In situ observation of aluminothermic reduction of MgO with high temperature optical microscope
In situ observation of aluminothermic reduction of MgO with high temperature optical microscope
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DOI：
10.2355/isijinternational.46.202
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发表时间：
2006-02
影响因子：
1.8
通讯作者：
Jian Yang;M. Kuwabara;Zhongzhu Liu;T. Asano;M. Sano
中科院分区：
文献类型：
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作者：
Jian Yang;M. Kuwabara;Zhongzhu Liu;T. Asano;M. Sano
研究了用氧化镁铝热还原原位生成的镁蒸气对铁液进行脱硫脱氧的方法。探讨了用氧化镁和铝粉组成的球团铝热还原氧化镁的机理。对不同温度下不同还原阶段的球团进行了SEM观察，结果表明，在1 473 K以上，铝颗粒表面氧化铝膜的破裂和消失被刺激，从而大大加速了氧化镁的还原。发现还原在熔融铝渗透到氧化镁相中之后进行。侵彻开始于1273 K，在1373 K以上加速。还原反应在1473 K时发生剧烈.对冷却后试样的SEM观察和EDS分析表明，铝液的渗透仅发生在氧化铝膜的裂纹处;对铝颗粒熔化过程的原位观察和冷却后试样的SEM观察表明，热应力和相变过程中形成的应力使氧化铝膜破裂，在高温下铝液确实发生了外流。
Desulfurization and deoxidation of molten iron with magnesium vapor produced in-situ by aluminothermic reduction of magnesium oxide has been developed. In the present study, the mechanism of aluminothermic reduction of magnesium oxide by use of pellets composed of magnesium oxide and aluminum powders was discussed. SEM observation of the pellets at different reduction stages for various temperatures showed that fracture and disappearance of the alumina films on the aluminum particles were stimulated above 1 473 K, and thus the reduction of magnesium oxide was greatly accelerated.From in-situ observation of the aluminothermic reduction of magnesium oxide using a high temperature optical microscope (HTOM), it was found that the reduction proceeded after the penetration of molten aluminum into the magnesium oxide phase. The penetration began at 1 273 K and it was accelerated above 1 373 K. The reduction took place violently at 1 473 K. SEM observation and EDS analysis of the cooled sample revealed that the penetration took place only through cracks of the alumina film.In-situ observation of the melting process of aluminum particles together with SEM observation of the cooled sample showed that the thermal stress and the stress formed during phase transformation could break up the alumina film and the outflow of molten aluminum did take place at the elevated temperature.