Research On Preparation Of Mn-Ti Alloy By Molten Salt Electrolysis

MnO₂-TiO₂powders are compacted into pellets,sintered and used as cathode, High-densitygraphite is used as anode.MnTi alloy is directly prepared form MnO₂-TiO₂by electrolysis process.The new technique with charcteristics of lower production cost, which has a short route, low energyconsumption and no pollute to encironment, include several processes:ball-milled, pressed, sintered,electrolyzed, cleaned. Through theory decomposition voltage is calculated and theory is analyzed,CaCl₂-NaCl（the mole ratio of1:1） is selected as electrolysis salt, Fe-Cr-Al wire as the cathode lead,and the high purity argon gas as protection air. The influence of pressure, sintering temperature.electrolysis voltage, and electrolytic time on composition of cathode pellet, electrolytic speed andelectrolysis degree are checked by XRD and current change curve, which are estimated the pissiblereaction mechanism.Experimental results show that the molten salt electric deoxidizing method （FFC method） ofpreparing the alloy of MnTi directly by MnO₂-TiO₂cathode is feasible. Technological conditions inelectrolytic process are as follows: pressing the MnO₂-TiO₂powder for shaping at the pressure of15MPa or20MPa, sintering at high temperature of900℃for3h,and electrolyzing in the CaCl₂-NaClmolten salt at the temperature of850℃for26hand application of the voltage of3.1V. The alloy ofMnTi could be found on the surface of the cathode obtained in the process of electrolysis. However,there are a lot of CaTiO₃found in the products out low content of MnTi alloy. Furthermore, the MnTialloy with different proportions will be acquired under different electrolytic conditions.In order to improve the electrolytic speed and electrolytic degree, NH₄HCO₃is added into theMnO₂-TiO₂powder to increase the porosity of cathode, and the electrolytic efficiency will beimproved. However, it is found in the actual electrolytic process that the method of adding NH₄HCO₃to improve the electrolytic efficiency is improper when produce the alloy of MnTi. Not only canelectrolytic efficiency be not improved after adding NH₄HCO₃, the alloy of MnTi is not electrolyzed.One of the reasons may be that the porosity of cathode is increased after adding the NH₄HCO₃, whichled to the loss of manganese diffusing from cathode to molten salt, and the MnTi alloy is difficult tobe electrolyzed and obtained. The other reason may be that if there exists calcium oxide andmanganese monoxide, the enrichment of titanium will make the titanium of oxidation stateaccumulated in the CaTiO₃, which is regarded as the main reason affecting the produce of the MnTialloy.