Structural and Optical Engineering of SiC/PVP Nanocomposite Films for Machine-Integrated Functional Components

Silicon carbide (SiC) is a wide-bandgap ceramic material recognized for its thermal stability, mechanical robustness, and optical reliability, making it highly suitable for machine-integrated functional components. In this study, SiC nanotubes synthesized via carbothermal reduction at 1800 °C were incorporated into a polyvinylpyrrolidone (PVP) matrix to fabricate SiC/PVP nanocomposite films with controlled filler loadings of 1–5 wt%. The structural, morphological, and optical properties were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy with EDS mapping (SEM/EDS), UV–Vis spectroscopy, and FTIR analysis to establish structure–property relationships relevant to engineered machine materials.

At low filler concentrations (1–3 wt%), uniform dispersion of SiC nanotubes induces crystallite refinement, increased microstrain, and enhanced interfacial defect density within the polymer matrix. This results in a gradual reduction in the optical bandgap from 5.78 eV for pure PVP to 5.51 eV at 3 wt% SiC loading. At a higher concentration (5 wt%), nanotube aggregation reduces the effective interfacial area, leading to lower microstrain and a partial recovery of the bandgap to 5.70 eV. FTIR spectra confirm strong interfacial interactions, including hydrogen bonding and dipolar interactions between PVP functional groups and surface –OH/Si–O groups on SiC, without the formation of new chemical bonds. SEM/EDS mapping clearly illustrates the transition from homogeneous dispersion to clustered structures at elevated filler contents.

The results identify an optimal SiC loading of 2–3 wt% for achieving balanced microstructural uniformity and defect-mediated optical tunability. These findings demonstrate that SiC/PVP nanocomposites can be effectively engineered for lightweight machine components, optically functional layers, and integrated dielectric or transparent elements where controlled optical behavior, thermal stability, and polymer–ceramic synergy are essential.