Electrochemical dissolution of nickel-rheniumcontaining alloys

Abstract

This work is devoted to the study of electrochemical dissolution of nickel-rhenium (10% wt.) alloy and nickel-rhenium (20% wt.) alloy. The study was carried out under pulsed current in acidic electrolytes (sulfuric, nitric and hydrochloric acids). It was established that the highest dissolution rate of alloys was achieved at the current pulse amplitude of 1.0-1.5 A, current pulse duration of 500 ms, pause between pulses 50 ms. It is difficult to know exactly which areas meet the electrochemical reaction, but at the expense of depolarization the polarization curve is divided into several sections, each of which correspond to electrochemical reactions. It was shown that both the galvanostatic and potentiostatic modes occur in the selective dissolution of nickel and rhenium. Moreover, the rate of dissolution of nickel and rhenium depends on the acidic electrolyte (sulfuric acid, nitric acid, hydrochloric acid), the ratio of the concentrations of components in the solution, and the content of nickel and rhenium on the surface of the alloy in the nickel-rhenium (10% wt.) and nickel-rhenium (20% wt.) alloys. It was revealed that the highest dissolution rate for the nickel-rhenium (10% wt.) alloy (10.76 g/A·h) is achieved by dissolving in nitric acid, which is less than the dissolution rate of the nickelrhenium (20% wt.) alloy (12.08 g/A·h) in nitric acid. In contrast, in sulfuric and hydrochloric acids the dissolution rate of nickel-rhenium (20% wt.) alloy is much higher compared to the nickel-rhenium (10% wt.) alloy.

Keywords

• nickel-rhenium alloys, potential, anodic dissolution, polarization curve, amperage, impulse current.