Investigating the trade-offs of microwave susceptors in energetic composites: Microwave heating versus combustion performance

Recently, microwave technology has been used to ignite energetic materials when studies showed that metal powders readily absorb microwave energy. This study investigates adding a graphite susceptor to an energetic composite consisting of aluminum (Al) and iron (III) oxide (Fe₂O₃) and examines microwave coupling to the sample. In a companion study, the combustion of this thermite as a function of susceptor concentration was also studied to evaluate the trade-off between enhancing microwave coupling and flame propagation speed. Results show that graphite enhances microwave coupling up to 10% by mass concentration but reduces heating at higher percentages that exceed a percolation threshold. As susceptor concentrations increased greater than one mass percent, the flame propagation speed correspondingly decreased.