常温固化TiB_2涂层阴极抗钠渗透性

Sodium Penetration Resistance ofAmbient Temperature Cured TiB_2 Cathode Coating

采用自行研制的改进型Rapoport钠膨胀测定仪,分别测定半石墨质阴极和不同TiB2含量的常温固化涂层阴极材料的钠膨胀率。当试样电解后,用扫描电镜观察试样径向剖面形貌,用X射线能谱仪检测试样径向剖面的元素分布。研究结果表明:TiB2涂层阴极的钠膨胀率小于半石墨质阴极的钠膨胀率;随着涂层中TiB2含量的增加,涂层阴极的钠膨胀逐渐减缓,最终钠膨胀率逐渐减小;TiB2含量为60%的涂层阴极的最终钠膨胀率最小,约为半石墨质阴极的最终纳膨胀率的60%;在电解初期,渗透进入TiB2涂层阴极的钠主要集中在涂层中,TiB2涂层本身也是钠渗透进入碳素阴极的阻挡层;常温固化TiB2阴极涂层能提高基体碳素阴极材料抗钠渗透性,减小钠膨胀危害,降低阴极破损率。

An apparatus for modified Rapoport test was applied to test the sodium expansion of semi-graphitic block sample and ambient temperature cured TiB_2 coating cathode samples with different TiB_2 content, and the section specimen after electrolysis was observed and analyzed by scanning electron microscope and energy dispersive spectrometer. The results show that the sodium expansion rate of TiB_2 coating cathode block is lower than that of semi-graphitic block; as content of TiB_2 increases, both the sodium expansion rate of coating cathode decreases; and the final sodium expansion decreases. The final sodium expansion of cathode coating with TiB_2 60% (mass fraction) is about 60% of the final sodium expansion of semi-graphitic block. At the beginning of electrolysis, the sodium penetrating the TiB_2 coating cathode mostly gathers in coating. The TiB_2 coating also is a barrier to the sodium penetration. The ambient cured TiB_2 cathode coating can advance the sodium penetration resistance of cathode block and slow down the sodium penetration rate. Thereby the coating contributes to reduction of the harm of sodium expansion.