Kuprin O. Physical and technological bases of synthesis of protective vacuum-arc coatings on zirconium elements for NPP

The original technological processes of obtaining vacuum-arc nanostructured protective coatings based on Cr, Ti, Al, Fe and their nitrides on products made of zirconium alloys were developed, their structure and properties were investigated. It is determined that the developed coatings based on chromium and its nitride are most promising for the protection of zirconium alloys fuel claddings, both under operating conditions and in accident conditions in air and in water vapor. It has been shown that the developed Cr and Cr/CrN coatings in the temperature range (350-550 °C) are a reliable barrier against hydrogen penetration and protect zirconium from the accumulation of hydrides and increase the corrosion resistance in 10 times of fuel rods models in conditions close to the reactor. Created Cr/CrN multilayer coatings with a thickness of ~ 10 μm reduce the rate of oxidation of zirconium alloys in air and in steam at a temperature of 1100 °C for at least 3600 sec. The high stability of the developed coatings is due to the formation of a dense layer of chromium oxide on their surface. It is revealed that the deposition of ion-plasma coatings leads to an increase in the strength properties of claddings. It was first established that the nanocrystalline metal and nitride coatings deposited by vacuum-arc method are suitable for use under irradiation conditions.