JPH01282182A - Composite propellant - Google Patents

Abstract

PURPOSE:To obtain a composite propellant wherein combustion efficiency is high and specific impulse is improved by incorporating both metallic powder having large calorific value and alkali metallic compd. of fluorine and specifying the rate of this incorporated compd. for the whole quantity. CONSTITUTION:The above-mentioned composite propellant is constituted by incorporating both metallic powder which consists of one or more kinds selected from among Al, B and Li, etc., and has preferably 0.1-50mum mean particle diameter and large calorific value and alkali metallic compd. of fluorine (e.g, LiF, NaF) as a main component. The ratio of the above-mentioned metallic powder incorporated in the propellant is preferably regulated to 5-20wt.%. Further the rate of the rate of the alkali metallic compd. of fluorine incorporated in the propellant is regulated to 0.5-5wt.%. Furthermore NH4NO3 is preferably utilized is an oxidizer utilized for the above-mentioned propellant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to composite propellants. Specifically, the present invention relates to a composite propellant that has high combustion efficiency and improved specific impulse by using a specific metal powder and a specific inorganic fluorine compound in combination.

(Prior art) Composite propellants are mainly composed of an oxidizing agent and a binder that serves as a fuel and binder. Usually, high calorific value metal powder is added as a combustion improver to improve combustion performance. Due to its excellent combustion and physical properties, it is widely used as a propellant for high-performance rocket motors.

The softening agents used in conventional composite propellants are
Perchlorates such as ammonium perchlorate (AP), nitrates such as ammonium nitrate, cyclotrimethylene trinitramine (RDX).

There are nitramines such as cyclotetramethylenetetranitramine (HMX), and synthetic rubbers such as polysulfide, polyester, polyurethane, and polybutadiene are used as binders, and hydroxyl-terminated polybutadiene (HTPB) or Polytutacine-based hinters such as polytutadiene with a terminal carboxyl group are used.

Also, as a combustion aid, a composite propellant using a combination of aluminum powder and metallic lithium powder is used.
This is proposed in Publication No. 489.

On the other hand, AP80% by weight, HTPB20! Lithium fluoride (LiF) was added to 100 parts by weight of a propellant consisting of i amount%.
A research report examining the combustion interruption mechanism by adding 1.0 and 2.0 parts by weight of 5.1.0 and 2.0 parts by weight ("Journal of the Industrial Explosives Association J, Vo 1.4
2. No. 6° 1981) is also known.

(Problem to be solved by the invention) In the composite propellant disclosed in the above-mentioned publication,
Since the metal powder used has an oxide film formed on its surface, there is a problem that it is not completely combusted due to the diffusion fire formed from the oxidizing agent decomposition product and the binder decomposition product.

That is, the improvement in specific impulse was still insufficient.

In particular, in the case of composite propellants that use ammonium nitrate as the oxidizing agent, the combustion temperature is low, so there is a problem that the combustibility (combustion completion) of the metal powder in the J (m propellant) decreases, and the specific impulse decreases. there were.

On the other hand, in the case of the above report, it was concluded that adding LiF to a propellant mixture of HTPB and AP lowers the combustion rate and that combustion interruption pressure exists. This report has no description or suggestion of the combined use of LiF and metal.

The purpose of the present invention is to increase the combustion efficiency of a metal powder by using a fluorine compound and using it in combination with a specific metal powder, although it has been conventionally believed that the addition of a fluorine compound lowers the combustion performance. The object of the present invention is to provide a composite propellant in which the specific impulse of the propellant is increased thereby.

(Means for Solving the Problems) The present invention provides a composite propellant comprising a high calorific value metal powder and an alkali metal compound of fluorine and fluorine, the proportion of the compound being 0.5 to 5% by weight in the composite propellant. It's medicine.

The high calorific value metal powder used in the present invention is aluminum,
One or two selected from the group consisting of boron, lithium, and magnalium (aluminum and magnesium alloy)
The size of the metal powder, which is a powder of a mixture of two or more species, is preferably 0.1 to 50 JLm in average particle size.If the particle size is less than 0゜IJLm, the productivity of the propellant will decrease. However, if the length exceeds 50 meters, the combustibility tends to decrease.

The proportion of these metal powders in the propellant is preferably 5 to 20% by weight. If it is less than 5% by weight or more than 20% by weight, the specific impulse tends to decrease.

Further, in the present invention, examples of the fluorine alkali metal compound used in combination with the metal powder include LiF, sodium fluoride (NaF), and the like. This compound is a commercially available product that has been pulverized and passed through a 200-mesh sieve, for example.

The proportion of this compound in the propellant is 0.5-5% by weight. If it is less than 0.5% by weight, the combustion reaction promoting effect of the metal powder will be reduced, and if it exceeds 5% by weight, the specific impulse of the propellant will be reduced.

The oxidizing agent used in the present invention can be any of the oxidizing agents conventionally used in composite propellants, such as perchlorine resistant salts such as ammonium perchlorate, nitrates such as ammonium nitrate, RDX, HMX, etc. Nitramine, etc.

In the present invention, when a high calorific value metal powder and a fluorine compound are used together, ammonium nitrate is an oxidizing agent that is particularly effective in terms of complete combustion of the metal powder.

