3D printing of gun propellants based on laminated object manufacturing

ABSTRACT The preparation of complex geometry gun propellant to improve combustion progressivity by conventional extrusion processes has been a challenge. An efficient and scalable 3D printing approach based on laminated object manufacturing (LOM) for gun propellant was proposed. A demonstration of the rosette-shaped 61-perf double-base gun propellant using conventional sheet double-base gun propellant and volatile solvent ethyl acetate was printed by a self-developed printer. The printed gun propellants were characterized in terms of printing qualities, mechanical properties, and combustion performances. The standard deviations of inner diameter and web thickness were 0.031 mm and 0.023 mm respectively. Moreover, its density (1.623 g·cm−3) was comparable to that of conventional double-based gun propellants. The tensile strength, compression strength, and impact strength were 10.37 MPa, 74.13 MPa, and 5.60 kJ·m−2, respectively. Importantly, the dynamic vivacity curve tested by the closed vessel matched the theoretical curve well, with a dynamic vivacity increment of 0.23 MPa−1·s−1. This indicated that printed grain has the highest progressive combustion (35% improvement) of the multi-perforated gun propellants to date. Hence, the gun propellant LOM process offers an attractive route to prepare complex geometry gun propellants with higher progressive combustion, breaking the technological bottleneck in the field of gun propellant manufacturing.