structure, thickness, and ion- concentration of corrosion product films formed on pipeline Carbon Steel in an acid sour solution were examined. The electrochemical behavior of the filmed steel was measured, and the film properties assessed using a range of advanced techniques including Scanning Electron Microscopy (SEM), and Raman spectroscopy (RS). The data will be discussed in terms of film formation mechanisms.

scholarly journals Vortex-induced vibration of a transversely rotating sphere

2018 ◽  
Vol 847 ◽  
pp. 786-820 ◽  
Author(s):  
Methma M. Rajamuni ◽  
Mark C. Thompson ◽  
Kerry Hourigan
Keyword(s):  
Reynolds Number ◽  
Drag Force ◽  
Rotation Rate ◽  
Lift Force ◽  
Oscillation Amplitude ◽  
Fluid Viscosity ◽  
Sphere Diameter ◽  
Force Coefficient ◽  
Vortex Induced Vibration ◽  
Rotation Rates

The effects of transverse rotation on the vortex-induced vibration (VIV) of a sphere in a uniform flow are investigated numerically. The one degree-of-freedom sphere motion is constrained to the cross-stream direction, with the rotation axis orthogonal to flow and vibration directions. For the current simulations, the Reynolds number of the flow, $Re=UD/\unicode[STIX]{x1D708}$, and the mass ratio of the sphere, $m^{\ast }=\unicode[STIX]{x1D70C}_{s}/\unicode[STIX]{x1D70C}_{f}$, were fixed at 300 and 2.865, respectively, while the reduced velocity of the flow was varied over the range $3.5\leqslant U^{\ast }~(\equiv U/(f_{n}D))\leqslant 11$, where, $U$ is the upstream velocity of the flow, $D$ is the sphere diameter, $\unicode[STIX]{x1D708}$ is the fluid viscosity, $f_{n}$ is the system natural frequency and $\unicode[STIX]{x1D70C}_{s}$ and $\unicode[STIX]{x1D70C}_{f}$ are solid and fluid densities, respectively. The effect of sphere rotation on VIV was studied over a wide range of non-dimensional rotation rates: $0\leqslant \unicode[STIX]{x1D6FC}~(\equiv \unicode[STIX]{x1D714}D/(2U))\leqslant 2.5$, with $\unicode[STIX]{x1D714}$ the angular velocity. The flow satisfied the incompressible Navier–Stokes equations while the coupled sphere motion was modelled by a spring–mass–damper system, under zero damping. For zero rotation, the sphere oscillated symmetrically through its initial position with a maximum amplitude of approximately 0.4 diameters. Under forced rotation, it oscillated about a new time-mean position. Rotation also resulted in a decreased oscillation amplitude and a narrowed synchronisation range. VIV was suppressed completely for $\unicode[STIX]{x1D6FC}>1.3$. Within the $U^{\ast }$ synchronisation range for each rotation rate, the drag force coefficient increased while the lift force coefficient decreased from their respective pre-oscillatory values. The increment of the drag force coefficient and the decrement of the lift force coefficient reduced with increasing reduced velocity as well as with increasing rotation rate. In terms of wake dynamics, in the synchronisation range at zero rotation, two equal-strength trails of interlaced hairpin-type vortex loops were formed behind the sphere. Under rotation, the streamwise vorticity trail on the advancing side of the sphere became stronger than the trail in the retreating side, consistent with wake deflection due to the Magnus effect. This symmetry breaking appears to be associated with the reduction in the observed amplitude response and the narrowing of the synchronisation range. In terms of variation with Reynolds number, the sphere oscillation amplitude was found to increase over the range $Re\in [300,1200]$ at $U^{\ast }=6$ for each of $\unicode[STIX]{x1D6FC}=0.15$, 0.75 and 1.5. The VIV response depends strongly on Reynolds number, with predictions indicating that VIV will persist for higher rotation rates at higher Reynolds numbers.

