RU2466118C2 - Method of producing finely dispersed ammonium perchlorate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to grinding solid materials, including ammonium perchlorate, to obtain particles with size from 80 nm to 500 nm, used in production of composite solid propellant. Disclosed is a method of producing finely dispersed ammonium perchlorate with particle size from 80 nm to 500 nm for composite solid propellant. The method involves obtaining a dispersion of ammonium perchlorate, grinding the suspension for 1 hour in the presence of grinding elements. The method is characterised by that the ammonium perchlorate is ground in a medium of butyl rubber with viscosity 1600…3000 P, with ratio of ammonium perchlorate to butyl rubber equal to 70:30.

EFFECT: high rate of combustion of ammonium perchlorate-based fuel.

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Description

The invention relates to the field of grinding solid materials, including ammonium perchlorate, to obtain particles with a size of from 80 nm to 0.5 μm, used in the manufacture of mixed solid rocket fuel.

A known method for producing highly dispersed PHA, including preparing a coating solution in a liquid carrier by dissolving leticin in trifluorotrichloroethane or methylene chloride, preparing PCA suspensions from PHA and preparing a coating solution in a liquid carrier, grinding the suspension in the presence of glass beads in two parallel bead mills for from 1 to 10 hours to obtain a PHA with a particle size of from 2.0 to 1.0 μm with a single load of leticin and for 8 to 16 hours to a particle size of PHA from 1.0 to 0.55 μm p and entering lecithin stepwise every 2 chasa grinding and drying [1].

The disadvantages of this method is the insufficient degree of grinding (0.55 ... 1.0 μm) and a long grinding time (up to 16 hours).

The closest in technical essence to the claimed invention (which the authors adopted as a prototype) is a method for producing PCA for CPTT, including: preparing a coating solution in a liquid carrier by dissolving lecithin in trifluorotrichloroethane or in methylene chloride, preparing a suspension of PCA from PCA and the resulting coating solution in liquid carrier, grinding the suspension in the presence of glass beads in a bead mill and drying [2]. The disadvantage of this method is the low quality of surface preparation and the particle size of the useful component of the material for their subsequent effective use in SRTT.

The technical results to which the claimed invention is directed is to increase the efficiency of the method for producing crushed PHA by increasing the burning rate of fuels based on PHA.

The technical result is achieved by the fact that in the method for producing highly dispersed PHA, including obtaining a dispersion of PHA, the formation of a suspension by mixing with a liquid medium, its grinding in the presence of grinding elements. The claimed method differs from the method disclosed in [2] in that butyl rubber with a viscosity of 1600 ... 3000 P is used as a liquid medium, mixing is carried out in the ratio of PHA: butyl rubber = 70: 30, the resulting suspension is crushed for 1 hour, followed by separation from grinding PCA particles with a size of 80 ... 500 nm.

An example of the method.

For grinding PHA, a ball mill with a volume of 2 l was used with a rotation frequency of 42 rpm. Glass balls with a diameter of 10 ... 20 mm with a total mass of 0.5 kP were used as grinding elements. A portion of a suspension of 70 g (70: 30 = PHA: BC). The liquid medium is butyl rubber (BK).

The grinding of material in a ball mill is as follows. Intensive abrasion of material particles against each other occurs in the working case by forced displacement of concentric layers of material in oncoming flows and destruction under conditions of volumetric compression of the material between the balls. Particles of the material undergo intensive mechanical deformations before their destruction, which intensifies the process of their destruction. When the crystals are destroyed, BK particles are enveloped, as if the crystalline phase is diluted. Envelopment of PCA particles with butyl rubber on the one hand contributes to the destruction process, since the butyl rubber molecules have a proppant effect on microcracks formed in deformable particles of the material - the effect of P. A. Rebinder. On the other hand, it prevents direct contact between PCA particles and their agglomeration without a layer of BK. The resulting material has a complex physical structure consisting of a crystalline phase (PCA) - an amorphous phase (BC) and a combined phase PHAcrystal - BK - PHAamorph - BK.

The components are weighed on a technical scale with an accuracy of 0.01 g. The fuel components are placed in a porcelain cup and manually mixed with an aluminum spatula until a homogeneous mass is obtained. The fuel mass is loaded into a ball mill, closed with a lid and the mill is turned on. At the end of the operating time, the mill is turned off and the mass with balls is unloaded on a grate installed above the porcelain cup to separate the mass from the balls.

For the manufacture of charges from the manufactured mass, the fuel mass is loaded into the mold channels by gravity. Then the mold is placed in a vacuum cabinet and vacuum for 1 hour at a residual pressure of 20 mm RT.article.

The top cover is closed and the mold is placed in an oven and thermostated for 70 hours at a temperature of 80 ° C for curing. Cured charges are pushed out of the mold.

Tests for determining the burning rate were carried out in a constant pressure device at a pressure of 70 kg / cm ² by the values of the charge burning time between two blown wires, one of which includes an electronic stopwatch, and the other turns off.

The test results are shown in table 1. As can be seen from the above data, in table 1, the optimal time for grinding is 1 hour. When grinding particles of PHA for 1 hour, the particle size of PHA reaches its minimum (80 ... 422 nm).

The burning rate of charges containing PCA with these particle sizes reaches a maximum.

The proposed method can significantly increase the burning rate of fuels. The method is simple and allows the use of industrial equipment.

Information sources

1. RF patent No. 2310635. A method of obtaining crushed ammonium perchlorate.

2. RF patent №2246472. A method of producing ammonium perchlorate.

Claims (1)

A method of producing finely dispersed ammonium perchlorate (PHA) with a particle size of from 80 to 500 nm for mixed solid rocket fuel, including obtaining a dispersion of PHA, grinding the suspension for 1 h in the presence of grinding elements, characterized in that the grinding of the PHA is carried out in butyl rubber (BC) ) with a viscosity of 1600 ... 3000 P with a ratio of PHA and BC equal to 70:30.