| Effects of NbN on the Microstructure and Mechanical
Properties of Mullite-Carbon Fiber Composite Prepared
Through Spark Plasma Sintering |
Sana Abdollahi Nasab,a
Sahebali Manafi,a, b,* and Davoud Ghahremanic
Pages : 219-224
DOI: 10.1080/0371750X.2025.2533461 |
| Abstract |
| This study investigates the influence of niobium nitride (NbN) particle reinforcement
on the microstructure and mechanical properties of mullite-carbon fiber (CF)
composites fabricated via spark plasma sintering. Two composite formulations were
prepared: mullite-1 wt% CF and mullite-10 wt% NbN-1 wt% CF. The raw materials
were mixed using wet milling and sintered at 1350oC under vacuum (15-25 Pa) with
an initial and final applied pressure of 10 and 50 MPa, respectively. Densification
analysis confirmed that both composites achieved relative densities exceeding 99%
of the theoretical value. X-ray diffraction analysis identified mullite and NbN as the
only crystalline phases. Microstructural evaluations using field emission scanning
electron microscopy revealed a uniform three-dimensional distribution of CFs, with
additional uniform dispersion of NbN particles in the hybrid composite. The
incorporation of NbN significantly enhanced mechanical properties, yielding a bending
strength of 506±28 MPa, Vickers hardness of 17.27±0.35 GPa, and fracture toughness
of 7.42±0.27 MPa.m1/2. The results demonstrate that hybrid reinforcement with NbN
particles effectively improves the mechanical performance of mullite-CF composites,
making them promising candidates for high-performance structural applications. The
CF pull-out effect and the crack deflection by NbN particles were the main factors
improving the fracture toughness and bending strength.
[Keywords: Mullite, NbN, Carbon fibers, Hybrid composite, Spark plasma sintering] |
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