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-  2018 

基于显微CT的石墨内衬的孔隙及其分形特征

DOI: 10.11951/j.issn.1005-0299.20170361

Keywords: 显微CT,孔隙结构,表征,石墨内衬,分形维数,孔隙率
microscopic
,CT,pore,structure,characterization,graphite,lining,fractal,dimension,porosit

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Abstract:

针对稀土电解槽石墨内衬破损问题,通过显微CT扫描对石墨内衬孔隙结构进行了定量表征,利用这些孔喉参数可以分析空气和电解质在石墨内衬中的流动情况.结果表明:该样品的孔隙度为19.44%,孔喉半径大都在1~6 μm;孔喉形状因子为0.02~0.05,这表明其形状大多不规则,空气和电解质在其内部的流动阻力大,从而减缓了其氧化腐蚀;平均孔喉比, 平均孔隙体积、平均喉道体积分别为2.28, 1 177.64、106.19 μm3,意味着孔隙间有较大的喉道连通,空气和电解质在其内部的流动阻力较小,从而加速了其氧化腐蚀.进一步应用分形理论分析发现:该石墨内衬孔隙构造符合分形规律,其分形维数可以很好的说明孔隙分布复杂程度.最后建立了石墨内衬孔隙率的分形表达式,由此计算石墨内衬的理论孔隙率为21.46%,这与其实际孔隙率19.44%相差不大,可以用此式来预测石墨的孔隙率.
In view of the graphite liner in rare earth electrolysis cell damage problem, the pore structure of graphite was quantitatively characterized by microscopic CT scanning, and the flow of air and electrolyte in graphite liner was analyzed by using these pore throat parameters.The results showed that the porosity of the sample was 19.44%, the pore throat radius was mostly in the range of 1~6 μm and the pore throat shape factor was 0.02~0.05, which indicates that the shape is mostly irregular, and the flow resistance of air and electrolyte in its interior is large, thus slowing down the oxidation corrosion; the average pore throat ratio, the average pore volume and the average throat volume were 2.28, 1 177.64 μm3, 106.19 μm3, respectively, which means that there is a large laryngeal connectivity between the pores, and the flow resistance of air and electrolyte in its interior is small, thus accelerating its oxidative corrosion.Further analysis of the fractal theory showed that the graphite lined pore structure was in well accordance with the fractal law, and its fractal dimension could well explain the complexity of the pore distribution.Finally, a fractal expression of porosity of graphite liner was established. The theoretical porosity of graphite liner was 21.46%, which was similar to its actual porosity of 19.44%. Thus, this method could be used to predict the porosity of graphite.

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