Kinetics and Mechanisms of Rapid Heterogeneous Reactions During Combustion Synthesis

燃烧合成过程中快速多相反应的动力学和机理

• 批准号: 9900357
• 负责人: Arvind Varma
• 金额: $ 32.1万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9900357&HistoricalAwards=false
• 关键词: Kinetics; Mechanisms; Rapid; Heterogeneous; Reactions

Abstract - VarmaThis work aims at a fundamental understanding of combustion synthesis especially in the volume combustion synthesis (VCS) mode. A knowledge of reaction mechanisms and chemical kinetics of VCS that incorporates phase changes and microstructure evolution is necessary to control product structure and properties. To achieve this, a set of new experimental methods is used. The kinetics of high-temperature (up to 3000o K) heterogeneous reactions at heating rates up to 106 oK/sec is studied by computer-assisted electrothermo- graphy (CAE). To overcome difficulties in determining laws from the time dependence of the reaction rate, time-resolved X-ray diffraction (TRXRD) is used; this provides continuous measurement of the kinetics of phase formation under reaction conditions. Temperature distribution across the sample during all stages of VCS is monitored by a set of thermocouples and by a high-speed infrared imaging system. Direct observation of microstructural transformation is done with a modified digital high-speed microscopic video recorder with rates up to 12,000 frames/sec. The first stage of the research will look at formation of nitrides and binary intermetallics of nickel, aluminum, titanium, and niobium. In the second stage, more complex systems will be examined including direct formation of ceramic-metal composites.

翻译后摘要- VarmaThis工作的目的是在燃烧合成的基本理解，特别是在体积燃烧合成（VIM）模式。 反应机理和化学动力学的知识，包括相变和微观结构的演变是必要的，以控制产品的结构和性能。 为了实现这一点，一套新的实验方法被使用。 本文用计算机辅助电热图（CAE）研究了升温速率高达106 oK/sec时高温（高达3000 oK）多相反应的动力学。 为了克服从反应速率的时间依赖性确定规律的困难，使用时间分辨X射线衍射（TRXRD）;这提供了在反应条件下相形成动力学的连续测量。 整个样品的温度分布，在所有阶段的监测由一组热电偶和高速红外成像系统。 显微组织转变的直接观察是用一台改进的数字高速显微录像机完成的，其速率高达12，000帧/秒。 研究的第一阶段将着眼于镍、铝、钛和铌的氮化物和二元金属间化合物的形成。 在第二阶段，将研究更复杂的系统，包括陶瓷-金属复合材料的直接形成。