Isotropic sintering shrinkage of 3D glass-ceramic nanolattices: backbone preforming and mechanical enhancement

Abstract

There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance. It is a promising idea to shape inorganic materials in three-dimensional (3D) forms to reduce their weight while maintaining high mechanical properties. A popular strategy for the preparation of 3D inorganic materials is to mold the organic–inorganic hybrid photoresists into 3D micro- and nano-structures and remove the organic components by subsequent sintering. However, due to the discrete arrangement of inorganic components in the organic-inorganic hybrid photoresists, it remains a huge challenge to attain isotropic shrinkage during sintering. Herein, we demonstrate the isotropic sintering shrinkage by forming the consecutive –Si–O–Si–O–Zr–O– inorganic backbone in photoresists and fabricating 3D glass–ceramic nanolattices with enhanced mechanical properties. The femtosecond (fs) laser is used in two-photon polymerization (TPP) to fabricate 3D green body structures. After subsequent sintering at 1000 °C, high-quality 3D glass–ceramic microstructures can be obtained with perfectly intact and smooth morphology. In-suit compression experiments and finite-element simulations reveal that octahedral-truss (oct-truss) lattices possess remarkable adeptness in bearing stress concentration and maintain the structural integrity to resist rod bending, indicating that this structure is a candidate for preparing lightweight and high stiffness glass–ceramic nanolattices. 3D printing of such glasses and ceramics has significant implications in a number of industrial applications, including metamaterials, microelectromechanical systems, photonic crystals, and damage-tolerant lightweight materials.

Keywords

• 3D printing
• isotropic shrinkage
• femtosecond laser
• two-photon polymerization
• structural glass-ceramics