By James E. Kloeppel Graduate students Sinil Chai, Chris Brdar, and J.C. Melcher and undergraduate Jason Brzozowski work in the Energetic Materials Lab with Professor Krier. Recent shock-tube experiments at the University of Illinois have shown that propellants containing fluorine can significantly enhance the combustion of energetic boron particles. According to Herman Krier, the Richard W. Kritzer Professor of Mechanical and Industrial Engineering, the number one performance factor for any rocket is the amount of energy obtained per pound of propellant.
More energetic material means a rocket can carry less propellant and more payload.
Liquid fuels and oxidizers provide more energy per pound than solid propellants, but liquids must be cryogenically cooled, adding to their cost and making them difficult to store. These materials are safe and reliable but not extremely energetic. New propellants being developed will likely contain highly energetic metals such as magnesium and boron. Boron has a low molecular weight and a high energy of combustion, making it an attractive additive for use in rocket propellants. But a thin layer of boron oxide that forms on the particle surface hinders combustion, resulting in long ignition delays.