Development of the electrochemical synthesis method of ultrafine cobalt powder for a superalloy production
Journal Title: Восточно-Европейский журнал передовых технологий - Year 2018, Vol 2, Issue 6
Abstract
<p>The electrochemical synthesis method for the preparation of ultrafine cobalt powder from the sulfate-ammonium electrolyte for the preparation of superalloys<span style="text-decoration: line-through;">,</span> has been developed. It was proposed to introduce ammonia to the electrolyte until рН=11. The electrolyte composition and the mechanism behind electrochemical processes during cobalt powder synthesis have been studied. The formation of the Co<sup>2+</sup>ammine complex has been observed. The precipitate dissolved in the mother liquor during a week, with the formation of a purple-red solution. By recording cathodic and cyclic cathodic-anodic curves, it was discovered that the solution with dissolved precipitate contained Со<sup>3+</sup>. It was revealed that the synthesis process occurs in two stages «Со<sup>3+</sup>–Со<sup>2+</sup>–Со<sup>0</sup>», which results in the increased polarization and formation of ultrafine cobalt powder. The influence of electrolyte temperature on electrolysis and powder characteristics has been studied. It was revealed that higher temperatures lead to larger particle size and formation of compact metal particles. It has been determined that the maximum electrolyte temperature should not exceed 30 °С. It is shown that under these conditions, the Co powder is composed of spherical particles that form coral-like aggregates with the size of 35–150 µm, which can be easily ground. The cobalt powder forms with the cathodic current yield of 39 % and specific power consumption of 48 kW·h/kg, which indicates a high effectiveness of the developed method.</p>
Authors and Affiliations
Vadym Kovalenko, Valerii Kotok, Sergey Vlasov
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