Niobium is the best metal for making superconducting accelerator resonators. Rf superconducting with RRR traditional method (residual resistivity) niobium tube cold forging or welding processing production, but there are many shortcomings, therefore a new technology of seamless niobium tube is developed, through the reasonable forging process, the rolling process, the tensile process and heat treatment process for many times, thus thoroughly with ingot casting grain crushing and recrystallization, end up with 60 mu grain size m, and uniform equiaxed grain structure, superconducting accelerating cavity is obtained with high RRR value of niobium tube.
The traditional niobium tubes used in RF superconducting cavity are welded or pressed tubes, which have many shortcomings. So a new process for preparing seamless niobium tube was developed. The key point of the new process is that the influence of gas element pollution on the residual resistivity ratio (RRR) of niobium tube is effectively controlled by the cold forging method which combines axial upsetting and axial drawing with batch forging. The recrystallized structure of the tubes with large grain size is ensured by the annealing process at 800℃ and 1h. The RRR value and comprehensive mechanical properties of seamless niobium tubes prepared by the new process both reach or exceed the technical indexes of niobium tubes used in RF superconducting cavity. The performance of the new seamless niobium tube is better than that of the welded tube and the stamping tube, the manufacturing cost is lower than that of the welded tube and the stamping method, and the production efficiency is higher.
Nb-Sn superconducting alloy refers to the Nb-Sn superconductor, which belongs to A15 type intermetallic compound and is cubic crystal system. The critical temperature T=18.1K and the critical magnetic field U=26T(4.2K). Nb-Sn superconducting alloy is brittle and difficult to be processed into profiles. Generally, Nb3Sn profiles are made by forming first and then diffusion reaction. New production techniques such as in-situ method and plasma spraying can produce Nb3Sn multistrand thin wire complexes. Adding titanium to the Nb3Sn line can significantly increase the magnetic field intensity.
