Electromagnetic Fields Produced by Self-Propagating High-Temperature Synthesis (SHS)

最近的实验表明，在自蔓延高温合成(SHS)过程中，形成了一个瞬时电压(电化学效应)和一个弱磁场(化学磁)。这是一项由燃烧过程引起的电化学效应和化学磁性的实验和理论相结合的研究，目的是阐明它们的来源、符号、大小和形状，并提供一种预测它们及其影响的方法。类似的反应，如金属的氧化或氮化，是用周期表中一行或一组中的金属进行的，以给出与电子结构、氧亲和力和氧化态的可能关联。在不同的气体压力、样品组成、孔隙率和颗粒大小下进行了实验，以确定这些因素的影响以及诱导信号与反应温度和燃烧波速的关系。用高温超导量子接口装置(SQUID)测量了小磁场。建立了一个预测电势形成的模型，该模型最初是基于这样的假设，即由于在燃烧过程中形成的产物层上的离子的梯度，在单个颗粒中形成了电变化。该模型预测了燃烧波速以及燃烧和燃烧后区域的电压、温度、氧气浓度和金属转化率的分布。然后使用预测的电压分布来计算感应磁信号。根据实验结果对模型进行了修正。

Recent experiments have shown that a transient electrical voltage ( electrochemical effect) and a weak magnetic field ( chemomagnetism) form during self-propagating high-temperature synthesis (SHS). This is a combined experimental and theoretical study of the electrochemical effect and chemomagnetism induced by combustion processes with the goals of elucidating their origin, sign, magnitude, and shape, and providing a means to predict them and their impact. Similar reactions, such as oxidation or nitridation of a metal, are done with metals from a row or group of the periodic table to give possible correlations with electronic structure, oxygen affinity, and oxidation state. Experiments are conducted at various gas pressures, sample compositions, porosities and particle sizes to determine the effects of these factors as well as the relationships between the induced signals and reaction temperature and combustion wave velocity. The small magnetic fields are measured with a high-Tc superconducting quantum interface device (SQUID). A model to predict the electrical potential formation is developed, initially based on the assumption that an electrical change is formed in individual particles due to a gradient of ions across a product layer formed during combustion. The model predicts combustion wave velocity and profiles of voltage, temperature, oxygen concentration, and metal conversion in the combustion and post-combustion zones. The predicted voltage profile is then used to calculate the induced magnetic signal. The model in revised on the basis of the experimental results.