Preparation method of composite energetic fragment with metal-based outer layer and explosive-based inner layer

Abstract

The invention relates to a preparation method of a composite energetic fragment with a metal-based outer layer and an explosive-based inner layer, and belongs to the field of energetic materials and active fragment materials. The method comprises the following steps: uniformly mixing tungsten powder / zirconium powder; then pre-pressing and forming; sintering to obtain a hollow cylindrical product A; the NTO-based mixed explosive molding powder is prepared by adopting a solution water suspension method. And filling the hollow cylindrical product A with mixed explosive molding powder, and performing compression molding to obtain a final product. Compared with the W / Zr fragment reported in the past, the W / Zr fragment has higher activity, and the penetration and explosion power is further improved. Through a target range test, the power of penetration and explosion is remarkably improved.

Description

Technical Field

[0001] The invention relates to a method for preparing a composite energetic fragment with an outer metal base and an inner explosive base, belonging to the field of energetic materials and active fragment materials. Background Art

[0002] Tungsten alloy fragments are increasingly used as a lethal element in anti-personnel munitions due to their high density, ability to maintain velocity, and armor-piercing capabilities. Tactical requirements often require fragments to possess both armor-piercing power and ignition or incendiary properties. This led to the development of a new tungsten alloy material with this capability: tungsten-zirconium alloy. Tungsten-zirconium alloy is a typical energetic structural material, quite stable at room temperature and possessing high strength. However, under impact loads, the zirconium-based elements in the alloy induce a chemical reaction, releasing significant heat. Tungsten-zirconium alloy fragments produced by utilizing this property can both penetrate the target using its strength and inflict additional damage using its energy-release properties, ultimately significantly enhancing the damage effectiveness. “Experimental Study on the Impact Response of W / Zr Active Materials with Different Ratios,” Liu Xiaojun et al., Materials Engineering, Issue 4, Volume 45, April 2017, pp. 77-83, discloses that W / Zr active material is a high-strength brittle material with a quasi-static compressive strength of 1022 to 1880 MPa. When subjected to strong impact loads, it reacts violently with air to produce ZrO2. Unlike the detonation effect caused by the impact of metal / polymer active materials, the reaction of W / Zr active materials is similar to a combustion effect.

[0003] Energetic fragments can be categorized by their mode of action into explosive and incendiary types. Explosive fragments primarily consist of low-sensitivity, high-energy mixed explosives that produce an explosive or semi-explosive effect upon impact, such as deactivated RDX and 8701. Their energy is primarily delivered via a detonation wave, enabling them to detonate and damage the main charge of incoming missile warheads. Explosive fragments, in which the energetic material is explosive, must withstand high overloads and maintain sufficient strength and stability, while also possessing sufficient penetration capability to damage targets. Therefore, the explosive must be encased in a high-strength inert metal casing. Advantages of explosives include high casing strength, a higher overall density compared to monolithic materials, simpler processing, and easier engineering implementation. However, disadvantages include lower chemical energy per unit volume compared to monolithic materials and limited energetic material loading. Summary of the Invention

[0004] The purpose of the present invention is to further improve the penetration and explosive power, and provide a method for preparing composite energetic fragments with an outer metal base and an inner explosive base. The method adopts a solution water suspension method to prepare NTO-based mixed explosive molding powder, and adopts powder mixing, molding, and sintering processes. The process is simple and does not require special process requirements.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A method for preparing composite energetic fragments with an outer metal base and an inner explosive base, comprising the following specific steps:

[0007] Step 1: Place tungsten powder / zirconium powder in an omnidirectional planetary ball mill and mix them evenly; wherein the mass of tungsten powder is 30-70% of the total mass of tungsten powder and zirconium powder;

[0008] Step 2: Place the uniform powder obtained in step 1 into a customized hollow pressing mold and pre-press into shape;

[0009] Step 3: Sinter the pre-pressed specimen obtained in step 2 to obtain product A.

