CN115536481A - Preparation method of aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material - Google Patents

Abstract

The invention relates to a preparation method of an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material, belonging to the technical field of material preparation. The method sequentially comprises the following steps: preparing raw materials, mixing, drying, pressing and sintering. The method takes aluminum fiber, aluminum powder and polytetrafluoroethylene powder as raw materials, and is easy to manufacture. Compared with the aluminum/polytetrafluoroethylene energetic material, the fiber reinforced aluminum/polytetrafluoroethylene energetic material has higher yield strength, dynamic compressive strength and impact reaction threshold. When the mass fraction of the aluminum fiber is 4%, the yield strength under quasi-static loading is improved by 40% to 21.2Mpa, and the impact reaction threshold is improved by 21% to 61.2J/cm ² (ii) a When the mass fraction of the aluminum fiber is 1%, the dynamic compressive strength is improved by 25% and reaches 67.3Mpa. In addition, the addition of aluminum fibers does not change the aluminum/polytetrafluoroethylene energy-containing materialThe chemical components and the proportion of the materials are the same as the theoretical release energy of the two materials.

Description

A kind of preparation method of aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material

technical field

The invention relates to a preparation method of an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material, belonging to the technical field of energetic material preparation

Background technique

Aluminum/PTFE is a new type of energetic material, which is usually prepared by mixing active aluminum powder and PTFE powder in a certain proportion. It is in an inert metastable state under normal conditions, but in Under the action of strong impact load, the aluminum filler and the PTFE matrix will rapidly undergo a chemical reaction to release a large amount of heat energy and generate gaseous products, which can form a detonation-like effect. The aluminum/polytetrafluoroethylene energetic material has the coupling effect of kinetic energy and chemical energy when it damages the target, and it will produce a unique penetration-explosion joint damage enhancement effect when it hits the target.

When the impact energy is higher than the critical reaction threshold of the material, the aluminum/PTFE energetic material will undergo a redox reaction to release a large amount of energy; when the ratio of aluminum to PTFE in the material reaches zero oxygen balance, the mass of the two components The fractions are 26.5% and 73.5%, respectively, and the Al/PTFE energetic material can theoretically react completely under this ratio.

Based on the above characteristics of aluminum/polytetrafluoroethylene energetic materials, it is often used as the structural material of anti-destructive fragments and drug-type covers; due to the characteristics of low strength and easy breakage of aluminum/polytetrafluoroethylene energetic materials, its practical application The scope is very limited, so the patent proposes a preparation method of aluminum fiber reinforced aluminum/PTFE energetic material, which can improve the quasi-static yield strength and elastic modulus of the prepared aluminum/PTFE energetic material , dynamic compressive strength and failure strain, and broaden the application prospects of aluminum/PTFE energetic materials in the field of efficient damage.

Contents of the invention

The invention proposes a method for preparing an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material. This method can improve the disadvantages of low strength and easy breakage of the existing aluminum/polytetrafluoroethylene energetic material, and prepare a zero-oxygen balance without affecting the chemical composition of the aluminum/polytetrafluoroethylene energetic material. The fiber-reinforced aluminum/polytetrafluoroethylene energetic material adopts a cold-press sintering preparation process, the preparation method is simple, the raw material cost is low, and it is suitable for mass production. The prepared aluminum fiber-reinforced aluminum/polytetrafluoroethylene energetic material can withstand impact Under the action of load, a chemical reaction occurs to release a large amount of energy, and when the target is damaged, both kinetic energy and chemical energy can act together.

The purpose of the present invention is achieved through the following technical solutions.

A method for preparing an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material, the specific steps are as follows:

Step 1. Submerge aluminum powder with a mass fraction of 22.5% to 26.5% and polytetrafluoroethylene powder with a mass fraction of 73.5% in absolute ethanol, and use a powder mixer to mix for 1 to 10 minutes to obtain a solid-liquid mixture , immerse the aluminum fiber in the sodium hydroxide solution, take it out before generating bubbles, dry it and weigh it;

Step 2. Stir the solid-liquid mixture obtained in step 1, and sprinkle aluminum fibers into the mixture evenly in multiple times. It is necessary to ensure that the mass fraction of aluminum fibers and aluminum powder added is 26.5%; The solid-liquid mixture is mixed for 6-12 hours;

Step 3. Put the solid-liquid mixture obtained in Step 2 into an electric thermostat and dry for 4 to 10 hours until the absolute ethanol in the mixture evaporates completely to obtain a mixed powder;

Step 4, placing the mixed powder obtained in Step 3 in a mold, and compressing with a universal press to obtain a pre-pressed molding test piece;

Step 5: Sinter the pre-pressed test piece in step 4 by using a vacuum sintering furnace to obtain an aluminum fiber reinforced aluminum/PTFE energetic material test piece.

