External Electrolyte Research Articles

Understanding Effective Electronic Conductivity of Slurry Electrodes Used in Electrochemical Flow Capacitors and All-Iron Redox Flow Batteries

Slurry electrodes are being considered in electrochemical systems1-5 for decoupling power and energy in electrochemical flow capacitors (EFCs) and for redox flow batteries (RFBs) involving electrodeposition reactions. In our all-iron slurry flow batteries (IFBs)3,4 utilizing very low-cost electrolyte materials, the slurry electrodes are used in the negative side involving iron plating/de-plating. During charging, iron is plated onto the slurry particles and then the particles carry the iron metal out of the electrochemical cell to be stored in the external electrolyte reservoirs. The slurry electrodes are synthesized by dispersing conductive carbon particles into electrolyte contained dissolved iron species. The effective electronic conductivity of slurry electrodes affects current density distributions, over-potential boundary layers, utilizations of slurry and electrochemical performance of EFCs and IFBs4. Therefore, fundamental studies of slurry electronic conductivity are needed. Possible factors affecting the effective electronic conductivity of a slurry include carbon loading, mean linear velocity or shear rate, electrolyte ionic strength, particle size, particle shape, surface chemistry, etc. In this work, we studied the effect of mean linear velocity through the slurry electrode channel ranging from stagnant to 22 cm/s on slurry effective electronic conductivity for various loadings of 660R carbon black dispersed in deionized water. A DC measurement using a chronoamperometry technique was made in a 3.5 cm2 electrode cell design. Figure 1 shows the variations of effective electronic conductivity for three different loadings, 5% w.t., 10% w.t. and 15% w.t. of 660R carbon black slurry under mean linear velocity increasing from 0 to 22 cm/s. The Figure 1 presents evidence that shear rates induced by different mean linear velocities/flow rates have certain effects on effective electronic conductivity of slurry electrodes. This is may be due to changes in the agglomeration patterns5of slurry particles. The motivation of this work is to explore possible mechanisms that lead to a better understanding of slurry electrodes. The ultimate goal is to improve the effective electronic conductivity of slurry electrodes and optimize the electrochemical performance of EFCs and IFBs. Acknowledgement This work is supported in-part by the all-iron flow battery project (award number: DE-AR0000352) funded by Department of Energy (DOE) of the United States.

All-Graphene Oxide Flexible Solid-State Supercapacitors with Enhanced Electrochemical Performance.

The rapid development of flexible and wearable electronics has led to an increase in the demand for flexible supercapacitors with enhanced electrochemical performance. Graphene oxide (GO) and reduced GO (rGO) exhibit several key properties required for supercapacitor components. Although solid-state rGO/GO/rGO supercapacitors with unique structures are promising, their moderate capacitance is inadequate for practical applications. Herein, we report a flexible solid-state rGO/GO/rGO supercapacitor comprising H2SO4-intercalated GO electrolyte/separator and pseudocapacitive rGO electrodes, which demonstrate excellent electrochemical performance. The resulting supercapacitor delivered an areal capacitance of 14.5 mF cm-2, which is among the highest values achieved for any rGO/GO/rGO supercapacitor. High ionic concentration and fast ion conduction in the H2SO4-intercalated GO electrolyte/separator and abundant CH defects, which serve as pseudocapacitive sites on the rGO electrode, were responsible for the high capacitance of this device. The rGO electrode, well separated by the H2SO4 molecular spacer, supplied highly efficient ion transport channels, leading to excellent rate capability. The highly packed rGO electrode and high specific capacitance resulted in a high volumetric energy density (1.24 mWh cm-3) observed in this supercapacitor. The structure, without a clear interface between GO and rGO, provides extremely low resistance and flexibility for devices. Our device operated in air (25 °C 40%) without the use of external electrolytes, conductive additives, and binders. Furthermore, we demonstrate a simple and versatile technique for supercapacitor fabrication by combining photoreduction and electrochemical treatment. These advantages are attractive for developing novel carbon-based energy devices with high device performance and low fabrication costs.

Construction of Er3+ :YAlO3 /RGO/TiO2 Hybrid Electrode with Enhanced Photoelectrocatalytic Performance in Methylene Blue Degradation Under Visible Light.

