## 2 Materials and Methods
### Materials
The ZrO\({}_{2}\)-TiO\({}_{2}\)-Al coating deposited on the basalt fabric in composite \(A\) was intended, similarly to the parylene C coating in composite \(B\), to improve the adhesion between the basalt fabric and silicone. Moreover, due to the relatively low values of the thermal conductivity coefficients of ZrO\({}_{2}\) (2.7 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\)) and TiO\({}_{2}\) (4.8 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\)), this layer was to serve as an additional thermal barrier. The silicone layer used in both composites acted as a connector between the coated basalt fabric and the Mylar(r) foil. Moreover, due to its geometry (the silicone layer constituted almost 50% of the composite thickness) and the low value of the thermal conductivity coefficient (0.14 W\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\)), this layer played an important thermal insulation role. The Mylar(r) foil acted as a smooth and stiff substrate for the ZrO\({}_{2}\)-TiO\({}_{2}\)-Al coating applied on its outer side. The outermost component of the coating (the Al layer) acted as a mirror reflecting infrared radiation and protected both composites against the penetration of radiant heat into their interiors. The spatial geometry of both tested composites was calculated using micro-computed tomography--micro-CT (SkyScan 1272; Bruker, Kontich, Belgium). High-resolution scans were performed using the following parameters: X-ray source voltage 90 kV, X-ray source current 111 \(\mu\)A, pixel size 3.5 \(\mu\)m, a rotation step of 0.2\({}^{\circ}\), frame averaging: 5, Al 0.5 + Cu 0.038 filter. The geometric parameters of the investigated composites were calculated using CTAn 1.17.7.2+ software (made by Bruker, Kontich, Belgium) and presented in Table 1.  
Three-dimensional micro-CT visualizations of the tested composites (shown in Figure 3) were obtained using NRecon 1.7.4.2 and CTvox 3.3.0 r1403 software (made by Bruker, Kontich, Belgium). Both visualizations include the same surface area of both composites, limited to the size of the basalt fabric repeat. All layers of the tested composites were identified and marked in different colors in the visualizations. Due to the too small relative difference in the absorption of X-rays by ZrO\({}_{2}\), TiO\({}_{2}\), and Al, it was not possible to visualize the components of the ZrO\({}_{2}\)-TiO\({}_{2}\)-Al coating. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Composite**} & \multirow{2}{*}{**Layer**} & \multirow{2}{*}{**Composition**} & \multicolumn{2}{c}{**Material/Composite**} & \multicolumn{2}{c}{**Material/Composite**} \\  & & & & **Thickness** & **Porosity** \\ \cline{3-6}  & & & & **[um]** & **[\%]** \\ \hline \multirow{6}{*}{\(A\)} & Fabric & Basalt & 500 (37.0\% *) & \multirow{2}{*}{
\begin{tabular}{c} 57 (12 *) \\ 0 \\ \end{tabular} } & Coating 1 & ZrO\({}_{2}\)-TiO\({}_{2}\)-Al & 30 (2.2\% *) & \multirow{2}{*}{10} \\ \cline{2-6}  & Silicone & Technicqll(r) & 650 (48.2\% *) & & & 0.2 \\ \cline{2-6}  & \multicolumn{1}{c}{Foil} & Mylar(r) & 140 (10.4\% *) & & 2 \\ \cline{2-6}  & Coating 1 & ZrO\({}_{2}\)-TiO\({}_{2}\)-Al & 30 (2.2\% *) & & 0 \\ \hline \multirow{6}{*}{\(B\)} & Coating 2 & Parylene C & 15 (1.1\% *) & & 0 \\ \cline{2-6}  & Fabric & Basalt & 500 (37.0\% *) & & 57 (12 *) \\ \cline{2-6}  & Coating 2 & Parylene C & 15 (1.1\% *) & 1350 & 0 \\ \cline{2-6}  & Silicone & Technicqll(r) & 650 (48.2\%) & (100\% *) & 0.2 \\ \cline{2-6}  & Feil & Mylar(r) & 140 (10.4\% *) & & 2 \\ \cline{2-6}  & Coating 1 & ZrO\({}_{2}\)-TiO\({}_{2}\)-Al & 30 (2.2\% *) & & 0 \\ \hline \hline \end{tabular}
* percentage of composite thickness. ** yarn porosity.  
\end{table} 
Table 1: Characteristics of two tested composites. Figure 3: Micro-CT 3D reconstructions of tested composites. An additional difficulty in distinguishing the component layers of the coating was their thickness, which was close to the size of a voxel in 3D visualization. It can be observed that in composite \(A\), there is a ZrO\({}_{2}\)-TiO\({}_{2}\)-Al coating.