The Experts below are selected from a list of 2196 Experts worldwide ranked by ideXlab platform
G. Trejo - One of the best experts on this subject based on the ideXlab platform.
-
characterization of the corrosion products of electrodeposited zn zn co and zn mn alloys coatings
Corrosion Science, 2009Co-Authors: Z.i. Ortiz, Y. Meas, P Diazarista, R Ortegaborges, G. TrejoAbstract:Abstract The morphology, composition, phase composition and corrosion products of coatings of pure Zn (obtained from two types of electrolytic Bath: an Acidic Bath (Zn acid ) and a cyanide-free alkaline Bath (Zn alkaline )) and of Zn–Mn and Zn–Co alloys on steel substrates were studied. To achieve this, diverse techniques were used, including polarization curves, atomic force microscopy (AFM), scanning electron microscopy (SEM), glow discharge spectroscopy (GDS), X-ray diffraction (XRD), and the salt spray test. In the salt spray test, the exposure time required for the coatings to exhibit red corrosion (associated with the oxidation of steel) decreased in the following order: Zn–Mn (432h) > Zn–Co (429h) > Zn alkaline(298h) > Zn acid(216h) . The shorter exposure times required for corrosion of the pure Zn coatings are related to the coating composition and the crystallographic structure. Analysis of the corrosion products disclosed that Zn 5 (OH) 8 Cl 2 ·H 2 O was a corrosion product of all of the coatings tested. However, the formation of oxides of manganese (MnO, Mn 0.98 O 2 , Mn 5 O 8 ) in the Zn–Mn coating, and the formation of the hydroxide Zn 2 Co 3 (OH) 10 ·2H 2 O in the Zn–Co coating, produced more compact and stable passive layers, with lower dissolution rates.
-
Electrochemical and AFM study of Zn electrodeposition in the presence of benzylideneacetone in a chloride-based Acidic Bath
Journal of Applied Electrochemistry, 2005Co-Authors: P. Díaz-arista, R. Ortega, Y. Meas, G. TrejoAbstract:The influence of benzylideneacetone (BDA) on the mechanism of zinc deposition and nucleation was studied by voltammetry, chronoamperometry and atomic force microscopy (AFM). The addition of BDA to the electrolyte solution partially inhibited (97%) the reduction of zinc at the potential E = −1.15 vs SCE/V, giving rise to an increase in the overpotential for the discharge of the metal ion. This leads to the existence of two reduction processes with different energies that involve the same species, ZnCl _4 ^2- . Analysis of chronoamperograms obtained in the absence and presence of BDA indicates that distinct nucleation mechanisms are involved during the initial stages of Zn deposition. In the absence of BDA, the transients are consistent with the model of 3D diffusion-controlled nucleation. In the presence of BDA, the transients exhibit a more complex form involving two growth processes. The first process, which occurs at short times, is explained in terms of a combination of three simultaneous nucleation processes: 2D progressive, 2D instantaneous, and 3D progressive nucleation, each limited by the incorporation of adatoms. The second process, which occurs at longer times, involves the three processes that occur at short times in conjunction with a principal contribution from a diffusion-controlled 3D nucleation mechanism. AFM imaging shows that the morphology of the deposited zinc depends on the applied electrode potential.
Z.i. Ortiz - One of the best experts on this subject based on the ideXlab platform.
-
characterization of the corrosion products of electrodeposited zn zn co and zn mn alloys coatings
Corrosion Science, 2009Co-Authors: Z.i. Ortiz, Y. Meas, P Diazarista, R Ortegaborges, G. TrejoAbstract:Abstract The morphology, composition, phase composition and corrosion products of coatings of pure Zn (obtained from two types of electrolytic Bath: an Acidic Bath (Zn acid ) and a cyanide-free alkaline Bath (Zn alkaline )) and of Zn–Mn and Zn–Co alloys on steel substrates were studied. To achieve this, diverse techniques were used, including polarization curves, atomic force microscopy (AFM), scanning electron microscopy (SEM), glow discharge spectroscopy (GDS), X-ray diffraction (XRD), and the salt spray test. In the salt spray test, the exposure time required for the coatings to exhibit red corrosion (associated with the oxidation of steel) decreased in the following order: Zn–Mn (432h) > Zn–Co (429h) > Zn alkaline(298h) > Zn acid(216h) . The shorter exposure times required for corrosion of the pure Zn coatings are related to the coating composition and the crystallographic structure. Analysis of the corrosion products disclosed that Zn 5 (OH) 8 Cl 2 ·H 2 O was a corrosion product of all of the coatings tested. However, the formation of oxides of manganese (MnO, Mn 0.98 O 2 , Mn 5 O 8 ) in the Zn–Mn coating, and the formation of the hydroxide Zn 2 Co 3 (OH) 10 ·2H 2 O in the Zn–Co coating, produced more compact and stable passive layers, with lower dissolution rates.