Much attention has been paid on doping TiO2 to narrow its band gap to promote the absorption of visible light and restrain the recombination of electron-hole pairs to improve its efficiency in photoelectrocatalysis (PEC) under visible-light irradiation. However, the oxidation potential energy of photo-induced holes for the modified catalysts by visible-light excitation is lower than that without modification by UV excitation. In this work, we synthesized a co-coupled TiO2 electrode (denoted ERT) with the Er3+ :YAlO3 and reduced graphene oxide (RGO), achieving the synergetic effect of visible-light-to-UV up-conversion and response and great electron transfer ability. The effects of external bias voltage, electrolyte concentration and pH on the PEC activity were studied with the methylene blue (MB) as the target pollutant. The results indicated that PEC by the ERT electrode showed the highest MB removal compared with those by the electrodes coupled with RGO or Er3+ :YAlO3 alone. In addition, the kinetic rate constant of the PEC process using the ERT electrode was higher than the sum of those of the photocatalytic and electrocatalytic processes. The optimal conditions for PEC by the ERT electrode were an external bias voltage of 1.0 V, 0.1 mol L-1 Na2 SO4 and pH = 10.

Nano "Koosh Balls" of Mesoporous MnO2 : Improved Supercapacitor Performance through Superior Ion Transport.

Manganese dioxide nanomaterials with "Koosh-ball"-like morphology (MnO2 -KBs) as well as worm-like nanotubes (MnO2 -NWs) are obtained by employing Tween 20 as the reducing and structure-directing agent, and KMnO4 as a MnO2 precursor. Whereas the MnO2 -KBs are interconnected through tubular extensions, the MnO2 -NWs are largely disconnected. Both MnO2 -KBs and MnO2 -NWs have large BET surface areas (>200 m2 g-1 ), and are thermally robust up to 300 °C. Electrochemical studies reveal that the highest specific capacitance (Csp ) obtained for MnO2 -KBs (272 F g-1 ) is significantly higher than that of MnO2 -NWs (129 F g-1 ). The Csp values correlate well with the electroactive surface areas of the materials: MnO2 -KBs have a significantly higher electrolyte-accessible surface area. Electrochemical impedance spectroscopy (EIS) reveals a higher electron-transfer rate at the electrode/electrolyte interface for MnO2 -KBs than for MnO2 -NWs. The multiple tubular interconnections between individual MnO2 -KBs allow improved ion penetration and act as conduits for their propagation, shortening the diffusion distances of the ions from external electrolytes to the interior of the MnO2 framework. Thus, this work exemplifies the importance of interconnections for enhancing the electrochemical performance of nanomaterials employed for energy storage.

Advances in corrosion protection by organic coatings: What we know and what we would like to know

Organic coatings are the single most widely applied method for corrosion protection of metallic materials and are of particular importance in transport and infrastructure. Nevertheless, despite over one hundred years of research and testing, the mechanisms of coatings failure are still somewhat obscure. This paper provides a brief overview of current knowledge in how protective coatings work and poses questions that we need to answer in order to develop a more predictive model for coating performance. It is shown how heterogeneity leading to electrochemical variations is important both in polymer structure (i.e. local variation in polymer conductivity influenced by the external electrolyte) and in light alloys (e.g. 2nd phase particles act as local cathodes or anodes). The conclusion is that no single protective mechanism is operative in organic coatings. Long-term performance is predicated on a number of complementary processes working holistically. By developing an understanding of the mechanisms and critical factors behind long-term performance, a predictive toolkit for “how paint fails” might usefully be created.

A Novel, Highly Effective, Chrome-Free, Smart-Release, Economically Viable Corrosion Inhibitor- from Lab Kinetics through to Industrial Coating Incorporation

