Papers by Keyword: Cathodic Polarization

Abstract: Cathodic polarization is a powerful technique largely used for the deposition of thin films on metallic substrates; it offers the distinctive advantage of an easy control over the composition, thickness, and morphology of the films by simply adjusting the process parameters such as the electrolyte bath composition, the applied potential (or current density), and the process duration. In this work, electrochemical deposition (ECD) was exploited to engender biopolymer blends composed by chitosan/collagen and chitosan/poly (ethylene oxide) and deposited at different weight ratios (5:1, 3:1) and compared to pristine material. Our findings demonstrate that ECD is an effective technique for the preparation of scaffolds made of chitosan blends in which morphology and mechanical properties can be optimized via scaffold composition.

Abstract: Hydrogen ingress into a metal has been observed at cavitation in distilled water and in 3% NaCl solution at open circuit potential. The measurements of hydrogen permeation rate have been made using an ultrasonic cavitation facility with an attached Devanathan-Stachurski double cell. Increase in vibration amplitude has been associated with the increase in amplitude of electrochemical voltage and current pulses and with the modification of hydrogen permeation rate. Hydrogen behavior within the metal has been affected by the cavitation induced dynamic stresses and metal deformation hardening, ascertained on the basis of the appearance of hydrogen permeation transients at cavitation in comparison with those recorded for the unstressed state. Metal damage has been a resultof associated effects of cavitation and hydrogen.

Abstract: In this paper, structural and electrochemical characteristics of the Cr-Al₂O₃ nano composite coatings were investigated. Cr-Al₂O₃ nano composite coatings were electrodeposited in electrolyte containing nano Al₂O₃ particles. The influences of nano Al₂O₃ particles on the chemical composition, morphological and structural characteristics of the electrodeposited Cr-Al₂O₃ nano composite coatings were investigated using energy dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffractometry. The electrodeposition behavior of Cr³⁺ ion and the action mechanism of electrolyte components such as auxiliary complexing agent, wetting agent, nano Al2O3 in the process of Cr-Al₂O₃ composite electrodeposition were investigated using the electrochemical measurement methods such as cyclic voltammetry and cathodic polarization. The results reveal that the nano Al₂O₃ particles can be codeposited in the Cr matrix, micro crystal structure of the Cr-Al₂O₃ nano composite coatings are obviously refined, Cr-Al₂O₃ nano composite coatings are amorphous structure.

Abstract: Ni-diamond composite coatings are conducted by electrodepositon. The crystal structure and surface morphology of the composite coatings were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the mechanism of Ni-diamond co-deposition is conducted by catholic polarization and cyclic voltammetry method. The result reveals that diamond particles are successfully embed in Ni matrix and the coatings have an amorphous structure. Cyclic voltammetry indicate that nickel deposition process is an irreversible electrode reaction and cathode polarization curve shift towards positive with the increase of scan rates. Cathodic polarization curve shows that reduction potential of nickel to shift to more negatives with the addition of complexing agent and the slope of the polarization curve is decrease; The addition of brightener and dispersant hinder the deposition of Ni2+ and promote the growth of crystal nucleus; The join of wetting agents and diamond particles have no big influence on the deposition of nickel.

Abstract: The influences of jet flow rate and temperature on cathodic polarization of nickel deposits have been studied in this paper. The results indicate that increasing jet flow rate and temperature of the electrolyte make the equilibrium electrode potential decrease. When jet flow rate increases from 1.0 L/min to 6.0 L/min, the grain size of nickel deposits decreases from 22.6 nm to 18.9 nm. X-ray diffraction patterns show that increasing jet flow rate results in (111) preferred growth orientation for nickel deposits.