Abstract

The article presents research results focused on high-temperature gas corrosion of sections of EcoSoderberg electrolyzers’ gas-collecting bells (GCB) made of high-strength VCh50 cast iron with spherical graphite. The gravimetric method was used to study the specific mass losses of the sections due to corrosion. The microstructure of cast iron, structure, chemical and phase composition of corrosion products were studied using optical, electron microscopy and electron microprobe analysis. It was established that the specific weight loss of the sections during operation reaches 0.36–0.46 g/(cm² month). Corrosion of cast iron sections of EcoSoderberg electrolyzers’ GCB is characterized by high unevenness by area. There are cases of decommissioning sections due to local through “burnouts” with a weight loss of 19–24 kg. With relatively uniform corrosion, the maximum allowable weight loss of the sections is 25–30 kg. To make predictive estimates based on experimental data, dependence of the sections’ mass loss on the operating time was obtained. It was found that the corrosion products of the sections consist of iron oxides and alloying elements of cast iron. Most samples are characterized by increased content of C, S, F, K, Al, and Na. Corrosion products have a pronounced layered structure and contain a large number of defects in the form of pores and cracks. The layers differ in chemical, phase composition, and macrostructure. All the studied samples are characterized by cyclic alternation of relatively dense layers of iron oxides Fe₂O₃ and Fe₃O₄ and more porous layers between them. The layers are characterized by increased content of C and F. Sulfur is evenly distributed over the thickness of corrosion products. The studied samples of corrosion products have high defectiveness, friability, large number of pores, cracks, discontinuities, and low adhesion to the surface of cast iron. This is due to the presence of phases and compounds with different coefficients of thermal expansion. The mechanism of corrosion product layer formation was established and scientifically proved.

中文翻译：

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Ecosoderberg电解槽集气钟铸铁部分的腐蚀

摘要

本文介绍的研究结果集中在用高强度VCh50铸铁和球形石墨制成的EcoSoderberg电解槽的集气罩（GCB）的高温气体腐蚀方面。重量法用于研究由于腐蚀引起的断面的特定质量损失。利用光学，电子显微镜和电子探针分析研究了铸铁的微观结构，腐蚀产物的结构，化学和相组成。已经确定，这些部分在操作过程中的比重损失达到0.36-0.46 g /（cm ²月）。EcoSoderberg电解槽GCB的铸铁部分腐蚀的特点是面积不均高。有些地区因局部疲劳而导致退役，重量减轻了19–24 kg。在腐蚀相对均匀的情况下，型材的最大允许失重为25–30 kg。为了根据实验数据做出预测性估计，获得了断面质量损失与运行时间的依赖关系。发现该部分的腐蚀产物由氧化铁和铸铁的合金元素组成。大多数样品的特点是C，S，F，K，Al和Na含量增加。腐蚀产物具有明显的分层结构，并含有大量以孔隙和裂纹形式出现的缺陷。这些层在化学，相组成和宏观结构上不同。₂ O ₃和Fe ₃ O ₄以及它们之间的多孔层。这些层的特征在于增加的C和F含量。硫均匀分布在腐蚀产物的整个厚度上。研究的腐蚀产物样品具有高缺陷，易碎性，大量气孔，裂纹，不连续性以及对铸铁表面的低附着力。这是由于存在具有不同热膨胀系数的相和化合物。建立了腐蚀产物层形成机理，并进行了科学证明。