The paper provides a review of results obtained when using metallization coatings to protect the outer surface of electric centrifugal pump (ECP) equipment against the complicating factors in oil wells. Metallization coating is applied by thermal spraying using the method selected based on the chemical composition, materials used and properties of the finished coating. The most common coatings on the Russian market are Monel and alloys based on austenitic stainless steel applied by methods of electric arc metallization or high-speed spraying. Traditional coatings obtained by thermal spraying feature by insufficiently high level of physical, mechanical and chemical properties. The studies of failed cases of submersible motors show that most critical shortcomings of the coatings used include insufficient resistance to mechanical impact and abrasive wear, higher electrochemical potential in relation to the base metal, application technology violations, and significant coating porosity. One of the main reasons for the observed shortcomings is the limited number of traditionally used methods and materials. In order to solve the problem of using protective coatings for submersible motors, significantly improve their properties, service life and economic efficiency, it is necessary to use modern achievements of science in the development of coatings to protect metal surfaces from wear and corrosion, namely: to expand the number of methods and materials for coating application; to develop a methodology for coating quality assessment; to develop a methodology for assessing the economic efficiency of protective coatings. Solving these tasks will enable a reasonable technical and economic choice of a specific submersible motor coating for specific operating conditions.

As is known, the current stage of the development of the oil industry of the Russian Federation is characterized by complicated conditions for field development, which is due to low production rates due to the high viscosity of oil, high aggressiveness and water cut in the media. Almost the entire well stock is operated mechanically, mainly with the help of electric submersible pumps (ESPs). To date, the use of metallization coatings applied by thermal spraying, due to their high physical, mechanical and chemical properties, is the most effective way to protect submersible equipment in the mining industry, in particular, the body of a submersible electric motor (SEM) from the influence of complicating factors. Nevertheless, there have been repeated cases of a decrease in the service life of equipment associated with the processes of destruction of metallization coatings. Abrasive wear is one of the most common reasons for the destruction of gas-thermal metallization coatings of SEM cases during operation. This article presents an overview of the main parameters that determine the wear resistance of gas-thermal metallization coatings, the main wear mechanisms and types of coating damage during wear are considered. Comparative tests of the wear resistance of gas-thermal metallization coatings deposited by the methods of electric arc metallization (EDM) and high-speed flame spraying (HSFP) under the influence of abrasive particles were carried out. It has been established that the destruction of gas-thermal metallization coatings proceeds mainly by chipping particles, for metallization coatings that have refractory compounds in their composition, fatigue failure is also characteristic, due to the accumulation of internal stresses during highcycle elastic-plastic deformation of the coating, which contribute to the formation of fatigue cracks and subsequent separation of particles with surface layer. The results obtained confirm the significant effect of the uniformity of the structure of gas-thermal metallization coatings on their wear resistance, as well as the staging of the wear process.

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