## 3 Quality Control of Silicon Carbide Printed Part Formation
### Densification Post-Processing Techniques
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Precursor Polymer** & **Description of the Precursor** & \begin{tabular}{c} **The Prepared** \\ **Ceramic Material** \\ \end{tabular} & \begin{tabular}{c} **Number of** \\ **PIP Cycles** \\ \end{tabular} & **Densification Effect** & **Ref.** \\ \hline Polyvinylsilane (PVS) & Liquid thermosetting & SiC fiber-reinforced & & & \begin{tabular}{c} The material shows a \\ relative density of \\ 70\%, corresponding \\ to approximately \\ 30\% porosity. \\ \end{tabular} & [160] \\ Polyvinylsilane (PVS) & \begin{tabular}{c} Liquid thermosetting \\ organo-silic compound \\ \end{tabular} & \begin{tabular}{c} SiC fiber-reinforced \\ SiC matrix \\ composites (SiC/SiC) \\ \end{tabular} & - & & \begin{tabular}{c} Near-stoichiometric \\ SiC matrix \\ (C/Si \(\approx\) 1:1) \\ achieved, with \\ improved \\ high-temperature \\ strength (380 MPa at \\ \\ data not reported. \\ \end{tabular} & [161] \\ \hline Allyhydropolycarbosilane contains alkyl groups (AHPCS) & \begin{tabular}{c} The molecular structure \\ contains alkyl groups \\ (-CH\({}_{2}\)-CH=CH\({}_{2}\)) and \\ hydride groups (-Si–H) \\ \end{tabular} & \
\begin{tabular}{c} SiC fiber-reinforced \\ SiC matrix composite \\ \end{tabular} & - &
\begin{tabular}{c} The porosity is \\ approximately 10\%, \\ with enhanced \\ thermal diffusivity \\ but reduced strength. \\ \end{tabular} & [162] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: _Cont._printing in producing large SiC components with complex geometries remain unmatched by traditional techniques. Secondly, among other recently reported AM processes for SiC components, samples fabricated via material extrusion 3D printing combined with pressureless solid-state sintering exhibited a flexural strength of 397 \(\pm\) 29 MPa (maintaining 382 MPa at 1700 \({}^{\circ}\)C) and a density of 3.06 g/cm\({}^{3}\)[169]. SiC components produced via vat DLP followed by LSI achieved a density of 2.75 g/cm\({}^{3}\) and a maximum flexural strength of 262.6 MPa [170]. Meanwhile, samples obtained through selective laser 3D printing integrated with PIP and liquid-phase sintering reached a peak flexural strength of only 150 \(\pm\) 6 MPa [171]. As shown by the comparative data in Section 3.2, although the flexural strength of samples fabricated via BJ 3D printing (1) is significantly higher than that of selective laser printed specimens combined with PIP, (2) is slightly lower than those produced by vat photopolymerization, and (3) still falls short of the absolute values achieved by material extrusion with pressureless sintering, it is noteworthy that, by optimizing the composition of PIP precursors, BJ 3D-printed SiC parts have demonstrated comparable high-temperature flexural strength to those produced by extrusion-based methods (see the second-to-last row in Table 6). Moreover, while the density of SiC components produced by BJ 3D printing is generally lower than that of those fabricated via material extrusion with sintering or vat photopolymerization, this inherent characteristic offers a distinct advantage in weight-sensitive applications--such as aerospace thermal-end components--where a high strength-to-weight ratio is prioritized over absolute material density. In conclusion, although extensive research has demonstrated that the mechanical properties of SiC components fabricated via BJ 3D printing still fall short of those produced by conventional manufacturing methods--particularly for extreme service conditions such as turbine blades or high-load-bearing structural components--the overall performance of BJ 3D-printed SiC parts already meets the integrated requirements for lightweight design, thermal stability, and chemical inertness in certain application fields. As outlined in this study, BJ 3D-printed SiC parts subjected to optimized LSI have achieved residual silicon contents as low as 5.2 vol%, which is well below the acceptable threshold (~10 vol% [172]) for aerospace and electronic applications.