Explosive and thermic compositions or charges – Containing free boron or binary compounds of boron or boranes
Reexamination Certificate
2001-10-17
2003-11-25
Carone, Michael J. (Department: 3641)
Explosive and thermic compositions or charges
Containing free boron or binary compounds of boron or boranes
C149S045000, C149S046000, C149S061000
Reexamination Certificate
active
06652682
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the field of propellant compositions and more particularly to propellants or fuel compositions containing boron particle solids which are less than about 500 nanometers in size and in concentrations ranging from about two percent to about forty-six percent by weight.
2. Brief Description of the Prior Art
Propellant compositions typically comprise an oxidizer, a fuel, a binder, a gelling agent, or a variety of other additives depending upon whether the propellant formulation is in a solid, liquid, or a gel form. While many chemicals have been used as fuels in propellant compositions, many metals have been preferred as fuels, particularly for solid propellant formulations, because metals can be used to increase the burning rate and the specific impulse of propellant formulations. Propellant compositions containing metals such as aluminum, boron, magnesium, and titanium have been designed, however, the majority of these types of propellant compositions used for rocket and missile propulsion use aluminum as a fuel. This is because of the low cost of aluminum and because aluminum tends to ignite and bum more easily than other ingredients. However, there are several problems with using aluminum in propellant compositions including the relatively low specific impulse generated by aluminum as well as potential environmental problems associated with aluminum compounds. In addition, the aluminum has a tendency to interfere with guidance controls of some missile and rocket systems. Also, aluminum is likely not stable in compositions containing water because aluminum has a tendency to react with water.
In order to address some of these potential problems associated with using aluminum as a fuel in propellant compositions as noted above and increase the efficiency of aluminum based propellants, researchers have begun to analyze the viability of incorporating nanotechnology to increase the burning rate associated with aluminum powder in current propellants. French and German scientists have begun testing nano-sized aluminum particles, on the order of 50 to 200 nanometers in diameter, in current propellant formulations and have made initial determinations indicating that under laboratory conditions, such nano-sized aluminum particles increase the burning rate and combustion characteristics of current propellant formulations. However, increasing the burning rate will not alleviate the potential for guidance system interference.
As noted above, propellant formulations containing boron have been developed that may address some of the limitations associated with propellant formulations containing aluminum. For instance, U.S. Pat. Nos. 3,354,172; 4,141,768; 5,074,938; and 5,837,930 all disclose propellant formulations that contain or may contain boron as a fuel. This is due to the fact that boron has a low molecular weight and a high energy of combustion, making it an attractive fuel for propellant formulations. However, due to a thin layer of boron oxide that forms on the particle surface that hinders combustion, ignition is difficult, making such compositions unrealistic for uses that require high precision and dependability such as for military applications.
Based upon the above, it would be desirable to provide a propellant composition that comprises nano-sized boron particles in order to address the ignition problems associated with boron and increase the specific impulse and combustion characteristics of current propellant formulations without interfering with missile or rocket guidance systems.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a propellant composition comprising nano-sized boron particles.
It is a further object of this invention to provide a solid propellant composition comprising nano-sized boron particles.
It is yet a further object of this invention to provide liquid or gel propellant compositions comprising nano-sized boron particles.
This invention accomplishes these objectives and other needs related to propellant compositions by providing a propellant formulation comprising from about 2 percent to about 46 percent, by weight, boron particles having a diameter of less than about 500 nanometers. In more preferred embodiments of the invention, the diameter of the boron particles will be less than about 150 nanometers; and a still more preferred embodiment of the invention, the boron particle diameter will be less than about 50 nanometers. Liquid or gel embodiments of the invention may also include adding the boron particles to a liquid fuel in order to form a liquid fuel system. Examples of such liquid fuels include ethyl ammonium nitrate (EAN), triethyl amine nitrate (TEAN), Cyclotetramethylenetetranitramine (HMX), trinitrotoluene (TNT), jet fuel formula (JP-10), kerosene, RJ-4, or other hydrocarbon based fuels. These liquid fuel systems can be part of bipropellants wherein the liquid fuel system is stored separately from an oxidizing agent and the two are mixed during operation. Examples of oxidizing agents may include nitrogen tetroxide, oxygen, hydrogen peroxide, hydroxyl ammonium perchlorate (HAP), hydoxyl ammonium nitrate (HAN), ammonium perchlorate, ammonium nitrate, ammonium dinitramide (ADN), or a combination of said chemicals. One specific preferred embodiment of the invention comprises a fuel comprising approximately 61.60 percent by weight EAN, approximately 23 percent by weight boron particles having a diameter of less than about 500 nanometers, approximately 3.85 percent by weight ammonium nitrate, and approximately 11.55 percent by weight water coupled with an oxidizing agent comprising approximately 38 percent by weight hydrogen peroxide, approximately 46 percent by weight ammonium nitrate, and approximately 16 percent by weight water. The present invention also comprises a monopropellant formed by adding the nano-sized boron particles to a fuel containing oxygen. Another embodiment of the invention is a solid propellant wherein the nano-sized boron particles are used as a metal fuel component or as a portion of a metal fuel component and are mixed with an oxidizing agent and bound with a binder.
DESCRIPTION OF THE PREFERRED EMBODIMENT
There are some fundamental differences associated with using fuels containing nano-sized particles within propellants versus standard sized fuel powders. For nano-sized particles, the combustion process is largely kinetically controlled rather than diffusion controlled as in standard sized powders. This difference in kinetic rates between nanoparticles and bulk material can greatly increase reaction rates. Therefore, by using nano-sized particles within propellants, one can arrive at high combustion efficiency and, thereby, increase the thrust produced by the propellant using the same actual weight of propellant.
As mentioned above, ignition problems have resulted in limited use of boron as a fuel in propellants, even though it has a high heat of oxidation, on the order of 140 kJ/cm
3
. However, the unique features of nanoparticle boron, boron particles having a diameter of less than about 500 nanometers, allows one to overcome this problem as well as producing many other physical characteristics that are beneficial for use in propellants. Nanoparticle boron overcomes the ignition problem by creating much greater surface areas for ignition (up to the order of 50 m
2
/g). Other unique features of nano-sized boron particles that make them ideal for use in propellants are: short burning times (as low as microseconds); possibility for storing excess amounts of energy; controlled ignition with special passivation materials; enhanced amount of energy released by catalytic reactions; particle size dependent reaction rates; ability to serve as gelling agents for gelled propellants; e
Dunn Timothy J.
Elstrodt Douglas
Fawls Christopher J.
Fields Joel P.
Hudson Michael L.
Carone Michael J.
Felton Aileen B.
Homer Mark
The United States of America as represented by the Secretary of
LandOfFree
Propellant composition comprising nano-sized boron particles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Propellant composition comprising nano-sized boron particles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Propellant composition comprising nano-sized boron particles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3180868