ABSTRACT
Specialized topics that have to do with thermitic reactions and thermites are presented. These include the pyrotechnic properties of aluminum-based compositions; the exothermic chemical reactions that produce borides, silicides, and intermetallics; the thermodynamic characteristics of metals and metalloids as fuels in combustion reactions; the chemical and pyrotechnic properties of sulfur and metal sulfides; and a few general comments on thermodynamics, combustion, and technology. Throughout, an emphasis is placed on thermodynamic and thermochemical properties. Adiabatic and isothermal formalisms are used to describe the probable reaction temperatures and energy contents and densities of fuels and pyrotechnic compositions. Regarding the elements as fuels, it is shown that metal and metalloid combustion reactions can involve oxidizers other than oxygen, such as carbon dioxide, water, nitrogen, sulfur, and the halogens. Similarly, it is shown that thermitic reactivity encompasses reactions involving oxidizers other than metal oxides, especially metal sulfides. In this context, pseudocomproportionations are shown to be chemical reactions that resemble actual comproportionations in a stoichiometric context. On a more practical note, the similarities between thermitic reactions and a method known as “self-propagating high-temperature synthesis” are explored. And, several pyrotechnic reactions are compared to the analogous transformations that take place within electrochemical cells.
