High-energy solid propellant additive manufacturing method based on adhesive spraying

Abstract

The invention relates to the technical field of high-energy solid propellant additive manufacturing, and particularly discloses a high-energy solid propellant additive manufacturing method based on adhesive spraying, which comprises the following steps: uniformly mixing a metal fuel component and an oxidant component to obtain uniformly dispersed solid particles; uniformly mixing the adhesive components to obtain an adhesive system; flatly paving the solid particles in a powder supply cylinder of the adhesive jet printer; loading the adhesive system into an extrusion device of an adhesive jet printer; a solid propellant grain model is designed according to computer software, and a printing file is obtained through software slicing; the adhesive jet printer jets an adhesive system layer by layer according to a printing file path to form a printing sample piece; and the printing sample piece is placed in a drying oven to be cross-linked and cured, and the high-energy solid propellant grain is obtained. The method can realize support-free rapid manufacturing of the high-energy solid propellant at room temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of high-energy solid propellant additive manufacturing, and in particular to a high-energy solid propellant additive manufacturing method based on binder jetting. Background Art

[0002] The traditional preparation of solid propellant grains is divided into several steps: mixing-pouring-curing-demolding-shaping. The operation is complicated, time-consuming, and a large proportion of manual labor is required. Therefore, additive manufacturing of solid propellant technology has been widely studied. It can not only simplify the process and eliminate the demolding and shaping steps, but also realize automated production and the printing of complex-shaped grains. However, the current additive manufacturing propellant technologies are mostly thermoplastic extrusion and photocuring, both of which are difficult to achieve unsupported printing. There is a chemical exothermic reaction during photocuring, and there are certain safety hazards in the processing of high-energy solid propellants. In addition, when preparing to print the slurry, the solid components and liquid components need to be mixed. There is friction and extrusion between the solid components during printing, which poses a risk of combustion and explosion. Summary of the invention

[0003] In view of the above problems, the first object of the present invention is to provide a high-energy solid propellant additive manufacturing method based on binder jetting. The method adopts binder jetting to perform additive manufacturing of high-energy solid propellant. During the printing process, there is only simple physical bonding between the binder and the solid particles, and no chemical reaction occurs. During the printing process, the system temperature is controllable and there is no safety risk. The high-energy solid propellant can be rapidly manufactured without support at room temperature, and the process is safe and controllable.

[0004] The first technical solution adopted by the present invention is: a high-energy solid propellant additive manufacturing method based on binder jetting, comprising the following steps:

[0005] S1: uniformly mixing the metal fuel component and the oxidant component to obtain uniformly dispersed solid particles; uniformly mixing the binder component to obtain a binder system;

[0006] S2: evenly laying the solid particles in a powder supply cylinder of a binder jet printer; loading the binder system into an extruder of the binder jet printer;

[0007] S3: Design the solid propellant grain model according to the computer software and obtain the printing file through software slicing;

[0008] S4: The binder jet printer jets the binder system according to the printing file path. After the forming cylinder of the binder jet printer completes printing of one layer, the solid particles are laid from the powder supply cylinder to the forming cylinder to print the next layer. The binder jet printer jets the binder system layer by layer according to the printing file path to form a printed sample.

[0009] S5: After printing is completed, the printed sample is left in the molding cylinder, and the molding cylinder is placed in an oven for cross-linking and curing to obtain a high-energy solid propellant grain.

[0010] Preferably, the metal fuel component includes one or more of aluminum powder, magnesium powder, and aluminum-lithium alloy powder.

[0011] Preferably, the oxidant component comprises one or more of ammonium perchlorate, octogen, hexogen, and hexanitrohexaazaisowurtzitane.

[0012] Preferably, the adhesive component is a polymer that can be blended with nitrate esters, including an adhesive, a plasticizer, a molding aid and a curing agent; in the adhesive system, the adhesive is 20%-40%, the plasticizer is 50%-70%, the molding aid is 2%-20%, and the curing agent is 0.1%-1%.

