## Materials and Methods
### Materials
#### 2.1.3 Additional Materials  
The following materials were used as additional reinforcement layers: Poron(r)XRDMA (Polting Foam Sp. zo.o, Gliwice, Poland) and Twaron(r)CT612 (Teijin, Wuppertal, Germany) with the physico-mechanical properties given in Tables 3 and 4. In addition, there were ceramic elements placed on a carrier film which was a self-adhesive film 4622/WS 40 (Bochemia, Radom, Poland) in order to stabilize them and improve the efficiency of the production process of silicone-ceramic composites. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**No.** & **Parameter** & **Unit** & & **Results** & **Test Method** \\ \hline
1. & Silicone name & — & Za 22 Mould & MM 228 & MM 922 & manufacturer’s \\  & & & & & & technical specification \\
2. & Density & g/cm\({}^{3}\) & \(1.09\pm 0.04\) & \(1.11\pm 0.01\) & \(1.23\pm 0.01\) & PBCH-09/2017 [31] \\
3. & Hardness & ShA & \(20\pm 1\) & \(28\pm 2\) & \(22\pm 1\) & PN-EN ISO 868:2005 [32] \\
4. & Tear strength under & MPa & \(3.35\pm 0.16\) & \(1.54\pm 0.32\) & \(3.64\pm 0.18\) & PN-ISO-37:2007 [33] \\
5. & Breaking strength & MPa & \(4.0\) & \(5.06\) & \(3.6\) & \\
6. & Elongation at break & \% & \(380\) & \(746\) & \(497\) & \\
7. & Tensile strength & kN/m & \(20.0\) & \(31.0\) & \(26.2\) & manufacturer’s \\
8. & Viscosity & mPas & \(4000\) & \(13,000\) & \(19,000\) & technical specification \\
9. & Lifetime & min & \(15\) & \(55\) & \(45\)–\(120\) & \\
10. & Demolding time & h & \(1\) & \(5\) & \(8\)–\(12\) & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical specification of silicone elastomers applied for the hybrid silicone-ceramic composites. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameter** & **Density** & **Young’s** & **Acoustic** & **Vickers** & **Resistance to** \\  & **[g/cm\({}^{3}\)]** & **Modulus** & **Impedance** & **Hardness** & **Brittle Fracturing**, \\  & & **[GP]** & **[10\({}^{5}\) g/cm\({}^{2}\) s]** & **[GP]** & **[MPa m\({}^{1/2}\)]** \\ \hline Test method & PN-EN 993-1:1998 [34] & ASTM C 1419-99a [35] & PN-EN-ISO 6507-1:2007 [36] \\ Al2O3 3.0 mm thickness & \(3.81\pm 0.1\) & \(464.0\pm 8.0\) & \(40.0\pm 0.2\) & \(15.4\pm 0.4\) & \(4.29\pm 0.4\) \\ Al2O3 3.5 mm thickness & \(3.81\pm 0.1\) & \(472.6\pm 10.0\) & \(40.0\pm 0.2\) & \(18.9\pm 0.3\) & \(4.32\pm 0.3\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical and mechanical parameters of Al2O3 ceramics (CeramTec, Plochingen, Germany). 1.4 The Tested System in a Form of a Hybride Silicone-Ceramic Composite and Soft Ballistic Inserts Hybrid silicone-ceramic composites (HSC) (Figure 1) consist of 5 layers, including:  
* outer layers made of elastomer;
* inner layer made of ceramic elements placed on the carrier film;
* reinforcement layers made of aramid fabrics and/or foamed polymer materials. The scheme showing the structure of the composite is presented in Figure 2.  
In the research conducted, the outer layer consisted of the following silicone elastomers: Za 22 Mold (Zhermack, Badia Polesine, Italy), MM 228 silicone (ACC Silicones, Bridgwater, England) and MM 922 silicone (ACC Silicones, Bridgwater, England). The inner layer consisted of hexagonal ceramic elements based on Al\({}_{2}\)O\({}_{3}\) ceramics with a thickness of (3.0 \(\pm\) 0.2) mm and (3.5 \(\pm\) 0.2) mm. These elements were placed on a carrier which was a self-adhesive film 4622/WS 40 in order to stabilize them and improve the efficiency of the production process. The following materials were used as reinforcing layers: Poron(r)XRDMA (Polting Foam Sp. zo.o, Gliwice, Poland) and Twaron(r)CT 612 (Teijin, Wuppertal, Germany).