Propellant formulation and projectiles and munitions employing same

Abstract

A solid, heterogeneous, high performance rocket propellant, operable at high pressure with a burn rate relatively insensitive to changes in pressure and temperature. The propellant includes a binder, ammonium perchlorate particles, metal particles, and iron oxide. The ammonium perchlorate particles comprise a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm. In one embodiment, the propellant includes a binder formed from the reaction of a hydroxy terminated polybutadiene with a diisocyanate, ammonium perchlorate as an oxidizer, aluminum as a fuel, and iron oxide as a burn rate modifier. The propellant may also include bonding agents, curing catalysts, a plasticizer, antioxidant/peroxide scavengers, and pot life extenders.

1 . A propellant, comprising: 
 a binder;    ammonium perchlorate particles;    metal particles; and    iron oxide,    wherein the ammonium perchlorate particles comprise a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.    
     
     
         2 . The propellant of  claim 1 , wherein the binder comprises a polyurethane.  
     
     
         3 . The propellant of  claim 1 , wherein the binder is a polyurethane formed by reacting in-situ a hydroxy functional prepolymer and a multifunctional isocyanate curing agent.  
     
     
         4 . The propellant of  claim 3 , wherein the hydroxy functional prepolymer is a hydroxy terminated polybutadiene having a hydroxy functionality of from about 2 to about 3 and a specific average molecular weight of less than about 10,000 and wherein the multifunctional isocyanate curing agent is a diisocyanate.  
     
     
         5 . The propellant of  claim 3 , wherein the hydroxy functional prepolymer comprises from about 7 percent to about 15 percent of a total weight of the propellant.  
     
     
         6 . The propellant of  claim 3 , wherein the multifunctional isocyanate curing agent comprises a sufficient amount of the propellant so that a isocyanate/hydroxy (“NCO/OH”) moiety ratio between the prepolymer and the multifunctional isocyanate curing agent is from about 0.8 to about 1.2.  
     
     
         7 . The propellant of  claim 1 , wherein a weight ratio of rounded ammonium perchlorate particles to nonrounded ammonium perchlorate particles is from about 40/60 to about 60/40, respectively.  
     
     
         8 . The propellant of  claim 1 , wherein the metal particles are aluminum particles that have a weight mean diameter of from about 3 μm to about 10 μm.  
     
     
         9 . The propellant of  claim 8 , wherein the aluminum particles comprise from about 10 percent to about 20 percent of a total weight of the propellant.  
     
     
         10 . The propellant of  claim 1 , wherein the iron oxide comprises from about 0.5 percent to about 3 percent of a total weight of the propellant.  
     
     
         11 . The propellant of  claim 1 , further comprising at least one of a bonding agent, a curing catalyst, a plasticizer, antioxidant/peroxide scavengers, and a pot life extender.  
     
     
         12 . The propellant of  claim 11 , wherein the bonding agent is a reaction product of tetraethylenepentamine, acrylonitrile, and glycidol.  
     
     
         13 . The propellant of  claim 11 , wherein the binder is a polyurethane and wherein the curing catalyst is selected from the group consisting of triphenyl bismuth, dibutyltin dilaurate, and mixtures thereof.  
     
     
         14 . The propellant of  claim 11 , wherein the plasticizer comprises dioctyl sebacate, dioctyl adipate, isodecyl perlargonate, dioctyl phthalate, or mixtures thereof.  
     
     
         15 . The propellant of  claim 11 , wherein the antioxidant comprises 2,2-methylene-bis-(4-methyl-tert-butylphenol).  
     
     
         16 . The propellant of  claim 11 , wherein the pot life extender is maleic anhydride.  
     
     
         17 . The propellant of  claim 1 , wherein the propellant comprises from about 7 weight percent to about 15 weight percent of the binder, from about 0.1 weight percent to about 0.4 weight percent of an antioxidant, from about 0.005 weight percent to about 0.2 weight percent of a peroxide scavenger, from about 0.01 weight percent to about 0.25 weight percent of a curing catalyst, from about 0.05 weight percent to about 0.15 weight percent of a bonding agent, from about 2.5 weight percent to about 4 weight percent of a plasticizer, from about 0.01 weight percent to about 1 weight percent of a pot life extender, from about 10 weight percent to about 20 weight percent of aluminum, from about 0.5 weight percent to about 3 weight percent of iron oxide, from about 65 weight percent to about 75 weight percent of ammonium perchlorate, and from about 0.5 weight percent to about 5 weight percent of a multifunctional isocyanate curing agent.  
     
     
         18 . The propellant of  claim 1 , wherein the propellant comprises about 8.503 weight percent of hydroxy-terminated polybutadiene, about 0.13 weight percent of 2,2-methylene-bis-(4-methyl-tert-butylphenol), about 0.13 weight percent of trinonylphenyl phosphite, about 0.015 weight percent of triphenyl bismuth, about 0.1 weight percent of a reaction product of tetraethylenepentamine, acrylonitrile, and glycidol, about 3.47 weight percent of dioctylsebacate, about 14.0 weight percent of aluminum, about 0.03 weight percent of maleic anhydride, about 2.0 weight percent of red iron oxide, about 46.15 weight percent of 90 μm aluminum perchlorate, about 24.85 weight percent of 10 μm aluminum perchlorate, and about 0.622 weight percent of isophorone diisocyanate.  
     
     
         19 . The propellant of  claim 1 , wherein the ammonium perchlorate particles comprise from about 65 percent to about 95 percent of the weight of the propellant.  
     
     
         20 . A rocket motor comprising a rocket motor casing and a propellant in contact with the rocket motor casing, wherein the propellant comprises: 
 a binder;    ammonium perchlorate particles;    metal particles; and    iron oxide,    wherein the ammonium perchlorate particles are in a form of a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.    
     
     
         21 . A ballistic trajectory munition comprising a projectile having a rocket motor attached thereto, the rocket motor including a propellant in contact with a rocket motor casing, wherein the propellant comprises: 
 a binder;    ammonium perchlorate particles;    metal particles; and    iron oxide,    wherein the ammonium perchlorate particles are in a form of a multimodal mixture of rounded particles having a weight mean diameter of from about 70 μm to about 110 μm and of nonrounded particles having a weight mean diameter of from about 7.5 μm to about 15 μm.