Abstract

In order to solve the problems of the complicated forming process, poor adaptability, low safety, and high cost of special-shaped energetic grains, light-curing 3D printing technology was applied to the forming field of energetic grains, and the feasibility of 3D printing (additive manufacturing) complex special-shaped energetic grains was explored. A photocurable resin was developed. A demonstration formula of a 3D printing energetic slurry composed of 41 wt% ultra-fine ammonium perchlorate (AP), 11 wt% modified aluminum (Al), and 48 wt% photocurable resin was fabricated. The special-shaped energetic grains were successfully 3D printed based on light-curing 3D printing technology. The optimal printing parameters were obtained. The microstructure, density, thermal decomposition, combustion performance, and mechanical properties of the printed grain were characterized. The microstructure of the grain shows that the surface of the grain is smooth, the internal structure is dense, and there are no defects. The average density is 1.606 g·cm−3, and the grain has good uniformity and stability. The thermal decomposition of the grain shows that it can be divided into three stages: endothermic, exothermic, and secondary exothermic, and the Al of the grain has a significant catalytic effect on the thermal decomposition of AP. The combustion performance of the grain shows that a uniform flame with a one-way jet is produced, and the average burning rate is 5.11 mm·s−1. The peak pressure of the sample is 45.917 KPa, and the pressurization rate is 94.874 KPa·s−1. The analysis of the mechanical properties shows that the compressive strength is 9.83 MPa and the tensile strength is 8.78 MPa.

Highlights

  • Special-shaped energetic grains can realize special functions and needs due to their special shape [1], complex structure, and partial or full height symmetry, which makes their demand in the fields of weaponry and aerospace more urgent [2]

  • In the field of weaponry, propellant is used as the energy source for barrel weapons to launch projectiles, and its composition and structure are the key factors that determine the power of the barrel weapon [3]

  • Improving ballistic efficiency is an important means to improve the power of a weapon [4]; at present, the main way to improve the ballistic efficiency of a propellant is to control the burning rate and burning surface of the propellant, and this requires special-shaped propellant grains to achieve

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Summary

Introduction

Special-shaped energetic grains can realize special functions and needs due to their special shape [1], complex structure, and partial or full height symmetry, which makes their demand in the fields of weaponry and aerospace more urgent [2]. The additive manufacturing technologies applied in the field of energetic material forming mainly include direct writing technology [17–23], melt extrusion technology [24], inkjet deposition printing technology [25–27], screen printing technology [28], and electrophoretic deposition technology [29]. Light-curing 3D printing technology is applied to the forming field of energetic materials to realize an efficient, safe, green, convenient and automated mold-free production pattern of complex special-shaped energetic grains. TNO researchers used SLA to print a photocurable energetic resin composed of 50 wt% RDX and 50 wt% UV polymerizable acrylate binder, and quincunx propellant grains with 19 longitudinal and radial perforations were obtained. 50 wt% RDX, 25 wt% acrylate binder, and 25 wt% energetic plasticizer was printed, and a new type of high bulk density propellant grain sample with 14 perforations was obtained. The microstructure, density and uniformity, thermal decomposition, combustion performance and mechanical properties of the printed grains were characterized

Experimental Materials
Characterization and Testing
Formula and Preparation of Energetic Slurry
Optimization of Printing Component
Optimization of Printing Parameters
Experimental Process of Light-Curing 3D Printing
Density and Uniformity Test
Surface and Internal Structure
Tensile compressive tests were tested
Analysis of Thermal Decomposition Behavior
12. DTA of the
Analysis of Combustion Characteristics
15. Combustion effect of diagram of the 3D-printed graintimes: at different
Conclusions
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