High-strength cellular ceramic composites with 3D microarchitecture

Abstract

Significance It has been a long-standing effort to create materials with low density but high strength. Technical foams are very light, but compared with bulk materials, their strength is quite low because of their random structure. Natural lightweight materials, such as bone, are cellular solids with optimized architecture. They are structured hierarchically and actually consist of nanometer-size building blocks, providing a benefit from mechanical size effects. In this paper, we demonstrate that materials with a designed microarchitecture, which provides both structural advantages and size-dependent strengthening effects, may be fabricated. Using 3D laser lithography, we produced micro-truss and -shell structures from ceramic–polymer composites that exceed the strength-to-weight ratio of all engineering materials, with a density below 1,000 kg/m 3 .

Reexamining the mechanical property space of three-dimensional lattice architectures

“…The mechanical properties of periodic lattices are commonly modeled using the bending or stretching behavior of the constituent beams [2,5,19,36,37,42]. In classical formulations, beams in a lattice are assumed to be slender and are approximated as Euler-Bernoulli or Timoshenko beams [39,43].…”

High‐Entropy Alloy (HEA)‐Coated Nanolattice Structures and Their Mechanical Properties

“…This is due to the dominating buckling and brittle fracture mechanism for the bare polymeric nanolattice and composite nanolattices, respectively, as shown in Movie S1 and S2 in the supporting information. [12] Specifically, the enhancement principle can be associated with the HEA coating (shell) carries compressive forces while the polymer core used to resist early surface cracking and to increase toughness. However, when the core is not still enough to increase the compressive capability and the buckling stress is dominated by the buckling stress of the shell.…”

“…[41] Therefore, a brittle behavior would be observed at a certain point, which is in good agreement with other reports. [12,41,42] To demonstrate the important role of the polymer core in the composite nanolattices, a loading-unloading compression test was employed ( Figure S4). As shown in the exhibited mechanical behaviors, nearly the same Young's modulus (74.5 AE 3.5 MPa) was observed, indicating the superior recoverability of the composite nanolattices under an applied strain of nearly 8%.…”

“…[1][2][3][4][5][6][7][8][9] The strength of lattices is determined not only by the order and periodicity of its structure, but also by the constituent materials. [10,11] Recently, numerous engineering materials such as Al 2 O 3, [12][13][14] Ni-P alloy, [4,15] glassy carbon, [16] copper, [17] gold, [18] and metallic glass [19,20] have been employed as constituent materials to significantly enhance the mechanical properties of pristine polymer scaffolds with respect to its strength and stiffness. Nevertheless, exploring a kind of lightweight, low-cost, and easily fabricated material with promising mechanical features that are easily to be coupled with pristine lattice structure is still a challenge.…”

“…[19] Additionally, the flexibility of two-photon lithography (TPL) allows countless number of different lattices with several orders of hierarchy and sizes to be fabricated. [12,34] By altering the design and material composition of these micro/nano-lattices, it is possible to produce a wide variety of materials with unprecedented properties that defies traditional mechanics, such as a strong, yet lightweight materials. [35,36] Rationally combining sputtering technique in preparation of HEA with TPL will possibly open an entirely new field of materials, which has the potential to reach theoretical limits and applications across multiple disciplines that would otherwise be impossible with macroscopic constructions.…”