Initiation and Combustion of Mechanoactivated Mixtures of Aluminum and Copper Oxide

Abstract

Thermite mixtures based on metals and solid oxidants allow to obtain a significant exothermic effect during combustion. Al+CuO mixture allows receiving one of the highest exothermic effects per unit of volume (more than 20kJ/cm3). However, the burning rate of initial mixtures of micron powders usually does not exceed several tens of mm/s, which limits the field of their application. This is because that development of chemical reactions in solid mixtures takes place on the contact surface of reactants, which in the case of large particles is rather small. To increase this surface, various methods are used: ultrasonic mixing of nanosized powders, electrochemical deposition of submicron metal-oxidizer layers, etc. [1]. One of the relatively new methods for obtaining thermite composition is the preliminary mechanochemical activation of mixtures of micron-sized particles in high energy intensity ball mills. Initial components in this process are shredded, mixed and acquire new defects of crystal structure, which leads to an increase in the surface area of contact of the reagents at the submicron and nanoscale levels and also to formation of additional reaction spots. Thus, by means of mechanoactivation of oxidizer-metal mixtures it is possible to regulate the rate of energy release for different of specific application. In Russia, the method of preliminary mechanoactivation of solid oxidant-metal fuel mixtures has been actively used since the beginning of the 2000s [2-5], and the resulting materials are called Mechanically Activated Energetic Composites (MAEC).