Electrical resistivity of TiB₂/C composite cathode coating for aluminum electrolysis

Abstract

The electrical resistivity of TiB₂/C cathode composite coating at different temperatures was measured with the electrical conductivity test device; the effects of TiB₂ content and kinds of carbonaceous fillers as well as their mean particle size on their electrical resistivities were investigated. The results show that electrical resistivity of the coating decreases with the increase of TiB₂ content and the decrease of its mean particle size. When the mass fraction of TiB₂ increases from 30% to 60%, the electrical resistivity of the coating at room temperature decreases from 31.2 µΘ · m to 23.8 µΘ · m. The electrical resistivity of the coating at 960 °C lowers from 76.1 µΘ · m to 38.4 µΘ · m with the decrease of TiB₂ mean particle size from 12 µm to 1 µm. The kinds of carbonaceous fillers have great influence on the electrical resistivity of TiB₂/C composite coating at 960 °C, when the graphite, petroleum coke and anthracite are used as fillers, the electrical resistivities of the coating are 20.3 µΘ · m, 53.7 µΘ · m and 87.2 µΘ · m, respectively. For the coating with petroleum coke filler, its electrical resistivity decreases with the increase of the mean particle size of petroleum coke filler. The electrical resistivity at 960 °C decreases from 56.2 µΘ · m to 48.2 µΘ · m with the mean particle size of petroleum coke increasing from 44 µm to 1200 µm. However, too big carbonaceous particle size has adverse influence on the abrasion resistance of coating. Its proper mean particle size is 420 µm.

Keywords

aluminum electrolysis / composite material / TiB₂ coating / electrical resistivity

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