Session: Government Agency Student Posters

Paper Number: 173151

Toughening Polymer Derived Ceramics With Boron Nitride Nanotubes 

Polymer-derived ceramics (PDCs) represent a unique class of materials characterized by their processability, high-temperature stability, and potential for advanced structural applications. Among them, silicon oxycarbide (SiOC) has attracted significant attention for applications in aerospace, electronics, and energy systems. However, a persistent challenge limiting the broader deployment of PDCs is their intrinsic brittleness and poor fracture toughness, primarily resulting from the porosity formed during pyrolysis. This study aims to address this limitation by incorporating boron nitride nanotubes (BNNTs) into the SiOC matrix as a nanofiller reinforcement.

BNNTs possess exceptional mechanical and thermal properties—including a Young’s modulus of ~1.3 TPa, tensile strengths exceeding 50 GPa, and thermal stability above 1800 °C in inert environments. Their high aspect ratio, anisotropic surface energy, and strong interfacial bonding capabilities make them ideal candidates for enhancing ceramic toughness and strength. Prior studies involving high BNNT loadings (e.g., >10 wt.%) often faced challenges such as aggregation, poor dispersion, and compromised mechanical integrity. Here, we explore the use of ultralow BNNT concentrations (up to 1.0 wt.%) to significantly reinforce SiOC without these drawbacks.

The nanocomposites were synthesized using a commercial preceramic polymer (H44), with BNNTs dispersed in a DMF/acetone solvent mixture. After crosslinking and solvent evaporation, the mixture was hot-pressed and subjected to pyrolysis at 1000 °C in an inert atmosphere, with selected samples further annealed at 1400 °C. Mechanical characterization was conducted via three-point bending tests, while the underlying toughening mechanisms and microstructural evolution were examined using SEM, energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), and in situ Raman micromechanical analysis.

The addition of just 1.0 wt.% BNNTs led to a 2.5-fold increase in flexural strength (from 55.5 MPa to 137.4 MPa) and a 3.3-fold increase in fracture toughness (from ~0.9 MPa·m¹ᐟ² to ~3.0 MPa·m¹ᐟ²). These enhancements were accompanied by improved deformability, as evidenced by an increase in flexural strain and the appearance of shear bands on fracture surfaces—indicative of a brittle-to-ductile transition in the ceramic matrix. Microstructurally, BNNTs were found to reduce porosity, enhance densification, and promote crystallization during high-temperature annealing. Raman spectroscopy revealed that BNNTs also facilitate the formation of smaller sp² carbon nanodomains, which contribute to mechanical reinforcement via interfacial load transfer and frictional sliding.

These findings establish that BNNTs, even at very low concentrations, are highly effective in reinforcing PDCs by combining nanoscale toughening mechanisms with favorable structural transformations. The implications of this work are far-reaching, offering a scalable route to fabricate lightweight, tough, and high-performance ceramics for extreme environments. Future research will focus on optimizing BNNT dispersion strategies, exploring multi-phase nanofiller systems, and extending this reinforcement approach to other polymer-derived ceramic matrices.

Presenting Author: Nasim Anjum Binghamton university

Presenting Author Biography: I am Nasim and I am a 4th-year Ph.D. student in the Department of Mechanical Engineering at Binghamton University working within the Nanomechanics Group led by Prof.Changhong Ke. Our research lab focuses on the design, fabrication, and mechanical characterization of advanced nanocomposite materials, with a focus on structure–property relationships and interfacial mechanics.
I have hands-on expertise in a wide range of manufacturing and testing techniques, including electrospinning, 3D printing, high-temperature sintering, and mechanical testing such as three-point bending, compression, and micro-indentation. My work integrates advanced material characterization tools such as Raman spectroscopy, SEM/EDS, XRD, 3D CT imaging, and digital image correlation to analyze and optimize mechanical performance metrics like fracture toughness and flexural strength.
For this poster, I will present new findings on the mechanical reinforcement of polymer-derived ceramics using boron nitride nanotubes. Their long-term goal is to apply their expertise in materials design and testing toward industry-focused research and development.

Authors:

Nasim Anjum Binghamton university
Dingli Wang Binghamton University
Changhong Ke Binghamton University