As a preferred solution: the aluminum fiber added in the second step is made of a metal aluminum rod through a drawing process, which can participate in the energy release reaction of energetic materials. The added aluminum fiber is a columnar structure with a diameter of 100 μm and a length of 3 ~ 5mm, the fiber mass fraction is less than 10%.

As a preferred solution: in the step 2, the aluminum fiber is evenly sprinkled into the solid-liquid mixture in the step 1 in 5 times, and mixed with a powder mixer for 1 to 10 minutes after each sprinkle, to obtain a fiber-containing solid liquid mixture.

As a preferred solution: in the second step, before adding the aluminum fiber, put the fiber into a sodium hydroxide solution to remove the oxide layer, and carry out dry weighing.

As a preferred solution: the pressure of the universal press in step 4 is 100MPa-200MPa, the pressurization rate is 50N/s, and the holding time is 4 minutes.

As a preferred solution: the sintering temperature in the sintering process described in step 5 is 320°C to 360°C, the sintering time is 1 to 3 hours, the heating rate is 60°C/hour, and argon is used for protection during the sintering process .

Technical effects and advantages of the present invention include:

1. A method for preparing an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material, using aluminum fiber, aluminum powder, and polytetrafluoroethylene powder as raw materials, which is low in cost and easy to manufacture.

2. The present invention provides a method for preparing an aluminum fiber reinforced aluminum/PTFE energetic material. Compared with ordinary aluminum/PTFE energetic materials, the prepared material has higher quasi-static yield strength and dynamic resistance Compressive strength, when the mass fraction of aluminum fiber is 4%, its quasi-static yield strength can reach 21.2Mpa, which is 1.4 times that of fiber-free aluminum/PTFE energetic material under the same process, when the mass fraction of aluminum fiber is 1% , the dynamic compressive strength of the Al/PTFE energetic material is 67.3Mpa at the strain rate of 2460/s, which is 125% of that of the non-fiber/PTFE energetic material at the strain rate of 2480/s.

3. Compared with the inert metal reinforced aluminum/PTFE energetic material, the prepared aluminum fiber reinforced aluminum/PTFE energetic material has zero oxygen balance, and the internal chemical composition of the material can theoretically react completely. Release energy is higher.

4. The mechanical properties of the prepared aluminum fiber reinforced aluminum/PTFE energetic material are affected by the fiber content. By changing the content of aluminum fiber, the yield strength and compressive strength of the energetic material can be adjusted, and the impact of the energetic material during the impact process can be controlled. Ability to penetrate targets.

5. The impact response threshold of the aluminum fiber reinforced aluminum/PTFE energetic material prepared in the present invention is positively correlated with the fiber content. When the fiber content is 4%, the prepared aluminum fiber reinforced aluminum/PTFE contains The specific incident energy required for the energetic material reaction is 61.2J/cm2, which is 21% higher than that of the fiberless aluminum/PTFE energetic material. By adjusting the fiber content, the impact response threshold of aluminum/PTFE energetic materials can be controlled, and targets with different degrees of protection can be damaged without affecting the theoretical total energy release.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is further described:

Fig. 1 is the quasi-static (strain rate 0.001/s) stress-strain curve figure of different aluminum fiber content aluminum/polytetrafluoroethylene energetic materials of the present invention;

Fig. 2 is the dynamic stress-strain curve diagram of different aluminum fiber content aluminum/polytetrafluoroethylene energetic materials of the present invention;

Fig. 3 is the image of the impact reaction of the Al/PTFE energetic material prepared by the method of the present invention when the content of aluminum fibers is 4% in the split Hopkinson bar experiment (the speed of the impact bar is 24.6m/s).

detailed description

The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Apparently, the described embodiments are part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

Based on the fiber spacing theory, the fiber spacing in aluminum/PTFE energetic materials with different fiber mass fractions is calculated. Small fiber spacing will lead to large internal residual stress in the material during sintering. Through analysis, it is considered that the fiber spacing should not exceed 500 μm. Therefore the added fiber content of this patent is no more than 10%. The relationship between fiber spacing and mass fraction:

l＝0.886d(η ₀ *V*ρ _Al/PTFE /ρ _Al ) ^-1/2

Wherein, l is the fiber spacing, d is the fiber diameter, η ₀ is the coefficient of the fiber insertion mode, and η ₀ is 0.41 during random scattering, V is the fiber mass fraction, ρ _Al/PTFE is the density of aluminum/polytetrafluoroethylene, ρ _Al is the density of aluminum.

