Enhancing the Strength and Toughness of 3D-Printed Alumina Reinforced with Boron Nitride Nanotubes

We investigate the mechanical enhancement of additively manufactured alumina nanocomposites reinforced with boron nitride nanotubes (BNNTs). In situ Raman micromechanical measurements reveal that incorporating 0.6 wt % BNNTs significantly improves the mechanical properties of alumina fabricated via digital light processing three-dimensional (3D) printing, yielding a ∼71% increase in flexural strength, a ∼74% increase in fracture toughness, a ∼28% increase in hardness, and a ∼15% reduction in the coefficient of thermal expansion. The enhancements are attributed to the exceptional mechanical properties of BNNTs, effective interfacial load transfer at the BNNT–alumina interface, BNNT-induced microstructural refinements, and the critical role of silica additives as high-temperature sintering aids. Our findings provide valuable insights into the process–structure–property relationships and the reinforcement mechanisms of BNNT-reinforced ceramics, paving the way for the optimal design and manufacturing of lightweight, strong, tough, and durable ceramic materials.