Fuel-rich aluminum–metal fluoride thermites

Siva Kumar Valluri, Ian Monk, Mirko Schoenitz, Edward Dreizin

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Nanocomposite thermite powders using aluminum as fuel with cobalt and bismuth fluorides as oxidizers were prepared by arrested reactive milling. Each material contained 50 wt% of aluminum and 50 wt% of a fluoride, resulting in fuel-rich compositions. The reactions in the prepared powders were characterized by thermo-analytical measurements; powders were ignited as coatings on an electrically heated filament and by electrostatic discharge. It was observed that the exothermic reactions begin in aluminum–metal fluoride thermites at lower temperatures than in any previously prepared reactive nanocomposites based on aluminum. Redox reactions in Al·CoF2 and Al·BiF3 nanocomposite started around 200 and 250°C, respectively. The results suggest that the initial reactions are rate-limited by the decomposition of fluorides. In the oxygenated environments, metals generated by reducing the starting fluorides oxidize readily. The newly formed oxides are rapidly reduced by excess aluminum, accelerating aluminum oxidation at low temperatures. The low-temperature thermally activated reactions lead to low ignition temperatures for the powders heated on the filament. Despite the low ignition temperatures, both prepared materials were relatively insensitive to ignition by an electric spark, making them attractive components of advanced energetic formulations.

Original languageEnglish (US)
Pages (from-to)81-101
Number of pages21
JournalInternational Journal of Energetic Materials and Chemical Propulsion
Volume16
Issue number1
DOIs
StatePublished - Jan 1 2017

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Keywords

  • Energetics
  • Mechanical milling
  • Metal combustion
  • Nanocomposites
  • Reactive materials

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