Effect of Cr(III) passivation layer on surface modifications of zinc-nickel coatings in chloride solutions

Surface chemical and morphological modifications of as-plated and Cr(III)-passivated monophasic zinc-nickel coatings induced by corrosion in chloride solutions are demonstrated. The passivated samples showed slower anodic dissolution, less significant de-alloying, smaller surface dezincification and lower coating cracking, as demonstrated by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDX) of the surface and inductively coupled plasma atomic emission spectroscopy solution analysis. Surface characterization by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and SEM-EDS indicated simonkolleite as the main corrosion product for both, as-plated and Cr(III)-passivated coatings. In contrast, only for as-plated coating, which experienced higher cracking, new Ni containing phases (metallic Ni and NiO) were evidenced. The phase transition via selective dissolution of zinc is supposed to increase the concentration of the structural defects and could explain cracking in the non-passivated Zn-Ni coating.

     

Diffusion Problem in Chronopotentio- and Chronoamperometry for Electrode with Rough Surface

By analyzing a rigorous solution of a nonstationary diffusion problem for an electrode with a sine-shaped crimped surface it is proved that the assumptions underlying the combined adsorption–diffusion method of determining the roughness factor of metals and alloys are correct.     

Synthesis and Anticoagulant Activity of New Ethylidene and Spiro Derivatives of Pyrrolo[3,2,1-ij]quinolin-2-ones

Russian Journal of Organic Chemistry - The reaction of pyrrolo[3,2,1-ij]quinoline-1,2-diones with methyl (het)aryl ketones gave the corresponding 1-(het)arylmethylidenepyrroloquinolin-2-ones, and...     

Anodic formation and properties of nanoscale oxide layers on silver–zinc alloys with different concentrations of non-equilibrium vacancies

Journal of Solid State Electrochemistry - Anodic oxidation of silver–zinc alloys with a concentration of zinc of up to 30 at.% (alpha phase) in a deaerated aqueous solution of 0.1 M...