Development of carbon fiber reinforced niobium particulate epoxy composites for high-performance structural and thermal management applications

The growing demand for lightweight, thermally stable, and mechanically robust materials in advanced engineering systems has driven the development of multifunctional structural composites. This study presents high-performance carbon fiber/epoxy laminates reinforced with niobium (Nb) particulates (0–5 wt%; C0–C5), with a focus on their mechanical, thermal, fatigue, and microstructural behavior. Incorporation of Nb significantly enhanced composite performance, with the 4 wt% Nb system (C4) exhibiting the most notable improvements among all samples. Tensile strength increased from 219.35 to 247.93 MPa, while flexural strength reached 254.91 MPa. Impact resistance improved from 19.43 to 31.49 kJ/m 2 , accompanied by an increase in surface hardness (Shore D: 151), attributed to effective stress transfer and crack-bridging mechanisms. Fatigue strength increased from 158 to 178 MPa at 50,000 cycles, indicating improved cyclic durability. Thermal conductivity increased substantially (0.92 to 4.12 W/mK), while the coefficient of thermal expansion decreased (2.98×10 -5 to 1.42×10 -5 °C -1 ), enhancing dimensional stability under thermal loading. Heat deflection temperature increased from 149 to 169 °C, and thermogravimetric analysis showed improved char yield (28% at 800 °C), confirming enhanced thermo-oxidative stability. Dynamic mechanical analysis revealed a higher storage modulus (7035 MPa at 120 °C) and reduced damping, indicating strong interfacial interactions. SEM-EDX analysis confirmed uniform Nb dispersion and improved fiber–matrix bonding. Collectively, the C4 composite demonstrates a balanced combination of mechanical strength and thermal performance, making it suitable for thermally efficient enclosures, heat spreaders, and high-performance structural applications.