目的 研究常压低温冷等离子体还原过程中气体常量对Fe2O3还原过程的影响.方法 采用冷压成形后高温烧结的方式制备Fe2O3试样块,利用射流型常压冷等离子体还原铁基氧化物,通过X射线衍射仪分析还原前后的物相,用扫描电镜观察还原前后的微观形貌,讨论了还原过程中气氛的作用和影响.结果 等离子体的还原能力取决于还原气体的成分与含量,其中氮等离子体在常温常压条件下无法还原Fe2O3,氨气+氮气混合气体为工作气体的常压低温冷等离子体能将Fe2O3还原成Fe3O4和金属Fe,还原能力随着氨气含量的增加而增强,还原速率随着氨气含量的增加而下降.氨气在等离子体中可产生多种还原性物质,如N2H4、H和H2*等,能将Fe2O3还原,且过程表现为过渡还原,即Fe2O3先被还原成Fe3O4,再被还原成金属Fe.结论 常压低温冷等离子体中的电子与热效应无法还原Fe2O3,添加氨气后的等离子体中产生了一系列的活性物质,才能还原金属Fe表面的氧化物.
The work aims to study effect of gas constant on reduction of Fe2O3 by atmospheric pressure plasma jet.The sample was prepared by cold forming and high temperature sintering from Fe2O3 test-pieces.Iron-based oxide was reduced by atmospheric pressure cold plasma jet.Phases of the samples treated by plasma were analyzed by virtue of X-ray diffraction (XRD),and morphology of the samples was observed by virtue of a scanning electron microscopy (SEM).The function and influence of atmosphere on reduction process were analyzed.Composition and content of reducing gas played a major role in reducing capacity of the plasma.The Fe2O3 couldn't be reduced by nitrogen plasma provided with normal pressure and temperature,while the Fe2O3 could be reduced to the Fe3O4 and Fe by mixed gas consisting of plasma and ammonia.The reducing capacity increased while the reduction rate decreased as the ammonia content increased.Various reducing substances could be produced by ammonia in the plasma,such as N2H4,H and H2*,which could reduce Fe2O3,and it was a transitional reduction process:Fe2O3 was first reduced to Fe3O4,and then reduced to Fe.The Fe2O3 could not be reduced by electrical and thermal effects in atmospheric pressure cold plasma.The Fe-based oxide could be reduced by a series of active materials produced in the plasma containing ammonia gas.
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