## 3 Results and Discussion
The obtained investigation results indicate that both the current density of the process and the electrolyte temperature significantly affect the surface nanoporosity of the aluminum oxide. An increase in the current density from 2 to 3 A/dm\({}^{2}\) increases the surface-share value of nanopores and their number (Figure 5a-c, Table 6), while a further increase in the current density from 3 to 4 A/dm\({}^{2}\) reduces the value of the studied stereological parameters. The opposite occurs depending on the studied parameters and the temperature of the electrolyte. With an increase in the electrolyte temperature from 293 to 298 K, the surface share of nanopores and their number decreases. However, a further increase in the electrolyte temperature causes an increase in the surface share of nanopores and their number (Figure 5a,d,e, Table 6). Table 7 presents the contact angle measurements, tested with diiodomethane and distilled water, together with the standard deviations. The highest contact angle value for all the used liquids was obtained for distilled water, where for Sample B this angle was 84\({}^{\circ}\). However, the surface of Sample B cannot be considered hydrophobic because the value of 90\({}^{\circ}\) was not exceeded. The contact angles for diiodomethane were much smaller, with the largest being 49.66\({}^{\circ}\) for Sample E. This was due in part to the density and viscosity of the liquid. Figure 5: Histogram of prevalence of pores to their surface (designations of samples in Table 1). Table 8 shows the contact angles of the non-polar liquid (\(\alpha\)-bromonaphthalene), for which the values are the lowest of all the applied liquids. The highest angle value was determined on Sample F (27.91\({}^{\circ}\)), together with the polar liquid (glycerin), whose angles are significantly larger than those of the other two non-polar liquids but smaller than those of water. The largest contact angle when using glycerin was on Sample B (79.55\({}^{\circ}\)). The change in the contact angle when using \(\alpha\)-bromonaphthalene is influenced by the \(Sv\) parameter, i.e., the maximum depth of the surface cavity, which changes inversely in proportion to the contact angle. In summary, the contact angles of the oxide layer surface depend on the applied liquid and are the largest for distilled water. The oxide layer deposited on the aluminum substrate was a hydrophilic surface, since the maximum angle with water was 84.06\({}^{\circ}\). It was found that the maximum depth of the surface cavity significantly affects the contact angle when using \(\alpha\)-bromonaphthalene. In other words, the smaller the maximum cavity, the larger the contact angle. The time between depositing the drop and the camera taking a picture also has an effect on the contact angle. SFE was calculated by means of the Owens-Wendt method, which uses a non-polar liquid (in our case \(\alpha\)-bromonaphthalene) and a polar liquid (in our case glycerin). The results of the SFE calculation together with the deviations are presented in Table 9.  
The research showed that the SFE value increases inversely proportionate to the contact angle. SFE increases in proportion to the maximum depth of the surface cavity, and the more porous the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & \
\begin{tabular}{c} **Wettability Angles** \\ **(Diodemetan)**[\({}^{\circ}\)] \\ \end{tabular} & \(\sigma\) [\({}^{\circ}\)] &
\begin{tabular}{c} **Wettability Angles** \\ **(Distilled Water)**[\({}^{\circ}\)] \\ \end{tabular} & \(\sigma\) [\({}^{\circ}\)] \\ \hline A & 44.95 & 6.56 & 74.6 & 2.22 \\ B & 49.66 & 6.29 & 84.06 & 5.71 \\ C & 49.6 & 4.52 & 79.41 & 7.19 \\ D & 47.03 & 2.24 & 66.83 & 2.97 \\ E & 46.57 & 6.79 & 75.34 & 5.09 \\ F & 49.16 & 3.56 & 79.23 & 4.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Contact angles of layers for diiodomethane and distilled water.