Study On 3D-Printed Shaped Energetic Grain And Its Properties

In order to solve the problems of poor adaptability,poor safety,tedious process,and high cost in the forming process of shaped energetic grains,aiming at providing the theoretical and technical basis for the 3D printing and molding of special-shaped energetic grain.The single-factor optimization method and orthogonal experimental design were used to obtain the light-curing resin formulation.Aluminum powder?AL?was coated by organic monomer copolymerization to improve the dispersion of Al in light cured resin.Ammonium perchlorate?AP?was refined by recrystallization to improve the suspension of AP in resin.The processed Al and AP meet the requirements of 3D printing paste for solid fillers.The 3D printed energetic paste was prepared,and the special-shaped energetic grains was printed and formed by the X8.9-type light-curing 3D printer,and the shaped grains had higher accuracy and better comprehensive performance.The details are as follows:?1?Combined with the single-factor optimization method,an orthogonal experiment design of 4 factors and 3 levels was carried out for the formulation of UV light curing resin,and the formulation of UV light curing resin with excellent comprehensive performance was obtained as follows:EA 44.06%?PUA 21.98%?HDDA 14.15%?TMPTA 14.15%?TPO 4.72%?Additive 0.94%%,The curing speed of the UV curing resin is 3.2 s,the viscosity is 197 mPa·s,the hardness is 2H,the adhesion force is 2,the gelation rate is 95.20%,and the shrinkage rate is 5.85%.?2?Different monomer combinations of HPA/BA,St/BA,AA/BA and MMA/BA were selected as coating agents.With the aid of mechanochemical force,the aluminum powder pretreated by SDS was coated by the copolymerization of organic monomers.The dispersion settlement experiment showed that the dispersion of aluminum powder coated by different monomer combinations in the UV-cured resin was significantly improved,and the dispersion of Al coated by HPA/BA was the best.FTIR,XRD and SEM analysis showed that the surface of aluminum powder adsorbed organic polymer monomer.?3?Using DMF as the solvent and EAC as the non-solvent,AP with a particle size of about 3 mm was ultra-refined by solvent-non-solvent recrystallization.The particle size of the AP after ultra-refining is about 8?m,the dispersibility and uniformity of AP particles are good,and the dispersion and suspension of ultrafine AP in the resin is improved.The particle size of the AP after ultra-refining is about 8?m,and the dispersibility and uniformity of the AP particles are good.Relatively good experimental conditions obtained by single factor analysis are:DMF is the solvent and EAC is the non-solvent,V_?solvent?:V_{?non-solvent?}is 1:10,initial AP solution concentration is 10%,water bath?precipitation?temperature is 60?,the stirring speed is 800 rmp,and the AP solution dropping acceleration is 0.5 mL/min.?4?Using light curing 3D printing technology,and setting the appropriate printing parameters on the X8.9 printer,the special-shaped energetic grain of the energetic slurry?self-made light curing resin/ultra-fined AP/modified Al=48%/41%/11%?were successfully the printed and formed.The performance test results of the grains show that:The surface of the light-cured 3D printed grain is smooth,the internal structure is dense,and there are no defects such as bubbles and cracks.The density of the grain is1.606 g/cm³,which is 3.7%higher than that of the mold-casting and curing molding grain,and the uniformity and stability of the density are better.The study on combustion performance study showed that the combustion of the grain was intense and the"platform effect"appeared during the combustion,indicating that the combustion of the grain was uniform,and the average burning rate of the grain was 7.11 mm/s.Differential thermal analysis showed that the grain was divided into three stages of endothermic-exothermic-secondary exothermic during the heating process,and the exothermic enthalpy H is 758.10 J/g.The quasi-static mechanical property test showed that the average compressive strength of the grain was 9.83 MPa,which was 315%higher than the mould solidified grain,and the compression ratio was 2.1%,which was an increase of 90.9%.The tensile strength at break of the printed test specimen was9.8171 MPa,which was an increase of 11.76%,and the tensile fracture stress was9.0800 MPa,which was an increase of 39.96%.