RU2344989C2 - Aluminium powdered material and method of obtaining thereof - Google Patents

Abstract

FIELD: metallurgy industry.

SUBSTANCE: inventions are used in pyrotechnics, chemistry, and power engineering for producing hydraulic reaction mixtures interacting with water thus releasing heat and hydrogen, or as metallic fuel in explosive compounds and mixed grains. Powdered material made from aluminium or its alloy is characterised by available gallium-containing interlayers between polycrystal material particles, at the following powder component ratio, wt %: aluminium or its alloy - 90-99, gallium - 0.2-6.0, indium and stannum - the rest. Method of obtaining powdered material consists in the fact that first there performed is embrittlement of aluminium or its alloy and destruction of its polycrystal structure by means of grain-boundary alloying with molten indium-gallium- stannum, and then powder is broken, and crushed to small pieces, and classified according to particle sizes.

EFFECT: reducing energy consumption required for the process, and improving capacity.

2 cl, 3 dwg, 2 ex

Description

The invention relates to the field of powder metallurgy, in particular to compositions and methods for producing powdered activated aluminum used in pyrotechnics, chemistry, and energy to produce hydroreactive mixtures that interact with water to produce heat and hydrogen, or as metal fuel in explosive and mixed formulations gunpowder.

Famous brands of aluminum powders of various shapes and sizes are obtained in a variety of ways:

- by spraying a molten metal with compressed gas followed by classification of the spray product, RF patent No. 2026157, 6 IPC B22F 9/08;

- by electric explosion of aluminum wire in a nitrogen gas atmosphere, RF patent No. 2112629, 6 IPC B22F 9/14;

- by means of electrospark dispersion of aluminum in a dielectric medium, which is used as hydroxycarboxylic and dicarboxylic acids, USSR author's certificate No. 1548950 7 IPC B22F 9/14;

- by means of dry mechanical grinding of an aluminum billet in an inert gas atmosphere in the presence of fat additives, which are products obtained from oil refining, RF patent No. 2108534, 6 IPC F42B 4/00, F42B 4/30;

- by spraying the melt with an inert gas heated to 300-400 ° C, with a melt temperature of 880 ° C, further cooling with an inert gas, RF patent No. 2081733, 6 IPC B22F 9/08, C22C 1/14;

- by obtaining a hydroreacting mixture comprising aluminum powder and nickel-doped magnesium powder, RF patent No. 2131841, 6 IPC C01B 3/08, C01B 6/24.

The disadvantages of the known methods are the high energy intensity of the smelting and spray redistribution and their limited applicability - only to certain types of aluminum billets (wire, shavings, powder).

A disadvantage of the known grades of aluminum powders is the presence on the surface of the particles of a dense and durable oxide film. In addition, the particles of these powders are a compact monolithic material. These circumstances make it difficult to use powders as components of hydroreactive or explosive compositions.

The technical solution protected by RF patent No. 2131841 from 09/18/97, taking into account the scope of its application, is the closest analogue of the invention. This decision was made as a prototype.

RF patent No. 2131841 protected "Hydroreacting mixture" used as a hydroreacting composition, consisting of a mixture of nickel alloyed aluminum and magnesium powders.

A disadvantage of the known mixture is the need to use as an activating additive a significant amount of doped magnesium powder, which reduces the energy yield of the material.

The technical task of the invention is to obtain aluminum powder with increased activity against gaseous and liquid oxidizing agents, in particular oxygen, water and aqueous solutions, suspensions and emulsions.

The problem is solved by implementing the method described below. The resulting aluminum powder by chemical composition is a pseudo-alloy based on aluminum (or its alloys) with gallium (0.2-6% by weight) and alloying components (0.1-3.0% by weight).

The particle shape according to GOST 25849-83 and size according to GOST 23403-78 depend on the processing mode and can be adjusted in shape from spherical to lamellar, in size - from fractions of microns to 1-2 mm (figure 1). By structure, each particle consists of crystals (aluminum or its alloy) and a clad layer in the form of gallium-containing nanofilms based on an aluminum-gallium alloy of variable composition. In this case, the polycrystalline particle is mechanically activated and the crystals are separated by gallium-containing nanofilms (interlayers). The surface of the cladding layer is covered with a loose nanofilm of aluminum oxide (figure 2). X-ray diffraction analysis of an individual powder particle (figure 3) shows the presence of aluminum, gallium, oxygen. The presence of oxygen indicates a minimal presence of alumina.

The amount of gallium required for the impregnation of aluminum and its alloys is determined by the size of the crystals of the initial rolled metal. The smaller the crystals of the starting material (for example, an aluminum alloy sheet), the larger their total surface and, consequently, the consumption of gallium increases.

The inventive aluminum powder material from polycrystalline particles of aluminum or its alloys is characterized by the presence of gallium-containing interlayers between polycrystalline particles, while the surface of the particles has a clad layer of an alumina nanofilm in the following ratio of components in the powder, mass,%:

 aluminum or its alloy  90 ÷ 99;  gallium  0.2 ÷ 6.0;  indium tin  rest.

No analogues having similar features with the claimed technical solution were found, therefore, we can assume that the claimed invention is new and has a sufficient inventive step.

