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- 저자 : Rasha Muneer Al Radadi (검색결과 2 건)
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Rasha Muneer Al Radadi,Magdy Ahmed Mahmoud Ibrahim 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.9
A systematic study was carried out to electrodeposit Ni-Co alloy coatings from a complexing acidic glycine bath on copper substrates. The effects of [Co2+]/[Ni2+] ratio, gly concentration, pH, current density and temperature on the current efficiency, Co content in the coatings and on polarization behavior were investigated. It was found that the CCE of these baths has a wide range starting from 55% up to a maximum value of 99.3%, relying on the operating parameters and the bath constituent. However, the CCE decreased from 96.2% to 84.8% when the gly content was enhanced from 25 to 150 g/L. On the other hand, the Co content in the deposit reached 97% (wt%) at [Co2+]/ [Ni2+]=0.43, i=16 mA cm2 , t=10 min, T=20 o C. The codeposition of Co and Ni from acidic gly baths obeys the anomalous type of codeposition. The kinetic results indicate that the Tafel slope increased in the case of alloy deposition, while both the transfer coefficient c and the exchange current io decreased. Moreover, the obtained results indicated that increasing the Co2+ content in the electrolytic solution has an inhibiting impact on the kinetics of the nickel-cobalt alloy plating. The throwing power is enhanced with enhancing [Co2+]/[Ni2+] ratios, while the addition of gly decre
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Rasha Muneer Al Radadi,Magdy Ahmed Mahmoud Ibrahim 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1
A study was carried out to synthesize Ni-Co alloy coatings electrochemically from complex acidic glycine (gly) bath. The impacts of some operating parameters such as Co2+ to Ni2+ concentration ratios in the bath, gly concentrations, pH, applied current, plating time and temperature on the morphology of Ni-Co alloy were investigated. The microstructure, microhardness, and electrochemical studies were also investigated. The electrochemical studies utilized cyclic voltammetry, anodic linear stripping voltammetry, and potentiostatic current-time transient techniques. It was realized that gly lowers the cathodic overvoltage for the Co2+ deposition while promoting cathodic overvoltage of Ni2+ deposition. Accordingly, the concurrent codeposition of Co2+ and Ni2+ ions was simplified. The morphology of Ni-Co alloy is significantly dependent on the operating parameters rather than on the bath composition. Moreover, increasing either pH or bath temperature produces Ni-Co deposits free from cracking. The roughness of the alloy is decreased in the presence of gly as shown by the atomic force microscope (AFM) study. In the presence of gly, the microhardness increases from 387 to 970 kg f mm2, i.e., it increased more than two-and-a-half times. On the other hand, X-ray diffraction analysis (XRD) data show that the crystallinity decreases with enhancing the percentage of cobalt in the deposits.
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