PHOSPHONIC ACID MONOLAYERS FOR CORROSION PROTECTION OF COPPER: EQCM AND EIS INVESTIGATIONS

2019 ◽  
Vol 27 (06) ◽  
pp. 1950166
Author(s):  
AYSEL YURT ◽  
ESRA SOLMAZ
Keyword(s):  
Molecular Structure ◽  
Corrosion Protection ◽  
Phosphonic Acid ◽  
Quantum Chemical ◽  
Electrochemical Impedance ◽  
Film Formation ◽  
Copper Surface ◽  
Chemical Mechanism ◽  
Frequency Change ◽  
Phosphonic Acids

Preparation, characterization and application of protective phosphonic acid monolayers formed by 1-Aminohexyl phosphonic acid (AHP), 1,4-butanediphosphonic acid (BDPA), 1-amino-1,3-dimethylbutyl phosphonic acid (ADBP) on copper surface as anticorrosive self-assembled molecular monolayers (SAMs) have been investigated by atomic force microscopy (AFM) analysis, electrochemical impedance spectroscopy (EIS) and in situ electrochemical quartz crystal microbalance (EQCM) techniques. Film formation and growth were monitored by EQCM and the step-by-step construction of monolayer was investigated through measurement of the frequency change, which corresponds to mass change due to the adsorption of molecules. Observed increase in electrode mass suggests that SAMs formed on copper surface by the adsorption of phosphonic acids. Results clearly demonstrate that adsorbed amounts of phosphonic acids were strongly influenced by immersion time and molecular structure. Quantum chemical calculations were performed by semi-empirical PM6 method, in order to explain the relationship between molecular structure and adsorption mechanism. Quantum chemical parameters of phosphonic acids propound that adsorption of molecules on copper surface has a chemical mechanism. Corrosion protection ability of SAMs against the acidic corrosion of copper has been evaluated in 0.1[Formula: see text]M H2SO4 solution. It was found that phosphonic acid SAMs act as protective barrier and the protection efficiencies increased in the following order: [Formula: see text].

scholarly journals Gravity-mode period spacings and near-core rotation rates of 611 γ Doradus stars with Kepler

2019 ◽  
Author(s):  
Gang Li ◽  
Timothy Van Reeth ◽  
Timothy R Bedding ◽  
Simon J Murphy ◽  
Victoria Antoci ◽  
...  
Keyword(s):  
Rotation Rate ◽  
Rotation Rates ◽  
The Core ◽  
Surface Rotation ◽  
Kepler Mission ◽  
Large Spread ◽  
Amplitude Spectra ◽  
Core Rotation ◽  
Composition Gradients ◽  
Gravity Mode

Abstract We report our survey of γ Dor stars from the 4-yr Kepler mission. These stars pulsate mainly in g modes and r modes, showing period-spacing patterns in the amplitude spectra. The period-spacing patterns are sensitive to the chemical composition gradients and the near-core rotation, hence they are essential for understanding the stellar interior. We identified period-spacing patterns in 611 γ Dor stars. Almost every star pulsates in dipole g modes, while about 30% of stars also show clear patterns for quadrupole g modes and 16% of stars present r mode patterns. We measure periods, period spacings, and the gradient of the period spacings. These three observables guide the mode identifications and can be used to estimate the near-core rotation rate. We find many stars are hotter and show longer period-spacing patterns than theory. Using the Traditional Approximation of Rotation (TAR), we inferred the asymptotic spacings, the near-core rotation rates, and the radial orders of the g and r modes. Most stars have a near-core rotation rate around 1 d−1and an asymptotic spacing around 4000 s. We also find that many stars rotate more slowly than predicted by theory for unclear reasons. 11 stars show rotational splittings with fast rotation rates. We compared the observed slope–rotation relation with the theory and find a large spread. We detected rotational modulations in 58 stars and used them to derive the core-to-surface rotation ratios. The interiors rotate faster than the cores in most stars, but by no more than 5%.

scholarly journals Dynamo Action in Evolved Stars

1991 ◽  
Vol 130 ◽  
pp. 336-341
Author(s):  
David F. Gray
Keyword(s):  
Angular Momentum ◽  
Magnetic Fields ◽  
Rotation Rate ◽  
Magnetic Activity ◽  
Dynamo Action ◽  
Rotation Rates ◽  
Evolved Stars ◽  
Solar Type ◽  
Limiting Value