-
Electrodeposition and characterization of Zn-Mn alloy coatings obtained from a chloride-based Acidic Bath containing ammonium thiocyanate as an additive
Surface and Coatings Technology, 2009Co-Authors: P. Díaz-arista, Z.i. Ortiz, H. Ruiz, R. Ortega, Yunny Meas, Gabriel TrejoAbstract:Abstract The electrodeposition of Zn–Mn alloys was performed using a chloride-based Acidic Bath containing ammonium thiocyanate (NH4SCN) as an additive. An electrochemical study using cyclic voltammetry (CV), performed for each of the metal ions (Zn(II) and Mn(II)), showed that neither metal ion forms complexes with NH3, and that Mn(II) but not Zn(II) forms complexes with SCN−. The influence of NH4SCN on the morphology, composition and crystallographic structure of the electrodeposited Zn–Mn alloys was studied using scanning electron microscopy (SEM), glow discharge spectroscopy (GDS) and X-ray diffraction (XRD). The results show that the presence of NH4SCN in the solution induces an increase in the Mn content of the alloy, from 3% in the Zn–Mn alloy obtained in the absence of additive to 6.2% in the alloy obtained in the presence of additive. In addition, the presence of NH4SCN favors the formation of coatings comprised of a mixture of e-phase Zn–Mn(002) + α-phase Zn–Mn(111) alloys. These coatings were compact and smooth and exhibited a lower corrosion rate compared to the coatings obtained in the absence of NH4SCN, which where comprised of a mixture of Zn, e-phase Zn–Mn and α-phase Zn–Mn alloys.
P. Díaz-arista - One of the best experts on this subject based on the ideXlab platform.
-
Electrodeposition and characterization of Zn-Mn alloy coatings obtained from a chloride-based Acidic Bath containing ammonium thiocyanate as an additive
Surface and Coatings Technology, 2009Co-Authors: P. Díaz-arista, Z.i. Ortiz, H. Ruiz, R. Ortega, Yunny Meas, Gabriel TrejoAbstract:Abstract The electrodeposition of Zn–Mn alloys was performed using a chloride-based Acidic Bath containing ammonium thiocyanate (NH4SCN) as an additive. An electrochemical study using cyclic voltammetry (CV), performed for each of the metal ions (Zn(II) and Mn(II)), showed that neither metal ion forms complexes with NH3, and that Mn(II) but not Zn(II) forms complexes with SCN−. The influence of NH4SCN on the morphology, composition and crystallographic structure of the electrodeposited Zn–Mn alloys was studied using scanning electron microscopy (SEM), glow discharge spectroscopy (GDS) and X-ray diffraction (XRD). The results show that the presence of NH4SCN in the solution induces an increase in the Mn content of the alloy, from 3% in the Zn–Mn alloy obtained in the absence of additive to 6.2% in the alloy obtained in the presence of additive. In addition, the presence of NH4SCN favors the formation of coatings comprised of a mixture of e-phase Zn–Mn(002) + α-phase Zn–Mn(111) alloys. These coatings were compact and smooth and exhibited a lower corrosion rate compared to the coatings obtained in the absence of NH4SCN, which where comprised of a mixture of Zn, e-phase Zn–Mn and α-phase Zn–Mn alloys.
-
Electrochemical and AFM study of Zn electrodeposition in the presence of benzylideneacetone in a chloride-based Acidic Bath
Journal of Applied Electrochemistry, 2005Co-Authors: P. Díaz-arista, R. Ortega, Y. Meas, G. TrejoAbstract:The influence of benzylideneacetone (BDA) on the mechanism of zinc deposition and nucleation was studied by voltammetry, chronoamperometry and atomic force microscopy (AFM). The addition of BDA to the electrolyte solution partially inhibited (97%) the reduction of zinc at the potential E = −1.15 vs SCE/V, giving rise to an increase in the overpotential for the discharge of the metal ion. This leads to the existence of two reduction processes with different energies that involve the same species, ZnCl _4 ^2- . Analysis of chronoamperograms obtained in the absence and presence of BDA indicates that distinct nucleation mechanisms are involved during the initial stages of Zn deposition. In the absence of BDA, the transients are consistent with the model of 3D diffusion-controlled nucleation. In the presence of BDA, the transients exhibit a more complex form involving two growth processes. The first process, which occurs at short times, is explained in terms of a combination of three simultaneous nucleation processes: 2D progressive, 2D instantaneous, and 3D progressive nucleation, each limited by the incorporation of adatoms. The second process, which occurs at longer times, involves the three processes that occur at short times in conjunction with a principal contribution from a diffusion-controlled 3D nucleation mechanism. AFM imaging shows that the morphology of the deposited zinc depends on the applied electrode potential.