[0010] Step 4: Prepare NTO-based mixed explosive molding powder by solution water suspension method, with fluororubber as the binder, and the mass of NTO accounts for 70% to 90% of the total mass of NTO and fluororubber.

[0011] Step 5: Fill the hollow part of the product A obtained in step 3 with the mixed explosive molding powder obtained in step 4, then place it in a mold and press it into shape to obtain a composite energetic fragment.

[0012] The mixing time in step 1 is 1 to 5 hours.

[0013] The pre-pressing pressure in step 2 and step 7 is 10-50 MPa.

[0014] The sintering temperature in step 3 is 450-550° C., and the sintering time is 2-4 hours.

[0015] Beneficial effects

[0016] 1. A method for preparing composite energetic fragments with an outer metal base and an inner explosive base, using conventional tungsten powder, zirconium powder, and fluororubber powder with NTO as raw materials; a conventional solution water suspension method is used to prepare NTO-based mixed explosive molding powder, and a powder mixing, molding, and sintering process is adopted. The process is simple, does not require special processing, is low in cost, and is easy to mass produce.

[0017] 2. The composite energetic fragments produced by this invention, with a metal outer layer and an explosive inner layer, have higher activity than previously reported W / Zr fragments, further enhancing penetration and explosive power. Range testing has shown significant improvements in penetration and explosive power.

[0018] 3. This invention is based on the strength of tungsten alloy fragments and the advantage of chemical reaction under impact load to release huge energy. It combines the characteristics of explosive energetic fragments that produce detonation and damage effects in the form of shock waves and the disadvantage of the inertness of current charge shells to further improve the power of penetration and explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a photograph of the comprehensive damage effect of a 10 mm glass fiber-based heat-resistant material plate after being impacted by the composite energetic fragments with an outer metal-based layer and an inner explosive-based layer prepared in Example 1 at an initial velocity of 950 m / s;

[0020] Figure 2 This is a photograph of the comprehensive damage effect of the composite energetic fragment with an outer metal base and an inner explosive base prepared in Example 2 after impacting a 5mm phenolic resin plate at an initial velocity of 900m / s;

[0021] Figure 3 This is a photograph of the comprehensive damage effect of a 5mm ceramic-based heat-resistant material plate after being impacted by the composite energetic fragments with an outer metal-based layer and an inner explosive-based layer prepared in Example 3 at an initial velocity of 950m / s; DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0023] Example 1

[0024] A method for preparing composite energetic fragments with an outer metal base and an inner explosive base, comprising the following specific steps:

[0025] (1) First, prepare a hollow cylindrical specimen with an outer metal base;

[0026] Weighing and mixing: The mass ratio of each component is: tungsten powder / zirconium powder = 30 / 70, that is, weigh 30g of tungsten powder and 70g of zirconium powder. Place them in an omnidirectional planetary ball mill and mix for 1 hour until mixed.

[0027] Molding: The mixed tungsten powder / zirconium powder is placed in a hollow cylindrical mold and compressed at a pressure of 30 MPa, a compression rate of 30 N / s, a holding time of 4 min, a pressure relief rate of 30 N / s, and demolding after pressure relief to obtain a molded part;

[0028] Sintering: The molded part after demolding was placed in a sintering furnace for sintering. Argon atmosphere was used during the sintering process. The sintering temperature was 450°C and the sintering time was 2h. The heating rate was 60°C / h and the cooling rate was 60°C / h. The part was cooled in the furnace to obtain a hollow cylindrical specimen A.

[0029] (2) Prepare composite energetic fragments with an outer metal base and an inner explosive base.

[0030] Preparation of mixed explosive molding powder: weigh 30g of fluororubber, add an appropriate amount of ethyl acetate as solvent, stir at room temperature, and let it stand to fully dissolve. Weigh 70g of NTO and put it in a glass beaker, and pour a saturated aqueous solution of NTO into the beaker. Use a stirring rod to dip the dispersant and drop it into the beaker to make a suspension. Stir thoroughly to make it evenly dispersed.