AbstractEvolved stars tell us a great deal about dynamos. The granulation boundary shows us where solar-type convection begins. Since activity indicators also start at this boundary, it is a good bet that solar-type convection is an integral part of dynamo activity for all stars. The rotation boundary tells us where the magnetic fields of dynamos become effective in dissipating angular momentum, and rotation beyond the boundary tells us the limiting value needed for a dynamo to function. The observed uniqueness of rotation rates after the rotation boundary is crossed can be understood through the rotostat hypothesis. Quite apart from the reason for the unique rotation rate, its existence can be used to show that magnetic activity of giants is concentrated to the equatorial latitudes, as it is in the solar case. The coronal boundary in the H-R diagram is probably nothing more than a map of where rotation becomes too low to sustain dynamo activity.

scholarly journals Applegate mechanism in post-common-envelope binaries: Investigating the role of rotation

2018 ◽  
Vol 615 ◽  
pp. A81 ◽  
Author(s):  
F. H. Navarrete ◽  
D. R. G. Schleicher ◽  
J. Zamponi Fuentealba ◽  
M. Völschow
Keyword(s):  
Orbital Period ◽  
Rotation Rate ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Main Sequence Star ◽  
Common Envelope ◽  
Rotation Rates ◽  
Critical Rotation ◽  
Period Variations ◽  
Time Variations

Context. Eclipsing time variations are observed in many close binary systems. In particular, for several post-common-envelope binaries (PCEBs) that consist of a white dwarf and a main sequence star, the observed-minus-calculated (O–C) diagram suggests that real or apparent orbital period variations are driven by Jupiter-mass planets or as a result of magnetic activity, the so-called Applegate mechanism. The latter explains orbital period variations as a result of changes in the stellar quadrupole moment due to magnetic activity. Aims. In this work we explore the feasibility of driving eclipsing time variations via the Applegate mechanism for a sample of PCEB systems, including a range of different rotation rates. Methods. We used the MESA code to evolve 12 stars with different masses and rotation rates. We applied simple dynamo models to their radial profiles to investigate the scale at which the predicted activity cycle matches the observed modulation period, and quantifiy the uncertainty. We further calculated the required energies to drive the Applegate mechanism. Results. We show that the Applegate mechanism is energetically feasible in 5 PCEB systems. In RX J2130.6+4710, it may be feasible as well considering the uncertainties. We note that these are the systems with the highest rotation rate compared to the critical rotation rate of the main-sequence star. Conclusions. The results suggest that the ratio of physical to critical rotation rate in the main sequence star is an important indicator for the feasibility of Applegate’s mechanism, but exploring larger samples will be necessary to probe this hypothesis.

Evaluating two new Schiff bases synthesized on the inhibition of corrosion of copper in NaCl solutions

RSC Advances ◽  
2015 ◽  
Vol 5 (19) ◽  
pp. 14804-14813 ◽  
Author(s):  
Yang Zhou ◽  
Shenying Xu ◽  
Lei Guo ◽  
Shengtao Zhang ◽  
Hao Lu ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Copper Surface ◽  
Nacl Solution ◽  
Organic Film ◽  
Copper Dissolution

An AND or DSM organic film can be formed onto a copper surface in 3% NaCl solution and acts as a barrier to copper dissolution and O2reduction.

Fast Degradation with Pulsed Light of a-Si:H P-I-N Photodiodes

1993 ◽  
Vol 297 ◽  
Author(s):  
J. Puigdollers ◽  
J. Bertomeu ◽  
J.M. Asensi ◽  
J. Andreu ◽  
J.C. Delgado
Keyword(s):  
Dark Current ◽  
Reverse Bias ◽  
Degradation Process ◽  
Open Circuit ◽  
Ring Electrode ◽  
Guard Ring ◽  
Substrate Holder ◽  
Long Time ◽  
Kinetics Of ◽  
Xenon Flash

Amorphous Silicon p-i-nphotodiodes were obtained by PECVD in a reactor with a rotating substrate holder. Reverse currents as low as 5 × 10−11 A/cm2 at a bias of − 2V were measured using a guard ring electrode to minimize lateral edge currents. The devices were degraded by a Xenon flash lamp in open circuit conditions. The kinetics of the degradation process was evaluated by studying the long time dark current transient under reverse bias.

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