Effect of a Constant Magnetic Field on Electrodeposition of CoMo, CoRe, and CoMoRe Alloys from a Citrate Electrolyte

Electrodeposition of CoMo and CoRe binary alloys and CoMoRe ternary alloys from a citrate electrolyte (pH 3.5) was studied depending on the presence of a magnetostatic field and the direction of the magnetic induction vector relative to the surface of the working electrode. It was shown that magnetoelectrolysis significantly increases the current efficiency of all investigated alloys, especially the CoMoRe ternary alloy. The forces acting in the liquid and on bubbles of hydrogen evolved during a reaction in a magnetostatic field were modeled. It was demonstrated that the generation of convective flows by magnetohydrodynamic effect is neither single, nor determining factor. In the case of intense gas evolution, the force balance varies depending on the size of the bubbles: the conduction force and the buoyancy force dominate for large bubbles (about 100 μm), whereas the magnetic gradient force is predominant for small bubbles (less than 1 μm).