Experimental studies of magnetite formation in the solar nebula
Experimental studies of magnetite formation in the solar nebula
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太阳星云中磁铁矿形成的实验研究
DOI：
10.1111/j.1945-5100.1998.tb01715.x
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发表时间：
1998
影响因子：
2.2
通讯作者：
B. Fegley
中科院分区：
文献类型：
--
作者：
Y. Hong;B. Fegley
在∼为4~41的H2/H2O摩尔比为4~41的H2和H2-He混合气体中，实验研究了常压下Fe金属和吉宾陨石金属氧化成磁铁矿的净反应3Fe(金属)+4H2O(气体)=Fe3O4(磁铁矿)+4H2(气体)。用X射线衍射法对生成的磁铁矿进行了鉴定。电子探针分析表明，在吉宾金属形成的磁铁矿中有3.3wt%的NiO和0.24wt%的CoO(可能是NiFe2O4和CoFe2O4)。在实验条件下，从金属与氧化物之间的平衡得到的NiO和CoO浓度高于预期。在Fe-Ni合金氧化的初始阶段，冶金专家也观察到磁铁矿中NiO含量的升高。用等表面积模型和粉末反应的Jander、Ginstling-Bronshtein和Valensi-Carter模型从增重数据计算了磁铁矿形成的速率常数。磁铁矿的形成遵循抛物线(即扩散控制)动力学。Fe金属和Gibeon金属的速率常数和表观活化能为：
Abstract— Oxidation of Fe metal and Gibeon meteorite metal to magnetite via the net reaction 3 Fe (metal) + 4 H2O (gas) = Fe3O4 (magnetite) + 4 H2 (gas) was experimentally studied at ambient atmospheric pressure at 91–442 °C in H2 and H2‐He gas mixtures with H2/H2O molar ratios of ∼4–41. The magnetite produced was identified by x‐ray diffraction. Electron microprobe analyses showed 3.3 wt% NiO and 0.24 wt% CoO (presumably as NiFe2O4 and CoFe2O4) in magnetite formed from Gibeon metal. The NiO and CoO concentrations are higher than expected from equilibrium between metal and oxide under the experimental conditions. Elevated NiO contents in magnetite were also observed by metallurgists during initial stages of oxidation of Fe‐Ni alloys. The rate constants for magnetite formation were calculated from the weight gain data using a constant surface area model and the Jander, Ginstling‐Brounshtein, and Valensi‐Carter models for powder reactions. Magnetite formation followed parabolic (i.e., diffusion‐controlled) kinetics. The rate constants and apparent activation energies for Fe metal and Gibeon metal are: