About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Molecular Approaches to Ceramics; Synthesis, Processing, Modeling, and Derived Ceramics
|
| Presentation Title |
Nanoscale Structural Evolution in Polycarbosilane-Derived Ceramics |
| Author(s) |
Md Shafiqul Islam, Prathiba Thamizhavel, Alex T. Hall, Taylor J. Woehl |
| On-Site Speaker (Planned) |
Md Shafiqul Islam |
| Abstract Scope |
Polycarbosilane (PCS)-derived ceramics exhibit excellent thermal stability and tunable microstructures suitable for advanced functional applications. However, the nanoscale structural evolution that controls phase formation during polymer-to-ceramic conversion remains incompletely understood. In this study, we use in situ scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), and ex situ X-ray diffraction (XRD) to establish the ceramization pathway of the PCS precursor SMP-10 from 230 °C to 1200 °C. At 400 °C, XRD shows diffuse scattering, indicating a disordered cross-linked polymer network. Upon heating to 1200 °C, a broad diffraction peak at 2θ ≈ 35.6° indicates the formation of nanocrystalline β-SiC. In situ heating with simultaneous STEM imaging reveals progressive volume shrinkage of microparticles without cracking while preserving nanoscale morphological features during ceramization. High-resolution imaging suggests the growth of β-SiC nanodomains (~10 nm) during heating. A stable Si:C ratio from EDS indicates ceramization by atomic rearrangement without compositional change. |