| Titanium is a silvery-white metal, which has the advantages of low density, high strength, good corrosion resistance, fatigue resistance, etc. It has a wide range of applications among civil, industry, aerospace, consumer goods, building materials,biomedicine and other fields. The method of preparation of titanium metal can be divided into traditional and new preparation methods. Recently, Kroll method is a representative method among traditional methods, which is main industrial method of production sponge titanium in the world. But Kroll method has several disadvantages which lead the cost of the preparation of titanium is expensive. The FFC method is the most promising method among new methods of preparation of titanium. This method is an environmental, simple, continuous, green technology processes, and it is expected to replace the traditional preparation of titanium. Currently, titanium has been successfully prepared in the laboratory by this method, and it is also widely used in the preparation of other metals and alloys.Ca Ti O3 is a necessary intermediate during electrolysis process of preparing titanium by FFC method. The purpose of this thesis is to investage the formation of Ca Ti O3 and the effect of process parameters(bath voltage and electrolysis temperature)on phase, morphology specific surface of the electrolysis products.Three views about the formation of Ca Ti O3 is vertified in this research. Whether Ca Cl2 can be hydrolyzed to Ca O is proved via detecting the p H of Ca Cl2 aqueous solution electrolysis and the presence of acidic gas during in the electrolysis. Whether the formation of Ca Ti O3 through sintering the maxture of the pre-sintered Ti O2 and Ca O is also demonstrated. To unveil whether Ca Ti O3 is formed in chemical way, we carried out two experiments. One is that oxygen vacancy could be proved by sintering Ti O2,and the other is that whether Ti O2 reacts with Ca Cl2 to form Ca Ti O3 by sintering raw materials. Products and exhaust are analysed during different electrolysis time, which is used to verify whether Ca Ti O3 is formed by an electrochemical approach with titanium-oxides. The results showed that Ca Ti O3 is formed by three ways. Firstly, a small amount of Ca O which be hydrolyzed by Ca Cl2 reacts with Ti O2 to form Ca Ti O3 on the cathode surface in early electrolytic period. Secondly, oxygen vacancies are formed in sintered Ti O2 in air atmosphere at high temperature, then the O2- in Ti O2 cathode migrates from the interior to the surface of the cathode through the oxygenvacancies and the reaction of O2-and Ca2+in the molten salt Ca Cl2 gives Ca Ti O3.Therefore, this pathway is formed chemically, ie. The formation of Ca Ti O3 isn’t relevant to whether voltage is applied. Thirdly, Ti O2 reacts with Ca2+ to generate Ca Ti O3 and titanium suboxide under the action of the outside power on the cathode surface.To study the effect of structure of Ca Ti O3, electrolysis voltage and electrolysis temperature, which are two main technological parameters in electrolysis of Ti O2, were considered. We found that the lattice parameter of Ca Ti O3 has been slightly changed via electrolyzing at different electrolysis voltage, indicating electrolysis voltage has little effect on structure of Ca Ti O3; however, lattice parameters of Ca Ti O3 were altered more prominent under different electrolysis temperature than that at different electrolysis voltage, though the changed lattice parameters show little difference compared the primitive as well. Moreover, the effect of technological parameters on the products of cathode has also been investigated by comparing the variation of cathodic product phase,microstructure and specific surface area under different electrolysis voltage and electrolysis temperature. |
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