Example 1

The aluminum fiber reinforced aluminum/PTFE energetic material provided in this embodiment is composed of the following components in mass ratio: 22.5% of aluminum powder, 73.5% of polytetrafluoroethylene powder, and 4% of aluminum fiber.

1) Raw material powder preparation: Weigh out 22.5g of aluminum powder with a particle size of 30μm, 73.5g of polytetrafluoroethylene powder with a particle size of 15μm, and 4g of columnar aluminum fibers with a diameter of 100μm and a length of 3-5mm.

2) Powder mixing step: mix the above weighed aluminum powder and polytetrafluoroethylene powder and immerse them in an appropriate amount of absolute ethanol, use a powder mixer to mix for 10 minutes, and evenly sprinkle 0.8g of aluminum fibers into the The solid-liquid mixture was mixed for 10 minutes, and the process of sprinkling into the fiber and mixing was repeated 4 times. After all 4g of aluminum fibers were sprinkled in, the solid-liquid mixture was mixed for 6 hours with a powder mixer.

3) Drying step: the above solid-liquid mixture is dried in an electric thermostat, and the temperature of the thermostat is set at 60° C. until the anhydrous ethanol in the mixture is completely evaporated to obtain a mixed powder.

4) Molding step: put the above-mentioned dried mixed powder in a steel cylindrical mold with a diameter of 10mm, compress it with a universal press, set the molding pressure to 150MPa, the pressure increase rate to 50N/s, and hold the pressure The time is 4 minutes. After the pressure holding is completed, the pressure is slowly unloaded at a rate of 100N/s, and the mold is demoulded.

5) Sintering step: use a vacuum sintering furnace to sinter the above-mentioned pressed test piece. Before sintering, the furnace is evacuated and argon is introduced to control the pressure of the furnace to 0.2 MPa. Set the sintering temperature to 350°C, the sintering time to 1 hour, the heating rate to 60°C/hour, the cooling rate to 40°C/hour, and hold at 297°C for 2 hours during the cooling process.

The elastic modulus of the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example is 397MPa, the quasi-static yield strength is 21.2Mpa, the compressive strength is 57.9MPa at a strain rate of 2510/s, and the failure strain is 1.14. The quasi-static stress-strain curve is shown in Figure 1, and the dynamic stress-strain curve is shown in Figure 2.

Based on the separated Hopkinson pressure bar experiment, the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example was tested for impact reaction, and the reaction was recorded with a high-speed camera. The photo of the material reaction when the speed of the impact bar was 24.6m/s As shown in Figure 3; when the aluminum fiber content is 4%, the minimum specific incident energy required for the reaction of the aluminum/PTFE energetic material is 61.2J/cm2.

Example 2

The aluminum fiber reinforced aluminum/PTFE energetic material provided in this embodiment is composed of the following components in mass ratio: 24.5% aluminum powder, 73.5% polytetrafluoroethylene powder, and 2% aluminum fiber.

1) Raw material powder preparation: Weigh out 24.5 g of aluminum powder with a particle size of 30 μm, 73.5 g of polytetrafluoroethylene powder with a particle size of 15 μm, and 2 g of columnar aluminum fibers with a diameter of 100 μm and a length of 3 to 5 mm.

2) Powder mixing step: mix the above weighed aluminum powder and polytetrafluoroethylene powder and immerse them in an appropriate amount of absolute ethanol, use a powder mixer to mix for 10 minutes, and evenly sprinkle 0.4g of aluminum fibers into the The solid-liquid mixture was mixed for 10 minutes, and the process of sprinkling into the fiber and mixing was repeated 4 times. After all the 2g of aluminum fiber was sprinkled in, the solid-liquid mixture was mixed for 6 hours with a powder mixer.

3) Drying step: the above solid-liquid mixture is dried in an electric thermostat, and the temperature of the thermostat is set at 60° C. until the anhydrous ethanol in the mixture is completely evaporated to obtain a mixed powder.