[0031] Place the beaker in a constant temperature water bath and start heating it to 50°C. Stir and slowly add the prepared fluororubber solution while observing the formation of the modeling powder. Adjust the speed of adding the fluororubber solution and keep the temperature constant for 20 minutes after addition.

[0032] The temperature is raised to 60°C to drive off the solvent. After the solvent is completely driven off, the suspension is cooled to below 25°C, filtered, washed, and dried to obtain the mixed explosive molding powder.

[0033] Molding: The mixed explosive molding powder is loaded into the test piece A and placed in a mold for compression to obtain mixed composite energetic fragments.

[0034] The density of the composite energetic fragment with an outer metal base and an inner polymer base prepared in this embodiment is 5.34 g / cm 3 The ultimate strength of the specimen at a strain rate of 1000 / s is 2609.53MPa, the yield strength is 818.69MPa, and the strength of the specimen in quasi-static compression test is 1800MPa. When the initial velocity of 950m / s hits a 10mm thick resin plate, it explodes and penetrates the target plate. Figure 1 shown.

[0035] Example 2

[0036] A method for preparing a composite energetic fragment with an outer metal base and an inner polymer base, comprising the following specific steps: (1) first preparing a hollow cylindrical specimen with an outer metal base;

[0037] Weighing and mixing: Weigh 100g of sample each time, with the mass ratio of each component being tungsten powder / zirconium powder = 50 / 50, i.e. weigh 50g of tungsten powder and 50g of zirconium powder. Place in an omnidirectional planetary ball mill and mix for 1 hour until thoroughly mixed.

[0038] Molding: The mixed tungsten powder / zirconium powder is placed in a hollow cylindrical mold and compressed at a pressure of 30 MPa, a compression rate of 30 N / s, a holding time of 4 min, a pressure relief rate of 30 N / s, and demolding after pressure relief to obtain a molded part;

[0039] Sintering: The molded part after demolding was placed in a sintering furnace for sintering. Argon atmosphere was used during the sintering process. The sintering temperature was 500°C and the sintering time was 2h. The heating rate was 60°C / h and the cooling rate was 60°C / h. The part was cooled in the furnace to obtain a hollow cylindrical specimen A.

[0040] (2) Prepare composite energetic fragments with an outer metal base and an inner explosive base.

[0041] Preparation of mixed explosive modeling powder: weigh 20g of fluororubber, add an appropriate amount of ethyl acetate as solvent, stir at room temperature, and let it stand to fully dissolve. Weigh 80g of NTO, put it in a glass beaker, and pour a saturated aqueous solution of NTO into the beaker. Use a stirring rod to dip the dispersant and drop it into the beaker to make a suspension. Stir thoroughly to make it evenly dispersed.

[0042] Place the beaker in a constant temperature water bath and start heating it to 50°C. Stir and slowly add the prepared fluororubber solution while observing the formation of the modeling powder. Adjust the speed of adding the fluororubber solution and keep the temperature constant for 20 minutes after addition.

[0043] The temperature is raised to about 60°C to drive off the solvent. After the solvent is completely driven off, the suspension is cooled to below 25°C, filtered, washed, and dried to obtain the mixed explosive molding powder.

[0044] Molding: The mixed explosive molding powder is loaded into the test piece A and placed in a mold for compression to obtain composite energetic fragments.

[0045] The density of the composite energetic fragment with an outer metal base and an inner polymer base prepared in this embodiment is 4.07 g / cm 3 The ultimate strength of the specimen at a strain rate of 1000 / s is 2102.37MPa, the yield strength is 718.29MPa, and the strength of the specimen in the quasi-static compression test is 1200MPa. When the initial velocity of 900m / s is applied to a 3mm carbon-silicon carbide-based insulation board, a deflagration occurs. Figure 2 shown.

