Microwave-Enhanced Solid State Reactions in Ionic Crystalline Solids

离子晶体固体中的微波增强固态反应

• 批准号: 9526035
• 负责人: John Booske
• 金额: $ 17.29万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-15 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526035&HistoricalAwards=false
• 关键词: Microwave; Enhanced; Solid; State; Reactions

The primary goal of this research project is to isolate and characterize a microwave-field-enhancement effect on ionic transport in ionic ceramics. The investigation will emphasize experiments to establish whether this microwave driving force is a dominant mechanism responsible for enhanced solid state diffusion and of interface chemical reactions. Measurements will made using halide salts, a 14 GHz microwave source, and a nonresonant waveguide applicator. Theoretical analyses will be conducted in collaboration with researchers from the Institute of Applied Physics, Russian Academy of Science (Nizhny Novgorod). Design of the experiments, the experimental applicator, and experimental operation will be completed in collaboration with a researcher from Rockwell International. Two sets of experiments are planned: (1) measurements of microwave effects on grain boundary diffusion of K+ ions into NaCl and Na+ ions into KCl, and (2) measurements of microwave effects on interface-limited solid-state reaction rates for (pseudo) binary compound formation. In both cases, th e reactions will be compared for microwave-irradiated and microwave-free samples as a function of sample temperature, microwave field strength, and electric field polarization. In addition, the PIs plan experimental studies of temperature distributions within microwave-heated ceramic specimen. This will address questions of accurate thermometry in microwave heating/materials processing and whether reports of enhanced reactions in microwave-heated glasses and ceramics can be (at least partially) explained by core-to surface temperature differentials of up to several hundred degrees Celsius. Specifically, the PIs will characterize internal temperature gradients due to inverted temperature profiles through the experimental examination of solid-state compound formation in microwave-heated oxide particulate composites in which the two component oxide phases in the starting compact react to form one or two quasi binary compounds. The results will be compared to predictions based on heat transport and microwave absorption modeling in oxide particulate composites.

该研究项目的主要目标是分离和表征微波场增强对离子陶瓷中离子传输的影响。 该研究将重点通过实验来确定这种微波驱动力是否是增强固态扩散和界面化学反应的主要机制。 测量将使用卤化物盐、14 GHz 微波源和非谐振波导涂抹器进行。 理论分析将与俄罗斯科学院（下诺夫哥罗德）应用物理研究所的研究人员合作进行。 实验设计、实验涂抹器和实验操作将与罗克韦尔国际的研究人员合作完成。 计划进行两组实验：（1）测量微波对 K+ 离子进入 NaCl 和 Na+ 离子进入 KCl 的晶界扩散的影响，以及（2）测量微波对（伪）二元化合物形成的界面限制固态反应速率的影响。 在这两种情况下，将比较微波辐射和无微波样品的反应作为样品温度、微波场强度和电场极化的函数。 此外，PI 还计划对微波加热陶瓷样品内的温度分布进行实验研究。 这将解决微波加热/材料加工中精确测温的问题，以及微波加热玻璃和陶瓷中增强反应的报告是否可以（至少部分）用高达数百摄氏度的核心到表面温差来解释。 具体来说，PI 将通过微波加热氧化物颗粒复合材料中固态化合物形成的实验检查来表征由于反向温度分布而产生的内部温度梯度，其中起始压块中的两种组分氧化物相反应形成一种或两种准二元化合物。 结果将与基于氧化物颗粒复合材料的热传输和微波吸收模型的预测进行比较。