Near-zero expansion of ceramics by 3D printing thermally induced torsional structures

Structural materials with high bearing capacity and low expansion have great application demand in precision instruments. Negative Poisson's ratio structure with thermally induced torsion ability is promising as the structure stretching, bending, and twisting can disperse the thermal stress. Besides, the thermal expansion performance can be further optimized by the coordinating control of macrostructure and composition. Herein, the work investigated the bearing capacity and expansion behavior of Negative Poisson's ratio structures fabricated by digital light processing (DLP) 3D printing. Negative expansive LiAlSiO₄ was further introduced to reduce thermal expansion. The thermal shrinkage of the LiAlSiO₄ compensated for the volume change caused by thermal expansion. Ultimately, the LiAlSiO₄ infiltrated Negative Poisson's ratio structures with torsion angles of 120° had an average CTE of 1.90 × 10^-6 /K. The compressive strength, Young's modulus, and work of fracture reached 7.36 MPa, 19.65 GPa, and 1.61 KJ/m², respectively, which had the potential in high bearing capacity and low expansion application.