As the binder used in the present invention, all binders conventionally used in composite propellants can be used, and particularly preferable binders from the viewpoint of combustion characteristics are HTPB,
These include CTPB and aliphatic polyethers with terminal hydroxyl groups.

The binder usually includes isophorone diisocyanate (IPDI), hexamethylene diisocyanate (H
A curing agent such as MDI) is used, and if necessary, dioctyl adipate (DOA).

Plasticizers such as dioctyl sebacate (DO3) are also used.

Additionally, tris(2methylaziridinyl)phosphine oxide (MAPO) is used to improve the adhesion between the oxidizing agent and the binder.

2 moles of MAPO, 0.7 moles of adipic acid, and 0.3 moles of tartaric acid.
The reaction product (MT-4) with Mol, ? A binder such as -'suisophthaloyl-1-(2-methyl)aziridine (HX-752, manufactured by 3M) may also be used as necessary.

Furthermore, anti-aging agents and combustion catalysts such as iron oxide, ferrocene derivatives, and carborane derivatives can also be used as required.

The proportions of each component of the composite propellant of the present invention are typically:
The oxidizing agent is 65 to 85% by weight, the binder is 10 to 15% by weight, the high calorific value metal powder is 5 to 20% by weight, and the alkali metal compound of fluorine is 0.5 to 5% by weight.

The composite propellant of the present invention is similar to the conventional composite 4
[It can be manufactured by a method similar to that of Ishinyaku.

(Effects of the Invention) By using a specific metal powder and a specific inorganic fluorine compound together, the composite propellant of the present invention is more effective than the conventional case where metal powder covered with an oxide film is used. ,
The metal has excellent combustion completion properties, and is therefore characterized by greatly improved combustion characteristics, especially specific impulse.

In addition, when ammonium nitrate was used as an oxidizing agent, conventionally there was a problem in the complete combustion of metal powder due to its combustion temperature and the coating film on the metal surface, but in the present invention, a specific fluorine compound is used in combination. It is also unique in that it has significantly improved specific impulse.

(Example) The present invention will be specifically explained below using examples.

Example: 14.66 parts by weight of hydroxyl-terminated polybutadiene (HTPB, rR-45MJ manufactured by Alco Chemical Co., Ltd.), 3.94 parts by weight of dioctyl adipate (DOA) as a plasticizer, and tris(2-methylaziridine) as a binder. 0.22 parts by weight of Ruid (rMAPOJ manufactured by Alcinco) and 0.50 parts by weight of lithium fluoride were added and mixed,
Next, 14.93 parts by weight of aluminum having an average particle size of 87 zm was added to the mixture as a combustion improver and mixed for 20 minutes to obtain a paste-like mixture. Next, a curing agent, influorone diisocyanate-1- (IPDI), was added to this mixture.
1.08 parts by weight was added and vacuum mixed for 10 minutes. Next, 64.67 parts by weight of ammonium nitrate as an oxidizing agent was charged, heated to 60°C, and vacuum mixed for 30 minutes to obtain a slurry-like mixture. This mixture was poured into a predetermined molding container under vacuum, and after degassing, it was cured at 60° C. for 7 days to obtain a composite propellant of the present invention.

A combustion test was conducted using this propellant using the method shown below.

That is, the diameter is 80 mm and the inner diameter is 40 ma+. length 140
A cylindrical propellant with a diameter of mm was prepared, and the outer peripheral side surface thereof was coated with an epoxy resin to prepare a drug substance.

This drug substance was loaded into a standard rocket motor chamber with an inner diameter of 84 mm, the nozzle throat diameter was adjusted so that the combustion pressure was 50 Kgf/am2, and a combustion test was conducted using a normal small rocket motor combustion stand device. The specific impulse of the propellant was measured. Note that the aperture ratio of the nozzle used in this test was 6.

The specific impulse of the propellant obtained is shown in the table together with the specific impulse calculated using the usual calculation method.

Comparative Example 1 A composite propellant was obtained in the same manner as in Example 1, except that lithium fluoride was not added.

The same combustion test as in Example 1 was conducted using this propellant.

The specific impulse of the propellant obtained is shown in the table together with the theoretical specific impulse.

Examples 2 to 10 and Comparative Examples 2 to 5 Composite propellants were manufactured in the same manner as in Example 1 using composite shift propellants having the compositions shown in the table.

The same combustion test as in Example 1 was conducted for each propellant.

The specific impulses of the obtained propellants are shown in the table together with the theoretical specific impulses.

Claims (4)

[Claims] (1) Contains a high calorific value metal powder and an alkali metal compound of fluorine, and the proportion of the compound is 0.5 in the composite propellant.
A composite propellant characterized in that it is ~5% by weight. (2) The high calorific value metal powder is one or two selected from the group consisting of aluminum, boron, lithium, and magnalium.
A composite propellant according to claim 1, which is a mixture of more than one species. (3) The composite propellant according to claim 2, wherein the proportion of the high calorific value metal powder in the composite propellant is 5 to 20% by weight. (4) The composite propellant according to claim 2, wherein the oxidizing agent is a nitrate.