Analysis of the Transition State of the Carbon and Iron Oxide Mixture Activated by Mechanical Milling
Analysis of the Transition State of the Carbon and Iron Oxide Mixture Activated by Mechanical Milling
复制标题
机械球磨活化碳与氧化铁混合物的过渡态分析
DOI：
10.2355/isijinternational.44.1981
复制
发表时间：
2004
影响因子：
1.8
通讯作者：
K. Ishii
中科院分区：
文献类型：
--
作者：
Y. Kashiwaya;K. Ishii
在以前的研究中，已经报道了通过机械研磨获得的极高的反应速率。结果表明，反应机理复杂，影响反应活性的因素很多。其中，赤铁矿的结晶状态和研磨过程中的气氛（空气和氩气）是非常重要的因素。赤铁矿和石墨混合物的研磨在空气和氩气中进行。通过动力学分析获得了反应的速率常数。根据过渡态理论估算了活化焓ΔH* 和活化熵ΔS*。进行ΔS* 和ΔH* 的解释以解释研磨对与研磨条件相关的反应性的影响。随着球磨时间的延长，反应曲线的峰温降低。在氩气气氛中研磨的样品的反应性比在空气中研磨的样品显示出更高的反应性。由实验速率常数求得活化焓ΔH* 和活化熵ΔS*。在空气和氩气中研磨的试样，ΔH* 和ΔS* 随研磨时间的变化趋势相反。认为在空气气氛中研磨时会形成键合松散的活性络合物。另一方面，可能形成具有与产物（金属铁）接近的结构的活性络合物。
In previous study, the extremely high reaction rate obtained by the mechanical milling has been reported. It was found that the phenomena were quite complicated and the many factors were affected on the reactivity. Among these factors, the crystal state of hematite and atmosphere (air and argon) during the milling were quite important ones. Milling of hematite and graphite mixture was carried out both in the air and in the argon. Rate constants for the reactions were obtained by kinetic analysis. The enthalpy ΔH* and entropy ΔS* of activation were estimated on the basis of transition state theory. The interpretation of ΔS* and ΔH* was performed to explain the effect of milling on the reactivity related to the milling conditions. The temperature of peak of reaction curve decreased with increasing milling time. The reactivity of the sample milled in the argon atmosphere showed higher reactivity than that milled in the air. The enthalpy ΔH* and entropy ΔS* of activation were obtained from experimental rate constants. The variation of ΔH* and ΔS* with milling time showed opposite tendency between the sample milled in the air and in the argon. It was considered that the active complex having loose bonding would form during milling in the air atmosphere. On the other hand, the active complex having a structure closed to the product (metallic iron) might form.