[0013] Preferably, the binder comprises one or more of polyazide glycidyl ether, polyethylene glycol, and terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether.

[0014] Preferably, the plasticizer includes one or more of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN); and the curing agent includes multifunctional aliphatic isocyanate (N-100).

[0015] Preferably, the molding aid is a thermoplastic polymer material.

[0016] Preferably, the step S1 comprises: uniformly mixing the metal fuel component and the oxidant component by dry mixing or wet mixing; and the mass ratio of the metal fuel component in the solid particles is less than 50%.

[0017] Preferably, the step S2 comprises: laying the solid particles evenly in a powder supply cylinder of a binder jet printer, and keeping the temperature at 20°C to 90°C; loading the binder system into an extruder of the binder jet printer, and keeping the temperature at 20°C to 90°C.

[0018] Preferably, the step S5 comprises: placing the molding cylinder in an oven at 40° C. to 70° C. for cross-linking and curing for 5 to 7 days.

[0019] Beneficial effects of the above technical solution:

[0020] (1) The present invention provides a high-energy solid propellant additive manufacturing method based on binder jetting, which uses a binder jetting method to perform additive manufacturing of high-energy solid propellants. During the printing process, there is only simple physical bonding between the binder and the solid particles, and no chemical reaction occurs. During the printing process, the system temperature is controllable and there is no safety risk. The high-energy solid propellant can be rapidly manufactured at room temperature without support, and the process is safe and controllable.

[0021] (2) The present invention adopts a binder jetting method for additive manufacturing of high-energy solid propellants. The nozzle prints a viscous liquid, which eliminates the risk of nozzle clogging. This makes it easy to control the solid content of the final printed high-energy solid propellant and achieves a higher printing accuracy.

[0022] (3) The present invention adopts a binder jetting method to carry out additive manufacturing of high-energy solid propellants. The binder jetting printing of high-energy solid propellants is carried out in a powder bed, and support-free stacking printing can be performed to achieve the preparation of propellant grains with complex structures.

[0023] (4) Binder jetting technology is an additive manufacturing technology based on the powder bed process. A viscous liquid binder is spread layer by layer on a solid particle powder bed through a printing nozzle, thereby achieving layer-by-layer bonding of the solid particles and the binder, and finally forming a printed sample. Therefore, the present invention adopts binder jetting technology to carry out additive manufacturing of high-energy solid propellants. The binder system is stored in the silo of the printing extrusion device, and the metal fuel and oxidant system are evenly filled in the powder bed. The binder is sprayed out from the nozzle and fully combined with the solid particles in the powder bed. The layers are printed and stacked layer by layer, so that the high-energy solid propellant can be manufactured rapidly at room temperature without support. Only the liquid component is extruded during printing, and the process is safe and controllable.

[0024] (5) The present invention can greatly improve the shaping efficiency and molding accuracy of the sprayed adhesive by adding a thermoplastic polymer material as a molding aid into the adhesive system.

[0025] (6) The present invention can print with a high solid content; the high-energy solid propellant of the nitrate system generally has a solid content of 75%-80% to ensure castability; 3D printing technologies such as photocuring and direct writing extrusion require the propellant materials to be completely mixed before printing, and the solid content is generally between 75%-85%; the use of the binder jetting method to prepare high-energy solid propellants only requires extrusion of the liquid component, without worrying about the extrusion difficulties and low safety caused by the high solid content. The solid content of the high-energy solid propellant prepared by this method can reach up to about 95%, which also means a higher energy level;

[0026] Moreover, the additive manufacturing of high-energy solid propellants using the binder jetting method has good controllability. In this method, the ratio of thermoplastic molding aids and thermosetting adhesives (such as adhesives GAP and N100 react to form a cross-linked structure) in the adhesive system can be freely adjusted. The former helps to quickly set the shape, and the latter can provide higher mechanical properties after a period of post-curing. Binder jet printing of high-energy solid propellants in a powder bed can be carried out without support stacking printing, thereby realizing the preparation of propellant grains with complex structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a high-energy solid propellant additive manufacturing method based on binder jetting provided in accordance with one embodiment of the present invention;

[0028] Among them, 1-powder scraping baffle; 2-extrusion device; 3-solid particles; 4-binder system; 5-propellant column; 6-powder supply baffle; 7-powder supply cylinder; 8-forming baffle; 9-forming cylinder. DETAILED DESCRIPTION

[0029] The present invention is further described below through specific embodiments. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the principle of the present invention, and these should also be regarded as belonging to the protection scope of the present invention.

