An integrally formed energetic ignition member and method of making the same

Abstract

The application provides an integrally formed energetic ignition component, characterized in that it comprises an outer layer combustible shell and an inner layer ignition core, the outer layer combustible shell is composed of energetic explosive powder and a photosensitive resin bonding system, the inner layer ignition core is composed of an ignition agent and a photosensitive resin binder, the photosensitive resin bonding system used in the outer layer combustible shell and the inner layer ignition core is the same system, and the outer layer combustible shell and the inner layer ignition core are combined in situ without any gap. The application also provides a preparation method of the integrally formed energetic ignition component, which realizes in-situ integrally forming of the outer layer combustible energetic shell and the inner layer microwave / laser ignition core.

Description

Technical Field

[0001] This invention belongs to the fields of additive manufacturing of energetic materials and pyrotechnics, and particularly relates to an integrated molded energetic ignition component and its preparation method. Background Technology

[0002] As core components in weaponry, aerospace, and civil blasting, pyrotechnics directly determine the overall system's performance through their structural precision, ignition reliability, and detonation transmission stability. Traditional pyrotechnics (such as detonators, detonating charges, and igniters) are often manufactured using conventional processes like press-fitting, casting, and mechanical assembly. However, these processes have revealed numerous insurmountable flaws in long-term application, as detailed below: 1. Separate preparation and subsequent assembly of the shell and ignition core, resulting in poor interfacial bonding performance: In traditional processes, the combustible shell and ignition core need to be molded separately and then assembled through mechanical nesting, bonding and other methods. Inevitably, gaps and delamination will occur at the interface between the two, leading to interruption of energy transfer during ignition and detonation, and easily causing problems such as misfires and detonation failure, which seriously affects the reliability of pyrotechnic products.

[0003] 2. Complex irregular structures are difficult to form and have low dimensional accuracy: With the development of micro pyrotechnics, the structural requirements for ignition components are becoming increasingly complex, such as thin-walled structures, porous structures, and gradient charge structures. Traditional press-fitting and casting processes are limited by molds and are difficult to form such complex structures. Moreover, the dimensional accuracy of the formed parts is low and the consistency is poor, which cannot meet the needs of high-precision pyrotechnics.

[0004] 3. Incompatible material systems prevent integrated in-situ molding: Traditional ignition propellants are mostly powders or pastes, requiring different bonding systems and molding processes from the combustible shell. This results in poor material compatibility between the ignition propellant and the shell, making it impossible to achieve integrated in-situ molding and further exacerbating the problem of poor interface bonding.

[0005] 4. Difficulty in molding microwave / laser ignition agents: Microwave and laser ignition agents, as new types of ignition agents, have advantages such as non-contact ignition, fast response speed, and strong controllability. However, these agents are mostly powder mixtures, which are difficult to directly mold into high-precision ignition core structures. They require additional binders, pressing, curing, and other processes, which are complicated and can easily lead to uneven density and unstable performance of the ignition core.

[0006] In recent years, DLP (Digital Permeation) 3D printing technology has been increasingly applied to the molding of energetic materials due to its advantages such as surface exposure, high forming accuracy, and strong ability to form complex structures. However, existing DLP 3D printing technologies for energetic materials mostly use a single material pool and a single energetic slurry for printing, which can only achieve the molding of energetic components with a single function and cannot achieve the integrated manufacturing of functional zones such as "outer combustible shell + inner ignition core". At the same time, existing technologies have not solved the problem of compatibility between photosensitive resin-bonded energetic explosives (RDX, HMX, CL-20, etc.) and microwave / laser ignition propellants, and cannot meet the requirements for the use of integrated ignition components.

[0007] Therefore, developing a manufacturing technology that can achieve integrated molding of a combustible shell and a microwave / laser ignition core, with strong interfacial bonding, high structural precision, and reliable ignition, has become the key to overcoming the shortcomings of existing technologies. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention discloses an integrated molded energetic ignition component and its preparation method, achieving in-situ integrated molding of an outer combustible energetic shell and an inner microwave / laser ignition core.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: An integrated molded energetic ignition component is characterized by comprising an outer combustible shell and an inner ignition core. The outer combustible shell is composed of energetic explosive powder and a photosensitive resin bonding system, and the inner ignition core is composed of an ignition agent and a photosensitive resin binder. The photosensitive resin bonding system used for the outer combustible shell and the inner ignition core is the same system. The outer combustible shell and the inner ignition core are bonded in situ without any gaps.

