The Effects of Soluble Impurities on the Flow and Fabric of Polycrystalline Ice

可溶杂质对多晶冰流动和结构的影响

• 批准号: 1141411
• 负责人: Ian Baker
• 金额: $ 33万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141411&HistoricalAwards=false
• 关键词: Effects; Soluble; Impurities; Flow; Fabric

Baker/1141411 This award supports a project to undertake a systematic examination of the effects of soluble impurities, particularly sulfuric acid, on the creep of polycrystalline ice as function of temperature, strain rate and impurity concentration. The working hypothesis is that soluble impurities will increase the flow rate of polycrystalline ice compared to high-purity ice, that this effect will be temperature dependent and that the impurities by affecting the re-crystallization and grain growth will change the fabric of the ice. Both H2SO4-doped and high-purity poly-crystalline ice will be produced by freezing sheets of ice, breaking them up, sieving the ice particles and then sintering them in a mold into fine-grained cylindrical specimens with at least ten grains across their diameter. The resulting microstructures (dislocation structure, grain size and shape, grain boundary character and micro-structural location of the acid) will be characterized using a variety of techniques including: optical microscopy, scanning electron microscopy, including secondary electron imaging, electron backscattered patterns, energy dispersive X-ray spectroscopy, electron channeling contrast imaging, and X-ray topography. The creep of both the H2SO4-doped and the high-purity polycrystalline ice will be undertaken at a range of temperatures and stresses. The ice?s response to the creep deformation (grain boundary sliding, dislocation motion, re-crystallization, grain boundary migration, impurity redistribution) will be studied using a combination of methods. The creep behavior will be modeled and related to the microstructure. Of particular interest is how impurities affect the activation energy for creep. The intellectual merit of the work is that it will lead to a better understanding of glacier ice and will enable glaciologists to model the influence of impurities on the flow and fabric development in polycrystalline ice. The broader impacts of the project include the knowledge that will be gained of the effects of impurities on the flow of ice which will allow paleoclimatologists to better interpret ice core data and will allow scientists developing predictive models to better address the flow of ice sheets under various climate change scenarios. The project will also lead to the education and training of a Ph.D. student, several undergraduates and some high school students. Results from the research will be published in refereed journals. Several undergraduates, typically two per year, will also perform the work. Dartmouth aggressively courts minority students at all degree levels, and we will seek women or minority group undergraduates for this project. The undergraduates will be supported by Dartmouth?s nationally-honored Women In Science Project or by REU funding. The undergraduates? research will integrate closely with the Ph.D. student?s studies. Hanover High School students will also be involved in the project and develop an educational kit to introduce students to the properties of ice. Results from the research will be published in refereed journals and presented at conferences.

贝克/1141411该奖项支持一个项目，以对可溶性杂质（尤其是硫酸）对多晶冰的蠕变的影响进行系统检查，这是温度，应变率和杂质浓度的功能。工作假设是，与高纯度冰相比，可溶性杂质将增加多晶冰的流速，这种作用将取决于温度，并且通过影响重结晶和谷物生长的杂质会改变冰的结构。 H2SO4掺杂和高纯度的多晶冰都将通过冷冻冰片，将它们弄碎，筛分冰颗粒，然后将它们在模具中烧成细粒度的圆柱形标本，至少在其直径上至少十种晶粒中，从而产生。 。将使用多种技术（包括：光学显微镜，扫描电子显微镜，包括二级电子成像，电子反向散射图案，电子反向散射，，扫描电子显微镜）来表征所得的显微结构（位错结构，晶粒尺寸和形状，谷物边界特征和酸的微结构位置）。能量色散X射线光谱，电子通道对比成像和X射线地形。 H2SO4掺杂和高纯度多晶冰的蠕变将在一系列温度和应力下进行。将使用方法组合研究冰对蠕变变形（晶界滑动，脱位运动，重结，晶界迁移，杂质再分配）的反应。蠕变行为将被建模并与微结构相关。特别有趣的是杂质如何影响蠕变的激活能。这项工作的智力优点在于，它将可以更好地理解冰川冰，并使冰川学家能够建模杂质对多晶冰中流动和织物发育的影响。该项目的更广泛的影响包括将获得杂质对冰流的影响的知识，这将使古气候学家能够更好地解释冰核数据，并允许科学家开发预测模型，以更好地解决各种冰盖的流动气候变化方案。该项目还将导致博士学位的教育和培训。学生，几个大学生和一些高中生。该研究的结果将发表在裁判期刊上。几名本科生通常每年两名，也将执行这项工作。达特茅斯（Dartmouth）积极地在各个程度上向少数民族的学生提供法院，我们将为该项目寻求妇女或少数族裔的本科生。本科生将得到达特茅斯（Dartmouth）在科学项目中或REU资助的全国性妇女的支持。本科生？研究将与博士密切集成。学生的研究。汉诺威高中的学生还将参与该项目，并开发一个教育套件，向学生介绍ICE的特性。该研究的结果将发表在卷轴期刊上，并在会议上介绍。