Microwave heating of energetic materials

Abstract

Mixtures of high explosives with materials that readily absorb microwaves ignite more readily when exposed to microwave energy than the corresponding neat explosives. A charge of HMX (0.5 gram) mixed with carbon nanotubes (1 percent by mass) ignited with 7.5 joules at an average rate of 750 W for 10 milliseconds. To raise a charge of the same mass of neat HMX to an autoignition temperature of 200 degrees Celsius would require much more energy (about 110 joules) for a longer duration (about 150 milliseconds).

1 . A method for igniting high explosive comprising preparing a mixture of high explosive having a first dielectric loss and a material having a second dielectric loss that is higher than the first dielectric loss of the high explosive, and thereafter exposing the mixture to microwave energy.  
     
     
         2 . The method of  claim 1 , wherein the explosive is selected from the group consisting of TNT, PETN, RDX, HMX, TATB, and mixtures thereof.  
     
     
         3 . The method of  claim 1 , wherein the material that strongly absorbs microwave energy is selected from the group consisting of carbon nanotubes, metal powder, semiconductor powder, and mixtures thereof.  
     
     
         4 . The method of  claim 3 , wherein the metal powder comprises finely divided powder.  
     
     
         5 . The method of  claim 3 , wherein the semiconductor powder comprises finely divided powder.  
     
     
         6 . The method of  claim 3 , wherein the mixture comprises about 1 percent by mass or less of carbon nanotubes.  
     
     
         7 . The method of  claim 1 , wherein the material that strongly absorbs microwave energy comprises a semiconductor.  
     
     
         8 . The method of  claim 1 , wherein the method further comprises adding a binder to the mixture of high explosive having a first dielectric loss and a material having a second dielectric loss that is higher than the first dielectric loss of the high explosive  
     
     
         9 . A mixture of high explosive having a first dielectric loss and about 1 percent by mass or less of a material having a second dielectric loss that is higher than the first dielectric loss of the high explosive.  
     
     
         10 . The mixture of  claim 9 , wherein the high explosive is selected from the group consisting of TNT, PETN, RDX, HMX, TATB, and mixtures thereof.  
     
     
         11 . The explosive of  claim 9 , wherein the material that strongly absorbs microwave energy is selected from the group consisting of carbon nanotubes, metal powder, and semiconductor powder.  
     
     
         12 . The explosive of  claim 11 , wherein the metal powder comprises finely divided powder.  
     
     
         13 . The explosive of  claim 11 , wherein the semiconductor powder comprises finely divided powder.  
     
     
         14 . The explosive of  claim 9 , further comprising a binder.