CAREER: Fabrication & Characterization of Reactive Multi- layer Foils for Joining Application and Development of a Database for Classroom Demonstrations

这项CAREER基金探索了纳米多层材料中一个相对较新的现象：自传播放热反应。利用溅射沉积的独立多层薄膜，利用光学技术对自传播反应的速度和温度进行了量化。使用量热法测量热力学驱动力，并使用电子显微镜和X射线衍射鉴定产生的微观结构。研究了结构和物理参数对反应的点火、速度和温度的影响，并将所得信息用于开发有助于理解反应和预测材料性能的模型。该教育计划旨在通过开发一个国家级的课堂演示数据库来加强材料科学教育基础设施。本教育计划为材料科学课堂演示提供了一个国家数据库的设计。该数据库可以连接到NSF的主页，以便快速访问课堂演示的想法、说明和信息。它可以包括材料科学中令人兴奋的新演示的描述、图片和视频。新的放热反应已经在厚的、独立的多层箔中得到证实。它们在室温下以简单的火花点燃，以大于10m/s的速度行驶，并达到1500℃以上的温度。作为独立的箔片，它们提供了快速和局部产生热量的能力，为连接材料提供了新的机会。＊＊＊

9702546 Weihs This CAREER grant explores a relatively new phenomena in nanoscale multilayer materials: self-propagating, exothermic reactions. Using free-standing multilayer foils that are sputter deposited, the velocities and temperatures of the self-propagating reactions are quantified using optical techniques. The thermodynamic driving forces are measured using calorimetry techniques, and resulting microstructures identified using electron microscopy and X- ray diffraction. The impact of structural and physical parameters on the ignition, velocity, and temperature of the reactions are investigated, and the resulting information used to develop models that aid in understanding the reactions and in predicting material properties. The educational program is designed to strengthen the materials science education infrastructure by developing a national database for classroom demonstrations. This educational program provides the design of a National Data Base for Classroom Demonstrations in Materials Science. The database could be linked to NSF's home page to permit quick access to ideas, instructions, and information for classroom demonstrations. It could include descriptions, pictures and videos of exciting new demonstrations in materials science. %%% Novel exothermic reactions have been demonstrated in thick, free-standing multilayer foils. They ignite at room temperatures with a simple spark, travel at speeds greater than 10m/s, and reach temperatures above 1500 C. As free- standing foils they offer the ability to generate heat rapidly and locally, providing new opportunities for joining materials. ***