The Investigation Of Preparation Of Single-phase Nb₃Sn By Electro-deoxidation Of Nb₂O₅-SnO₂ In The Molten Salt

Nb3Sn, as a typical low temperature superconducting, was primarily used in the high-energy physics(HEP), intenational thermonuclear experimental reactor(ITER) and nuclear magnetic resonance(NMR). In present work, an electrochemical approach was developed using the method of the electro-deoxidation to reduce Nb2O5-SnO2 directly to the compound of Nb3Sn in the melt of CaCl2-NaCl. Electrolysis was carried out in which the sintered Nb2O5-SnO2 pellet used as cathode and graphite crucible as anode. After electrolysis, the oxide cathode Nb2O5-SnO2 transformed into the compound of Nb3Sn. The method is novel and friendly for the environment.In the experimental, two methods were applied to produce cathode in the FFC process, i.e. making the SnO2 preheated before mixing with the Nb2O5 and adding more SnO2 to the Nb2O5-SnO2 pellet properly in order to restrain and equalize the loss of Sn. The microstructure of Nb2O5-SnO2 pellet and the results of the electrolytic product of the cathode prepared by the two methods were investigated. The influences electrolysis factors, which are considered affected products of cathode, such as decomposing temperature and the electrolysis voltage were also investigated. At last, the different steps of the process of electro-deoxidation to the pellet was investigated. The results showed, the size of the SnO2 preheated will increase. And the content of Nb3Sn in electrolytic product of the pellet which is made with the SnO2 preheated will be more. The Nb2O5-SnO2 pellet which is mixed with the Nb-Sn atom ratio of 1:1,1.5:1 and 2:1 were feasible to product single-phase Nb3Sn electrolyzed at 800℃,3.1V for 13 hours; The reaction path of preparation of Nb3Sn by electro-deoxidation is ascertained.