[0030] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

[0031] like Figure 1 As shown, the present invention discloses a high-energy solid propellant additive manufacturing method based on binder jetting, comprising the following steps:

[0032] S1: uniformly mix the metal fuel component and the oxidant component to obtain uniformly dispersed solid particles; uniformly mix the adhesive component to obtain an adhesive system; the adhesive system comprises 20%-40% of the adhesive, 50%-70% of the plasticizer, 2%-20% of the molding aid, and 0.1%-1% of the curing agent.

[0033] S2: laying the solid particles 3 evenly in the powder supply cylinder 7 of the binder jet printer, and keeping the temperature at 20°C to 90°C; loading the binder system 4 into the extruder 2 of the binder jet printer, and keeping the temperature at 20°C to 90°C;

[0034] S3: Design the solid propellant grain model according to the computer software and obtain the printing file through software slicing;

[0035] S4: The binder jet printer jets the binder system according to the printing file path. After the forming cylinder 9 completes printing of one layer, the forming baffle 8 descends to a layer thickness, the powder supply baffle 6 ascends to a layer thickness, and the powder scraping baffle 1 spreads the solid particles 3 from the powder supply cylinder 7 to the forming cylinder 9 to print the next layer. The binder jet printer jets the binder system layer by layer according to the printing file path to form a printed sample.

[0036] S5: After printing is completed, the printed sample is left in the molding cylinder, and the molding cylinder is placed in a 40°C to 70°C oven for cross-linking and curing for 5 to 7 days; after curing is completed, the loose powder on the surface of the printed sample is removed to obtain a printed high-energy solid propellant grain 5.

[0037] Among them, the mass ratio of solid particles in the high-energy solid propellant grain is 70% to 95%; the mass ratio of metal fuel components in the solid particles is less than 50%.

[0038] The metal fuel component includes but is not limited to one or more of active metal powders such as aluminum powder, magnesium powder, and aluminum-lithium alloy powder; the oxidant component includes but is not limited to one or more of ammonium perchlorate, octogen, hexogen, hexanitrohexaazaisowurtzitane (CL-20), etc.

[0039] The metal fuel component and the oxidizer component are mixed by dry mixing or wet mixing to make the various solid particles evenly distributed without agglomeration, so as to ensure that the composition of the final solid propellant grain is uniform.

[0040] The adhesive component is a thermosetting adhesive mainly composed of a polyether adhesive system plasticized by nitrate ester; the adhesive component is a polymer that can be blended with nitrate ester, and the adhesive component includes an adhesive, a plasticizer, a molding aid and a curing agent; the adhesive includes but is not limited to one or more of polyazide glycidyl ether (GAP), polyethylene glycol (PEG), and terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether (PET); the plasticizer includes but is not limited to one or more of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN); the curing agent includes but is not limited to multifunctional aliphatic isocyanate (N-100); the molding aid is a thermoplastic polymer material, including but not limited to polyethylene glycol, polycaprolactone diol, tri-(ethoxyphenyl) bismuth (TEPB) and GAP-based energetic thermoplastic polymers (such as GAP thermoplastic elastomers) with a softening point below 70°C and soluble in the nitrate ester system.