[0010] Furthermore, the energetic explosive powder is one or more of RDX, octogen, and hexanitrohexaazaisowulzane, the ignition agent is a microwave-sensitive ignition agent or a laser-sensitive ignition agent, and the sensitive resin bonding system is an acrylate system or an epoxy system.

[0011] Furthermore, the microwave-sensitive ignition agent is one or more combinations of nano-aluminothermic agent, silicon carbide, carbon nanotubes, carbon black, boron / potassium nitrate, and zirconium / potassium perchlorate.

[0012] Furthermore, the laser-sensitive ignition agent is one or more combinations of nano-aluminothermic agents, carbon nanotubes, graphene, nano-aluminum, nano-titanium, energetic coordination compounds, and boron / potassium nitrate.

[0013] The above-mentioned method for preparing an integrated molded energetic ignition component specifically includes the following steps: Step 1: Preparation of outer combustible shell slurry. Mix 60-80 parts of energetic explosive powder, 20-40 parts of photosensitive resin binder system and 0.5-2 parts of additives and stir thoroughly. The photosensitive resin binder system includes 8-15 parts of prepolymer, 5-12 parts of reactive diluent monomer and 1-3 parts of photoinitiator. Step 2, preparation of inner ignition core slurry: mix 70-90 parts of ignition agent, 10-30 parts of photosensitive resin binder system and 0.5-1 part of dispersant evenly. The ignition agent is a laser-sensitive ignition agent or a microwave-sensitive ignition agent. Step 3: DLP photopolymerization 3D printing prepares an integrated molded energetic ignition component. The outer combustible shell slurry and the inner ignition core slurry are added to the two independent slurries of the DLP dual-pool photopolymerization 3D printer for photopolymerization printing. Step 4: Post-processing of the integrated ignition component. The 3D printed integrated component is removed and placed in a UV curing equipment for post-curing treatment. The curing time is 20~60 minutes. Then, the integrated component is placed in a low temperature drying oven and vacuum dried at a temperature of ≤60℃ for 2~4 hours.

[0014] Furthermore, the additives mentioned in step one are dispersant and defoamer in a 1:1 ratio; the prepolymer is one or a mixture of two of epoxy acrylate or polyurethane acrylate; the reactive diluent monomer is one or more of tripropylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate; and the photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and diaryliodomonium salt.

[0015] Furthermore, step three specifically includes the following steps: S31. Model Design: Construct a three-dimensional model of the integrated ignition component using 3D modeling software, clearly defining the outer combustible shell area and the inner ignition core area; import the 3D model into the slicing software of the DLP printing equipment, perform layer slicing processing, set parameters such as single-layer curing thickness and exposure time, and define the material switching path for each layer, i.e., the shell layer corresponds to material pool A, and the ignition core layer corresponds to material pool B1 or B2, and generate the printing control program; S31. Dual Material Pool System Debugging: Select a DLP photopolymerization 3D printing equipment with dual independent material pools. This equipment is equipped with an automatic lifting forming platform, a material pool switching mechanism, and a slurry cleaning mechanism. Load the prepared combustible shell slurry and ignition slurry into the corresponding material pools respectively, and adjust the material pool level and the level of the forming platform to ensure a stable printing process. S33. Layer-by-layer printing, in-situ molding.

[0016] Furthermore, S33 specifically includes the following steps: S331. The lifting molding platform descends below the slurry surface of the combustible shell slurry pool, so that the slurry evenly covers the surface of the molding platform; the DLP light source projects a pattern of the corresponding cross section of the outer combustible shell according to the slice data; S332. The lifting molding platform is slowly raised and separated from the combustible shell slurry pool. The residual shell slurry on the surface of the molding platform is cleaned by the cleaning mechanism to avoid the residual slurry from contaminating the subsequent ignition slurry. The slurry is irradiated with ultraviolet light to achieve photocuring molding of an outer combustible shell. S333. The equipment moves the lifting and forming platform above the inner ignition core slurry pool through the material pool switching mechanism. The lifting and forming platform descends below the slurry surface of the inner ignition core slurry pool. The DLP light source projects the pattern of the corresponding cross section of the inner ignition core. Ultraviolet light irradiation realizes the curing and forming of one layer of ignition core. This layer of ignition core is combined with the lower shell in situ without any gaps. S334. Repeat steps S331 to S333, printing the combustible shell and ignition core layer by layer alternately according to the slicing order and material switching path, until the entire integrated component is printed.

[0017] Furthermore, the photocuring ultraviolet light used in S332 and S333 is 365nm or 405nm ultraviolet light, the curing thickness of the single-layer outer combustible shell and the single-layer ignition core is 20~100μm, and the exposure time is 5~20s.

