Development of Heat-Resistant Coatings for Protection of Niobium and Tantalum from the Oxidizing Effect of Air at Temperatures 1700–1900°C

The paper presents the results of creating protective coatings on niobium and tantalum samples.These coated samples are tested for heat resistance in air in the temperature range of 1700-1900C.The coating is formed by the method of activated vacuum diffusion saturation at temperatures of 1150-1310C.When forming a part of the protective coatings, a layer of slurry is applied to the surface of the samples, followed by chemical and thermal treatment in a vacuum in the presence of NaCl vapours.A thermodynamic analysis of possible chemical reactions taking place in the process of formation of protective coatings is carried out.The developed heat-resistant coatings provide protection of niobium samples from air oxidation at a temperature of 1700C from 8 to 13.5 hours.Heat-resistant coatings created on samples with Nb and Ta protect them from exposure to an oxidizing environment from 3 to 6.3 hours at a temperature of 1800C and for 0.5 hours at a temperature of 1900C.