A method for preparing aluminum-nickel energetic material based on hot pressing and friction stir processing

Abstract

The application discloses a kind of based on hot-pressing and friction stir processing composite preparation aluminum nickel energetic material method, aluminum powder, nickel powder and additive are weighed in proportion, then the aluminum powder, nickel powder and additive weighed are mixed evenly, and mixed material is obtained, mixed material is placed into mould and is hot-pressed by hot-pressing forming process Hot-pressing composite, prepared by metallurgical reaction with certain shape block blank;Aluminum nickel composite blank is plastically processed by friction stir processing process, and finally aluminum nickel energetic material is obtained.The application is suitable for manufacturing larger aluminum nickel energetic material structural member, and the preparation process does not need vacuum sintering, the manufacturing cycle is shorter, and the production cost is lower.The structural strength and reaction energy release density of the aluminum nickel energetic material prepared by the application are higher, meet the demand of weapon equipment for efficient damage, and have good application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing aluminum-nickel energetic materials based on a combination of hot pressing and friction stirring. Background Technology

[0002] Energetic materials are metastable substances that can rapidly undergo chemical reactions and release large amounts of energy under external stimuli such as force, heat, electricity, and laser. Energetic materials with a certain structural strength can be used as destructive elements in weapon systems, such as warhead fragments and shaped charge liner, exhibiting coupled destructive effects including penetration, incendiary incendiary activity, and detonation. AlNi energetic materials, due to their inherent reactive energy release characteristics, low manufacturing cost, and high compressive strength, show promising application prospects in warhead fragmentation.

[0003] Domestic and international researchers generally use cold-pressing sintering to prepare aluminum-nickel energetic materials. This involves first cold-pressing a blank in a mold to form a billet, and then sintering it under vacuum or a protective atmosphere to form an aluminum-nickel energetic material with a certain energy release density and structural strength. For example, Zhang Dubao et al. from Nanjing University of Aeronautics and Astronautics (Preparation and Performance Study of Ni-Al Metal Reactive Materials [D]. Nanjing: Nanjing University of Aeronautics and Astronautics, 2016.) found that the quasi-static compressive strength of the aluminum-nickel energetic material prepared by sintering at 550℃ was 294.6 MPa, and the reactive energy release density was 413.1 J / g. During the sintering process, the aluminum and nickel components inside the aluminum-nickel energetic material react to generate a certain amount of aluminum-nickel intermetallic compounds, resulting in a loss of energy release density. Therefore, the higher the sintering temperature and the longer the sintering time, the lower the energy density and the higher the structural strength of the aluminum-nickel energetic material; conversely, the lower the sintering temperature and the shorter the sintering time, the higher the energy density and the lower the structural strength. This contradiction severely weakens the destructive effect of aluminum-nickel energetic materials, hindering their widespread application.

[0004] As a destructive element in weaponry, the design goal of AlNi energetic materials is to achieve both high energy density and high structural strength. Given that the contradiction between structural strength and energy release density in AlNi energetic materials prepared by cold pressing and sintering stems from the high-temperature sintering process, a new preparation method needs to be developed to minimize the heating temperature and time during material preparation while simultaneously ensuring high structural strength in the microstructure. Summary of the Invention

[0005] This invention provides a method for preparing aluminum-nickel energetic materials based on hot pressing and friction stirring to solve the problems existing in the prior art. This invention combines hot pressing and friction stirring processes, and the prepared aluminum-nickel energetic materials not only have high reaction energy release density, but also high mechanical structural strength.

[0006] The technical solutions adopted in this invention are as follows:

[0007] A method for preparing aluminum-nickel energetic materials based on hot pressing and friction stir processing involves weighing aluminum powder, nickel powder, and additives in proportion, thoroughly mixing the weighed aluminum powder, nickel powder, and additives to obtain a mixture, placing the mixture into a mold, and hot pressing it into a composite material. A block blank with a certain shape is prepared through a metallurgical reaction. The aluminum-nickel composite blank is then plastically processed using friction stir processing to finally obtain the aluminum-nickel energetic material.

[0008] Furthermore, the heating temperature used for hot pressing composite is 300-500℃, the holding time is 2-6h, and the holding pressure is 50-300MPa.

