Preparation Of TiC By Electrolytic Titanium - Containing Material By NaCl - CaCl 2

Titanium carbide (TiC) is an important ceramic materials and the TiC/SiC composites have been developed to be used in more severe condition because the properties of the composites are superior to those of the any component. At present, the carbothermal reduction between SiO2 or TiO2 and C is the appropriate route to produce TiC on an industrial scale. However, this conventional synthesis procedure is usually energy-extensive consumption and it also presents the problem of agglomerated particles and impure product. In 2000, a new electrolytic technique called FFC Cambrige Process was developed to extract metal Ti from TiO2. This technique was quickly applied to the preparation of other metal or metallic compound. Based on the FFC process, The TiC and TiC/SiC are obtained directly from TiO2, CaTiO3 and Ti-enriched slag via an electro-deoxidization process in this paper. The reaction temperature and energy consumption are lowered and the production process is cutted down.Electrolysis is conducted at an applied voltage of 3.2V using a graphite anode and a composite cathode composed of TiO2/C, CaTiO3/C and Ti-enriched slag/graphite in molten CaCl2-NaCl eutectic melt at 700℃. At last, the TiC is obtained from the TiO2/C and CaTiO3/C cathode; TiC/SiC composites is also successfully prepared from Ti-enriched slag/graphite cathode.Experimental results show the TiC is not obtained from TiO2/C directly during electrolysis. Some intermediate products are observed, which mainly contain CaTiO3, TiO, Ti2O and TiCxO1-x. These intermediate products can be further converted into TiC by prolonging the electrolysis time. An increase in temperature enhances the electrolysis rate obviously.The thermodynamic calculation and experimental results show when electrolyze the CaTiO3/C composite cathode the CaTiO3 can react with C to form TiC, and the CaTiO3 can be reduced to TiO and Ti2O firstly and then form TiC. In addition, the current efficiency calculated higher than that of the electrolysis of TiO2/C. This may partly attribute to the absence of electrochemical reaction xTiO2+Ca2++2e=CaTiO3 +Tix-1O2x-3 for electrolysis of CaTiO3/C compared with TiO2/C. The experiments indicate the mainly intermediate product at low cell voltage (2.7V,3.0V) is TiO and at high cell voltage (3.0V,3.5V) are TiO and Ti2O. Take the electrolysis rate and decomposition of electrolyte into account, the appropriate cell voltage is selected as 3.2V.Thermomechanical analysis shows the TiC/SiC can be obtained from Ti-enriched slage/graphite by electrolysis.The actual electrolysis process is complex and a possible reaction pathway for the formation of TiC/SiC is suggested: firstly the complex Ti-compounds are decomposed into TiO2-based simple oxides; then a mass of CaTiO3 and a spot of CaSiO3 formed accompanied by the reduction of titanium dioxide to titanium sub-oxide such as TiO, Ti2O; finally the graphite powder involves in the formation of SiC, TiC1-xOx, which are further converted into SiC and TiC.