合氟铁矿在高炉中冶炼时,炉顶煤气中含有微量的氟化氢(6—14 p.p.m.);本研究观察了含氟模拟煤气对三号结构钢的腐蚀情况。所用合成煤气的成分为:0.05—5％HF,1.5—2.5％H_2,0—1％H_2O,6—8％CO_2,19—23％CO,余为N_2;实验的温度范围为250—530℃。在～390℃以下,腐蚀产物为FeF_2,有保护作用。煤气中氢的存在,能阻止FeF_2的生成。在～390℃以上,所生成的FeF_2即被水蒸气转化为Fe_3O_4;即使在原先干燥的合成煤气中,组份中的CO_2和H_2作用所生成的水蒸气,已足够推动此转化反应到完毕。所以在～390℃以上,腐蚀产物都为Fe_3O_4。以上所得的各实验结果,都与热力学计算的结果相符。将氟化氢浓度自0.05％提高到5％,在390℃以下,腐蚀作用并不显著地增加。
Mild steel specimens were exposed to synthetic blast furnace exhaust gases of the following composition: HF 0.05—5%, H_2 1.5—2.5%, H_2O 0—1%, CO_2 6—8%, CO 19—23%, N_2—hal., at a temperature range of 250° to 530℃. Below ～390℃, the corrosion product was identified by X-ray diffraction as FeF_2 and formed a compact protective film. It was further observed that the existence of H_2 in synthetic gases greatly retards the formation of FeF_2. Above ～390℃, FeF_2 first formed is transformed immediately into Fe_3O_4 by the reaction with the existing water vapor. Even in a dry synthetic gas under this temperature range, the reaction of CO_2 and H_2 will produce sufficient partial pressure of water vapor to drive this transformation to its completeness. These results conform with the existing thermodynamic data. On increasing the HF concentration from 0.05% to 5%, no obvious enhancement of corrosion rate of mild steel has ever been noted below 390℃.
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