Mechanistice Studies of Combustion Synthesis and Product Structure Formation

摘要CTS-9528941 VARMA拟议的研究集中在金属间化合物形成过程中的自蔓延高温合成过程的基本方面。为了有效地利用这一技术，并控制该过程，燃烧合成机理的基础知识是至关重要的，该机理涉及非平衡初始产物向最终产物的演化。拟议工作的两个主要目标是：(1)分析初始产品结构的形成；(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。该方法包括清楚地了解从产品第一次出现到通过燃烧后过程形成最终产品的产品结构的演变。提出了无气燃烧合成的四种基本初始产物形成机理。通过改变生坯密度、颗粒大小、初始温度、冷却速度等实验条件，并从初始产品结构出发，PI希望确定每种形成机理的合适条件。在拟议的研究中，将使用各种实验技术。其中包括燃烧波猝灭技术、改进的粒子箔技术、时间分辨X射线衍射技术、显微高速摄像的新方法以及一种监测反应区内混合气体析出和电离动力学的新实验装置。

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.