TiB_2-C复合阴极中碱金属(K、Na)的渗透及其对阴极电解膨胀的影响(英文)

Alkali metals(K and Na) penetration and its effects on expansion of TiB_2-C composite cathode during aluminum electrolysis

在不同电解条件下,研究纯KF熔体、纯NaF熔体及其复合电解质熔体中,碱金属(K、Na)在TiB2-C复合阴极中的渗透迁移行为及其引起的阴极电解膨胀。揭示影响阴极电解膨胀性能的主要因素,同时对阴极剖面进行元素微区分析。结果表明:在非极化以及不含铝的电解质熔体中,阴极不会发生膨胀;直接放电所生成的碱金属是造成阴极膨胀的主要因素,引起的阴极最大电解膨胀率可达20.40%;含钾电解质熔体中阴极的电解膨胀率远高于不含钾电解质熔体中阴极的电解膨胀率,最高超出35.13%;与纯钾盐相比,复合电解质对阴极的破坏作用降低;此外,无论是在极化条件还是在非极化条件下,含铝电解质熔体中阴极的电解膨胀率均大于不含铝电解质熔体中阴极的电解膨胀率;同时,在非极化条件下电解质熔体中加入铝后比极化条件下电解质熔体中加入铝后所引起的阴极电解膨胀的增加更为明显。

The behavior of alkali metals (K and Na) penetration in TiB2?C composite cathode and the induced electrolysis expansion under various conditions in KF melt, NaF melt and their composite melts were investigated. The most important influence factor on the electrolysis expansion properties of the cathode was revealed, and the elements micro-analysis of cathode profiles was performed. The results indicate that, under the condition of non-polarization and Al free, no electrolysis expansion occurs. The alkali metal produced by direct discharge reduction is the most important factor causing the electrolysis expansion, and the maximal expansion is 20.40%. Electrolysis expansion in electrolyte with K is higher than that in electrolyte without K, and the maximal excess magnitude is 35.13%. Compared with pure potassium salt, composite electrolyte has less destructive effects on the cathode. In addition, no matter under the condition of polarization or non-polarization, electrolysis expansion in electrolyte with Al is always greater than that in electrolyte without Al, and the increase amplitude of electrolysis expansion in non-polarization conditions with Al is significantly greater than that in polarization conditions with Al.