J. Creus - One of the best experts on this subject based on the ideXlab platform.
-
Corrosion behaviour in saline solution of pulsed-electrodeposited zinc-nickel-ceria nanocomposite coatings
Materials and Corrosion Werkstoffe und Korrosion, 2017Co-Authors: L. Exbrayat, C. Rébéré, R. Ndong Eyame, Philippe Steyer, J. CreusAbstract:Pure Zn-Ni and Zn–Ni–ceria (CeO2) nanocomposite coatings were deposited onto steel substrates using pulse electrodeposition process from an Acidic Bath combined with preliminary sonication. Influences of different parameters such as pulse parameters, addition of nanoparticles in the electroplating Bath, use of sonication to ensure their dispersion, were studied in terms of morphology, composition, and corrosion behaviour in saline solution. Results revealed a strong influence of the electrodeposition parameters on the corrosion behaviour of the Zn-Ni coatings. Incorporation of ceria nanoparticles is enhanced for the very short duration of the pulse due to the refinement of the microstructure. It was proved that composite coatings present an enhanced corrosion behaviour, while sonification does not afford a further improvement. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
-
Electrodeposition of Zn–Mn alloys in Acidic and alkaline Baths. Influence of additives on the morphological and structural properties
Journal of Applied Electrochemistry, 2005Co-Authors: D. Sylla, C. Rébéré, J. Creus, M. Gadouleau, C. Savall, Ph. RefaitAbstract:Electrodeposition of Zn–Mn alloys on steel was achieved using alkaline pyrophosphate-based Baths or Acidic chloride-based Baths. Cyclic voltammetry was used to determine the potential ranges where the various redox processes were taking place. It appeared that the reduction of Mn(II) was generally hidden by the other reduction reactions, especially by the hydrogen evolution reaction. Zn–Mn alloys containing up to 25 at.% Mn in the alkaline Bath and 12 at.% in the Acidic Bath could be obtained at the cost of very low current efficiencies. The characterisation of the deposits obtained either by galvanostatic polarisation or potentiostatic polarisation was performed by Scanning Electron Microscopy and X-Ray Diffraction. Various Zn–Mn phases were obtained, depending on the current densities, the composition of the deposit and that of the electrolytic Bath. Two commercial additives usually used for zinc electrodeposition, one in alkaline Baths, the other in Acidic Baths, were tested. Their effects upon the composition, the morphology and the microstructure of the deposit were investigated.
Abdel Z Hamid - One of the best experts on this subject based on the ideXlab platform.
-
electrodeposition of cobalt tungsten alloys from Acidic Bath containing cationic surfactants
Materials Letters, 2003Co-Authors: Abdel Z HamidAbstract:Abstract The present work is devoted to the replacement of chromium coatings with a particular coating that has good properties and nonpolluting nature. Cobalt–tungsten alloys having high hardness were prepared by electrodeposition process. Optimum conditions of plating process including temperature, current density, concentration of metal ions and the critical concentration of the surfactants were studied. The surface properties of cationic surfactants were determined through surface tension measurements of the solution/air interface. Data of some surface and thermodynamic properties of the components were calculated. The alloys were subjected to heat treatment under nitrogen atmosphere at 400 °C. The surface morphologies of cobalt–tungsten alloy electrodeposits were studied before and after thermal treatment. The properties of the alloys such as microhardness and corrosion resistance were also examined and compared with chromium deposit.
-
development of electroless nickel phosphorous composite deposits for wear resistance of 6061 aluminum alloy
Materials Letters, 2002Co-Authors: Abdel Z Hamid, M Abou T ElkhairAbstract:Abstract Electroless nickel–phosphorous composite deposits incorporating ZrO 2 , TiO 2 , and Al 2 O 3 on 6061 Al alloy have been investigated from Acidic Bath. The mechanism of incorporation of reinforced particles was suggested and confirmed in view of zeta potential and the calculated free energy of adsorption of the particles (Δ G ads °) of the composites. Scanning electron microscope evaluated the distributions of the reinforced particles in the deposits. The effect of different composites on the mechanical properties of the deposit such as hardness and wear resistance was studied and the wear mechanism of the deposit was suggested. The results indicate that the reinforced particles as well as the heat treatment provide satisfactory improvement in hardness and wear resistance of the deposits.