Electrothinning and Electrodeposition of Metals in Magnetic Fields

Abstract

Experiments have shown that metals can be electrothinned and electrodeposited more uniformly if the electrolysis is performed in a magnetic field. In addition, the resistance of electrolytic cells is reduced in a magnetic field. These effects have been characterized for various orientations and strengths of the electric and magnetic fields.In an earlier, preliminary report, some results were presented to show that the application of magnetic fields during electrolysis increases the uniformity of anodic dissolution of metals (1). These studies have been continued in order to investigate both anode and cathode processes for additional orientations and strengths of the electric fields (E) and magnetic fields (B) and other types of electrodes and electrolytes. Figure 1 shows a diagram of the circuit used for electrolysis. The constant current device was used to compensate automatically for changes in resistance of the electrolytic cell. In this way it was possible to maintain constant current during electrolysis and thus to follow the changes in cell resistance by means of the voltage-time recorder. The cell with the electrode arrangement used for the initial electrothinning experiments is shown in Fig. 2. Later experiments were performed with a plate disk cathode, shown in Fig. 3, which also shows the schematic positioning of the electrolytic cell between the polepieces of the 4 in. electromagnet, used for all experiments. Still other Key words: electrothinning, eleetrodeposition, magnetic fields. experiments were performed with a 19 mm ID cylindrical cathode surrounding the sample (anode). Experimental Methods and ResultsExperiments with the cell of Fig. 2 on A1-3.4 atomic per cent (a/o) Zn were performed at various applied magnetic field strengths in order to determine the minimum B required to produce relatively large electron-transparent films. As previously described (1), the 0.1 mm thick samples used for these experiments were in the solution-treated and air-cooled condition. The electrolyte consisted of 33 volume per cent (v/o) conc HNO3 and 67 v/o methyl alcohol. This was cooled to --13~ prior to each experiment. Current was maintained at 0.075A during every experiment. Thus, the initial current density was approximately the same for all experiments (about 0.25 A/cm2). No insulating lacquer was used for edge protection during electrolysis. After electrothining, profiles were obtained by mounting the samples on clear glass in the object plane of a photographic enlarger and recording the patterns of transmitted light on printing paper.The results obtained with B of increasing strength applied normal to the plane of the sample are shown in Fig. 4. Without an applied B, thinning is concentrated at the air-electrolyte interface, and perforation first occurs here. Application of B during the process lowers the air-electrolyte interface and causes the POTENTIAL SOURCE m I ,-I CA) I RECORDER J CONSTANT CURRENT DEVICE VOLTAGE DIVIDER 8.5 VOJ.TS 4-4 VOLTS ~ OUTPUT Fig. 1. (a) Schematic diagram of the circuit used for ...

Influence of external magnetic field on the etching of a steel ball in an aqueous solution of nitric acid

“…Also the Zeeman splitting under 10 kOe magnetic field is 4 orders of magnitude less than the energies involved in chemical reactions [6]. The only principal difference of the system, investigated in this work from the typical problems of magnetoelectrolysis [6,[8][9][10][11][12] is the absence of external voltage and current density through an electrolyte. However, as revealed experimentally, rotation of an electrolyte is observed in the same direction at pole regions around the symmetry axis of the steel ball, which is parallel to the external magnetic field.…”

Applications of magnetoelectrolysis

“…Under carefully chosen conditions the following effects can be promoted: (i) a more uniform deposit morphology (microscopic as well as macroscopic) [27,31,33,39,[40][41][42][43], (ii) inhibition of dendrite growth [37,44], (iii) change in macrostress of the deposit [45], (iv) increased hardness of the deposit [29,41,46], (v) a more uniform current distribution [47,48], (vi) increased corrosion resistance [28,29] and (vii) composition shift in alloy plating [46].…”

The Effect of Magnetic Fields on Electrochemical Processes

“…[33][34][35][36][37][38] O'Brien and co-workers [39][40] indicate the important effect of electrode configuration on the denseness and uniformity of zinc deposits; in pulsed electric fields, microturbulence generated by polarity reversal contributes to evenness of deposit. The variety of micro-and macroscopic deposit structures has been illustrated by Chiba and co-workers, 41,42 Young, 43 and Ismail et al 44 i n nonuniform magnetic fields.…”