[0009] Furthermore, when performing friction stir processing on the aluminum-nickel composite billet, the rotation speed of the stirring tool is: stirring speed: 600~1200r / min, and the moving speed of the tool during stirring is: 30~60mm / min.

[0010] Furthermore, the additive is tungsten powder, iron oxide, or copper oxide.

[0011] Furthermore, the atomic ratio of the aluminum powder to the nickel powder is 1:(1-3).

[0012] Furthermore, the total mass percentage of aluminum powder and nickel powder added is 90-100%, and the mass percentage of additives added is 0-10%.

[0013] The present invention has the following beneficial effects:

[0014] 1) This invention combines hot pressing with friction stir processing, making it suitable for manufacturing large-sized aluminum-nickel energetic material structural components. The preparation process eliminates the need for vacuum sintering, resulting in a shorter manufacturing cycle and lower production costs. The aluminum-nickel energetic material prepared by this invention exhibits high structural strength and reaction energy release density, meeting the requirements of weaponry for efficient damage and demonstrating promising application prospects.

[0015] 2) When using the hot pressing process, this invention controls the heating temperature between 300 and 500°C. Higher hot pressing temperatures and longer hot pressing times significantly reduce the energy density of the AlNi energetic material, while lower hot pressing temperatures and shorter hot pressing times weaken its structural strength. Therefore, the AlNi energetic material exhibits optimal overall performance when the hot pressing temperature is between 300 and 500°C and the hot pressing time is between 2 and 6 hours.

[0016] 3) During friction stir processing, if the rotational and moving speeds of the stirring tool are not properly selected, when the stirring speed exceeds 1200 r / min, numerous defects such as pores will appear inside the AlNi energetic material, resulting in low structural strength. The friction stir processing parameters provided in this invention can obtain a denser microstructure with higher structural strength.

[0017] 4) The present invention selects aluminum powder, nickel powder and additives as the matrix for making blanks. Since aluminum powder and copper oxide powder can undergo aluminothermic reaction and release additional energy, when copper oxide is selected as the additive, the energetic material can obtain a higher energy density. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of the present invention.

[0019] Figure 2 Quasi-static compressive stress-strain curves of three AlNi energetic material samples prepared in Example 1.

[0020] Figure 3 The reaction energy release characteristic curve of the aluminum-nickel energetic material sample in Example 1 was obtained by DSC experiment. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Example 1

[0023] like Figure 1 As shown, the present invention discloses a method for preparing aluminum-nickel energetic materials based on a combination of hot pressing and friction stir processing, comprising the following steps:

[0024] 1) Weighing and mixing: aluminum powder, nickel powder and additives to be mixed. The average particle size of aluminum powder and nickel powder is 500 mesh.

[0025] 2) Mixing raw materials: Weigh the aluminum powder, nickel powder and additives (the additives are tungsten powder, iron oxide or copper oxide) and put them into a sealed container and shake to premix. Then, put the premixed powder into a ball mill jar and add stainless steel balls at a ball-to-material ratio of 1:1. Then, install the sealed ball mill jar in a planetary ball mill for thorough mixing. The ball mill speed is 200 r / min and the ball milling time is 1 hour.

[0026] 3) Hot pressing: Pour the above-mentioned uniformly mixed material and stainless steel balls out of the ball mill jar, and use a stainless steel mesh screen to separate the mixture from the steel balls.

[0027] A certain amount of the mixture is weighed and placed into a rectangular cavity (100mm in length, 100mm in width, and 5mm in height) of a mold. The mold is then placed in a hot press at a temperature of 400℃ for 4 hours, with a holding pressure of 150MPa. Under heating and pressurization, the mixture undergoes a metallurgical reaction to form a rectangular block material. After cooling and mold opening, the material is removed to obtain an aluminum-nickel alloy billet with dimensions of 100mm × 100mm × 5mm.

[0028] 4) Friction stir processing: The above-mentioned rectangular aluminum-nickel alloy billet is clamped on the worktable of the friction stir welding equipment. The aluminum-nickel alloy billet is subjected to friction stir processing with a stirring tool at a stirring speed of 800 r / min and a moving speed of 40 mm / min, and finally the desired aluminum-nickel energetic material structural parts are obtained.

