Pulse current electrodeposition

This paper studies the effects of the addition of ethylene diamine to the Au-Sn plating solution reported in ref.[7]. The changes in the composition and microstructure of the Au-Sn solder coating produced by pulsed current electrodeposition are noted. The electroplating solution developed for the co-deposition of Au and Sn is slightly acidic so that it can be used in conjunction with alkaline-developable photoresists. 

At the University of South Carolina, Pt/C electrodes were fabricated by using direct current (DC) and pulse current electrodeposition methods. With the use of current pulses rather than DC, a higher deposition current density could be used and Pt deposits with a higher surface area were possible. Figure 3 compares the polarization performance of electrodes prepared by pulse electrodeposition (current density=50 mA/cm and duty cycle=0.25) and DC deposition. Electrodes fabricated under pulse deposition conditions display better performance than the DC-plated electrode. The best performance is obtained when the ON time is 100 ms and OFF time is 300 ms. 

This is of course not the case when working with room temperature ionic liquid systems. Electrochemical and spectroscopic studies of cobalt, copper, and nickel, have been carried out in the AlClj-butylpyridinium chloride molten salt system. The direct current and pulsed current electrodeposition of Ni-Al alloys has also been shown in acidic AlCls-butylpyridinium chloride ionic liquids. This particular alloy has also been shown to be successful in AlCl3-[C2-mim]Cl ashave Co-Al andCu-Al. Electrochemical techniques can also be used to calculate the diffusion coefficients of metal ions. Table 21.2.6 shows the calculated diffusion coefficients and stokes-Einstein products of cobalt(II), copper(I), nickel(II) and zinc(II) in the 40-60 mol% [Cj-mimlCl-AlClj ionic liquid. 

Liu] Pulsed-current electrodeposition/ thin films Room temperature / y-a mixture... 

Liu] Liu, X., Zangari, G., High Moment FeCoNi Alloy Thin Films Fabricated by Pulsed-Current Electrodeposition , IEEE Trans. Magn., 37(4), 1764-1766 (2001) (Experimental, Magn. Prop., Phys. Prop., 9)... 

Saber K, Koch C, Fedkiw P (2003) Pulse current electrodeposition of nanocrystalline zinc. Mater Sci Eng A 341 174-181. doi 10.1016/S0921-5093(02)00198-3... 

Mouanga M, Ricq L, Douglade J, Bergot P (2009) Corrosion behaviour of zinc deposits obtained under pulse current electrodeposition effects of coumarin as additive. Corros Sci 51 690-698. doi 10.1016/j.corsci.2008.12.020... 

There are three types of electrolytic metal deposition processes direct current electrodeposition, pulse plating, and laser-induced metal deposition. ... 

Electrodeposition using pulsed currents is known as pulse plating. The pulsed currents can be unipolar (on-off) or bipolar (current reversal). Pulses can be used along or be superimposed on a DC feed. By using the bipolar pulse, metal deposition occurs in the cathodic pulse period, with a limited amount of metal being... 

Pulsed currents with a density of 15 mA cm-2 resulted in a homogenous Ca-deficient HAp coating that after an appropriate thermal treatment consisted of a biphasic mixture of 52% HAp and 48% P-TCP (Drevet and Benhayoune, 2012). Moreover, addition of 9% hydrogen peroxide to the electrolyte also modified the chemical composition of the electrodeposited coating. Under these conditions, a stoichiometric and fully crystallised HAp coating was obtained... 

The experimental conditions were pulse off-times 16,80,400, and 16(X) s, duty cycle 0.2, pulse current density /on = 100 mA cm , current density during off-time /off = 0.2 mA cm, and RPM= 1400. Under such hydrodynamic conditions, a limiting current density for copper electrodeposition was /l(Cu) = 9.7 mA cm . The number of cycles (depending on the on-time and off-time) was 11022, 2204, 441, and 110, respectively, in order to obtain approximately 1.3 mm thick electrodeposits. The SEMs of etched cross sections presented in Fig. 7.32 illustrate the phase distribution obtained in the experiments. Except for the electrodeposit shown in Fig. 7.32d, which had the lowest Cu content, the electrodeposits exhibited a colunuiar structure. The Co alloy columns apparently go through the entire electrodeposit, indicating that atoms are added to existing growth sites in each phase [55]. 

Taking into account that Sand s equation is valid only as long as the change of concentration occurs within a stagnant layer undisturbed by convection and introducing the Nemst diffusion layer boundary 8 and hydrodynamic layer boundary Ah, the minimum current density that must be applied in the first pulse for electrodeposition of the second layer to take place is given by... 

Zemanova M (2009) Corrosion resistance of zinc electrodeposited from acidic and alkaline electrol5hes using pulse current Chem Pap 63 574—578. doi 10.2478/sll6%-009-0051-5... 

Employ pulse current deposition method Maximize amount of zinc electrodeposited from electrolyte solution Need to identify optimal deposition conditions, followed by electrochemical tests to characterize improvements in system efficiency... 

This conclusion may be extended to other refractory metals, at least to tantalum, knowing the similarity of behavior of Nb and Ta, and may encourage the use of pulsed currents rather than DC current for the electrodeposition. 

Pulse electrodeposition (pulsed potential or pulsed current) has been also employed for CdSe formation [30]. In addition, EC-ALE has been employed for the electrochemical synthesis of CdSe on Au substrates through the layer-by-layer UPD of Se and Cd in sequence [45,46]. 

Kozlov et al. [193] reported the two-stage electrodeposition of InAs from aqueous solutions. First, a 3-pm-thick As film was electrodeposited on an Fe substrate from a HCl solution containing AS2O3 solution at 50 °C with a current density of 1.5 A dm . A 1-mm-thick layer was subsequently electrodeposited at 25 °C on the As surface using a pulsed current from a pH 1.8 aqueous InCls bath. After electrodeposition, the In-As samples were annealed to form the InAs compound via reaction-diffusion at the In-As interface. The values of the In diffusion... 

The electrodeposition process can either occur under potential (potentiostatic deposition) or current (galvanostatic deposition) control. In practice, the common approach is to control the deposition flux (current) in order to obtain the deposit with desired thickness and properties. The electrodeposition under galvanostatic control can be executed as either the constant current process or using some more complex currenttime function profile. In the latter case, the electrodeposition process is commonly called the pulse current deposition and it has been widely used in industrial and academic applications. The typical pulse current function has the simple on/off profile shown in Fig. 11. ... 

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