Recent advances in new oxidizers for solid rocket propulsion

Abstract

Ammonium perchlorate (AP), the workhorse of oxidizers in solid rocket and missile propellants, exhibits various environmental issues resulting from the release of perchlorate into ground water, which have been directly linked to thyroid cancer. Furthermore, the generation of hydrochloric acid causes the depletion of the ozone layer and leads to high concentrations of acid rain. Nowadays, considerable efforts have been devoted to developing solid propellants using green oxidizers which demonstrate less hazards and environmentally friendly chlorine free combustion products. Although many candidates for AP replacement have been identified, most of them are far from being practically employed in real applications because of a number of severe difficulties, including cost. In this review, the potential green chemicals for use as oxidizers are highlighted and these reveal interesting physicochemical properties and performance. After a quick definition of green solid propellants and their main ingredients, the current status of AP propellants issues is discussed in light of possible substitution with potential green ingredients. Particular attention will be paid to the recent advances in the green oxidizers, their production and their characteristic properties. The advantages and shortcomings of various green oxidizers for specific and potential propellant uses are also discussed together with the attempts made to overcome these problems. As a consequence, efforts will certainly continue to seek AP alternatives and efficient green oxidizers for solid rocket propulsion in the near future.