Metallic iron whisker formation and growth during iron oxide reduction: basicity effect
Metallic iron whisker formation and growth during iron oxide reduction: basicity effect
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DOI：
10.1179/174328109x463020
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发表时间：
2009-07
影响因子：
2.1
通讯作者：
K. A. Abdel Halim;M. Bahgat;H. A. El-Kelesh;M. Nasr
中科院分区：
文献类型：
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作者：
K. A. Abdel Halim;M. Bahgat;H. A. El-Kelesh;M. Nasr
本文研究了碱度对金属铁晶须生长的影响。合成了纯钨钛矿和掺CaO/SiO2钨钛矿的致密体。在800-1100℃用CO气体等温还原热重仪。在减肥过程之后，测量体重减轻作为时间的函数。利用x射线衍射（XRD）、扫描电镜（SEM）、光学显微镜和孔隙率测量对退火和还原后的样品进行了表征。研究了温度和碱度（CaO/SiO2）对退火样品的还原行为和形貌的影响。还原速率随温度升高而升高，但随碱度值的增加而降低。在高温还原后的纯钨<s:1>石试样中检测到金属铁晶须状结构，而在碱性钨<s:1>石试样中，在致密物表面形成了金属铁晶须。从活化能值来看，纯钨的还原很可能是由气体扩散和界面化学反应机制共同作用的结果。碱度比为0.2和0.5时，还原速率主要受化学反应机制控制，而碱度比为0.8时，还原速率主要受固相反应机制控制。
The effect of basicity on the metallic iron whisker growth during wüstite reduction was studied in the present investigation. Compacts of pure and CaO/SiO2 doped wüstite were synthesised. The annealed compacts were isothermally reduced in thermogravimetric apparatus with CO gas at 800–1100°C. The course of reduction was followed by measuring the weight loss as a function of time. X-ray diffraction (XRD), scanning electron microscope (SEM), optical microscope and porosity measurements were used to characterise the annealed and reduced samples. The influence of temperature and basicity (CaO/SiO2) on the reduction behaviour and the morphology of the annealed samples were investigated. The reduction rate increased with temperature but decreased by increasing basicity value. Metallic iron whisker shape structure was detected in the pure wüstite samples after reduction at high temperatures while in basic wüstite samples, whiskers were formed at the surface of the compacts. From the activation energy values, the reduction of pure wüstite is most likely controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. The reduction of basic wüstite compacts with 0·2 and 0·5 basicity ratios are most likely controlled by chemical reaction mechanism while for 0·8 basicity ratio, the reduction rate is most likely controlled by solid state reaction mechanism.