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Achieve integrated assembly-free molding: The combustible shell and the ignition core are bonded in situ through DLP layer-by-layer photocuring, eliminating the need for subsequent assembly processes. This completely solves the problems of interface gaps, delamination, and assembly defects in traditional pyrotechnics, greatly improving the reliability of ignition and detonation transmission and avoiding faults such as misfires and interruptions in detonation transmission. 2. High molding precision and strong adaptability to complex structures: DLP photopolymerization technology adopts surface exposure molding, and the dimensional accuracy can reach ±20~50μm. It can easily realize the molding of complex structures such as thin walls, porous, irregular shapes, and gradient charges, meet the high precision requirements of micro-sized pyrotechnics, and the molded parts have good consistency. 3. Good material compatibility and strong interface bonding: Improvements to the ignition propellant material enable it to be printed. The addition of laser-sensitive or microwave-sensitive agents allows the laser or microwave ignition shell and the ignition core to use the same system of photosensitive resin as a binder. The curing speed is synchronized, the interface bonding strength is high, and there is no delamination or cracking, ensuring that the ignition energy can be transferred efficiently.

[0019] 4. Precise ignition response, safe and controllable: The microwave / laser ignition propellant's absorption / photosensitive properties can be flexibly controlled through formula adjustments. Ignition delay can reach the millisecond level, with a low energy threshold. It adopts a non-contact ignition method, making it safe to operate and highly controllable, suitable for a variety of complex ignition scenarios. 5. High process flexibility and short R&D cycle: No molds are required. By adjusting the three-dimensional model and slurry formula, integrated ignition components with different structures and properties can be quickly prepared. It is suitable for the R&D and production of small batches and multiple varieties of pyrotechnic products, which greatly shortens the R&D cycle and reduces production costs. Detailed Implementation

[0020] The present invention will be further described below with reference to the scheme and specific embodiments.

[0021] Example 1: Dual-cell DLP printing of an integrated microwave ignition component (CL-20 shell + nAl / CuO ignition propellant) The integrated component prepared in this embodiment has an outer CL-20 combustible shell and an inner nAl / CuO microwave ignition core. The specific steps are as follows: Step 1. Preparation of combustible shell slurry: Weigh 75 parts of CL-20 nanoparticles, 10 parts of epoxy acrylate, 8 parts of TPGDA, 2 parts of photoinitiator 1173, and 1 part of dispersant by weight; add the above components to a ball mill jar, add an appropriate amount of dispersion medium, and ball mill for 2-3 hours until the slurry is uniform and there is no obvious agglomeration, to obtain a high solids content energetic photosensitive slurry for later use.

[0022] Step 2. Preparation of microwave ignition slurry: Weigh out 80 parts by weight of nano-Al / CuO (molar ratio 2:3), 5 parts of SiC, 3 parts of carbon nanotubes, 17 parts of photosensitive resin (epoxy acrylate + TPGDA, mass ratio 10:8), and 11732 parts of photoinitiator; add the above components to a ball mill jar and ball mill and disperse for 1.5~2 hours to obtain a uniform microwave ignition slurry for later use; Step 3. Model Design and Slicing: Construct a three-dimensional model of the integrated component using SolidWorks, with a shell thickness of 0.5 mm, an ignition core diameter of 1 mm, and a height of 5 mm; import the model into slicing software, set the single-layer curing thickness to 30 μm, the exposure time to 10 s, define the material pool A corresponding to the shell layer and the material pool B1 corresponding to the ignition core layer, and generate the printing control program; Step 4. DLP Printing: Select a dual-cell DLP printing device with a 405nm light source. Fill cell A and cell B1 with the prepared slurry. After the device is tested and working properly, start the printing program. The forming stage switches between cell A and cell B1 in sequence to print the shell and ignition core layer by layer until the entire component is printed. Step 5. Post-processing: Remove the printed components and place them in a UV curing device for 30 minutes; then place them in a 50℃ vacuum drying oven for 2 hours to obtain the finished product.