[0041] Example 1

[0042] Aluminum powder (Al), ammonium perchlorate (AP), and octogen (HMX) are selected as solid particle materials, and a thermosetting adhesive system (multifunctional aliphatic isocyanate / polyazide glycidyl ether / nitroglycerin / 1,2,4-butanetriol trinitrate) (N-100 / GAP / NG / BTTN) and an auxiliary agent tri-(ethoxyphenyl) bismuth (TEPB) are selected as the adhesive system. The high-energy solid propellant formula based on binder jetting is shown in Table 1:

[0043] Table 1 Recipe Examples

[0044] Recipe composition Mass content% GAP 6 NG 3.5 BTTN 3.5 GAP Thermoplastic Elastomer 1 AP 40 Al 17 N-100 0.99 HMX 28 TEPB 0.01

[0045] A high-energy solid propellant additive manufacturing method based on binder jetting comprises the following steps:

[0046] S1: The Al, AP, and HMX are mixed in cyclohexane by stirring and ultrasonication, and uniformly dispersed solid particles are obtained after the solvent is completely volatilized; the adhesive component N-100 / GAP / NG / BTTN / GAP thermoplastic elastomer and TEPB are uniformly mixed at 50° C. to obtain an adhesive system to be printed;

[0047] S2: the solid particles 3 are evenly laid in the powder supply cylinder 7 of the binder jet printer, and the temperature is kept at 45°C; the binder system 4 is loaded into the extruder 2 of the binder jet printer, and the temperature is kept at 45°C;

[0048] S3: Design the solid propellant grain model according to the computer software and obtain the printing file through software slicing;

[0049] S4: The binder jet printer jets the binder system according to the printing file path. After the forming cylinder 9 completes printing of a layer, the forming baffle 8 descends by the layer thickness, the powder supply baffle 6 rises by the layer thickness, and the powder scraping baffle 1 spreads the solid particles from the powder supply cylinder 7 to the forming cylinder 9 to print the next layer. The binder jet printer jets the binder system layer by layer according to the printing file path to realize layer-by-layer printing until the entire printed sample is completed;

[0050] S5: After printing is completed, the sample is left in the molding cylinder, and the molding cylinder is placed in a 50° C. oven for cross-linking and curing for 5 days; after curing is completed, loose powder on the surface of the sample is removed to obtain a printed high-energy solid propellant grain 5.

[0051] Example 2

[0052] Aluminum powder (Al), ammonium perchlorate (AP), and hexanitrohexaazaisowurtzitane (CL-20) are selected as solid particle materials, and a thermosetting adhesive system (multifunctional aliphatic isocyanate / terminated hydroxyl ethylene oxide-tetrahydrofuran copolyether / nitroglycerin / 1,2,4-butanetriol trinitrate) (N-100 / PET / NG / BTTN) and an auxiliary agent tri-(ethoxyphenyl) bismuth (TEPB) are selected as the adhesive system. The high-energy solid propellant formula based on adhesive jetting is shown in Table 2:

[0053] Table 2 Formulation examples

[0054] Recipe composition Mass content% PET 8 NG 3.5 BTTN 3.5 AP 20 Al 16 N-100 0.99 CL-20 48 TEPB 0.01

[0055] A high-energy solid propellant additive manufacturing method based on binder jetting comprises the following steps:

[0056] S1: The Al, AP, and CL-20 are mixed in cyclohexane by stirring and ultrasonication, and uniformly dispersed solid particles are obtained after the solvent is completely volatilized; the adhesive components N-100 / PET / NG / BTTN and TEPB are uniformly mixed at 50° C. to obtain an adhesive system to be printed;

[0057] S2: the solid particles 3 are evenly laid in the powder supply cylinder 7 and kept at 40°C, and the binder system 4 is loaded into the extrusion device 2 of the binder jet printer and kept at 50°C;

[0058] S3: Design the solid propellant grain model according to the computer software and obtain the printing file through software slicing;

[0059] S4: The binder jet printer jets the binder system according to the printing file path. After a layer of printing is completed in the forming cylinder 9, the forming baffle 8 descends by the layer thickness, the powder supply baffle 6 rises by the layer thickness, and the powder scraping baffle 1 spreads the solid particles from the powder supply cylinder 7 to the forming cylinder 9 to print the next layer. The binder jet printer jets the binder system layer by layer according to the printing file path to realize layer by layer printing until the entire printed sample is completed;

[0060] S5: After printing is completed, the sample is left in the molding cylinder, and the molding cylinder is placed in a 50° C. oven for cross-linking and curing for 5 days; after curing is completed, loose powder on the surface of the sample is removed to obtain a printed high-energy solid propellant grain 5.