[0029] The method of this invention yields aluminum-nickel energetic material structural components. These components are then processed into cylindrical and sheet-like specimens in the friction stir processing region, respectively, for use in quasi-static compression tests (e.g., ...). Figure 2 ) and thermal analysis experiments (such as Figure 3 Differential scanning calorimetry (DSC) was used for testing. The final measured average quasi-static compressive strength was 417 MPa; the measured exothermic reaction energy release density was 843 J / g. Therefore, this invention combines hot pressing with friction stir processing to prepare an aluminum-nickel energetic material with high structural strength and high reaction energy release density, meeting the requirements of weaponry for efficient damage and showing promising application prospects.

[0030] Example 2

[0031] Example 2 provides an aluminum-nickel energetic material, wherein the hot-pressing temperature is 350℃, the holding time at temperature is 6h, the stirring speed is 1000r / min, and the remaining preparation process parameters are the same as in Example 1. The average quasi-static compressive strength of the obtained aluminum-nickel energetic material is 385MPa; its exothermic reaction energy release density is measured to be 871J / g.

[0032] Comparative Example 1

[0033] Comparative Example 1 provides an aluminum-nickel energetic material, wherein the hot-pressing process parameters are: holding at 550℃ for 8 hours, stirring speed of 1300 r / min, and other preparation process parameters are the same as in Example 1. The average quasi-static compressive strength of the obtained aluminum-nickel energetic material is 305 MPa; its exothermic reaction energy release density is measured to be 492 J / g.

[0034] Comparative Example 2

[0035] Comparative Example 1 provides an aluminum-nickel energetic material, wherein the hot-pressing process parameters are: holding at 300℃ for 1 hour, stirring speed of 1200 r / min, and other preparation process parameters are the same as in Example 1. The average quasi-static compressive strength of the obtained aluminum-nickel energetic material is 246 MPa; its exothermic reaction energy release density is measured to be 937 J / g.

[0036] Table 1. Performance of Samples from Examples 1-2 and Comparative Examples 1-2 (Average Compressive Strength and Exothermic Reaction Energy Release Density)

[0037]

[0038] Therefore, when formulating a hot-pressing process, higher hot-pressing temperatures and longer hot-pressing times will significantly reduce the energy density of AlNi energetic materials, while lower hot-pressing temperatures and shorter hot-pressing times will weaken the structural strength of AlNi energetic materials. This invention achieves the optimal overall performance of AlNi energetic materials when the hot-pressing temperature is controlled between 300 and 500°C and the hot-pressing time is between 2 and 6 hours.

[0039] When using friction stir processing, if the stirring speed and welding movement speed are not properly selected, when the stirring speed exceeds 1200 r / min, numerous defects such as pores will appear inside the AlNi energetic material, resulting in low structural strength. The friction stir processing parameters provided in this invention can obtain a denser microstructure with higher structural strength.

[0040] This invention combines hot pressing and friction stirring processes. The aluminum-nickel energetic materials prepared by this new method have higher structural strength and reaction energy release density compared to the traditional cold pressing and sintering method, which meets the requirements of weaponry for efficient damage and has good application prospects.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing aluminum-nickel energetic material based on the combination of hot pressing and friction stir processing, characterized by: The aluminum powder, the nickel powder and the optional additive are weighed in proportion, then the weighed aluminum powder, the weighed nickel powder and the optional additive are mixed uniformly to obtain a mixture, the mixture is placed into a mold and is hot-pressed by a hot-pressing process to prepare a bulk blank with a certain shape; the bulk blank is plastically processed by a friction stir processing process, and finally an aluminum-nickel energetic material is obtained; When the hot-pressing process is used for hot-pressing, the heating temperature is 300-500℃, the temperature holding time is 2-6h, and the pressure holding pressure is 50-300Mpa; When the friction stir processing process is used for plastic processing of the bulk blank, the stirring speed is 600-1200r / min, and the moving speed of the tool during stirring is 30-60mm / min; The atomic ratio of the aluminum powder to the nickel powder is 1:(1-3); The total mass percentage of the aluminum powder and the nickel powder is 90-100%, and the mass percentage of the additive is 0-10%; The additive is tungsten powder or iron oxide or copper oxide.

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