In order to develop a green solid propellant AP must be replaced with a chlorine free solid oxidizer. Unfortunately the number of oxidizers is very limited and only two useful green oxidizers exist:
● Ammonium nitrate, AN (NH4NO3)
● Ammonium dinitramide, ADN (NH4N(NO2)2)
both having their respective pros and cons.
AN is a very cheap oxidizer, mainly used as fertilizer. Propellants based on AN have low performance and low burning rate and thus AN based propellants have mainly been used in low performance applications such as gas generators.
ADN is a new oxidizer still in the development phase. It provides very high performance and high burning rate, but is more costly and more explosively hazardous compared to AP.
In the table below some of the properties of ADN and AN are presented qualitatively in relation to AP.
It can be seen that neither AN, nor ADN are able to replace AP. However, by combining the two, bringing the best of each, the properties can be tuned to meet, or even exceed, the properties of AP.
The research in the project will to a large extent build on the experience gained in the EU FP7 project HISP.
FOI, Swedish Defence Research Agency
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 638719.