Mechanistic Aspects of Pit Growth on Nickel in Diluted Chloride Solutions

CORROSION ◽  
1985 ◽  
Vol 41 (12) ◽  
pp. 715-719 ◽  
Author(s):  
P. Heimgartner ◽  
H. Bohni
Keyword(s):  
Charge Transfer ◽  
Transition Time ◽  
Dissolution Mechanism ◽  
Current Response ◽  
Applied Potential ◽  
Pulse Technique ◽  
Chloride Solutions ◽  
Diffusion Controlled ◽  
Current Densities ◽  
Dependent Mechanism

Abstract Pit current densities (CDs) in small pits have been found to be potential dependent, indicating an ohmic or mixed ohmic-charge transfer controlled dissolution mechanism. In a later stage of pit growth, a diffusion-controlled dissolution has often been reported. The potential-dependent mechanism is not always restricted to only the beginning of pit development, as has been shown in galvanostatic tests with rather low CDs. In this paper, the mechanism change from ohmic-charge transfer to diffusion-controlled pit growth was also studied in potentiostatic experiments by means of potential pulses added to the applied potential. The current response to fast potential changes differs for the two mechanisms. The influence of a number of parameters [such as potential, position of the specimen (horizontal or vertical), agitation of the bulk electrolyte, and pit diameter] on the transition time for mechanism change could be investigated using this pulse technique. Results also show that the rate law for pit growth can be very similar for the two types of mechanisms and different pit geometry (artificial pits of the wire type or “naturally” growing pits).

Chemical relaxations in micellar solutions by ultrasonic spectroscopy. II. Sodium heptylsulfate and hexylammonium chloride solutions

1976 ◽  
Vol 54 (7) ◽  
pp. 1162-1167 ◽  
Author(s):  
Douglas A. W. Adair ◽  
Vincent C. Reinsborough ◽  
Hayden M. Trenholm ◽  
John P. Valleau
Keyword(s):  
Relaxation Behaviour ◽  
Micellar Solutions ◽  
Ultrasonic Spectroscopy ◽  
Pulse Technique ◽  
Chloride Solutions

Ultrasonic absorptions have been measured by the pulse technique for the dilute and concentrated micellar range for Na heptylsulfate and hexylammonium chloride solutions. The dilute micellar range was also investigated for the Li, K, Rb, and Cs heptylsulfate systems. Single-valued relaxations were found in each system. The relaxation frequencies increased linearly with concentration in the concentrated micellar range but in the dilute range were relatively constant. The relaxation behaviour was interpreted in terms of monomer exchange between micelles.

scholarly journals Impedance Characterization of an LCO-NMC/Graphite Cell: Ohmic Conduction, SEI Transport and Charge-Transfer Phenomenon

Batteries ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 43 ◽  
Author(s):  
Victoria Ovejas ◽  
Angel Cuadras
Keyword(s):  
Charge Transfer ◽  
Solid Electrolyte Interphase ◽  
Impedance Spectrum ◽  
Half Cell ◽  
Electrochemical Processes ◽  
Sei Layer ◽  
Current Densities ◽  
Li Ion ◽  
Impedance Characterization

Currently, Li-ion cells are the preferred candidates as energy sources for existing portable applications and for those being developed. Thus, a proper characterization of Li-ion cells is required to optimize their use and their manufacturing process. In this study, the transport phenomena and electrochemical processes taking place in LiCoO2-Li(NiMnCo)O2/graphite (LCO-NMC/graphite) cells are identified from half-cell measurements by means of impedance spectroscopy. The results are calculated from current densities, instead of absolute values, for the future comparison of this data with other cells. In particular, impedance spectra are fitted to simple electrical models composed of an inductive part, serial resistance, and various RQ networks—the parallel combination of a resistor and a constant phase element—depending on the cell. Thus, the evolution of resistances, capacitances, and the characteristic frequencies of the various effects are tracked with the state-of-charge (SoC) at two aging levels. Concretely, two effects are identified at the impedance spectrum; one is clearly caused by the charge transfer at the positive electrode, whereas the other one is presumably caused by the transport of lithium ions across the solid electrolyte interphase (SEI) layer. Moreover, as the cells age, the characteristic frequency of the charge transfer is drastically reduced by a factor of around 70%.

scholarly journals Portable Chronic Alcohol Consumption Monitor in Human Sweat through Square-Wave Voltammetry

2017 ◽  
Vol 23 (2) ◽  
pp. 144-153 ◽  
Author(s):  
David Kinnamon ◽  
Sriram Muthukumar ◽  
Anjan Panneer Selvam ◽  
Shalini Prasad
Keyword(s):  
Charge Transfer ◽  
Alcohol Consumption ◽  
Square Wave Voltammetry ◽  
The United States ◽  
Current Response ◽  
Chronic Alcohol ◽  
Chronic Alcohol Consumption ◽  
Square Wave ◽  
Human Sweat ◽  
Wave Voltammetry

Chronic alcohol consumption is a significant financial and physical burden in the United States each year. Alcohol consumption monitors focus on establishing a state of intoxication, not assessing a user’s health risks as a function of consumed alcohol. This work demonstrates a biosensor for a chronic alcohol consumption monitor through the electrochemical detection of ethyl glucuronide (EtG) in human sweat using square-wave voltammetry (SWV). A novel affinity assay was demonstrated in which monoclonal antibodies were chemically coabsorbed onto a gold electrode surface in parallel with thiolated charge transfer molecule. Concentration-dependent EtG binding was detected by measuring a reduction in the charge transfer of the sensor, manifesting as a current response during SWV measurement. A companion compact electronic reader was constructed, demonstrating comparable sensitivity to a conventional lab instrument. Both tools demonstrated a limit of detection of 0.1 µg/L and a linear dynamic range of 0.1–100 µg/L corresponding to the physiologically relevant range of EtG expression in human sweat. This device can address the need for a chronic alcohol consumption monitor toward establishing a user’s long-term consumption habits to assess the risk of developing specific diseases and conditions associated with regular alcohol consumption, through integration with existing technologies.

The recombination of atoms, IV. Iodine atom complexes

1961 ◽  
Vol 262 (1311) ◽  
pp. 476-488 ◽  
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Iodine Atom ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Equilibrium Constants ◽  
Vapour Phase ◽  
Charge Transfer Complexes ◽  
Transient Absorption Spectra ◽  
Diffusion Controlled

Transient absorption spectra have been detected after flash photolysis of iodine in a variety of solvents. There is some correlation between the wavelength of maximum absorption and the ionization potential of the solvent and the spectra are attributed to the charge transfer complexes between iodine atoms and the solvent which were predicted in part III. In the case of methyl iodide as chaperon a weak transient has also been observed in the vapour phase. The decay of the complex follows a second-order law and rate constants have been measured in six solvents. Values for the extinction coefficient are derived by assuming that the reaction is diffusion controlled. Equilibrium constants of complex formation have been measured in ethyl iodide and ethyl bromide.

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