4) Molding step: put the above-mentioned dried mixed powder in a steel cylindrical mold with a diameter of 10mm, compress it with a universal press, set the molding pressure to 150MPa, the pressure increase rate to 50N/s, and hold the pressure The time is 4 minutes. After the pressure holding is completed, the pressure is slowly unloaded at a rate of 100N/s, and the mold is demoulded.

5) Sintering step: use a vacuum sintering furnace to sinter the above-mentioned pressed test piece. Before sintering, the furnace is evacuated and argon is introduced to control the pressure of the furnace to 0.2 MPa. Set the sintering temperature to 350°C, the sintering time to 1 hour, the heating rate to 60°C/hour, the cooling rate to 40°C/hour, and hold at 297°C for 2 hours during the cooling process.

The elastic modulus of the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example is 331MPa, the quasi-static yield strength is 20.4Mpa, the compressive strength is 59.9MPa at a strain rate of 2530/s, and the failure strain is 1.04. The quasi-static stress-strain curve is shown in Figure 1, and the dynamic stress-strain curve is shown in Figure 2.

Based on the separate Hopkinson pressure bar experiment, the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example was subjected to impact reaction tests. The experimental results showed that when the aluminum fiber content was 2%, the aluminum/PTFE energetic material The minimum specific incident energy required for the material reaction is 53.9J/cm2.

Example 3

The aluminum fiber reinforced aluminum/PTFE energetic material provided in this embodiment is composed of the following components by mass ratio: 25.5% aluminum powder, 73.5% polytetrafluoroethylene powder, and 1% aluminum fiber.

1) Raw material powder preparation: Weigh out 25.5 g of aluminum powder with a particle size of 30 μm, 73.5 g of polytetrafluoroethylene powder with a particle size of 15 μm, and 1 g of columnar aluminum fibers with a diameter of 100 μm and a length of 3 to 5 mm.

2) Powder mixing step: mix the above-mentioned aluminum powder and polytetrafluoroethylene powder and immerse them in an appropriate amount of absolute ethanol, mix them for 10 minutes with a powder mixer, and evenly sprinkle 0.2g of aluminum fibers into the The solid-liquid mixture was mixed for 10 minutes, and the process of sprinkling into the fiber and mixing was repeated 4 times. After all the 1g of aluminum fiber was sprinkled in, the solid-liquid mixture was mixed for 6 hours with a powder mixer.

3) Drying step: the above solid-liquid mixture is dried in an electric thermostat, and the temperature of the thermostat is set at 60° C. until the anhydrous ethanol in the mixture is completely evaporated to obtain a mixed powder.

4) Molding step: put the above-mentioned dried mixed powder in a steel cylindrical mold with a diameter of 10mm, compress it with a universal press, set the molding pressure to 150MPa, the pressure increase rate to 50N/s, and hold the pressure The time is 4 minutes. After the pressure holding is completed, the pressure is slowly unloaded at a rate of 100N/s, and the mold is demoulded.

5) Sintering step: use a vacuum sintering furnace to sinter the above-mentioned pressed test piece. Before sintering, the furnace is evacuated and argon is introduced to control the pressure of the furnace to 0.2 MPa. Set the sintering temperature to 350°C, the sintering time to 1 hour, the heating rate to 60°C/hour, the cooling rate to 40°C/hour, and hold at 297°C for 2 hours during the cooling process.

The elastic modulus of the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example is 302MPa, the quasi-static yield strength is 19.1Mpa, the compressive strength is 67.3MPa at a strain rate of 2460/s, and the failure strain is 1.02. The quasi-static stress-strain curve is shown in Figure 1, and the dynamic stress-strain curve is shown in Figure 2.

Based on the separate Hopkinson pressure bar experiment, the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example was subjected to impact reaction tests. The experimental results showed that when the aluminum fiber content was 1%, the aluminum/PTFE energetic material The minimum specific incident energy required for material reaction is 50.1J/cm2.

Example 4

The aluminum fiber reinforced aluminum/PTFE energetic material provided in this embodiment is composed of the following components by mass ratio: 25.5% of aluminum powder, 73.5% of polytetrafluoroethylene powder, and 0% of aluminum fiber

1) Raw material powder preparation: Weigh out 26.5 g of aluminum powder with a particle size of 30 μm, 73.5 g of polytetrafluoroethylene powder with a particle size of 15 μm, and 0 g of columnar aluminum fibers with a diameter of 100 μm and a length of 3 to 5 mm.

2) Powder mixing step: mix the above weighed aluminum powder and polytetrafluoroethylene powder and immerse them in an appropriate amount of absolute ethanol, and use a powder mixer to mix the solid-liquid mixture for 6 hours.

