# Polymer-Derived SiOC Ceramics by Digital Light Processing-Based Additive Manufacturing
## 3 Results and Discussion
### Microstructure of the Printed Ceramic Components  
To study the crystallization behavior of the SiOC precursor transformation ceramics. XRD was used to analyze the SiOC ceramics pyrolyzed at 1000 \({}^{\circ}\)C, 1200 \({}^{\circ}\)C, and 1400 \({}^{\circ}\)C in detail. Figure 7a presents the XRD patterns of the SiOC ceramics during pyrolysis at 1000-1400 \({}^{\circ}\)C. The SiOC matrix predominantly exhibited an amorphous state within the tested temperature range. The samples treated at 1000 \({}^{\circ}\)C showed no sharp diffraction peaks, but a broad peak around 20 = 22\({}^{\circ}\) was observed, corresponding to the amorphous phase of SiO\({}_{2}\)[67]. As the pyrolysis temperature increased, the broad diffraction peak at 20 = 22.0\({}^{\circ}\) intensified, indicating an increase in crystallinity [68]. A weak broad peak at 20 = 35.6\({}^{\circ}\), corresponding to the (111) crystal plane of \(\beta\)-SiC microcrystals, emerged at 1200 \({}^{\circ}\)C due to the low content of \(\beta\)-SiC [69]. Figure 7b shows the Raman spectra of the SiOC ceramics. The Raman spectra at different pyrolysis temperatures exhibited two bands: the D band (-1300 cm\({}^{-1}\)) and the G band (-1600 cm\({}^{-1}\)). These confirmed the presence of free carbon [70; 71]. Additionally, the intensity ratio of I\({}_{\mathrm{D}}\) to I\({}_{\mathrm{G}}\) (I\({}_{\mathrm{D}}\)/I\({}_{\mathrm{G}}\)) was used to evaluate the degree of graphitization of the free carbon [72]. The I\({}_{\mathrm{D}}\)/I\({}_{\mathrm{G}}\) ratios for SiOC-1000 \({}^{\circ}\)C, SiOC-1200 \({}^{\circ}\)C, and SiOC-1400 \({}^{\circ}\)C were 2.20, 2.23, and 2.28, respectively, indicating a slight decrease in carbon content with increasing pyrolysis temperature. Furthermore, the relatively high I\({}_{\mathrm{D}}\)/I\({}_{\mathrm{G}}\) ratios across all the samples suggest that the free carbon in the samples was predominantly amorphous. The XPS spectra of the full spectrum of SiOC ceramics pyrolyzed at different temperatures (Figure 7c) revealed that, after high-temperature pyrolysis, the SiOC ceramics contained three elements: Si, O, and C. As the pyrolysis temperature increased from 1000 \({}^{\circ}\)C to 1200 \({}^{\circ}\)C and then to 1400 \({}^{\circ}\)C, no significant shifts or intensity changes were observed in the Si 2p and C 1s peaks of the XPS spectra. This suggests that the chemical environment of the ceramic surface remained stable, resulting in minimal changes in the XPS spectra. The sintering process of SiOC ceramics primarily manifested as surface densification and a reduction in porosity without significant phase transitions [73]. The high-resolution Si 2p spectrum (Figure 7d) showed two bonding states of the Si: Si-O and Si-C bonds, corresponding to binding energies \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Pyolysis** & **Liner** & **Bulk Density** & **Skeleton** & **Ceramic** \\
**Temperature** & **Shrinkage** & **(g/cm\({}^{3}\))** & **Density** & **Yield** \\
**(\%)** & **(\%)** & **(g/cm\({}^{3}\))** & **(g/cm\({}^{3}\))** & **(\%)** \\ \hline
1000 & 31.5 \(\pm\) 0.1 & 0.747 \(\pm\) 0.001 & 2.177 \(\pm\) 0.001 & 49.1 \(\pm\) 0.1 \\
1100 & 32.2 \(\pm\) 0.1 & 0.752 \(\pm\) 0.001 & 2.213 \(\pm\) 0.001 & 48.2 \(\pm\) 0.1 \\
1200 & 32.8 \(\pm\) 0.1 & 0.756 \(\pm\) 0.001 & 2.238 \(\pm\) 0.001 & 47.6 \(\pm\) 0.1 \\
1300 & 33.8 \(\pm\) 0.1 & 0.759 \(\pm\) 0.001 & 2.254 \(\pm\) 0.001 & 46.4 \(\pm\) 0.1 \\
1400 & 35.5 \(\pm\) 0.2 & 0.762 \(\pm\) 0.001 & 2.273 \(\pm\) 0.001 & 42.6 \(\pm\) 0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Typical data of the printed ceramic components after pyrolysis. of 103.1 eV and 101.4 eV, respectively [74]. Similarly, the high-resolution O 1s spectrum (Figure 7e) indicated the presence of C=O and Si-O bonds, with binding energies of 531.4 eV and 533.1 eV, respectively [75]. Furthermore, the high-resolution C 1s spectrum (Figure 7f) identified the presence of C-Si, C-C, and C=O bonds, corresponding to the binding energies of 284.02 eV, 284.8 eV, and 288.2 eV, respectively [76].