Each of the above features of the claimed invention is necessary, and their combination is sufficient to achieve novelty in the quality of the material obtained.

The closest solution to the claimed method according to the technical nature and the achieved result is a method for producing a powder by fusing aluminum with magnesium or zinc and then removing them by leaching or evaporation. "Sintered Materials from Aluminum Powders", ed. V.G. Gopienko, I.E. Smagorinsky, A.A. Grigoriev, A.D. Belavin, M. Metallurgy, 1993, p. 31.

This technical solution was made as a prototype. As indicated above, the main disadvantages of this method are its high energy intensity (fusion, evaporation), low process safety and low productivity in the chemical leaching of alloying components.

The technical task of the invention is to increase the technical and economic indicators of the process of obtaining aluminum powder, i.e. decrease in energy intensity, increase in productivity by embrittlement of aluminum and destruction of its crystalline structure by means of grain-boundary doping with gallium.

The problem is solved in that the proposed method for producing aluminum powder includes alloying (impregnation) of compact polycrystalline aluminum with gallium or its alloys, mechanical crushing, grinding and size classification. The use of gallium or its alloys allows alloying (impregnation) of pieces of aluminum at a temperature of 10-30 ° C, and the embrittling effect of gallium allows mechanical grinding, grinding-dispersing of large pieces of aluminum.

Analogues having a combination of features similar to the claimed technical solution were not found, therefore, we can say that the claimed invention is new and has a sufficient inventive step.

Each of the above features of the claimed invention is necessary, and their combination is sufficient to achieve the novelty of the quality of the new super-effect, which is not inherent in the signs of their disunity.

Based on theoretical and experimental studies, examples of specific implementation of the proposed method for producing aluminum powder are presented:

Example 1

Aluminum plates of grades A5 and A7 with a thickness of 3 mm and a weight of 100 g in a box filled with argon are coated with a 7.3 g indium-gallium-tin eutectic melt by mechanical rubbing. This technology uses a eutectic melt of an indium-gallium-tin mixture in a ratio of 25:62:13 by weight. This mixture has a melting point of ≈5 ° C, which is convenient in the technology of rubbing plates at room temperature. With a decrease in gallium temperature, the melt melting temperature increases. Only gallium extrudes from this eutectic into an aluminum plate, while indium and tin remain on the surface of the plate. After 10-15 minutes, the ratio in the melt of gallium, as alloying, and other components changes and the melt begins to solidify on the surface of the plate. It is removed with a spatula, but a small portion of indium and tin may remain on the surface of the plate.

After doping (impregnation) and preliminary crushing of activated aluminum of grades A5 and A7, two batches of grits weighing ≈100 g each were obtained.

Then, after a 2-minute treatment in an impeller grinder, the powder was passed through a No. 1 sieve, and the upper fraction of particles was removed from the samples. The remainder was subjected to sieve analysis, the results of which are presented in figure 1.

As a result of X-ray spectral analysis, the following powder composition was obtained (in mass fractions, in percent):

Aluminum  96.67 Gallium  3.27 Indium  0.04 Tin  0.02

Example 2

Plates of aluminum alloy D16AT with a thickness of 2 mm, weighing 100 g each in a box filled with argon, are covered with a layer of eutectic melt indium gallium-tin in an amount of 6.9 g by mechanical rubbing. The composition of the eutectic melt indium-gallium-tin is prepared respectively in mass fractions of 25:62:13.

At the end of the impregnation process, the plate is preliminarily crushed into pieces no larger than 8 × 8 × 2 mm, then it is crushed in an inertia conical crusher (KID-100), the elevator is fed to a vibrating sieve, where the crushed powder is divided into fractions. The processing equipment is located in a box filled with argon.

According to the results of x-ray analysis, the aluminum powder obtained using the inventive method contains (mass fraction in percent):

Aluminum  90.01 Gallium  3.15 Indium  0,03 Tin  0.015 Silicon  0.5 Iron  0.415 Copper  2.18 Manganese  0.8 Magnesium  1,6 Chromium  0.1 Zinc  0.23 Titanium  0.13

Aluminum powder obtained from aluminum alloys preserves the chemical composition of the feedstock and alloying elements used to produce the powder are added.

Aluminum powder material obtained by the method of impregnation with gallium can be used as a source of thermal energy both in the process of combustion in the presence of an oxidizing agent, and in hydroreactive compositions based on it.

A hydroreacting composition (TU 847512006.9-2005) was developed on the basis of aluminum powder material, which successfully passed tests during the thermogasochemical treatment of oil and gas reservoirs in the well intake zone.

Claims (2)

1. Aluminum powder material of aluminum or its alloy, characterized by the presence of gallium-containing interlayers between polycrystalline particles of the material in the following ratio of components in the powder, wt.%:
aluminum or its alloy 90-99 gallium 0.2-6.0 indium tin rest 2. The method of producing a powder material from aluminum or its alloy according to claim 1, which consists in the fact that the first is embrittlement of aluminum or its alloy and the destruction of its polycrystalline structure by grain-boundary alloying with an indium gallium-tin melt, then crushing, grinding and classification are carried out powder by particle size.

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