Abstract
The microstructure of polymer-derived ceramics (PDCs) was closely related to processing. This study demonstrated that SiCN matrix prepared by polymer infiltration and pyrolysis (PIP) at 900 °C inside a Si3N4 whisker (Si3N4w) preform with submicro-sized pores differed from its powder-consolidated analogue in both the content and structure of free carbon. Chemical analysis showed that PIP process had a higher free carbon yield. Raman spectroscopy and transmission electron microscopy (TEM) observation discovered a higher graphitization degree of free carbon and the existence of nanocrystalline graphite in SiCN matrix. Dielectric properties of Si3N4w/SiCN composites were greatly enhanced when volume fraction of SiCN matrix reached 24.5% due to dielectric percolation caused by highly-lossy free carbon. Reconsolidation of hydrocarbon released during pyrolysis by gas-state carbonization in Si3N4 whisker preform was supposed to account for the high yield and graphitization degree of free carbon in PIP process.
| Original language | English |
|---|---|
| Pages (from-to) | 1256-1272 |
| Number of pages | 17 |
| Journal | Journal of Advanced Ceramics |
| Volume | 10 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2021 |
Keywords
- carbonization
- dielectric property
- free carbon
- polymer-derived ceramics (PDCs)
- silicon carbonitride (SiCN)