Self-propagating high-temperature synthesis (SHS) is a method for producing both inorganic and organic compounds by exothermic combustion reactions in solids of different nature.
Since the process occurs at high temperatures, the method is ideally suited for the production of refractory materials including powders, metallic alloys, or ceramics.
The high-temperatures generated during synthesis also lead to problems with energy dissipation and suitable reaction vessels, however, some systems use this excess heat to drive other plant-processes.
The temperature of the reaction can be moderated by the addition of inert salt that absorbs heat in the process of melting or evaporation, such as sodium chloride, or by adding "chemical oven"—a highly exothermic mixture—to decrease the ratio of cooling.
[11] SHS has been used to vitrify various nuclear waste streams including ashes from incineration, spent inorganic ion exchangers such as clinoptilolite and contaminated soils.
[12] Due to the solid-state nature of SHS processes, it is possible to measure reaction kinetics in-situ using a variety of experimental techniques, including electrothermal explosion, differential thermal analysis, combustion velocity approaches, among others.