Uncertainties in the shock devolatilization of hydrated minerals: A nontronite case study
Uncertainties in the shock devolatilization of hydrated minerals: A nontronite case study
复制标题
DOI：
10.1002/jgre.20147
复制
发表时间：
2013-10-01
影响因子：
4.8
通讯作者：
Tosca, N. J.
中科院分区：
文献类型：
--
作者：
Kraus, R. G.;Stewart, S. T.;Tosca, N. J.
由于天然样品和用作回收胶囊的工程材料之间的冲击阻抗存在巨大差异，因此受平面冲击载荷影响的水合矿物的受控回收具有挑战性。回收舱设计的显着差异混淆了对水合矿物冲击改性现有数据的直接解释。我们展示了绿脱石（在火星上观察到的一种蒙脱石粘土）的新冲击恢复实验的 X 射线衍射和红外光谱结果，并确定了恢复样品解释中的主要问题。先前的工作假设环上配置中的第一个冲击压力步骤是解释冲击修改的最重要因素。通过比较具有相似第一冲击步骤但最终冲击状态显着不同的实验的 X 射线衍射和红外光谱数据，我们表明不能简单地根据第一冲击压力步骤解释回收的样品。这项工作表明需要更深入地了解环升实验的热力学，以便能够根据行星应用的等效单冲击载荷压力来解释结果。在这项工作中，我们还表明，样品的排气在低压下并不重要，但在高压下可能很重要。我们开发了一种恢复方法和验证测试，使我们能够通过挥发性材料的冲击恢复实验来解决主要问题和技术权衡。
Controlled recovery of hydrated minerals subjected to planar shock loading is challenging because of the large difference in shock impedance between the natural samples and the engineering materials used as the recovery capsules. Significant differences in recovery capsule design confound straightforward interpretation of existing data on shock modification of hydrated minerals. We present X-ray diffraction and infrared spectroscopy results from new shock recovery experiments on nontronite (a smectite clay observed on Mars) and identify major issues in the interpretation of recovered samples. Previous work assumes that the first shock pressure step in a ring-up configuration is the most important factor in the interpretation of shock modification. By comparing the X-ray diffraction and infrared spectroscopy data from experiments with similar first shock steps but significantly different final shock states, we show that one cannot simply interpret the recovered samples based upon the first shock pressure step. This work demonstrates the need for a deeper understanding of the thermodynamics of ring-up experiments in order to be able to interpret the results in terms of an equivalent single shock loading pressure for planetary applications. In this work, we also show that venting of the samples does not matter significantly at low pressures but may be important at high pressures. We have developed a recovery method and validation test that allows us to address the major issues and technical tradeoffs with shock recovery experiments on volatile materials.