DETERMINING HEAT TREATMENT METHODS FOR ADDITIVE MANUFACTURED SILICON NITRIDE-BNNT COMPOSITES

Abstract

Silicon nitride (Si₃N₄) ceramics are renowned for their exceptional mechanical and thermal properties, making them attractive for high-performance applications. However, their inherent brittleness and challenges associated with high-temperature sintering limit their wider adoption. This thesis investigates the potential of incorporating boron nitride nanotubes (BNNTs) into Si₃N₄ matrices via additive manufacturing and molten salt synthesis (MSS) to enhance their properties and enable low-temperature sintering. The primary goal was to achieve successful low-temperature sintering while preserving BNNT integrity. Initial trials revealed challenges with incomplete sintering, leading to sample fragility. However, MSS effectively prevented BNNT oxidation, even in air, demonstrating its potential for composite fabrication. XRD analysis confirmed Si₃N₄ phases but faced limitations in detecting BNNTs due to low concentration and peak overlap. Future work will focus on optimizing sintering parameters, employing advanced characterization techniques, controlling KBr crystallization, and refining sample geometry to unlock the full potential of Si₃N₄-BNNT composites for diverse applications.