[0046] Example 3

[0047] A method for preparing a composite energetic fragment with an outer metal-based layer and an inner polymer-based layer, comprising the following specific steps:

[0048] (1) First, prepare a hollow cylindrical specimen with an outer metal base;

[0049] Weighing and mixing: Weigh 100g of sample each time, with the mass ratio of each component being tungsten powder / zirconium powder = 70 / 30, i.e. weigh 70g of tungsten powder and 30g of zirconium powder. Place in an omnidirectional planetary ball mill and mix for 1 hour until thoroughly mixed.

[0050] Molding: The mixed tungsten powder / zirconium powder is placed in a hollow cylindrical mold and compressed at a pressure of 30 MPa, a compression rate of 30 N / s, a holding time of 4 min, a pressure relief rate of 30 N / s, and demolding after pressure relief to obtain a molded part;

[0051] Sintering: The molded part after demolding was placed in a sintering furnace for sintering. Argon atmosphere was used during the sintering process. The sintering temperature was 550°C and the sintering time was 2h. The heating rate was 60°C / h and the cooling rate was 60°C / h. The part was cooled in the furnace to obtain a hollow cylindrical specimen A.

[0052] (2) Prepare composite energetic fragments with an outer metal base and an inner explosive base.

[0053] Preparation of mixed explosive molding powder: weigh 10g of fluororubber, add an appropriate amount of ethyl acetate as solvent, stir at room temperature, and let it stand to fully dissolve. Weigh 90g of NTO and put it in a glass beaker, and pour a saturated aqueous solution of NTO into the beaker. Use a stirring rod to dip the dispersant and drop it into the beaker to make a suspension. Stir thoroughly to make it evenly dispersed.

[0054] Place the beaker in a constant temperature water bath and start heating it to 50°C. Stir and slowly add the prepared fluororubber solution while observing the formation of the modeling powder. Adjust the speed of adding the fluororubber solution and keep the temperature constant for 20 minutes after addition.

[0055] The temperature is raised to about 60°C to drive off the solvent. After the solvent is completely driven off, the suspension is cooled to below 25°C, filtered, washed, and dried to obtain the mixed explosive molding powder.

[0056] Molding: The mixed explosive molding powder is loaded into the test piece A and placed in a mold for compression to obtain composite energetic fragments.

[0057] The density of the composite energetic fragment with an outer metal base and an inner polymer base prepared in this embodiment is 4.13 g / cm 3 The ultimate strength of the specimen at a strain rate of 1000 / s is 2402.37MPa, the yield strength is 923.17MPa, and the strength of the specimen is 1035MPa in quasi-static compression test. When the initial velocity of 950m / s is applied to a 5mm carbon-silicon carbide-based insulation board, a deflagration occurs. Figure 3 shown.

[0058] The above specific description further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing composite energetic fragments with an outer metal base and an inner explosive base, characterized by: The specific steps are as follows: Step 1: Place tungsten powder and zirconium powder in an omnidirectional planetary ball mill and mix them evenly; wherein the mass of tungsten powder is 30-70% of the total mass of tungsten powder and zirconium powder; Step 2: Place the uniform powder obtained in step 1 into a customized hollow pressing mold and pre-press into shape; Step 3: Sintering the pre-pressed specimen obtained in step 2 to obtain product A; Step 4: Prepare NTO-based mixed explosive molding powder by solution water suspension method, with fluororubber as the binder, and the mass of NTO accounts for 70% to 90% of the total mass of NTO and fluororubber; Step 5: Fill the hollow part of the product A obtained in step 3 with the mixed explosive molding powder obtained in step 4, then place it in a mold and press it into shape to obtain a composite energetic fragment.

2. The method for preparing a composite energetic fragment with an outer metal base and an inner explosive base as claimed in claim 1, characterized in that: The mixing time in step 1 is 1 to 5 hours.

3. The method for preparing a composite energetic fragment with an outer metal base and an inner explosive base as claimed in claim 1, characterized in that: The pre-pressing pressure in step 2 and step 7 is 10-50 MPa.

4. The method for preparing a composite energetic fragment with an outer metal base and an inner explosive base as claimed in claim 1, characterized in that: The sintering temperature in step 3 is 450-550° C., and the sintering time is 2-4 hours.

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