[0023] Performance testing: The finished component was placed in a 2.45GHz, 1kW microwave environment. The ignition delay was 150ms. After ignition, the shell could burn rapidly and undergo stable detonation. There was no separation or cracking at the component interface, and the detonation transmission was reliable. The compressive strength of the shell was ≥15MPa, which met the structural requirements. Example

[0024] Dual-pool DLP printing laser ignition integrated energetic ignition component (HMX shell + B / KNO3 igniter) The integrated component prepared in this embodiment has an outer HMX combustible shell and an inner B / KNO3 laser ignition core. The specific steps are as follows: Step S1. Preparation of combustible shell slurry: Weigh 70 parts of HMX micron powder, 12 parts of polyurethane acrylate, 7 parts of EO-TMPTA, 2 parts of photoinitiator 184, and 1 part of dispersant according to the following mass ratios; add the above components to a ball mill jar and ball mill and disperse for 2 hours to obtain a uniform energetic shell slurry for later use. Step S2. Preparation of laser ignition slurry: Weigh out 80 parts by weight of B / KNO3 (mass ratio 1:3), 4 parts by weight of graphene, 2 parts by weight of carbon nanotubes, 22 parts by weight of photosensitive resin of the same system (polyurethane acrylate + EO-TMPTA, mass ratio 12:7), and 2 parts by weight of photoinitiator 184; add the above components into a ball mill jar and ball mill and disperse for 1.5 h to obtain a uniform laser ignition slurry for later use.

[0025] Step S3. Model Design and Slicing: Construct an integrated 3D model of the component with a shell thickness of 0.4 mm, an ignition core diameter of 0.8 mm, and a height of 4 mm; set the single-layer curing thickness to 25 μm and the exposure time to 8 s in the slicing software, define the material pool A corresponding to the shell layer and the material pool B2 corresponding to the ignition core layer, and generate the printing program; Step S4. DLP Printing: Select a dual-cell DLP printing device with a 365nm light source. After loading the slurry, start printing and print the shell and ignition core layer by layer to complete the molding. Step S5. Post-treatment: UV post-curing for 40 min, vacuum drying at 55℃ for 2.5 h to obtain the finished product.

[0026] Performance testing: The ignition core was ignited using a 1064nm, 5W laser. The ignition delay was 200ms, and the ignition was reliable with no misfires. The shell burned completely, the interface was firmly bonded, and there were no delamination defects, meeting the requirements for laser-ignited pyrotechnics. Example

[0027] Dual-battery DLP printing of microwave-laser dual-sensor ignition integrated energetic ignition component (RDX+HMX shell+composite ignition propellant) The integrated component prepared in this embodiment has an outer layer of RDX+HMX composite combustible shell and an inner layer of microwave-laser dual-sensitive ignition core. The specific steps are as follows: Step S1. Preparation of combustible shell slurry: Weigh out 35 parts of RDX, 35 parts of HMX, 10 parts of epoxy acrylate, 8 parts of TPGDA, 2 parts of photoinitiator diaryliodonium salt, 1 part of dispersant, and 0.5 parts of defoamer by weight; ball mill and disperse for 3 hours to obtain a uniform composite energetic shell slurry for later use. Step S2. Preparation of dual-sensitive ignition slurry: Weigh out 90 parts of nAl / Fe2O3, 8 parts of SiC, 5 parts of graphene, 7 parts of B / KNO3, 18 parts of photosensitive resin of the same system, and 2 parts of photoinitiator diaryliodonium salt according to the mass ratio; ball mill and disperse for 2 hours to obtain microwave-laser dual-sensitive ignition slurry for later use.

[0028] In this embodiment, the model design, printing, and post-processing steps all refer to the process parameters of Embodiment 1 to complete the printing and post-processing of the integrated component.

[0029] Performance testing: Microwave (2.45GHz, 0.8kW) ignition delay is 180ms, laser (808nm, 4W) ignition delay is 220ms, both ignition methods are reliable; the shell detonation performance is stable, the interface bonding strength is high, and it is suitable for ignition scenarios in complex environments.

[0030] Those skilled in the art should understand that the above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated molded energetic ignition component, characterized in that, It includes an outer combustible shell and an inner ignition core. The outer combustible shell is composed of energetic explosive powder and a photosensitive resin bonding system, and the inner ignition core is composed of an ignition agent and a photosensitive resin binder. The photosensitive resin bonding system used for the outer combustible shell and the inner ignition core is the same system. The outer combustible shell and the inner ignition core are bonded in situ without any gaps.

2. The integrated molded energetic ignition component according to claim 1, characterized in that, The energetic explosive powder is one or more of RDX, octogen, and hexanitrohexaazaisowulzane; the ignition agent is a microwave-sensitive ignition agent or a laser-sensitive ignition agent; and the sensitive resin bonding system is an acrylate system or an epoxy system.

3. The integrated molded energetic ignition component according to claim 2, characterized in that, The microwave-sensitive ignition agent is one or more combinations of nano-aluminothermic agent, silicon carbide, carbon nanotubes, carbon black, boron / potassium nitrate, and zirconium / potassium perchlorate.

