Nb₃Sn 超导线材中 Ta 层的去除及腐蚀机理

High-quality superconducting joints play a key role in the construction and stable operation of superconducting magnets. The preparation of superconducting joints for Nb₃Sn wires is often affected by the presence of an internal tantalum barrier layer. Thus, this study examined the effectiveness of different removal methods of the Ta barrier layer in Nb₃Sn superconducting wire. For this, the superconducting wire prepared by an internal tin method was considered as the experimental object, and the corrosion behavior and characteristics of the wire in HF solution, HF atmosphere, mixed solution of HF and H₂O₂, and mixed solution of HF and HNO₃ were investigated. The microstructure and corrosion morphology of the wire were analyzed using SEM and OM. Furthermore, high-purity Ta sheets were selected as the research object, and corrosion experiments were carried out in the above-mentioned media. The corrosion morphology, phase structure, and valence state of the elements of the specimens were analyzed using OM, XRD, and X-ray photoelectron spectroscopy (XPS) to reveal the corrosion mechanism of Ta. The results showed that the corrosion of the Ta layer was the fastest in the mixed solution of HF and HNO₃, followed by the mixed solution of HF and H₂O₂, the HF atmosphere, and then the HF solution. Based on the effect after corrosion, the mixed solution of HF and H₂O₂ was found to be the best method to remove the Ta barrier layer in Nb₃Sn superconducting wire. Moreover, the presence of an oxidation agent can accelerate the corrosion rate of Ta by HF by accelerating the formation of Ta₂O₅ film on the Ta surface.