Stacking effects on dynamic mechanical behavior of bilayer hexagonal boron nitride under impact

Abstract

Hexagonal boron nitride (h-BN) is a promising material for ballistic armor due to its excellent mechanical properties, enriched by different bilayer stacking arrangements. Molecular dynamics methods are used to study the stacking effects on the static and dynamic mechanical properties of bilayer h-BN. The AB (nitrogen) stacked bilayer structure attracts our attention because of its superior interlayer synergistic ability to resist projectile indentation up to a maximum force of 152.89 nN, which is about 22.9 % higher than the average value of other stacked bilayers. The impact response of bilayer h-BN with AB (nitrogen) stacking arrangement is then investigated at velocities of 2–4 km/s, which has the highest critical perforation velocity of 3.075 km/s, increased by 36.7 % compared to monolayer h-BN. At a low impact velocity of 2.5 km/s, the AB (nitrogen) stacked h-BN bilayer spends the shortest time to dissipate the impact energy of projectile and remains intact, while the top layers of other stacked bilayers are penetrated. At high impact velocities, a perforation event occurs, accompanied by multiple deflections of crack tips from zigzag to armchair to zigzag again, which intrinsically enhances the toughness of material. This study provides more understanding of the dynamic mechanical behavior of bilayer h-BN, as well as the design of armor structures based on stacking arrangements of 2D materials.