Process Optimization Of Ti(C, N) Powders And Composite Powders From Ilmenite With Low Cost

According to the characteristics of mineral resources in China, ilmenite (FeTiO₃), which is very abundant in PanZhiHua, is used as a starting material in the present work. The main purpose of this study is to obtain a set of process parameters for preparing Ti(C,N) powders and composite powders more stable and more convenient by optimizing the process of carbothermic reduction of ilmenite directly.With the help of integraed thermal analysis,granularity analysis technique,X—ray diffraction analysis and SEM analysis , the effects of mixing methods, raw material ratios, reaction temperature and holding time on the types of reaction products were mainly investigated in this dissertation. The reasonable process parameters for preparing Ti(C,N) powders and composite powders were suggested, and the effect mechanism was discussed.It was showed that the effects of mixing methods, raw material ratios, reaction temperature and holding time on the products of carbothermic reduction of ilmenite were very obvious. The results show that the temperature of carbothermic reduction was obviously decreased, the reduction rate was increased, and the reduction extent was enhanced when the mixing technique of high-energy ball milling was used. The longer the time for ball milling is, the higher the degree of reduction is. The optimum time for ball milling is 2⁶h.The higher carbon content is, the higher reaction rate and the greater reduction extent are. If the carbon content is excessive, the content of residual carbon is high; but if the carbon content is deficient, the intermediate titanium oxides cannot be completely reduced. The optimum ratio of FeTiO₃ to C (carbon) is 1:3.25 (mol). The higher reaction temperature is, the higher reaction rate and the greater reduction extent are. If the reaction temperature is too high, the production can not be easily dispersed; but if the reaction temperature is too low, there will be a lot of intermediate resultant TiO₂ and Ti₃O₅ in the products. The optimum reaction temperature is about 1300℃ 1400℃.The desired Ti(C, N) composite powders can be synthesized without the existence of intermediate oxides and retained carbon under the control of certain process parameters. With the increase of reaction temperature, the value of x in the TiC_1-xN_x decreases gradually, that is: the ratio of C to N in the TiC_1-xN_x increases. With the increase of holding time, the value of x in the TiC_1-xN_x increases gradually, that is, the ratio of C to N in the TiC_1-xN_x decreases.The optimum reduction time is 2⁶h.