Morphological and structural evolution of boron-containing electrospun nanofibers toward B4C formation
摘要
In this study, nanofibers serving as precursors for B₄C formation were produced by electrospinning solutions containing boric acid (H3BO3) and polyvinyl alcohol (PVA) at various concentrations. The effect of key processing parameters, including applied voltage, solution flow rate, and the distance between the tip and the collector plate, on fiber morphology were systematically investigated, and the optimal production conditions were determined. The nanofibers have been phase-transformed by calcination for two hours in air at 500 °C. After calcination, a certain quantity of the sample was mixed with elemental boron and magnesium at a specific weight ratio. The mixture was then shaped under 4 atm pressure into pellets and sintered at 1300 °C for 2 h under an argon atmosphere with a heating rate of up to 5 °C/min. Structural and morphological changes at different stages of the production process were evaluated using FT-IR, XRD, and SEM analyses. It was determined that the nanofibers obtained after electrospinning exhibit a homogeneous morphology with a diameter range of approximately 300–947 nm. The results demonstrated that electrospun nanofibers can serve as effective precursors for B4C formation; however, the pre-sintering steps significantly altered the nanofiber morphology. The optimal electrospinning conditions were determined to be a flow rate of 0.4 mL/h, an applied voltage of 28 kV, and a distance of 15 cm between the spinning needle and the collection plate.