CaO-CaCl2-NaCl熔盐电解高钛渣/C制备TiC/SiC纳米复合粉体

Preparation of TiC/SiC Nano Composite Powders from High Titanium Slag and C Mixture by Electrolysis in CaO-CaCl2-NaCl Molten Salt

在CaO-CaCl2-NaCl熔盐中,以高钛渣和石墨粉混合物料为阴极,石墨棒为阳极,电解制备出了TiC/SiC纳米级复合粉体。研究了电解时间、槽电压等参数对阴极电解产物的影响。实验结果表明,高钛渣中的钛氧化物在直接电解还原过程中生成了CaTiO3,Ti2O3,TiO等中间产物,CaTiO3的后续电解还原是该过程的控速环节。探讨了CaO在CaCl2-NaCl熔盐中的含量对高钛渣电脱氧过程的影响。结果表明,当熔盐中CaO含量小于1%（摩尔分数,下同）时,添加少量的CaO,可促进CaTiO3的还原;当CaO含量大于2%时,过多的CaO则不利于CaTiO3的进一步电解还原,说明CaO的加入对CaTiO3的电脱氧影响显著。分析了高钛渣中Ca,Mg,Al等氧化物的去向。实验结果表明,在高槽压下Ca,Mg,Al氧化物均能被电解还原成相应金属,经过HCl浸出后,上述金属杂质可以除去。研究表明,采用CaCl2-NaCl熔盐中CaO加入量为1%、电解温度为900℃、槽电压3.2 V,电解时间为6 h的高钛渣被完全还原,经HCl浸出后所得产物TiC/SiC复合粉体为纳米级材料,粉体粒径分布均匀,平均值约为50 nm。

TiC/SiC composite powders were prepared via molten salt electrolysis by using the high-titanium slag and graphite powder mixture as cathode and the graphite rod as anode in CaO-CaCl2-NaCl melts.The effects of electrolytic time and cell voltage on the cathodic products were investigated.The experiment results showed that the intermediates CaTiO3,Ti2O3,TiO were produced in the durations of the direct electrolytic reduction of high titanium slag,and the further reduction of CaTiO3 was proved to be the rate-controlling step of the overall process.The role of the CaO content in molten salt played on the deoxidization process was analyzed.The results showed that adding a small amount of CaO（less than 1%（mole fraction）） into the molten salt could promote the reduction of CaTiO3;but adding more CaO,such as more than 2%,was unfavorable for the further reduction of CaTiO3.The impurities of Ca,Mg and Al containing high titanium slag were observed during the reduction.The results showed that the Ca,Mg and Al contained in high titanium slag were electrolyzed to produce the corresponded metals and they were removed from the products by the HCl leaching treatment.The results showed that as the addition of CaO reached to 1% in CaCl2-NaCl molten salts,the electrolysis temperature was 900 ℃,the cell voltage was 3.2 V and the electrolysis time was 6 h,the reduction could be proceed completely,the particle size distribution in the products TiC/SiC which was nano-materials was uniform and the average size was about 50 nm after HCl leaching treatment particularly.