Formulation, casting, and evaluation of paraffin-based solid fuels containing energetic and novel additives for hybrid rockets

Daniel B. Larson, John D. Desain, Eric Boyer, Trevor Wachs, Kenneth K. Kuo, Russell Borduin, Joseph H. Koo, Brian B. Brady, Thomas J. Curtiss, George Story

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

This investigation studied the inclusion of various additives to paraffin wax for use in a hybrid rocket motor. Some of the paraffin-based fuels were doped with various percentages of LiAlH4 (up to 10%). Addition of LiAlH4 at 10% was found to increase regression rates between 7 and 10% over baseline paraffin through tests in a gaseous oxygen hybrid rocket motor. Mass burn rates for paraffin grains with 10% LiAlH4 were also higher than those of the baseline paraffin. RDX (or cyclotrimethylen-etrinitramine, C3H6N6O6) was also cast into a paraffin sample via a novel casting process which involved dissolving RDX into dimethylformamide (DMF) solvent and then drawing a vacuum on the mixture of paraffin and RDX/DMF in order to evaporate out the DMF. It was found that although all the DMF was removed, the process was not conducive to generating small RDX particles. The slow boiling generated an inhomogeneous mixture of paraffin and RDX. It is likely that superheating the DMF to cause rapid boiling would likely reduce RDX particle sizes. In addition to paraffin/LiAlH4 grains, multiwalled carbon nanotubes (MWNT) were cast in paraffin for testing in a hybrid rocket motor, and assorted samples containing a range of MWNT percentages in paraffin were imaged using scanning electron microscopy and thermally tested using thermogravimetric analysis. The fuel samples showed good distribution of MWNT in the paraffin matrix, but the MWNT were often agglomerated, indicating that a change to the sonication and mixing processes is required to achieve better uniformity and debundled MWNT. Fuel grains with MWNT fuel grains had a slightly lower regression rate, likely due to the increased thermal conductivity to the fuel subsurface, reducing the burning surface temperature.

Original languageEnglish (US)
Pages (from-to)453-478
Number of pages26
JournalInternational Journal of Energetic Materials and Chemical Propulsion
Volume14
Issue number6
DOIs
StatePublished - 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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