Advanced susceptors for microwave heating of energetic materials. (15th January 2016)

• Record Type: Journal Article
• Authors: Vargas, Evan; Pantoya, Michelle L.; Saed, Mohammed A.; Weeks, Brandon L.
• Is Part Of: Materials & design. Volume 90(2016)
• Page Start: 47
• Page End: 53
• Publication Date: 2016-01-15
• Subjects: Microwave heating -- Powder compacts -- Susceptors -- Particle connectivity -- Particle shape -- Advanced energetic composites; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2015.10.110
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Trinitrotoluene (TNT) like many monomolecular organic explosives is transparent to microwave energy. This study examines the influence of carbon additives to TNT purposefully selected to absorb microwave energy and enable heating throughout the composite. Five carbon additives with different shapes are analyzed including carbon nanotubes, spherical powder, diamond nanoparticles, graphene nano-flakes, and graphite micron-flakes. Each was added to TNT at a constant 1 wt.% concentration then subjected to 1.7 GHz of microwave energy for up to one minute. In-situ two-dimensional transient temperature is measured using a high-resolution high-speed infrared (IR) camera. ANSYS high frequency structural simulator (HFSS) software simulated power absorption for each additive. Simulations predict tubes absorb more energy but experimentally flakes induce melting of the TNT faster. Further analysis of additive connectivity through the matrix suggests that inter-particle connectivity plays a strong role in enhancing heat transfer upon microwave attenuation; and flakes show the greatest inter-connectivity. Engineering composite materials with optimized additives could lead to advances in microwave technologies. Graphical abstract: Highlights: Most organic explosives are transparent to microwave energy; susceptors are added to absorb energy and heat the composite. Five susceptor shapes were analyzed and found to significantly influence microwave absorption. For the same susceptor concentration, flake and tube shapes absorb more energy than spheres and induce TNT melting. Upon microwave absorption, percolation enhances conductive energy transport and promote higher composite heating rates.