Novel, smart-release in-coating corrosion-inhibiting pigments for hot dip galvanised (HDG) steel, were investigated as a low cost replacements for hexavalent chromate. Organic anions were exchanged into the smart-release divynl benzene resin based pigment, dispersed in a model coating and analysed using an in-situ scanning kelvin probe (SKP) technique, for their effectiveness at preventing cathodic delamination. SKP allows rapid screening of the inhibitor-containing pigment when dispersed in a model organic polyvinyl butyral (PVB) coating. Each experiment lasts 24 hours, enabling a larger experimental through-put in comparison to traditional screening techniques, such as EIS or salt spray (ASTM-B117). SKP gives spacially resolved corrosion potential (Ecorr) profiles enabling identification of the delamination front and subsequent measurement of its progression and rate kinetics. Figure 1 shows plots of delamination distance vs. time for the anions screened in these experiments. Results indicate that a benzotriazolate-containing pigment system is the most effective, where delamination rates were reduced by 95% and the onset of cathodic delamination was increased by ca. 2160 hours from the point of initiation with an external electrolyte. It has been reported previously that benzotriazole is an effective corrosion inhibitor for a range of metals when in solution (1-5), the divynl benzene matrix allows benzotriazolate to be stored and released only when the coating encounters a corrosive electrolyte, via ion exchange mechanisms. Open circuit potential measurements show an increase in Ecorr measurements where benzotriazole is present in the experimental electrolyte suggesting anodic inhibition. Results from salt-spray testing carried out on a commercial coil coating are also presented where benzotriazole is shown to be effective after a period of 1000 hours. The current study suggests that a benzotriazolate-containing pigment system is a strong, environmentally friendly, contender to replace chromate for the inhibition of corrosion on hot dip galvanised steel. 1. Finšgar M, Milošev I (2010) Corros Sci 52:2737–2749. 2. Kosec T, Merl DK, Milošev I (2008) Corros Sci 50:1987–1997. 3. Aramaki K (2001) Corros Sci 43:1985–2000. 4. Müller B, Imblo G (1996) Corros Sci 38:293–300. 5. LEROY RL (1978) Corrosion 34:98–110. Figure 1

Axial loading capacity of concrete‐jacketed RC columns with pre‐ and post‐corrosion damage

AbstractThe main objective of this study is to investigate the effect of pre‐ and post‐jacketing corrosion and loading damage on concrete‐jacketed reinforced concrete (RC) columns under uniaxial loading and to develop a methodology for predicting the corresponding compressive strength. The pre‐ and post‐damage involved preloading up to 50 % of the peak load of the core column, an electrochemical process to accelerate the migration of chlorides from an external electrolyte into the test columns and a wetting–drying cycle process with a controlled current to speed up the corrosion of the steel reinforcing bars in the test columns. Uniaxial loading tests were performed to determine the structural performance of the concrete‐jacketed columns with and without corrosion damage. The failure mode and load–displacement and load–strain responses of the test columns were recorded, and the related mechanisms are discussed. A model capable of evaluating the compressive strength of unjacketed or jacketed RC columns with and without corrosion damage was then developed. The analytical approach considered the effect of reinforcement corrosion on the effective loadbearing area of the concrete and the confinement effect of the stirrups. The analytical results agree well with the experimental results, indicating the reliability and effectiveness of the models developed.

Use of Surface Photovoltage Spectroscopy to Measure Built-in Voltage, Space Charge Layer Width, and Effective Band Gap in CdSe Quantum Dot Films.

Surface photovoltage spectroscopy (SPS) was used to study the photochemistry of mercaptoethanol-ligated CdSe quantum dot (2.0-4.2 nm diameter) films on indium doped tin oxide (ITO) in the absence of an external bias or electrolyte. The n-type films generate negative voltages under super band gap illumination (0.1-0.5 mW cm(-2)) by majority carrier injection into the ITO substrate. The photovoltage onset energies track the optical band gaps of the samples and are assigned as effective band gaps of the films. The photovoltage values (-125 to -750 mV) vary with quantum dot sizes and are modulated by the built-in potential of the CdSe-ITO Schottky type contacts. Deviations from the ideal Schottky model are attributed to Fermi level pinning in states approximately 1.1 V negative of the ITO conduction band edge. Positive photovoltage signals of +80 to +125 mV in films of >4.0 nm nanocrystals and in thin (70 nm) nanocrystal films are attributed to electron-hole (polaron) pairs that are polarized by a space charge layer at the CdSe-ITO boundary. The space charge layer is 70-150 nm wide, based on thickness-dependent photovoltage measurements. The ability of SPS to directly measure built-in voltages, space charge layer thickness, sub-band gap states, and effective band gaps in drop-cast quantum dot films aids the understanding of photochemical charge transport in quantum dot solar cells.

Self-contained tubular bending actuator driven by conducting polymers

The low voltage operation and relatively high strain response of conducting polymer actuators has made their use in tubular actuators such as actively steerable catheter tips of interest. Previous work has shown that bending can be achieved by simply coating a commercial catheter with conducting polymer and patterning. However, these actuators require an external electrolyte to operate. This work presents instead a self-contained tubular actuator in which all ion conduction between active polymer layers occurs internally.The conducting polymer PEDOT provides the active deformation to control its maneuverability and actuation. To form the body of the actuator and an electrolyte medium to enable transfer of ions during the actuation of conducting polymer, a highly ionically conductive interpenetrating polymer network composed of ionically conductive polyethylene oxide and stretchable nitrile butadiene rubber (NBR) is used. This compliant medium also enables a tight radius of curvature. Laser micromachining is used to pattern PEDOT on the surface. A 0.95mm diameter device is shown to achieve a 22mm radius of curvatures under activation of 2V. A closed form beam bending model for tubular trilayer actuators is derived which predicts the radius of curvature as a function of applied voltage and free strain. This model enables easy prediction of deflection, as is demonstrated.