3) Drying step: the above solid-liquid mixture is dried in an electric thermostat, and the temperature of the thermostat is set at 60° C. until the anhydrous ethanol in the mixture is completely evaporated to obtain a mixed powder.

4) Molding step: put the above-mentioned dried mixed powder in a steel cylindrical mold with a diameter of 10mm, compress it with a universal press, set the molding pressure to 150MPa, the pressure increase rate to 50N/s, and hold the pressure The time is 4 minutes. After the pressure holding is completed, the pressure is slowly unloaded at a rate of 100N/s, and the mold is demoulded.

5) Sintering step: use a vacuum sintering furnace to sinter the above-mentioned pressed test piece. Before sintering, the furnace is evacuated and argon is introduced to control the pressure of the furnace to 0.2 MPa. Set the sintering temperature to 350°C, the sintering time to 1 hour, the heating rate to 60°C/hour, the cooling rate to 40°C/hour, and hold at 297°C for 2 hours during the cooling process.

The elastic modulus of the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example is 227MPa, the quasi-static yield strength is 15.8Mpa, the compressive strength is 53.7MPa at a strain rate of 2480/s, and the failure strain is 0.80. The quasi-static stress-strain curve is shown in Figure 1, and the dynamic stress-strain curve is shown in Figure 2.

Based on the separated Hopkinson pressure bar experiment, the aluminum fiber reinforced aluminum/PTFE energetic material prepared in this example was subjected to the impact reaction test. The experimental results showed that when the aluminum fiber content was 0%, the aluminum/PTFE energetic material The minimum specific incident energy required for material reaction is 50.7J/cm2.

The above are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application shall be included in the protection of the application. within range. Other structures and principles are the same as those of the prior art, and will not be repeated here.

Claims (6)

1. A preparation method of an aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material is characterized by comprising the following steps: the method comprises the following specific steps:

step one, uniformly mixing aluminum powder and polytetrafluoroethylene powder, and immersing the mixture in absolute ethyl alcohol to obtain a solid-liquid mixture; wherein the mass fraction of the aluminum powder is 22.5-26.5%;

step two, stirring the solid-liquid mixture obtained in the step one, and uniformly scattering aluminum fibers into the mixture, wherein the sum of the mass fraction of the scattered aluminum fibers and the mass fraction of the aluminum powder is required to be 26.5%; mixing the solid-liquid mixture containing the fibers for 6 to 12 hours by using a powder mixer;

step three, putting the solid-liquid mixture obtained in the step two into an electric heating thermostat to dry for 4-10 hours until the absolute ethyl alcohol in the mixture is completely evaporated to obtain mixed powder;

step four, placing the mixed powder obtained in the step three in a die, and compressing the mixed powder by using a universal press machine to obtain a pre-pressed forming test piece;

and step five, sintering the prepressing molding test piece in the step four at high temperature to obtain the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material test piece.

2. The method for preparing the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material according to claim 1, wherein the method comprises the following steps: and in the second step, the added aluminum fiber is a metal aluminum bar which is manufactured through a drawing process and can participate in the energy release reaction of the energetic material, the added aluminum fiber is of a columnar structure, the diameter is 100 micrometers, the length is 3-5 mm, and the mass fraction of the fiber is less than 5%.

3. The method for preparing the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material according to claim 1, wherein the method comprises the following steps: and in the second step, uniformly scattering the aluminum fibers into the solid-liquid mixture in the first step in 5 times on average, and mixing for 1-10 minutes by using a powder mixer after each scattering to obtain the fiber-containing solid-liquid mixture.

4. The method for preparing the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material as claimed in claim 1, wherein the method comprises the following steps: and in the second step, before the aluminum fiber is added, the fiber is put into a sodium hydroxide solution to remove an oxide layer, and is dried and weighed.

5. The method for preparing the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material as claimed in claim 1, wherein the method comprises the following steps: and in the fourth step, the pressure intensity of the universal press during compression is 100 MPa-200 MPa, the pressurization rate is 50N/s, and the pressure maintaining time is 4 minutes.

6. The method for preparing the aluminum fiber reinforced aluminum/polytetrafluoroethylene energetic material according to claim 1, wherein the method comprises the following steps: in the step five, the sintering temperature is 320-360 ℃, the sintering time is 1-3 hours, the heating rate is 60 ℃/hour, and argon is used for protection in the sintering process.

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