Hydrochloric acid emissions from perchlorate-based solid propellants are a threat to the environment and the ozone layer. Past efforts in developing greener solid propellants have resulted in solutions with a non-insignificant performance decrease. The use of a novel intermetallic alloy as fuel is shown to be able to both increase the specific impulse and neutralize the environmental impact. The intermetallic powder was characterized (granulometry, active content, and reactivity with TG-DTA) and its ageing behaviour has been investigated, showing a very quick degradation in non-dry environments. Additionally, compatibility issues with the main components of a solid propellant were checked and possible reaction mechanisms have been proposed to explain them. In order to protect the powder from humidity and aforementioned incompatibilities various protective organic coatings were investigated. The produced coated powders were characterized and showed similar granulometries and minimal decrease in metallic active content with respect to the virgin powder, important factors to preserve the ballistic performances of the propellant. Nevertheless, while similar coating solutions were proven to work on nano-aluminum particles, they were not able to protect the intermetallic-alloy powders from humidity during ageing tests.
Le emissioni di acido cloridrico dei propellenti solidi a base di perclorato sono una minaccia per l’ambiente e lo strato di ozono. Gli sforzi compiuti in passato per sviluppare propellenti solidi più ecologici hanno portato a soluzioni con una riduzione significativa delle prestazioni. L’uso di una nuova lega intermetallica come combustibile ha dimostrato di poter aumentare l’impulso specifico e neutralizzare l’impatto ambientale. La polvere intermetallica è stata caratterizzata (granulometria, contenuto attivo e reattività con TG-DTA) ed è stato studiato il suo comportamento all’invecchiamento, che ha mostrato una degradazione molto rapida in ambienti non secchi. Inoltre, sono stati verificati i problemi di compatibilità con i principali componenti di un propellente solido e sono stati proposti possibili meccanismi di reazione per spiegarli. Per proteggere la polvere dall’umidità e dalle suddette incompatibilità, sono stati studiati diversi rivestimenti organici protettivi. Le polveri rivestite prodotte sono state caratterizzate e hanno mostrato granulometrie simili e una diminuzione minima del contenuto attivo metallico rispetto alla polvere vergine, fattori importanti per preservare le prestazioni balistiche del propellente. Tuttavia, mentre soluzioni di rivestimento simili si sono dimostrate efficaci sulle particelle di nano-alluminio, non sono state in grado di proteggere le polveri di leghe intermetalliche dall’umidità durante i test di invecchiamento.
Characterization, ageing and compatibility of organic-coated intermetallic-alloy powders for green solid propulsion
Tognola, Paolo
2022/2023
Abstract
Hydrochloric acid emissions from perchlorate-based solid propellants are a threat to the environment and the ozone layer. Past efforts in developing greener solid propellants have resulted in solutions with a non-insignificant performance decrease. The use of a novel intermetallic alloy as fuel is shown to be able to both increase the specific impulse and neutralize the environmental impact. The intermetallic powder was characterized (granulometry, active content, and reactivity with TG-DTA) and its ageing behaviour has been investigated, showing a very quick degradation in non-dry environments. Additionally, compatibility issues with the main components of a solid propellant were checked and possible reaction mechanisms have been proposed to explain them. In order to protect the powder from humidity and aforementioned incompatibilities various protective organic coatings were investigated. The produced coated powders were characterized and showed similar granulometries and minimal decrease in metallic active content with respect to the virgin powder, important factors to preserve the ballistic performances of the propellant. Nevertheless, while similar coating solutions were proven to work on nano-aluminum particles, they were not able to protect the intermetallic-alloy powders from humidity during ageing tests.File | Dimensione | Formato | |
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2023_12_Tognola_Executive_Summary_02.pdf
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Descrizione: Executive Summary
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2023_12_Tognola_Tesi_01.pdf
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Descrizione: Tesi
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https://hdl.handle.net/10589/215261