JPS609999B2 - smokeless composite propellant - Google Patents

Description

Detailed Description of the Invention The present invention is a smokeless composite propellant that sustains stable combustion at a relatively low combustion rate under a wide range of pressures, and does not generate excessive smoke, solid particles, corrosive gases, etc. Regarding.

Smokeless composite propellants conventionally used include ammonium nitrate or nitrate, which is also used in part in the composite propellant according to the present invention, as an oxidizing agent. Tetramethylenetetranitramine (commonly known as octogen or HMX; hereinafter referred to as HMX) was used alone or as a mixture of the two. However, although ammonium nitrate undergoes various processes, it is ultimately converted into Cape N.

Approximately 20% of the total amount is used as an oxidizing agent in the combustion reaction, and this decomposition is endothermic. Therefore, when ammonium nitrate is used as an oxidizing agent, the combustion stability of the propellant is insufficient, and the combustion rate and combustion gas temperature are also low.

To compensate for this, there is a method of adding a large amount of catalyst to accelerate the decomposition of ammonium nitrate and activate the combustion reaction, and ammonium dichromate is currently the most commonly used catalyst. Ammonium acid produces solid particles such as chromium oxide in its combustion products, which has the disadvantage of impeding the smokeless properties of the propellant.

In addition, in the above-mentioned HMX, although various processes go through 0, the final change is (CH2・N・N02)4→4CO+
It decomposes like 2014N2 on the 4th.

In other words, HMX only contains the minimum amount of oxygen necessary for its own decomposition, but does not contain enough oxygen to oxidize other substances, so although it is not an oxidizer in the true sense of the word, it is still a fuel and binder. Compared to synthetic rubbers used in agents, it has a high oxygen content and has properties similar to those of oxidizing agents. Since the decomposition of HMX is carried out exothermically, a large amount of energy is generated, which has the advantage of significantly contributing to improving the performance of the propellant. However, there is a drawback that the fuel/binder such as synthetic rubber or synthetic resin is decomposed due to the heat generated by the decomposition, and a large amount of soot is generated at that time, impairing the dust-free property.
Unlike these conventional oxidizing agents, the present invention uses ammonium nitrate and cyclotrimethylene trinitramine (commonly known as hexogen, cyclonite or RDX).

Hereinafter, it will be abbreviated as RDX. ) is used. RDX has almost the same chemical structure as HMX, as shown in the molecular formula below, and both were originally used as high-performance explosives.

They are also similar in that decomposition generates a large amount of energy, which can improve the performance of the propellant.

However, when HMX is heated to about 360 qo, it begins to decompose exothermically, first generating nitrogen oxide and aldehydes.
While RDX leads to the final product with further heat generation,
Almost the same reaction occurs with HMX, but the difference is that the decomposition starts at about 24,000 ℃, which is significantly lower than that of HMX.
The important point here is that the temperature at which RDX decomposes exothermically (approximately 240°C) is approximately the same as the temperature at which ammonium nitrate, which is used in combination with RDX in the present invention, begins to decompose endothermically and generates oxygen. Therefore, in a propellant that uses this mixture as an oxidizing agent, the endothermic decomposition reaction of ammonium nitrate is thermally compensated by the exothermic decomposition reaction of RDX, which takes place at approximately the same temperature, so the entire system is maintained stably. The result is that the combustion reaction is significantly stabilized compared to when ammonium nitrate RDX is used alone. The present invention was completed as a result of research focusing on the fact that ammonium nitrate and RDX undergo an endothermic decomposition reaction and the latter exothermically decompose at approximately the same temperature.

At this time, HMK, which has traditionally been used as an oxidizing agent in place of RDX, has a large difference in decomposition initiation temperature even though its chemical structure and decomposition reaction process are very similar, so ammonium nitrate and HMX decomposition occurs independently at different temperatures, and there is no thermal compensation as seen in the present invention, and as a result, no contribution to stabilizing combustion is recognized. Hereinafter, the present invention and the effects achieved by the present invention will be specifically explained based on Examples.

Example Ammonium nitrate undergoes crystal transformation accompanied by volume changes several times from around room temperature until it starts to decompose. In order to apply it to a practical propellant, synthetic rubber, which exhibits excellent rubber elasticity, must be used as a fuel and binder. You need to choose.

In this example, polyj-urethane or polybutadiene synthetic rubber was selected as the fuel and binder, and propellants having the compositions shown in Table 1 were obtained. Composition numbers 1 and 2 are propellants according to the present invention, 3 and 4
, 5 are comparative examples. Regarding the above in Table 1, RDX has traditionally been more stable than HMX.
Although it was said that there was a problem in terms of safety, composition number 1
No significant difference was observed in the drop hammer sensitivity test values between propellants No. 2 and No. 3, and it became clear that both were sufficiently safe.

Next, the performance of the propellant is shown in Table 2.

As shown in the upper table of Table 2, the propellants according to the present invention containing 20% by weight of RDX all continue to burn stably at 0.1 MPa or less, while the propellant No. 3 containing HMX continues to burn stably at 0.1 MPa or less. ．． In the case of propellants below Betsu Naka A, and propellants containing neither RDX nor HMX, such as Nos. 4 and 5, the stable combustion pressure was below IMPa, and combustion was unstable and often caused extinction.

In addition, the fuel velocity is determined by the propellant of the present invention containing RDX or HM
For propellant number 3 containing X, 2.6 to 2.7 at 7 MPa
willow per second, whereas propellants Nos. 4 and 5, which do not contain these and use ammonium nitrate as an oxidizing agent, have a rate of 2 per second under the same conditions.
．． The difference was less than 0, and a remarkable difference was observed between the two.

Furthermore, in terms of smokelessness, if only ammonium nitrate is used, it is necessary to add ammonium dichromate or the like to stabilize combustion, but this will generate a small amount of smoke.

In contrast, the product of the present invention was almost smokeless. As described above, the product of the present invention sufficiently ensures the characteristics that this type of propellant should have, and the combination of ammonium nitrate and RDX as oxidizing agents is extremely useful.

Claims (1)

[Claims] 1. A smokeless composite propellant that uses synthetic rubber or synthetic resin as a fuel and binder, and is characterized in that it contains a mixture of ammonium nitrate and cyclotrimethylene trinitramine as an oxidizing agent.