C.N. Cao

The cooperative effect of calcium ions and tartrate ions on the corrosion inhibition of pure aluminum in an alkaline solution

Abstract The cooperative effect of calcium ion and tartrate ion on the corrosion inhibition of pure aluminum in an alkaline solution was investigated by hydrogen collection, electrochemical methods and XPS. The results of electrochemical experiments showed that the inhibition of calcium ion was enhanced by the addition of tartrate ion, while tartrate ion itself has only a little inhibition effect. Analysis by XPS, it was found that calcium and tartrate ions did not contribute to the formation of the surface film on aluminum. This fact indicates that these two ions act as interface inhibitor rather than inter-phase one. The cooperative effect of the two ions might be due to formation of complex, which makes it easier for Ca2+ to adsorb on the aluminum surface.

Study on the behavior of Zn–Fe alloy electroplating

The electroplating behavior of Zn, Fe and Zn-Fe alloy onto copper from light acid chloride solutions (LACS, pH 3.07 containing H3BO3, Na2C6H5O7. 2H(2)O and different amounts of Zn2+ and Fe2+) was investigated by means of cyclic voltammetry and the steady-state polarization technique. It was found that, in the experimental conditions, during the Zn-Fe alloy formation no underpotential deposition (upd) was observed, and the deposition of Zn-Fe followed the mechanism of three-dimensional (3-D) nucleation and subsequent grain growth. The Zn2+ ions in the electrolyte inhibit the deposition of Fe, while Fe2+ ions promote the deposition of Zn. It was also found experimentally that the co-deposition of Zn and Fe behaved anomalously, and the result was interpreted theoretically in the light of quantum chemistry

Electrochemical impedance spectroscopy analysis on the electrochemical dissolution of aluminum in an alkaline solution

The process of electrochemical dissolution of aluminum in an alkaline solution was investigated by electrochemical impedance spectroscopy (EIS). A model based on its reaction mechanism was proposed. The kinetic parameters including rate constants of each step and covering densities of intermediates were obtained. The EIS was well analyzed by this model.

Physicochemical Properties and Electrochemical Performance of Al-substituted α ­ Ni ( OH ) 2 with Additives for Ni-Metal Hydride Batteries

Al-substituted alpha-Ni(OH)(2) coprecipitated with the additives Mg2+ and Co2+ was prepared by a complexation-coprecipitation method. The physical properties of Al-substituted alpha-Ni(OH)(2) samples containing different amounts of Mg2+ or Co2+ were examined by X-ray diffraction, AES and ICP. The effects of Mg2+ and Co2+ on the electrochemical performance of Al-substituted alpha-Ni(OH)(2) such as charge-discharge and diffusion coefficient of the proton (DH+) measured by current pulse relaxation and cycle life were investigated. The results show that the addition of Mg2+ increases the crystal cell parameters and the charge and discharge potentials and decreases the electrochemical polarization. A higher charge efficiency and cycle life are obtained by the addition of Co2+. The addition of both Mg2+ and Co2+ improves DH+ and the stability in alkaline solution at high temperature. The DH+ and R-t of alpha-Ni(OH)(2) electrode reach their maximum and minimum values at about 50% depth of discharge (DOD) and 75% DOD, respectively

Cooperation behavior of iron and phosphorus in electrodeposition of zinc-iron-phosphorus coating

The co-operation behavior of iron and phosphorus in clectrodeposition of Zn-Fe-P alloy onto copper from light acid chloride solutions (LACS) was investigated by means of cyclic voltammetry and steady-state polarization techniques. It was found that, under the experimental conditions, the phosphorous and the iron promote the reduction of each other and their contents in Zn-Fe-P coating change synchronously, which has been interpreted theoretically in the view of quantum chemistry. The theoretical results showed that, because the orbital radius of 4S of iron atom is shorter than that of zinc atom, the overlapping integral of iron and phosphorus (SFe-P) is smaller than that of zinc and phosphorus (SZn-P) which resulted in the synchronous variation of the contents of the phosphorus and the iron in the electrodeposits, and which also showed that there exist the cooperative effect of phosphorus with iron series metal among their co-depositing coatings

Investigation of the Secondary Current Distribution in a Hull Cell

A new equation of secondary current distribution of the Hull cell is derived which can explain the influence of some electrochemical kinetics and mass transport on the quality of electrodeposit, and can give some instructions for the electroplating using indirect current and for the study of secondary current distribution in a modified Hull cell. The results from the theoretical equation and experimental measurement are compared with that of other experimental formula. It is shown that the result from the theoretical equation is more suitable to the actual conditions than that from the empirical formula