CaCl_2熔盐中自烧结电解制备粉体Cr_3C_2及其机制

Preparation and Reaction Mechanism of Cr_3C_2 by Electrochemical Reduction of the Cathode Self-Sintered in Molten CaCl_2 Salt

以氧化铬和石墨粉为原料,采用聚乙烯醇粘接,压制成阴极片,以光谱石墨棒为阳极,在800℃氯化钙熔盐中,恒电压3.2 V下,阴极片自烧结电解制备碳化铬。采用XRD、SEM和EDX对样品进行表征。结果表明:粘接的阴极片满足熔盐电解的强度要求,通过熔盐电解过程的自烧结阴极片有效地粘接在一起,并制备出具有良好烧结性能、组分单一的Cr3C2粉体。该法制备Cr3C2的电流效率不低于37.3%。采用恒电位电解法和循环伏安法对电解机制的研究表明,熔盐电解制备Cr3C2的反应机制为:Cr2O3+e-→Cr+O2-,Cr+C→Cr3C2两步完成。

The Cr203 and C powder with polyvinyl alcohol were mixed and pressed to form the pellets. The pellets of the Cr203-C mixtures were self-sintered and directly electrochemically reduced to Cr3C2 at the same time in molten CaC12 at 800 ℃ and 3.2 V with a graphite ＇ i anode. The samples were characterized by XRD, SEM, and EDX. The results show that the Cr203-C mixtures satisfy the bond strength requirement when electrolyzing, High purity Cr3C2 powder with the excellent sintering nature is obtained. The current efficiency is no less than 37.3%. The results of the cyclic voltammetry measurement and the potentiostatic electrolysis reveal that the reaction mechanism of Cr3C2 formation by the directly electrochemical reduction is two steps： Cr203＋e→Cr ＋ O2 and Cr＋C→Cr3C2.