Structure, texture, and properties of superconductive electrolytic niobium coatings on glassy carbon

Abstract

Superconductive electrolytic niobium coatings 0.1–100 μm thick are prepared via electrochemical deposition onto SU-2000 glassy carbon substrates in (LiF + NaF + KF)_eut–K₂NbF₇ molten salt. Their structure, texture, and residual stresses are investigated by X-ray diffraction methods. It is shown that, when depositing the coatings, the diffusion superconductive layer of niobium carbide is formed at the substrate–coating interface. The sequence of changes in the axis of the texture of niobium coating from 〈100〉 through 〈211〉 to a textureless state with an increase in their thickness is established. It is found that, in the interval 0.5–5 μm, the sign of the stress changes (compressive stresses change into tensile stresses) and it reaches its maximum value. With an increase in the coating thickness from 5 to 100 μm, tensile stresses decrease from 345 to 80 MPa. It is shown that the coatings formed can be used as the material for creating a working layer of a superconducting cryogenic gyroscope rotor.