[0061] The present invention stores the binder system and solid particle components of the high-energy solid propellant separately, lays the evenly mixed solid particle components (such as reducing metal powders such as aluminum powder, magnesium powder, aluminum-lithium alloy powder, and oxidant components such as ammonium perchlorate, octogen, hexogen, CL-20, etc.) into a flat powder bed, sprays the binder system layer by layer through a nozzle, combines with the solid particles for printing and forming, and finally cures the entire system for 5 to 7 days under appropriate conditions to obtain the final high-energy solid propellant grain with a complex shape; the present invention can realize the rapid manufacturing of high-energy solid propellant at room temperature without support, and the process is safe and controllable.

[0062] The present invention is described in detail above in combination with specific implementation methods and exemplary examples. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments; the above description cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, the technical solution of the present invention and its implementation methods may be subjected to a variety of equivalent substitutions, modifications or improvements, all of which fall within the scope of the present invention; the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A high energy solid propellant additive manufacturing method based on binder jetting, characterized in that: The following steps are involved: S1: uniformly mixing the metal fuel component and the oxidant component to obtain uniformly dispersed solid particles; uniformly mixing the binder component to obtain a binder system; S2: evenly laying the solid particles in a powder supply cylinder of a binder jet printer; loading the binder system into an extruder of the binder jet printer; S3: Design the solid propellant grain model according to the computer software and obtain the printing file through software slicing; S4: The binder jet printer jets the binder system according to the print file path. After the forming cylinder of the binder jet printer completes printing of one layer, the solid particles are laid from the powder supply cylinder to the forming cylinder to print the next layer. The binder jetting printer jets the binder system layer by layer according to the printing file path to form a printed sample; S5: After printing is completed, the printed sample is left in the molding cylinder, and the molding cylinder is placed in an oven for cross-linking and curing to obtain a high-energy solid propellant grain.

2. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The metal fuel component includes one or more of aluminum powder, magnesium powder, and aluminum-lithium alloy powder.

3. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The oxidant component includes one or more of ammonium perchlorate, octogen, hexogen, and hexanitrohexaazaisowurtzitane.

4. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The adhesive component is a polymer that can be blended with nitrate ester, including an adhesive, a plasticizer, a molding aid and a curing agent; in the adhesive system, the adhesive is 20%-40%, the plasticizer is 50%-70%, the molding aid is 2%-20%, and the curing agent is 0.1%-1%.

5. The high energy solid propellant additive manufacturing method according to claim 4, characterized in that: The adhesive comprises one or more of polyazide glycidyl ether, polyethylene glycol, and terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether.

6. The high energy solid propellant additive manufacturing method according to claim 4, characterized in that: The plasticizer includes one or more of nitroglycerin (NG) and 1,2,4-butanetriol trinitrate (BTTN); and the curing agent includes multifunctional aliphatic isocyanate (N-100).

7. The high energy solid propellant additive manufacturing method according to claim 4, characterized in that: The molding aid is a thermoplastic polymer material.

8. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The step S1 comprises: uniformly mixing the metal fuel component and the oxidant component by dry mixing or wet mixing; and the mass ratio of the metal fuel component in the solid particles is less than 50%.

9. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The step S2 comprises: laying the solid particles evenly in a powder supply cylinder of a binder jet printer, and keeping the temperature at 20°C to 90°C; loading the binder system into an extruder of the binder jet printer, and keeping the temperature at 20°C to 90°C.

10. The high energy solid propellant additive manufacturing method according to claim 1, characterized in that: The step S5 comprises: placing the molding cylinder in an oven at 40° C. to 70° C. for cross-linking and curing for 5 to 7 days.

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