Novosibirsk State Technical University (NSTU) investigated the features of the structure formation and evaluated the properties of the composite coatings of the copper-chromium system obtained from detonation spraying. The work was carried out jointly with scientists from the SB RAS Institute of Hydrodynamics named after M. A. Lavrentieva.
The materials of the copper-chromium system are most often used in the manufacture of contacts for medium- and high voltage vacuum circuit breakers. The service life of the electrical contacts is mainly determined by the structure and properties of their surface layers. Therefore, it is important to create protective coatings on copper contacts that have the necessary set of properties.
"Detonation spraying of mechanical mixtures of copper and chromium powders makes it possible to obtain composite coatings with a copper matrix and uniformly distributed chromium -reinforcing particles in it. In such materials, the copper matrix provides electrical and thermal conductivity, and the addition of chromium increases the hardness and wears resistance, as well as reduces the tendency of the contacts to weld. Powder metallurgy methods are mainly used to produce the copper-chromium composites. In my scientific work, an approach based on the application of the detonation spraying method has been proposed. The structure and properties of the copper coatings formed under various technological parameters of the detonation spraying process were studied. The processes of deformation, heating and cooling of the materials during detonation spraying of the copper particles on the copper and steel substrates were analyzed. The influence of the fractional composition, spraying distance, and the ratio of the components in mixtures on the structure and properties of the sprayed materials was assessed. The behavior of the composite coatings of the copper-chromium system under conditions of arc erosion was studied," said Polina Ryabinkina, a junior researcher at the Research Laboratory of Physico—Chemical Technologies and Functional Materials, an assistant at the Department of Materials Science in Mechanical Engineering, who successfully defended her dissertation on the topic "Structure and properties of composite coatings of the copper-chromium system obtained by detonation spraying".
During the study, optimal detonation deposition parameters were established, ensuring the production of composite coatings of the copper-chromium system, characterized by a uniform distribution of particles of the reinforcing phase in the matrix, low porosity, high hardness, and adhesive strength.
"Based on the conducted research, composite coatings of the copper-chromium system have been developed, which have a set of properties that meet the requirements for materials for manufacturing electrical contacts of high—voltage equipment," added Polina Ryabinkina.
The research results formed the basis of technological recommendations on the selection of powder mixtures used for spraying and modes of obtaining coatings on copper substrates. The developed recommendations were transferred to companies engaged in the production of high-voltage equipment and the application of functional coatings for various purposes.
As for the prospects for further development of the topic, it is planned to evaluate the effect of additional heat treatment of the obtained composite coatings on their structure, electrical conductivity, and resistance to arc erosion.
The work was carried out with the support of the Ministry of Science and Higher Education of the Russian Federation, as well as the NSTU-NETI R&D program.