Modulation and Salt-Induced Reverse Modulation of the Excited-State Proton-Transfer Process of Lysozymized Pyranine: The Contrasting Scenario of the Ground-State Acid–Base Equilibrium of the Photoacid

Here we report on the excited-state behavior in terms of the excited-state proton-transfer (ESPT) reaction as well as the ground-state acid-base property of pyranine [8-hydroxypyrene-1,3,6-trisulfonate (HPTS)] in the presence of an enzymatic protein, human lysozyme (LYZ). HPTS forms a 1:1 ground-state complex with LYZ having the binding constant KBH = (1.4 ± 0.05) × 10(4) M(-1), and its acid-base equilibrium gets shifted toward the deprotonated conjugate base (RO(-)), resulting in a downward shift in pKa. This suggests that the conjugate base (RO(-)) is thermodynamically more favored over the protonated (ROH) species inside the lysozyme matrix, resulting in an increased population of the deprotonated form. However, for the release of the proton from the excited photoacid, interestingly, the rate of proton transfer gets slowed down due to the "slow" acceptor biological water molecules present in the immediate vicinity of the fluorophore binding region inside the protein. The observed ESPT time constants, ∼140 and ∼750 ps, of protein-bound pyranine are slower than in bulk aqueous media (∼100 ps, single exponential). The molecular docking study predicts that the most probable binding location of the fluorophore is in a region near to the active site of the protein. Here we also report on the effect of external electrolyte (NaCl) on the reverse modulation of ground-state prototropy as well as the ESPT process of the protein-bound pyranine. It is found that there is a dominant role of electrostatic forces in the HPTS-LYZ interaction process, because an increase in ionic strength by the addition of NaCl dislodges the fluorophore from the protein pocket to the bulk again. The study shows a considerably different perspective of the perturbation offered by the model macromolecular host used, unlike the available literature reports on the concerned photoacid.

Bidirectional electromigration of a corrosion inhibitor in chloride contaminated concrete

Triethylenetetramine (TETA), as a corrosion inhibitor for steel in aqueous media, was introduced into chloride-contaminated concrete, specimens by using a novel method called bidirectional electromigration rehabilitation (BIEM). An electric field was applied between embedded steel cathodes and external anodes to inject the corrosion inhibitor from external electrolytes into the concrete, and at the same time to extract the chloride ions from the concrete cover zone. In part 1, after the treatment, the specimens were drilled to determine the concentration profiles of the corrosion inhibitor, chloride and hydroxyl ions within the concrete. The effects of variations in the applied current density, duration of electrolysis, water/cement ratio, initial chloride content and surface carbonation on the concentration profiles of the proposed ions were determined. Electrochemical chloride extraction (ECE), in which saturated calcium hydroxide solution was used as an external electrolyte, was applied in control experiments. As expected, chloride content decreased and alkalinity increased after the treatment. Also, the concentration of the inhibitor injected around the embedded steel bars was adequate to provide corrosion protection. The results can provide a direction in designing the BIEM process.

Organic corrosion inhibitor of triethylenetetramine into chloride contamination concrete by eletro-injection method

Triethylenetetramine (TETA), a corrosion inhibitor for steel in aqueous media, was introduced into chloride-contaminated concrete specimens using a novel method called bidirectional electromigration rehabilitation (BIEM). An electric field was applied between the embedded steel cathodes and external anodes to inject the corrosion inhibitor from the external electrolytes to the concrete specimens and extract the chloride ions from the concrete cover zone. After treatment, the specimens were drilled to determine the concentration profiles of the corrosion inhibitor, chloride, and hydroxyl ions within the concrete. Effects of variations in the applied current density, duration of electrolysis, water/cement ratio, initial chloride content, and surface carbonation on the concentration profiles of the proposed ions were determined. Electrochemical chloride extraction (ECE) was applied as a control experiment using saturated Ca(OH)2 solution as an external electrolyte. As expected, the chloride content decreased and alkalinity increased after treatment. The concentration of the inhibitor injected around the embedded steel bars was adequate to provide corrosion protection. Concrete strength and pore distribution were measured before and after the electrochemical process was applied. The ability of TETA to inhibit further corrosion after BIEM treatment was also analyzed. The effects of BIEM and ECE were also compared. The results obtained can provide a direction in designing the BIEM process.

