Study of Hillock and Zinc Whisker Evolution in Five Different Cable Tray Coatings

The main objective of this work is the study of the hillock and zinc whisker evolution of five different commercial zinc coatings applied on the same base steel wires of the patented EASYCONNECT system cable trays manufactured by VALDINOX Ltd.: white zinc alkaline electrolyte, yellow zinc trivalent electrolyte, acid zinc electrolyte, hot dip galvanized, and zinc nickel coating. The limited literature on the subject is summarized, and then the coating thickness, chemical composition, hardness and surface rugosity are characterized. The hillock and whisker density evolution are evaluated over a period of 12 months, considering the presence of compression bending stresses. It is concluded that the white alkaline and yellow trivalent coatings are the most affected, while the zinc-nickel shows the best behavior with no presence of whiskers; the acid zinc electrolyte also shows good results despite the delayed appearance of whiskers from the ninth month; the hot-dip galvanized coating does not show any presence of zinc whiskers or hillocks.

The energy storage behavior of a phosphate-based cathode material in rechargeable zinc batteries

Li3V2(PO4)3 transforms into a VOPO4 type structure and delivers high electrochemical activity as well as stability with a water–acetonitrile zinc electrolyte.

Reduction of silver ions in molybdates: elucidation of framework acidity as the factor controlling charge balance mechanisms in aqueous zinc-ion electrolyte

Across four molybdates, reduction of silver ions in aqueous zinc electrolyte is more facile with increasing acidity.

Lead-silver anode behavior for zinc electrowinning in sulfuric acid solution

In recent years, a renewed interest in studying the electrochemical corrosion behavior of lead anodes during zinc electrowinning is probably due to the particularly high sulfuric acid concentrations in zinc electrolyte where lead alloy anodes have high cell voltage and high corrosion rate of lead. The high corrosion rate of lead alloy resulted in Pb contamination on zinc deposit. In zinc electrometallurgy, the electrolyte from a zinc-rich ore contains a significant amount of Mn2+. Mn2+ in the zinc electrolyte results in forming an oxide film on lead anodes during electrolysis. Pb-0.7% Ag anode is generally used in the zinc industry. To improve the technical performance and decrease product cost, other anodes, such as Pb-Ca or Pb-Ag-Ca or Pb-Ag-Ti or Pb-Ag-Se alloys were tested. Till now, none of them has succeeded in the substitution of Pb-Ag anodes in the zinc electrowinning. As an alloying element, silver in small quantities is considered because of the benefits that generates on the anode during electrolysis. During zinc electrolysis, lead dissolution into the zinc electrolyte can be harmful to the quality of zinc deposit. However, the lead silver alloy anode can decrease the lead content in the zinc deposit by pre-treated methods such as blasting and preconditioning.

ELECTROPHYSICAL PROPERTIES OF ZINC SULFATE SOLUTIONS IN PRESENCE OF WATER DISPERSION OF MULTI-LAYERED CARBON NANOTUBES

Multi-layered carbon nanotubes were synthesized via hydrocarbons pyrolysis method in the presence of argon overpressure in the reaction system. With the use of the scanning electron microscope method, a morphology of the obtained materials were investigated. Synthetized nanotubes were modified by treating with solutions of various reagents: sodium hydroxide (10 mass. %), azotic (40 mass. %) and perchloric (40 mass. %) acids, chloroform. The sample was placed in the reagent solution with the volume of 10 ml and exposed for 24 h. Electrophysical investigation of multi-layered carbon nanotubes dispersions with zinc sulfate additions was carried with the use of the impedance meter Z - 1500J in a range of frequencies of 10 Hz - 2 MHz. It was found that the carbon nanomaterials effect on the electrophysical properties of zinc electrolyte. A change in electrical conductivity of zinc sulfate solutions with the addition of multi-layered carbon nanotubes with various morphology and surface modifications was studied. With the use of impedance spectroscopy method, there were examined the electrophysical properties of zinc electrolyte with additions of carbon nanotubes in the presence of various components concentration and pH level of the environment, that was obtained via the original technique. It is shown that electron conduction increases with the rise of nanotubes concentration, but substantially levels with the rise of zinc sulfate concentration. Moreover, insertion of multi-layered carbon nanotubes in the solution changes a state of equivalent circuit and its elements. It is concluded that insert of multi-layered carbon nanotubes has unambiguous impact on the electrophysical properties of zinc sulfate solutions. Based on the obtained data, a scheme of electrolyte and nanotubes interaction is offered.

Autoclave Precipitation Of Iron From Zinc Sulfate Solutions

<p>Zinc concentrates processing technology that includes high-temperature roasting – leaching of cinder – purification of leached liquor – electrowinning is the most widely used technology. Purified solution, which is fed to the electrowinning stage, has a high sensitivity to such an impurity as iron. The presence of iron in the zinc electrolyte has a negative influence both on the current efficiency and the quality of the cathode zinc. </p><p>The application of autoclave equipment for iron removal from zinc sulfate solutions, obtained after the leaching stage of zinc cinder, is described in this article. All experiments were carried out with a model solution of following composition, g/L: 10-33 H₂SO₄, 1.5 Cu, 5 Mn, 110 Zn, 2.5 Fe. Neutralization and purification of the solution was implemented during low-temperature pressure leaching of the zinc cinder. </p><p>The optimum conditions for iron precipitation from zinc solution are following: molar flow rate Zn(cinder) / H₂SO₄ = 1.3, t = 80 °C, τ = 1 hour, P_O2 = 0.2 MPa. It was found, that the concentration of iron can be reduced up to 1-2 mg/L, whereas 83.5% of Zn and 52.1% of Cu being recovered into the solution from zinc cinder.</p>

Phenol-Formaldehyde Resin to Improve Corrosion Resistance of Zinc Layers

The present work has the purpose to study and to evaluate the corrosion resistance of zinc layers and phenol – formaldehyde resin/Zn composite layers obtained by electrodeposition. For the best results it was used different parameters for electrodeposition such as: current density between 3 – 5 A/dm2, time for electrodeposition: 30 minutes and 60 minutes, stirring rate: 500 rpm and 800 rpm. Different sizes (mean diameter size between 0.1 – 5.0μm and 6.0 – 10.0μm) of dispersed phases were used with concentration into electrolyte solution from 10g/L to 25 g/L of polymer particles. The morphology of the layers was investigated by SEM – EDX methods. The surface morphology of composite layers was different as compared with pure zinc layers. By adding polymer particles into zinc electrolyte during electroplating a very good distribution of polymer on zinc layer surface was obtained. The electrochemical behavior of the composite layers in the corrosive environment was investigated by polarization potentiodynamic and electrochemical impedance spectroscopy methods. As electrochemical test solution 0.5M sodium chloride was used in a three electrode open cell.