Hydrometallurgical synthesis of copper composites in the presence of cerium and niobium oxides for protection of rescue equipment

Abstract

Purpose. To determine the optimal conditions for the hydrometallurgical synthesis of new nanostructured materials with improved functional properties for modifying parts of emergency rescue equipment.

Methods. The following research methods were used: gravimetry, voltammetry, radiography, X-ray spectral analysis, scanning electron microscopy, standard methods for testing the physical and mechanical properties of metal coatings.

Findings. It has been determined that coatings with a significantly distorted crystal lattice, without admixtures of amorphous phases are formed from a silicofluoride copper plating electrolyte, modified with an oxide phase. In the permissible range of current densities in silicofluoride electrolytes, side processes are minimized; in this case, cerium oxide exhibits electroactivity, but niobium oxide does not, creating diffusion difficulties and slowing down the rate of copper deposition. Inclusions of cerium and niobium compounds in the coatings were not detected, but the near-surface layers include copper and silicon oxides. The surface microstructure of Cu-CeO₂ and Cu-Nb₂O₅ coatings is dense and uniform. When CeO₂ is introduced into the electrolyte, the sizes of the grains composing the crystallites of the composites are noticeably smaller than in pure copper films synthesized under the same conditions; whereas the presence of niobium oxide in the electrolyte has virtually no effect on the microstructure of the films. It has been established that composites, synthesized in the presence of CeO₂, with the most uniform and fine-grained surface morphology, have increased corrosion resistance and 10–20 % higher microhardness compared to copper ones.

Application field of research. Corrosion protection and performance enhancement of fire rescue equipment parts, sealing of threaded joints of pipelines for various purposes.