## 3 Results
### Mechanical Testing  
Mechanical properties of the selected samples were determined to estimate the effect of type and experimental conditions of the manufacturing process on these properties. The results of the pressure tests were evaluated especially concerning the structure and porosity of the samples. Observed mechanical characteristics (e.g., yield strength, tensile strength) of the test specimens were compared. Mechanical testing of samples and evaluation of their behavior under pressure exposure was performed on all six types of samples. The resulting deformations of the samples that occurred were bending (Figure 10a), fracturing (Figure 10b), and crushing (Figure 10c). The representative pictures of sample failure types are shown in Figure 10. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Type** & **Pore size (\(\upmu\)m)** & **Topology** & \multicolumn{3}{c}{**Weight (g)**} & \multicolumn{3}{c}{**Porosity (\%)**} \\  & & **Nominal** & **Actual** & **Difference** & **Nominal** & **Actual** & **Difference** \\ \hline
1 & 200 & trabecular & 7.08 & 6.14 & \(-\)0.94 & 24.6 & 16.3 & \(-\)8.3 \\
2 & 400 & trabecular & 4.63 & 4.27 & \(-\)0.36 & 35.9 & 35.6 & \(-\)0.3 \\
3 & 600 & trabecular & 2.88 & 3.12 & +0.24 & 60.9 & 54.8 & \(-\)6.3 \\
4 & 200 \(\lx@math@degree\)/160 \(\math@degree\) ** & cubic & 4.7 & 6.5 & +1.8 & 36.1 & 5.5 & 30.6 \\
5 & 400 \(\lx@math@degree\)/270 \(\math@degree\) ** & cubic & 2.9 & 5.3 & +2.4 & 60.2 & 22.6 & \(-\)3.6 \\
6 & 600 \(\lx@math@degree\)/410 \(\math@degree\) ** & cubic & 2.0 & 3.8 & +1.8 & 73.0 & 43.6 & \(-\)2.4 \\
7 & - & solid & & 7.3 & & & & \(\rho\) = 0.0043 g/mm\({}^{3}\) & \\ \hline \hline \end{tabular}  
* nominal; ** actual.  
\end{table} 
Table 5: Comparison of nominal and actual weight and porosity of the prepared samples. During the pressure test of sample type 1, an identical fracture occurred in 9 of the 10 testing samples. Due to the height of the sample, deformation occurred in the longitudinal direction (the sample began to deviate off the longitudinal axis). Subsequently, there was a diagonal break, the shear, caused by shear forces. The top and bottom of the sample were completely separated after failure. Fracture of the test specimens occurred at approximately 20% of deformation. The area of elastic deformation of type 1 sample lasted on average up to 775 MPa at a force of 52 kN, which is approximately 8% of the relative compression of the sample. The maximum stress that was applied to the failure of the samples was on average 1789 MPa at a maximum force of 81 kN. The difference between the yield strength and the fracture is approximately 400 MPa. The modulus of elasticity was around 10 GPa. The linear deformation of the samples can be seen from the diagram in Figure 10a. The yield strength is not visible and the transition between plastic and elastic deformation is smooth. All type 2 specimens had the same behavior during pressure testing. The failure of the samples occurred due to shear stress, but further, the samples were deformed by crushing the individual layers of pores. Crushing occurred in the middle part of the sample. Fracture deformation of the samples began at approximately 25% of the relative compression of the sample. The samples began to plastically deform at an average value of 363 MPa, where the applied force was approximately 18 kN. The maximum stress generated in the test specimens is on average 481 MPa at a maximum applied force of 23 kN. The difference between the yield strength and the stress limit is 118 MPa. The modulus of elasticity was about 6.8 GPa. It can be seen from the diagram in Figure 11b that the area of plastic deformation is not linear. The area where the fracture of the samples occurred, and the subsequent failure of the individual pore layers was observed. At the specific pore size of sample 3, the samples were deformed by crushing. The individual layers of the sample were crushed gradually.