Research on the processes of forming heat-resistant coatings used to protect niobium from the effects of oxidizing environments at elevated temperatures

The article presents the results of research on the creation of heat-resistant coatings on niobium samples that provide protection against oxidation in air at temperatures T = 1973 T. Heat-resistant coatings on niobium, obtained by processing in sodium chloride vapors in powders of the composition of [(20-25)Si+(20-24)ZrSi₂+(20-24)HfB₂+(30-35)MoSi₂] wt.% at a temperature T = 1300 °C for 6 h and subsequent borosilicification, were approbated. Such heat-resistant coatings provide protection against oxidation in the air for 4…6 h. Complex coating obtained by applying a layer of 20HfB₂+20MoSi₂+20ZrSi₂+16TiB₂+8.5Ni+8.5Zr+3B+4Si wt.% slip on the surface of the niobium sample and subsequent processing in the [(20-25)Si+(20-24)ZrSi₂+(20-24)HfB₂+(30-35)MoSi₂] wt.% powder composition at T = 1300 °C for 6 h. The final stage of heat-resistant coating formation was borosilicification. Such a coating provides protection against the influence of an oxidizing environment for 6…10 h. Another method of creating a protective layer was the preliminary vanadium of the surface of the niobium sample followed by complex chemical and thermal treatment. This coating protects against oxidation for 10…12 h. (author)