不同粘结剂基TiB_2-C复合阴极中碱金属的渗透迁移行为(英文)

Penetrative and migratory behavior of alkali metal in different binder based TiB_2-C composite cathodes

在含K低温电解质熔体中,采用EDS及改进型电解膨胀率测试仪,分别研究电解过程中沥青、呋喃、酚醛、环氧基TiB2-C复合阴极中碱金属(K和Na)的渗透迁移路径。同时,计算并讨论相应的电解膨胀率、碱金属的扩散系数以及复合阴极的腐蚀率。结果表明:无论使用何种粘结剂,电解过程中,碱金属在阴极中表现出相似的渗透迁移路径:碱金属首先渗透进入阴极的孔隙当中,随后渗透进入粘结剂相中,随着电解的不断进行,最后渗透进入复合阴极的骨料相当中。渗透进入粘结剂相和炭质骨料相当中的K和Na均会引起复合阴极的电解膨胀,同时,K比Na有着更强的渗透力。树脂基复合阴极的电解膨胀率、碱金属在其中的扩散系数以及腐蚀率均小于沥青基复合阴极,即,树脂基复合阴极的抗碱金属渗透力强于沥青基复合阴极。而就树脂基TiB2-C复合阴极而言,酚醛基TiB2-C复合阴极的抗渗透力最强,碱金属在其中的渗透速率、扩散系数和相应的腐蚀率分别为4.72mm/h,2.24×10-5 cm2/s和2.31 mm/a.

In electrolyte melts containing K at low temperature, the penetrative and migratory path of alkali metals （K and Na） in pitch, furan, phenolic aldehyde and epoxy based TiB2-C composite cathodes during the electrolysis process were studied by EDS and self-made modified Rapoport apparatus. The electrolysis expansion rates, the diffusion coefficients of the alkali metals and the corrosion rates of the composite cathode were also calculated and discussed. The results show that no matter what kind of binder is used, alkali metals have the same penetrative path in composite cathodes：firstly in pore, then in binder and finally in carbonaceous aggregates. K and Na penetrate into both binder and carbonaceous aggregates, which leads to the expansion of composite cathodes, and K has stronger penetration ability than Na. Electrolysis expansion rate of resin based composite cathode is smaller than that of pitch based composite cathodes, and so do the diffusion coefficient and corrosion rate. Resin based composite cathode has better resistance ability to the penetration of alkali metals than pith based composite cathode, and phenolic aldehyde based composite cathode exhibits the strongest resistance ability. The penetration rate, the diffusion coefficient of alkali metals in phenolic aldehyde based TiB2-C composite cathode and the corresponding corrosion rate are 4.72 mm/h, 2.24×10^-5 cm^2/s and 2.31 mm/a, respectively.