Mechanistice Studies of Combustion Synthesis and Product Structure Formation

提出的研究重点是涉及金属间化合物形成的SHS过程的基本方面。为了有效地利用这一技术，并控制这一过程，对燃烧合成机制的基本知识涉及到非平衡初始产物向最终产物的演变是至关重要的。提出的工作的两个主要目标是：(1)分析初始产物结构的形成，(2)测量燃烧状态下金属间化合物形成的有效和详细的动力学。该方法涉及到从产品首次出现到最终产品通过燃烧后过程形成的产品结构演变的清晰理解。介绍了无气燃烧合成的四种基本初始产物形成机理。通过改变实验条件，如生坯密度、颗粒大小、初始温度、冷却速度等，并从初始产物结构出发，PI希望确定每种形成机制的合适条件。各种实验技术将在拟议的研究中使用。其中包括燃烧波猝灭、改性颗粒箔技术、时间分辨x射线衍射（TRXRD）、微观高速视频记录新方法以及用于监测反应区混合气体演化和电离动力学的新型实验装置。

Abstract CTS-9528941 Varma The proposed research focuses on the fundamental aspects of the SHS processes involved in the formation of intermetallic compounds. In order to utilize this technique effectively, and to control the process, a fundamental knowledge of combustion synthesis mechanisms involving the evolution of non-equilibrium initial products toward the final product is of critical importance. The two major objectives of the proposed work are: (1) the analysis of the initial product structure formation, and (2) the measurement of the effective and detailed kinetics of the formation of intermetallics in a combustion regime. The approach involves obtaining a clear understanding of the evolution of product structure from when the product first appears to when the final product is formed by the post combustion processes. Four basic initial product formation mechanisms are presented for gasless combustion synthesis. By varying the experimental conditions such as green density, particle size, initial temperature, cooling rate, etc., and from the initial product structure, the PI hopes to determine the appropriate conditions for each of the formation mechanisms. A variety of experimental techniques will be used in the proposed research. These include combustion wave quenching, modified particle-foil technique, time resolved X-ray diffraction (TRXRD), new method of microscopic high speed video recording and a novel experimental apparatus for monitoring the kinetics of admixed gas evolution and ionization in the reaction zone.