Constructing a two-layer oblique honeycomb sandwich structure by LCD 3D printing for efficient electromagnetic wave absorbing.

• A kind of two-layer oblique honeycomb sandwich structure of flaky carbonyl iron powder/photosensitive resin composites with high precision was prepared by liquid crystal display (LCD) 3D printing method. • The structure is beneficial to improve the microwave absorption strength, and has the characteristics of light weight and low material consumption. • LCD 3D printing technology has the advantages of high precision, free forming and less time consumption. Carbonyl iron powder (CIP) is one of the most widely used magnetic loss absorbents due to its high saturation magnetization, strong wave absorption performance and low cost. However, CIP has a very high density (7.86 g/cm2) and requires a high addition amount (more than 50 wt%) when used as a microwave absorbing filler, which leads to high weight and low mechanical properties of the composite. Taking the diverse attenuation mechanisms during the electromagnetic energy conversion process into considerations, this paper designs a two-layer oblique honeycomb sandwich structure, which was prepared by liquid crystal display (LCD) 3D printing. This structure combines porous structure with strong absorbing materials to achieve strong electromagnetic wave (EMW) absorption performance at low concentrations and improve mechanical properties. When the inclined honeycomb core angle is 15° with only 15 wt% FCIP addition, the EMW absorption and mechanical properties of the composite are significantly improved compared with the full-filled structure. [ABSTRACT FROM AUTHOR]