4. The integrated molded energetic ignition component according to claim 2, characterized in that, The laser-sensitive ignition agent is one or more combinations of nano-aluminothermic agents, carbon nanotubes, graphene, nano-aluminum, nano-titanium, energetic coordination compounds, and boron / potassium nitrate.

5. A method for preparing an integrated molded energetic ignition component according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Preparation of outer combustible shell slurry. Mix 60-80 parts of energetic explosive powder, 20-40 parts of photosensitive resin binder system and 0.5-2 parts of additives and stir thoroughly. The photosensitive resin binder system includes 8-15 parts of prepolymer, 5-12 parts of reactive diluent monomer and 1-3 parts of photoinitiator. Step 2, preparation of inner ignition core slurry: mix 70-90 parts of ignition agent, 10-30 parts of photosensitive resin binder system and 0.5-1 part of dispersant evenly. The ignition agent is a laser-sensitive ignition agent or a microwave-sensitive ignition agent. Step 3: DLP photopolymerization 3D printing prepares an integrated molded energetic ignition component. The outer combustible shell slurry and the inner ignition core slurry are added to the two independent slurries of the DLP dual-pool photopolymerization 3D printer for photopolymerization printing. Step 4: Post-processing of the integrated ignition component. The 3D printed integrated component is removed and placed in a UV curing equipment for post-curing treatment. The curing time is 20~60 minutes. Then, the integrated component is placed in a low temperature drying oven and vacuum dried at a temperature of ≤60℃ for 2~4 hours.

6. The method for preparing an integrated molded energetic ignition component according to claim 5, characterized in that, The additives mentioned in step one are dispersant and defoamer in a 1:1 ratio. The prepolymer is one or a mixture of two of epoxy acrylate or polyurethane acrylate. The reactive diluent monomer is one or more of tripropylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate. The photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and diaryliodonium salt.

7. The method for preparing an integrated molded energetic ignition component according to claim 5, characterized in that, Step three specifically includes the following steps: S31. Model Design: Construct a three-dimensional model of the integrated ignition component using 3D modeling software, clearly defining the outer combustible shell area and the inner ignition core area; import the 3D model into the slicing software of the DLP printing equipment, perform layer slicing processing, set parameters such as single-layer curing thickness and exposure time, and define the material switching path for each layer, i.e., the shell layer corresponds to material pool A, and the ignition core layer corresponds to material pool B1 or B2, and generate the printing control program; S31. Dual Material Pool System Debugging: Select a DLP photopolymerization 3D printing equipment with dual independent material pools. This equipment is equipped with an automatic lifting forming platform, a material pool switching mechanism, and a slurry cleaning mechanism. Load the prepared combustible shell slurry and ignition slurry into the corresponding material pools respectively, and adjust the material pool level and the level of the forming platform to ensure a stable printing process. S33. Layer-by-layer printing, in-situ molding.

8. The method for preparing an integrated molded energetic ignition component according to claim 7, characterized in that, S33 specifically includes the following steps: S331. The lifting molding platform descends below the slurry surface of the combustible shell slurry pool, so that the slurry evenly covers the surface of the molding platform; the DLP light source projects a pattern of the corresponding cross section of the outer combustible shell according to the slice data; S332. The lifting molding platform is slowly raised and separated from the combustible shell slurry pool. The residual shell slurry on the surface of the molding platform is cleaned by the cleaning mechanism to avoid the residual slurry from contaminating the subsequent ignition slurry. The slurry is irradiated with ultraviolet light to achieve photocuring molding of an outer combustible shell. S333. The equipment moves the lifting and forming platform above the inner ignition core slurry pool through the material pool switching mechanism. The lifting and forming platform descends below the slurry surface of the inner ignition core slurry pool. The DLP light source projects the pattern of the corresponding cross section of the inner ignition core. Ultraviolet light irradiation realizes the curing and forming of one layer of ignition core. This layer of ignition core is combined with the lower shell in situ without any gaps. S334. Repeat steps S331 to S333, printing the combustible shell and ignition core layer by layer alternately according to the slicing order and material switching path, until the entire integrated component is printed.

9. The method for preparing an integrated molded energetic ignition component according to claim 8, characterized in that, The photocuring ultraviolet light used in S332 and S333 is 365nm or 405nm ultraviolet light, the curing thickness of the single-layer outer combustible shell and the single-layer ignition core is 20~100μm, and the exposure time is 5~20s.