Complex Formation of Divalent Cations with Carboxylic Acid Resins as a Factor Determining Different Stationary States of Their Swelling

ABSTRACTThree samples of carboxylic acid gel-type cross-linked polyelectrolytes were examined by registering the extent and kinetics of their volume change depending on the temperature, concentration, and nature of external electrolyte solutions, as well as the initial state (ionic form, water content) of the bead. It is found that in some systems the swelling of the bead (as a result of lowering the temperature) proceeds much more slowly than the preceding shrinking (as a result of the increase of temperature). Moreover, the initial volume of the bead is not restored, and a new stationary state of swelling is established. By means of optical dilatometry, it is found that in the systems in which the differences in the stationary states of swelling are found, the beads display plasto-elastic properties, whereas in the absence of such differences the beads show elastic properties. It is found that different stationary states of swelling are also established when the beads of copolymer of methacrylic acid cross-linked with divinylbenzene in Na+ form in the dry state and in the NaCl solution-swollen state are placed into a solution of a divalent cation salt. The difference in the stationary states of swelling reaches 12% in 4 N NiCl2 solution. The substantial differences in the swelling behavior and viscoelastic properties of the resins in their Na+, Mg2+, Ca2+, and Ni2+ forms are interpreted in terms of formation of different kinds of complexes of functional groups of the polymer with Ca2+ and Ni2+ ions.

Lithium-ion battery structure that self-heats at low temperatures.

Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40 per cent. Previous attempts to improve the low-temperature performance of lithium-ion batteries have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells. Here we report a lithium-ion battery structure, the 'all-climate battery' cell, that heats itself up from below zero degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favourable for high discharge/charge power. We show that the internal warm-up of such a cell to zero degrees Celsius occurs within 20 seconds at minus 20 degrees Celsius and within 30 seconds at minus 30 degrees Celsius, consuming only 3.8 per cent and 5.5 per cent of cell capacity, respectively. The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50 per cent state of charge and at minus 30 degrees Celsius, delivering 6.4-12.3 times the power of state-of-the-art lithium-ion cells. We expect the all-climate battery to enable engine stop-start technology capable of saving 5-10 per cent of the fuel for 80 million new vehicles manufactured every year. Given that only a small fraction of the battery energy is used for self-heating, we envisage that the all-climate battery cell may also prove useful for plug-in electric vehicles, robotics and space exploration applications.

Ultrahigh Performance of Novel Capacitive Deionization Electrodes based on A Three-Dimensional Graphene Architecture with Nanopores.

In order to achieve optimal desalination during capacitive deionization (CDI), CDI electrodes should possess high electrical conductivity, large surface area, good wettability to water, narrow pore size distribution and efficient pathways for ion and electron transportation. In this work, we fabricated a novel CDI electrode based on a three-dimensional graphene (3DG) architecture by constructing interconnected graphene sheets with in-plane nanopores (NP-3DG). As compared to 3DG, NP-3DG features a larger specific surface area of 445 m2 g−1 and therefore the higher specific capacitance. The ultrahigh electrosorptive capacity of NP-3DG predicted from Langmuir isotherm is 17.1 mg g−1 at a cell potential of 1.6 V. This can be attributed to the interconnected macropores within the graphene networks and nanopores on graphene sheets. Both of macropores and nanopores are favorable for enhancing CDI peroformance by buffering ions to reduce the diffusion distances from the external electrolyte to the interior surfaces and enlarging the surface area.

Capacitance Optimization in Nanoscale Electrochemical Supercapacitors

We perform constant voltage Gibbs ensemble based grand canonical Monte Carlo simulations for nanosized supercapacitors comprising graphene slit electrodes in symmetric and asymmetric electrolytes. Our simulations demonstrate that external electrolyte at the electrode surface can be exploited to positively influence the structure and packing of that inside the slit, when the system is engineered to allow these to interact. Oscillatory dependence of capacitance on slit-pore size, seen in recent results from molecular dynamics simulation and density functional theory, is observed also in our Monte Carlo simulations. A detailed analysis suggests that maximum in capacitance occurs in subnanometre pores because of the interference between internal double layers (largely the Helmholtz parts) on the opposite sides of the slit, expelling the co-ions; and that the oscillatory character of capacitance with pore width is due to relative changes in counterion and co-ion populations with pore width, also dictated by th...

Electrochemical Characterization of Cellulose Acetate Butyrate-Prmutit Composite Membrane in Aqueous Uni-Uni Valent Electrolyte Solutions

Co-mixed cellulose acetate butyrate and permutit in a definite composition was prepared and coded as MRS-2. The membrane potential was measured with uni-uni valent electrolyte, NaCl solutions using saturated calomel electrodes (SCEs).The effective fixed charge density of the membrane was determined by TMS method and it showed dependence on the porosity, charge on the membrane matrix, charge and size of permeating ions. Other important electrochemical parameters were calculated. Conductance-time data were generated for the kinetic study of the permeating ions in terms of membrane permeability, flow and flux parameters. Donnan membrane equilibrium condition was examined. Membrane adsorbability showed concave dependence with external electrolyte solution and convex type dependence was showed by swelling and conductance parameters. This membrane had no characteristic of anomalous osmosis, indicates that there is no water flooding will take place during membrane operation.Int J Appl Sci Biotechnol, Vol 3(2): 337-341 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12748

Modification of microstructure and magnetic properties of electrodeposited Co nanowire arrays: A study of the effect of external magnetic field, electrolyte acidity and annealing process

High aspect ratio Co nanowire arrays are fabricated through the ac electrodeposition method using anodic aluminum oxide templates. The effect of electrolytic bath acidity (pH) as well as applied external magnetic field during the electrodeposition process together with the effect of annealing process after sample preparation on the crystal structure and magnetic properties of nanowires are investigated. The experimental results show that the pH value of electrolyte affects the magnetic properties of the nanowire arrays due to modification of the microstructure and quality of electrodeposition. The Co nanowires form in fcc, a mixture of fcc and hcp, and hcp crystal structure at pH = 2.5, pH = 3.5, and pH = 5, 6, respectively. The experimental results also reveal that applying appropriate external magnetic field parallel to the nanowire axis improves the magnetic properties of deposited Co NWs probably due to increase in mass transport in the diffusion layer by applied external magnetic field, which results in lowering the porosity generated due to formation of hydroxide at high pH value. Our studies show that appropriate annealing process can also enhance the crystal texture in the hcp phase and therefore significantly improve the magnetic properties of NW arrays deposited at either high pH regime or under external magnetic field. Moreover, it is shown that although each factor individually affects the magnetic properties of the Co NW arrays, the combination of annealing process, external magnetic field and electrolyte acidity allows the control of the quality of samples and enhance the magnetic properties of Co nanowire arrays.

In-Coating Phenyl Phosphonic Acid as an Etch-Primer Corrosion Inhibitor System for Hot Dip Galvanized Steel

In-coating phenyl phosphonic acid (H2PP) additions are investigated as inhibitors of corrosion-driven organic coating disbondment on hot-dip galvanized (HDG) steel surfaces. In-situ scanning Kelvin probe (SKP) experiments under atmospheric corrosion conditions are used to study the influence of the quantity of dissolved H2PP in the organic coating on the kinetics of delamination. It is demonstrated that increasing levels of in-coating H2PP progressively lengthen the time for organic coating delamination to become established. Once underfilm corrosion becomes initiated, rates of cathodic disbondment are significantly slowed by H2PP additions in comparison with the uninhibited case. From the observed delamination kinetics, an inhibition mechanism is proposed whereby H2PP additions interact with the underlying zinc to form an interfacial salt layer which blocks underfilm oxygen reduction. The contribution of other possible modes of inhibition, such as H2PP release from the coating into the external defect electrolyte and a buffering of underfilm pH, are also discussed.

On the peculiarities of work of promising anode alloys for portable aluminum-air current sources

Peculiarities of Work of promising anode alloys for portable current sources, referred to Al-In-Ga and Al-Sn-Ga systems, are considered. The use of such alloys makes it possible to increase specific energy of portable aluminum-air current sources (AA CSs) without external service circuits by a factor of 2.5–3 compared to the two-component alloys proposed in the literature. The use of anodes of promising alloys in aluminum-air current sources with flow-through cells and an external electrolyte regeneration circuit appreciably simplifies restart of the source after long continuance in the no-load condition.